diff --git a/README b/README
index a7759171..8c5561ae 100644
--- a/README
+++ b/README
@@ -45,6 +45,8 @@ you'll need also:
 	alsa-lib-devel doxygen libjpeg-turbo-devel qt5-qtbase-devel
 	libudev-devel mesa-libGLU-devel
 
+The v4l2-tracer also needs the json-c library.
+On Debian: libjson-c-dev; on Fedora: json-c-devel.
 
 After downloading and installing the needed packages, you should run:
 
@@ -227,6 +229,12 @@ v4l2-sysfs-path:
 FIXME add description.
 Installed by make install under <prefix>/bin.
 
+v4l2-tracer:
+Tool to trace, record and replay userspace applications
+that implement the v4l2 memory-to-memory stateless video
+decoder interface.
+Installed by 'make install' under <prefix>/bin.
+
 xc3028-firmware:
 Xceive XC2028/3028 tuner module firmware manipulation tool.
 xc3028-firmware does not get installed by make install.
diff --git a/configure.ac b/configure.ac
index 9b7c371d..d2e126d1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -32,6 +32,8 @@ AC_CONFIG_FILES([Makefile
 	utils/v4l2-ctl/Makefile
 	utils/v4l2-dbg/Makefile
 	utils/v4l2-sysfs-path/Makefile
+	utils/v4l2-tracer/Makefile
+	utils/v4l2-tracer/v4l2-tracer.1
 	utils/qv4l2/Makefile
 	utils/libcecutil/Makefile
 	utils/cec-ctl/Makefile
@@ -311,6 +313,15 @@ AS_IF([test "x$with_libudev" != xno -o "x$enable_libdvbv5" != xno],
 
 AC_SUBST([JPEG_LIBS])
 
+JSONC_VERSION_REQUIRED="0.15";
+PKG_CHECK_MODULES(JSONC, [json-c >= $JSONC_VERSION_REQUIRED], [jsonc_pkgconfig=yes], [jsonc_pkgconfig=no])
+AC_SUBST([JSONC_CFLAGS])
+AC_SUBST([JSONC_LIBS])
+AM_CONDITIONAL([HAVE_JSONC], [test x$jsonc_pkgconfig = xyes])
+if test "x$jsonc_pkgconfig" = "xno"; then
+    AC_MSG_WARN(json-c $JSONC_VERSION_REQUIRED or higher required for v4l2-tracer)
+fi
+
 # Check for pthread
 
 AS_IF([test x$enable_shared != xno],
@@ -645,6 +656,7 @@ compile time options summary
     QT version                 : $QT_VERSION
     ALSA support               : $USE_ALSA
     SDL support		       : $sdl_pc
+    JSON-C                     : $jsonc_pkgconfig >= $JSONC_VERSION_REQUIRED
 
     build dynamic libs         : $enable_shared
     build static libs          : $enable_static
diff --git a/utils/Makefile.am b/utils/Makefile.am
index 0e68a612..6f59515e 100644
--- a/utils/Makefile.am
+++ b/utils/Makefile.am
@@ -15,6 +15,11 @@ SUBDIRS = \
 	cec-follower \
 	rds-ctl
 
+if HAVE_JSONC
+SUBDIRS += \
+	v4l2-tracer
+endif
+
 if WITH_LIBDVBV5
 SUBDIRS += \
 	dvb
diff --git a/utils/v4l2-tracer/.gitignore b/utils/v4l2-tracer/.gitignore
new file mode 100644
index 00000000..48fbfc47
--- /dev/null
+++ b/utils/v4l2-tracer/.gitignore
@@ -0,0 +1,7 @@
+trace-gen.h
+trace-gen.cpp
+retrace-gen.cpp
+retrace-gen.h
+v4l2-tracer-info-gen.h
+v4l2-tracer
+v4l2-tracer.1
diff --git a/utils/v4l2-tracer/Makefile.am b/utils/v4l2-tracer/Makefile.am
new file mode 100644
index 00000000..1e3a96d0
--- /dev/null
+++ b/utils/v4l2-tracer/Makefile.am
@@ -0,0 +1,32 @@
+if HAVE_JSONC
+
+lib_LTLIBRARIES = libv4l2tracer.la
+libv4l2tracer_la_SOURCES = libv4l2tracer.cpp trace-gen.cpp trace-helper.cpp \
+trace.cpp v4l2-tracer-common.cpp $(top_srcdir)/utils/common/v4l2-info.cpp $(top_srcdir)/utils/common/media-info.cpp
+libv4l2tracer_la_CPPFLAGS = -I$(top_srcdir)/utils/common $(JSONC_CFLAGS)
+libv4l2tracer_la_LDFLAGS = -avoid-version -module -shared -export-dynamic -ldl $(JSONC_LIBS)
+libv4l2tracer_la_LIBTOOLFLAGS = --tag=disable-static
+
+bin_PROGRAMS = v4l2-tracer
+man_MANS = v4l2-tracer.1
+
+v4l2_tracer_SOURCES = v4l2-tracer.cpp retrace-gen.cpp retrace-helper.cpp retrace.cpp \
+v4l2-tracer-common.cpp $(top_srcdir)/utils/common/v4l2-info.cpp $(top_srcdir)/utils/common/media-info.cpp
+v4l2_tracer_CPPFLAGS = -I$(top_srcdir)/utils/common -DLIBTRACER_PATH=$(libdir) $(JSONC_CFLAGS) $(GIT_SHA) $(GIT_COMMIT_CNT) $(GIT_COMMIT_DATE)
+v4l2_tracer_LDFLAGS = -lrt -lpthread $(JSONC_LIBS)
+
+V4L2_TRACER_GEN_PREREQS = $(top_srcdir)/include/linux/v4l2-controls.h \
+$(top_srcdir)/include/linux/videodev2.h $(top_srcdir)/include/linux/media.h $(top_srcdir)/include/linux/v4l2-common.h
+V4L2_TRACER_GEN = trace-gen.cpp trace-gen.h retrace-gen.cpp retrace-gen.h v4l2-tracer-info-gen.h
+v4l2-tracer.cpp: $(V4L2_TRACER_GEN)
+$(V4L2_TRACER_GEN): gen.intermediate;
+.INTERMEDIATE: gen.intermediate
+gen.intermediate: v4l2-tracer-gen.pl $(V4L2_TRACER_GEN_PREREQS)
+	$(AM_V_GEN) $(top_srcdir)/utils/v4l2-tracer/v4l2-tracer-gen.pl $(V4L2_TRACER_GEN_PREREQS)
+
+clean-local:
+	-rm -vf $(V4L2_TRACER_GEN)
+
+EXTRA_DIST = v4l2-tracer.1, v4l2-tracer-gen.pl
+
+endif
diff --git a/utils/v4l2-tracer/libv4l2tracer.cpp b/utils/v4l2-tracer/libv4l2tracer.cpp
new file mode 100644
index 00000000..8eae783f
--- /dev/null
+++ b/utils/v4l2-tracer/libv4l2tracer.cpp
@@ -0,0 +1,307 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2022 Collabora Ltd.
+ */
+
+#include <dlfcn.h>
+#include <stdarg.h>
+#include <config.h> /* For PROMOTED_MODE_T */
+#include "trace.h"
+
+extern struct trace_context ctx_trace;
+
+std::list<unsigned long> ioctls = {
+	VIDIOC_QUERYCAP,
+	VIDIOC_STREAMON,
+	VIDIOC_STREAMOFF,
+	VIDIOC_ENUM_FMT,
+	VIDIOC_G_FMT,
+	VIDIOC_S_FMT,
+	VIDIOC_REQBUFS,
+	VIDIOC_QUERYBUF,
+	VIDIOC_QBUF,
+	VIDIOC_EXPBUF,
+	VIDIOC_DQBUF,
+	VIDIOC_G_PARM,
+	VIDIOC_S_PARM,
+	VIDIOC_G_CTRL,
+	VIDIOC_S_CTRL,
+	VIDIOC_QUERYCTRL,
+	VIDIOC_G_CROP,
+	VIDIOC_S_CROP,
+	VIDIOC_TRY_FMT,
+	VIDIOC_G_EXT_CTRLS,
+	VIDIOC_S_EXT_CTRLS,
+	VIDIOC_TRY_EXT_CTRLS,
+	VIDIOC_ENCODER_CMD,
+	VIDIOC_TRY_ENCODER_CMD,
+	VIDIOC_CREATE_BUFS,
+	VIDIOC_PREPARE_BUF,
+	VIDIOC_G_SELECTION,
+	VIDIOC_S_SELECTION,
+	VIDIOC_DECODER_CMD,
+	VIDIOC_TRY_DECODER_CMD,
+	VIDIOC_QUERY_EXT_CTRL,
+	MEDIA_IOC_REQUEST_ALLOC,
+	MEDIA_REQUEST_IOC_QUEUE,
+	MEDIA_REQUEST_IOC_REINIT,
+};
+
+int open(const char *path, int oflag, ...)
+{
+	errno = 0;
+	mode_t mode = 0;
+
+	if (oflag & O_CREAT) {
+		va_list ap;
+		va_start(ap, oflag);
+		mode = va_arg(ap, PROMOTED_MODE_T);
+		va_end(ap);
+	}
+
+	int (*original_open)(const char *path, int oflag, ...);
+	original_open = (int (*)(const char*, int, ...)) dlsym(RTLD_NEXT, "open");
+	int fd = (*original_open)(path, oflag, mode);
+
+	if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "fd: %d, path: %s\n", fd, path);
+	}
+
+	/* Don't trace the opening if tracing is paused. */
+	if (getenv("V4L2_TRACER_PAUSE_TRACE"))
+		return fd;
+
+	/* Only trace the opening of video/media devices. */
+	if (is_video_or_media_device(path)) {
+		trace_open(fd, path, oflag, mode, false);
+		add_device(fd, path);
+	}
+
+	if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+		fprintf(stderr, "%s:%s:%d\n", __FILE__, __func__, __LINE__);
+		print_devices();
+	}
+
+	return fd;
+}
+
+int open64(const char *path, int oflag, ...)
+{
+	errno = 0;
+	mode_t mode = 0;
+	if (oflag & O_CREAT) {
+		va_list ap;
+		va_start(ap, oflag);
+		mode = va_arg(ap, PROMOTED_MODE_T);
+		va_end(ap);
+	}
+
+	int (*original_open64)(const char *path, int oflag, ...);
+	original_open64 = (int (*)(const char*, int, ...)) dlsym(RTLD_NEXT, "open64");
+	int fd = (*original_open64)(path, oflag, mode);
+
+	if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "fd: %d, path: %s\n", fd, path);
+	}
+
+	/* Don't trace the opening if tracing is paused. */
+	if (getenv("V4L2_TRACER_PAUSE_TRACE"))
+		return fd;
+
+	if (is_video_or_media_device(path)) {
+		add_device(fd, path);
+		trace_open(fd, path, oflag, mode, true);
+	}
+
+	if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+		fprintf(stderr, "%s:%s:%d\n", __FILE__, __func__, __LINE__);
+		print_devices();
+	}
+
+	return fd;
+}
+
+int close(int fd)
+{
+	errno = 0;
+	int (*original_close)(int fd);
+	original_close = (int (*)(int)) dlsym(RTLD_NEXT, "close");
+
+	if (getenv("V4L2_TRACER_PAUSE_TRACE"))
+		return (*original_close)(fd);
+
+	std::string path = get_device(fd);
+	if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "fd: %d, path: %s\n", fd, path.c_str());
+	}
+
+	/* Only trace the close if a corresponding open was also traced. */
+	if (!path.empty()) {
+		json_object *close_obj = json_object_new_object();
+		json_object_object_add(close_obj, "fd", json_object_new_int(fd));
+		json_object_object_add(close_obj, "close", json_object_new_string(path.c_str()));
+		write_json_object_to_json_file(close_obj);
+		json_object_put(close_obj);
+		ctx_trace.devices.erase(fd);
+
+		/* If we removed the last device, close the json trace file. */
+		if (!ctx_trace.devices.size())
+			close_json_file();
+	}
+
+	if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+		fprintf(stderr, "%s:%s:%d\n", __FILE__, __func__, __LINE__);
+		print_devices();
+	}
+
+	return (*original_close)(fd);
+}
+
+void *mmap(void *addr, size_t len, int prot, int flags, int fildes, off_t off)
+{
+	errno = 0;
+	void *(*original_mmap)(void *addr, size_t len, int prot, int flags, int fildes, off_t off);
+	original_mmap = (void*(*)(void*, size_t, int, int, int, off_t)) dlsym(RTLD_NEXT, "mmap");
+	void *buf_address_pointer = (*original_mmap)(addr, len, prot, flags, fildes, off);
+
+	set_buffer_address_trace(fildes, off, (unsigned long) buf_address_pointer);
+
+	if (buffer_in_trace_context(fildes, off))
+		trace_mmap(addr, len, prot, flags, fildes, off, (unsigned long) buf_address_pointer, false);
+
+	return buf_address_pointer;
+}
+
+void *mmap64(void *addr, size_t len, int prot, int flags, int fildes, off_t off)
+{
+	errno = 0;
+	void *(*original_mmap64)(void *addr, size_t len, int prot, int flags, int fildes, off_t off);
+	original_mmap64 = (void*(*)(void*, size_t, int, int, int, off_t)) dlsym(RTLD_NEXT, "mmap64");
+	void *buf_address_pointer = (*original_mmap64)(addr, len, prot, flags, fildes, off);
+
+	set_buffer_address_trace(fildes, off, (unsigned long) buf_address_pointer);
+
+	if (buffer_in_trace_context(fildes, off))
+		trace_mmap(addr, len, prot, flags, fildes, off, (unsigned long) buf_address_pointer, true);
+
+	return buf_address_pointer;
+}
+
+int munmap(void *start, size_t length)
+{
+	errno = 0;
+	int(*original_munmap)(void *start, size_t length);
+	original_munmap = (int(*)(void *, size_t)) dlsym(RTLD_NEXT, "munmap");
+	int ret = (*original_munmap)(start, length);
+
+	/* Only trace the unmapping if the original mapping was traced. */
+	if (!buffer_is_mapped((unsigned long) start))
+		return ret;
+
+	json_object *munmap_obj = json_object_new_object();
+
+	if (errno)
+		json_object_object_add(munmap_obj, "errno", json_object_new_string(strerrorname_np(errno)));
+
+	json_object *munmap_args = json_object_new_object();
+	json_object_object_add(munmap_args, "start", json_object_new_int64((int64_t)start));
+	json_object_object_add(munmap_args, "length", json_object_new_uint64(length));
+	json_object_object_add(munmap_obj, "munmap", munmap_args);
+
+	write_json_object_to_json_file(munmap_obj);
+	json_object_put(munmap_obj);
+
+	return ret;
+}
+
+int ioctl(int fd, unsigned long cmd, ...)
+{
+	errno = 0;
+	va_list ap;
+	va_start(ap, cmd);
+	void *arg = va_arg(ap, void *);
+	va_end(ap);
+
+	int (*original_ioctl)(int fd, unsigned long cmd, ...);
+	original_ioctl = (int (*)(int, long unsigned int, ...)) dlsym(RTLD_NEXT, "ioctl");
+
+	/* Don't trace if v4l2-tracer has paused tracing. */
+	if (getenv("V4L2_TRACER_PAUSE_TRACE"))
+		return (*original_ioctl)(fd, cmd, arg);
+
+	/* Don't trace ioctls that are not in the specified ioctls list. */
+	if (find(ioctls.begin(), ioctls.end(), cmd) == ioctls.end())
+		return (*original_ioctl)(fd, cmd, arg);
+
+	json_object *ioctl_obj = json_object_new_object();
+	json_object_object_add(ioctl_obj, "fd", json_object_new_int(fd));
+	json_object_object_add(ioctl_obj, "ioctl",
+	                       json_object_new_string(val2s(cmd, ioctl_val_def).c_str()));
+
+	/* Don't attempt to trace a nullptr. */
+	if (arg == nullptr) {
+		int ret = (*original_ioctl)(fd, cmd, arg);
+		if (errno)
+			json_object_object_add(ioctl_obj, "errno",
+			                       json_object_new_string(strerrorname_np(errno)));
+		write_json_object_to_json_file(ioctl_obj);
+		json_object_put(ioctl_obj);
+		return ret;
+	}
+
+	/* Get info needed for writing the decoded video data to a yuv file. */
+	if (cmd == VIDIOC_S_EXT_CTRLS)
+		s_ext_ctrls_setup(static_cast<struct v4l2_ext_controls*>(arg));
+	if (cmd == VIDIOC_QBUF)
+		qbuf_setup(static_cast<struct v4l2_buffer*>(arg));
+	if (cmd == VIDIOC_STREAMOFF)
+		streamoff_cleanup(*(static_cast<v4l2_buf_type*>(arg)));
+
+	/* Trace userspace arguments if driver will be reading them i.e. _IOW or _IOWR ioctls */
+	if (cmd & IOC_IN) {
+		json_object *ioctl_args_userspace = trace_ioctl_args(cmd, arg);
+		/* Some ioctls won't have arguments to trace e.g. MEDIA_REQUEST_IOC_QUEUE. */
+		if (json_object_object_length(ioctl_args_userspace))
+			json_object_object_add(ioctl_obj, "from_userspace", ioctl_args_userspace);
+		else
+			json_object_put(ioctl_args_userspace);
+	}
+
+	/* Make the original ioctl call. */
+	int ret = (*original_ioctl)(fd, cmd, arg);
+
+	if (errno)
+		json_object_object_add(ioctl_obj, "errno", json_object_new_string(strerrorname_np(errno)));
+
+	/* Trace driver arguments if userspace will be reading them i.e. _IOR or _IOWR ioctls */
+	if (cmd & IOC_OUT) {
+		json_object *ioctl_args_driver = trace_ioctl_args(cmd, arg);
+		/* Some ioctls won't have arguments to trace e.g. MEDIA_REQUEST_IOC_QUEUE. */
+		if (json_object_object_length(ioctl_args_driver))
+			json_object_object_add(ioctl_obj, "from_driver", ioctl_args_driver);
+		else
+			json_object_put(ioctl_args_driver);
+	}
+
+	write_json_object_to_json_file(ioctl_obj);
+	json_object_put(ioctl_obj);
+
+	/* Get additional info from driver for writing the decoded video data to a yuv file. */
+	if (cmd == VIDIOC_G_FMT)
+		g_fmt_setup_trace(static_cast<struct v4l2_format*>(arg));
+	if (cmd == VIDIOC_S_FMT)
+		s_fmt_setup(static_cast<struct v4l2_format*>(arg));
+	if (cmd == VIDIOC_EXPBUF)
+		expbuf_setup(static_cast<struct v4l2_exportbuffer*>(arg));
+	if (cmd == VIDIOC_QUERYBUF)
+		querybuf_setup(fd, static_cast<struct v4l2_buffer*>(arg));
+
+	/* Get info needed for tracing dynamic arrays */
+	if (cmd == VIDIOC_QUERY_EXT_CTRL)
+		query_ext_ctrl_setup(fd, static_cast<struct v4l2_query_ext_ctrl*>(arg));
+
+	return ret;
+}
diff --git a/utils/v4l2-tracer/retrace-helper.cpp b/utils/v4l2-tracer/retrace-helper.cpp
new file mode 100644
index 00000000..c17618d1
--- /dev/null
+++ b/utils/v4l2-tracer/retrace-helper.cpp
@@ -0,0 +1,250 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2022 Collabora Ltd.
+ */
+
+#include "retrace.h"
+
+struct retrace_context ctx_retrace = {};
+
+bool buffer_in_retrace_context(int fd, __u32 offset)
+{
+	bool buffer_in_retrace_context = false;
+	for (auto &b : ctx_retrace.buffers) {
+		if ((b.fd == fd) && (b.offset == offset)) {
+			buffer_in_retrace_context = true;
+			break;
+		}
+	}
+	return buffer_in_retrace_context;
+}
+
+int get_buffer_fd_retrace(__u32 type, __u32 index)
+{
+	int fd = 0;
+	for (auto &b : ctx_retrace.buffers) {
+		if ((b.type == type) && (b.index == index)) {
+			fd = b.fd;
+			break;
+		}
+	}
+	return fd;
+}
+
+void add_buffer_retrace(int fd, __u32 type, __u32 index, __u32 offset)
+{
+	struct buffer_retrace buf = {};
+	buf.fd = fd;
+	buf.type = type;
+	buf.index = index;
+	buf.offset = offset;
+	ctx_retrace.buffers.push_front(buf);
+}
+
+void remove_buffer_retrace(int fd)
+{
+	for (auto it = ctx_retrace.buffers.begin(); it != ctx_retrace.buffers.end(); ++it) {
+		if (it->fd == fd) {
+			ctx_retrace.buffers.erase(it);
+			break;
+		}
+	}
+}
+
+void set_buffer_address_retrace(int fd, __u32 offset, long address_trace, long address_retrace)
+{
+	for (auto &b : ctx_retrace.buffers) {
+		if ((b.fd == fd) && (b.offset == offset)) {
+			b.address_trace = address_trace;
+			b.address_retrace = address_retrace;
+			break;
+		}
+	}
+}
+
+long get_retrace_address_from_trace_address(long address_trace)
+{
+	long address_retrace = 0;
+	for (auto &b : ctx_retrace.buffers) {
+		if (b.address_trace == address_trace) {
+			address_retrace = b.address_retrace;
+			break;
+		}
+	}
+	return address_retrace;
+}
+
+void print_buffers_retrace(void)
+{
+	for (auto &b : ctx_retrace.buffers) {
+		fprintf(stderr, "fd: %d, offset: %d, address_trace:%ld, address_retrace:%ld\n",
+		        b.fd, b.offset, b.address_trace, b.address_retrace);
+	}
+}
+
+void add_fd(int fd_trace, int fd_retrace)
+{
+	std::pair<int, int> new_pair;
+	new_pair = std::make_pair(fd_trace, fd_retrace);
+	ctx_retrace.retrace_fds.insert(new_pair);
+}
+
+int get_fd_retrace_from_fd_trace(int fd_trace)
+{
+	int fd_retrace = -1;
+	std::unordered_map<int, int>::const_iterator it;
+	it = ctx_retrace.retrace_fds.find(fd_trace);
+	if (it != ctx_retrace.retrace_fds.end())
+		fd_retrace = it->second;
+	return fd_retrace;
+}
+
+void print_fds(void)
+{
+	if (ctx_retrace.retrace_fds.empty())
+		fprintf(stderr, "all devices closed\n");
+	for (auto it = ctx_retrace.retrace_fds.cbegin(); it != ctx_retrace.retrace_fds.cend(); ++it)
+		fprintf(stderr, "fd_trace: %d, fd_retrace: %d\n", it->first, it->second);
+}
+
+std::string get_path_retrace_from_path_trace(std::string path_trace, json_object *open_obj)
+{
+	bool is_media = path_trace.find("media") != path_trace.npos;
+	bool is_video = path_trace.find("video") != path_trace.npos;
+
+	if (is_media && getenv("V4L2_TRACER_OPTION_SET_MEDIA_DEVICE")) {
+		if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+			fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+			fprintf(stderr, "Use path set by user: %s ",
+			        getenv("V4L2_TRACER_OPTION_SET_MEDIA_DEVICE"));
+		}
+		return getenv("V4L2_TRACER_OPTION_SET_MEDIA_DEVICE");
+	}
+
+	if (is_video && getenv("V4L2_TRACER_OPTION_SET_VIDEO_DEVICE")) {
+		if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+			fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+			fprintf(stderr, "Use path set by user: %s ",
+			        getenv("V4L2_TRACER_OPTION_SET_VIDEO_DEVICE"));
+		}
+		return getenv("V4L2_TRACER_OPTION_SET_VIDEO_DEVICE");
+	}
+
+	std::string driver;
+	json_object *driver_obj;
+	if (json_object_object_get_ex(open_obj, "driver", &driver_obj))
+		driver = json_object_get_string(driver_obj);
+	if (driver.empty())
+		return "";
+
+	std::string path_media = get_path_media(driver);
+	if (path_media.empty()) {
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "warning: driver: %s not found\n", driver.c_str());
+		return "";
+	}
+
+	if (is_media)
+		return path_media;
+
+	if (is_video) {
+		std::list<std::string> linked_entities;
+		json_object *le_obj;
+		if (json_object_object_get_ex(open_obj, "linked_entities", &le_obj)) {
+			for (size_t i = 0; i < array_list_length(json_object_get_array(le_obj)); i++) {
+				std::string ename = json_object_get_string(json_object_array_get_idx(le_obj, i));
+				linked_entities.push_back(ename);
+			}
+		}
+		if (linked_entities.size() == 0)
+			return "";
+
+		setenv("V4L2_TRACER_PAUSE_TRACE", "true", 0);
+		int media_fd = open(path_media.c_str(), O_RDONLY);
+		unsetenv("V4L2_TRACER_PAUSE_TRACE");
+
+		std::string path_video = get_path_video(media_fd, linked_entities);
+		setenv("V4L2_TRACER_PAUSE_TRACE", "true", 0);
+		close(media_fd);
+		unsetenv("V4L2_TRACER_PAUSE_TRACE");
+		return path_video;
+	}
+
+	return "";
+}
+
+void write_to_output_buffer(unsigned char *buffer_pointer, int bytesused, json_object *mem_obj)
+{
+	int byteswritten = 0;
+	json_object *line_obj;
+	size_t number_of_lines;
+	std::string compressed_video_data;
+
+	json_object *mem_array_obj;
+	json_object_object_get_ex(mem_obj, "mem_array", &mem_array_obj);
+	number_of_lines = json_object_array_length(mem_array_obj);
+
+	for (long unsigned int i = 0; i < number_of_lines; i++) {
+		line_obj = json_object_array_get_idx(mem_array_obj, i);
+		compressed_video_data = json_object_get_string(line_obj);
+
+		for (long unsigned i = 0; i < compressed_video_data.length(); i++) {
+			if (std::isspace(compressed_video_data[i]))
+				continue;
+			try {
+				/* Two values from the string e.g. "D9" are needed to write one byte. */
+				*buffer_pointer = (char) std::stoi(compressed_video_data.substr(i,2), nullptr, 16);
+				buffer_pointer++;
+				i++;
+				byteswritten++;
+			} catch (std::invalid_argument& ia) {
+				fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+				fprintf(stderr, "\'%s\' is an invalid argument.\n",
+				        compressed_video_data.substr(i,2).c_str());
+			} catch (std::out_of_range& oor) {
+				fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+				fprintf(stderr, "\'%s\' is out of range.\n",
+				        compressed_video_data.substr(i,2).c_str());
+			}
+		}
+	}
+
+	if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "bytesused: %d, byteswritten: %d\n", bytesused, byteswritten);
+	}
+}
+
+void compare_program_versions(json_object *v4l2_tracer_info_obj)
+{
+	json_object *package_version_obj;
+	json_object_object_get_ex(v4l2_tracer_info_obj, "package_version", &package_version_obj);
+	std::string package_version_trace = json_object_get_string(package_version_obj);
+	std::string package_version_retrace = PACKAGE_VERSION;
+	if (package_version_trace != package_version_retrace) {
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "warning: trace package version \'%s\' does not match current: \'%s\':\n",
+		        package_version_trace.c_str(), package_version_retrace.c_str());
+		print_v4l2_tracer_info();
+		return;
+	}
+
+	json_object *git_sha_obj;
+	json_object_object_get_ex(v4l2_tracer_info_obj, "git_sha", &git_sha_obj);
+	std::string git_sha_trace = json_object_get_string(git_sha_obj);
+	std::string git_sha_retrace = (STRING(GIT_SHA));
+	if (git_sha_trace != git_sha_retrace) {
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "warning: sha in trace file \'%s\' does not match current sha: \'%s\'\n",
+		        git_sha_trace.c_str(),  git_sha_retrace.c_str());
+		print_v4l2_tracer_info();
+		return;
+	}
+}
+
+void print_context(void)
+{
+	print_fds();
+	print_buffers_retrace();
+	fprintf(stderr, "\n");
+}
diff --git a/utils/v4l2-tracer/retrace.cpp b/utils/v4l2-tracer/retrace.cpp
new file mode 100644
index 00000000..b736e835
--- /dev/null
+++ b/utils/v4l2-tracer/retrace.cpp
@@ -0,0 +1,1374 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2022 Collabora Ltd.
+ */
+
+#include "retrace.h"
+
+extern struct retrace_context ctx_retrace;
+
+void retrace_mmap(json_object *mmap_obj, bool is_mmap64)
+{
+	json_object *mmap_args_obj;
+	if (is_mmap64)
+		json_object_object_get_ex(mmap_obj, "mmap64", &mmap_args_obj);
+	else
+		json_object_object_get_ex(mmap_obj, "mmap", &mmap_args_obj);
+
+	json_object *len_obj;
+	json_object_object_get_ex(mmap_args_obj, "len", &len_obj);
+	size_t len = (size_t) json_object_get_int(len_obj);
+
+	json_object *prot_obj;
+	json_object_object_get_ex(mmap_args_obj, "prot", &prot_obj);
+	int prot = json_object_get_int(prot_obj);
+
+	json_object *flags_obj;
+	json_object_object_get_ex(mmap_args_obj, "flags", &flags_obj);
+	int flags = s2number(json_object_get_string(flags_obj));
+
+	json_object *fildes_obj;
+	json_object_object_get_ex(mmap_args_obj, "fildes", &fildes_obj);
+	int fd_trace = json_object_get_int(fildes_obj);
+
+	json_object *off_obj;
+	json_object_object_get_ex(mmap_args_obj, "off", &off_obj);
+	off_t off = (off_t) json_object_get_int64(off_obj);
+
+	int fd_retrace = get_fd_retrace_from_fd_trace(fd_trace);
+	if (fd_retrace < 0) {
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "bad or missing file descriptor.\n");
+		return;
+	}
+
+	/* Only retrace mmap calls that map a buffer. */
+	if (!buffer_in_retrace_context(fd_retrace, off))
+		return;
+
+	void *buf_address_retrace_pointer;
+	if (is_mmap64)
+		buf_address_retrace_pointer = mmap64(0, len, prot, flags, fd_retrace, off);
+	else
+		buf_address_retrace_pointer = mmap(0, len, prot, flags, fd_retrace, off);
+
+	if (buf_address_retrace_pointer == MAP_FAILED) {
+		if (is_mmap64)
+			perror("mmap64");
+		else
+			perror("mmap");
+		if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+			fprintf(stderr, "%s:%s:%d\n", __FILE__, __func__, __LINE__);
+			print_context();
+		}
+		exit(EXIT_FAILURE);
+	}
+
+	/*
+	 * Get and store the original trace address so that it can be matched
+	 * with the munmap address later.
+	 */
+	json_object *buffer_address_obj;
+	json_object_object_get_ex(mmap_obj, "buffer_address", &buffer_address_obj);
+	long buf_address_trace = json_object_get_int64(buffer_address_obj);
+	set_buffer_address_retrace(fd_retrace, off, buf_address_trace,
+	                           (long) buf_address_retrace_pointer);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0)) {
+		fprintf(stderr, "fd: %d, offset: %ld, ", fd_retrace, off);
+		if (is_mmap64)
+			perror("mmap64");
+		else
+			perror("mmap");
+		if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+			fprintf(stderr, "%s:%s:%d\n", __FILE__, __func__, __LINE__);
+			print_context();
+		}
+	}
+}
+
+void retrace_munmap(json_object *syscall_obj)
+{
+	json_object *munmap_args_obj;
+	json_object_object_get_ex(syscall_obj, "munmap", &munmap_args_obj);
+
+	json_object *start_obj;
+	json_object_object_get_ex(munmap_args_obj, "start", &start_obj);
+	long start = json_object_get_int64(start_obj);
+
+	json_object *length_obj;
+	json_object_object_get_ex(munmap_args_obj, "length", &length_obj);
+	size_t length = (size_t) json_object_get_int(length_obj);
+
+	long buffer_address_retrace = get_retrace_address_from_trace_address(start);
+
+	if (buffer_address_retrace < 0)
+		return;
+
+	munmap((void *)buffer_address_retrace, length);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0)) {
+		fprintf(stderr, "unmapped: %ld, ", buffer_address_retrace);
+		perror("munmap");
+	}
+}
+
+void retrace_open(json_object *jobj, bool is_open64)
+{
+	json_object *fd_trace_obj;
+	json_object_object_get_ex(jobj, "fd", &fd_trace_obj);
+	int fd_trace = json_object_get_int(fd_trace_obj);
+
+	json_object *open_args_obj;
+	if (is_open64)
+		json_object_object_get_ex(jobj, "open64", &open_args_obj);
+	else
+		json_object_object_get_ex(jobj, "open", &open_args_obj);
+
+	json_object *path_obj;
+	json_object_object_get_ex(open_args_obj, "path", &path_obj);
+	std::string path_trace = json_object_get_string(path_obj);
+	std::string path_retrace = get_path_retrace_from_path_trace(path_trace, jobj);
+
+	/*
+	 * Don't fail if a retrace path can't be found.
+	 * Try using the same path as in the trace file.
+	 */
+	if (path_retrace.empty()) {
+		if (getenv("V4L2_TRACER_OPTION_VERBOSE")) {
+			fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+			fprintf(stderr, "warning: can't find retrace device. Attempting to use: %s\n",
+			        path_trace.c_str());
+		}
+		path_retrace = path_trace;
+	}
+
+	json_object *oflag_obj;
+	json_object_object_get_ex(open_args_obj, "oflag", &oflag_obj);
+	int oflag = s2val(json_object_get_string(oflag_obj), open_val_def);
+
+	int mode = 0;
+	json_object *mode_obj;
+	if (json_object_object_get_ex(open_args_obj, "mode", &mode_obj))
+		mode = s2number(json_object_get_string(mode_obj));
+
+	int fd_retrace = 0;
+	if (is_open64)
+		fd_retrace = open64(path_retrace.c_str(), oflag, mode);
+	else
+		fd_retrace = open(path_retrace.c_str(), oflag, mode);
+
+	if (fd_retrace <= 0) {
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "cannot open: %s\n", path_retrace.c_str());
+		exit(fd_retrace);
+	}
+
+	add_fd(fd_trace, fd_retrace);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || errno != 0) {
+		fprintf(stderr, "path: %s ", path_retrace.c_str());
+		if (is_open64)
+			perror("open64");
+		else
+			perror("open");
+		if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+			fprintf(stderr, "%s:%s:%d\n", __FILE__, __func__, __LINE__);
+			print_context();
+		}
+	}
+}
+
+void retrace_close(json_object *jobj)
+{
+	json_object *fd_trace_obj;
+	json_object_object_get_ex(jobj, "fd", &fd_trace_obj);
+	int fd_retrace = get_fd_retrace_from_fd_trace(json_object_get_int(fd_trace_obj));
+
+	/* Only close devices that were opened in the retrace context. */
+	if (fd_retrace < 0)
+		return;
+
+	close(fd_retrace);
+	ctx_retrace.retrace_fds.erase(json_object_get_int(fd_trace_obj));
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0)) {
+		fprintf(stderr, "fd: %d ", fd_retrace);
+		perror("close");
+		if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+			fprintf(stderr, "%s:%s:%d\n", __FILE__, __func__, __LINE__);
+			print_context();
+		}
+	}
+}
+
+void retrace_vidioc_reqbufs(int fd_retrace, json_object *ioctl_args)
+{
+	struct v4l2_requestbuffers *ptr = retrace_v4l2_requestbuffers_gen(ioctl_args);
+	ioctl(fd_retrace, VIDIOC_REQBUFS, ptr);
+
+	if (ptr)
+		free(ptr);
+}
+
+struct v4l2_plane *retrace_v4l2_plane(json_object *plane_obj, __u32 memory)
+{
+	struct v4l2_plane *pl = (struct v4l2_plane *) calloc(1, sizeof(v4l2_plane));
+
+	json_object *bytesused_obj;
+	json_object_object_get_ex(plane_obj, "bytesused", &bytesused_obj);
+	pl->bytesused = (__u32) json_object_get_int64(bytesused_obj);
+
+	json_object *length_obj;
+	json_object_object_get_ex(plane_obj, "length", &length_obj);
+	pl->length = (__u32) json_object_get_int64(length_obj);
+
+	json_object *m_obj;
+	json_object_object_get_ex(plane_obj, "m", &m_obj);
+	if (memory == V4L2_MEMORY_MMAP) {
+		json_object *mem_offset_obj;
+		json_object_object_get_ex(m_obj, "mem_offset", &mem_offset_obj);
+		pl->m.mem_offset = (__u32) json_object_get_int64(mem_offset_obj);
+	}
+
+	json_object *data_offset_obj;
+	json_object_object_get_ex(plane_obj, "data_offset", &data_offset_obj);
+	pl->data_offset = (__u32) json_object_get_int64(data_offset_obj);
+
+	return pl;
+}
+
+struct v4l2_buffer *retrace_v4l2_buffer(json_object *ioctl_args)
+{
+	struct v4l2_buffer *buf = (struct v4l2_buffer *) calloc(1, sizeof(struct v4l2_buffer));
+
+	json_object *buf_obj;
+	json_object_object_get_ex(ioctl_args, "v4l2_buffer", &buf_obj);
+
+	json_object *index_obj;
+	json_object_object_get_ex(buf_obj, "index", &index_obj);
+	buf->index = (__u32) json_object_get_uint64(index_obj);
+
+	json_object *type_obj;
+	json_object_object_get_ex(buf_obj, "type", &type_obj);
+	buf->type = s2val(json_object_get_string(type_obj), v4l2_buf_type_val_def);
+
+	json_object *bytesused_obj;
+	json_object_object_get_ex(buf_obj, "bytesused", &bytesused_obj);
+	buf->bytesused = (__u32) json_object_get_uint64(bytesused_obj);
+
+	json_object *flags_obj;
+	json_object_object_get_ex(buf_obj, "flags", &flags_obj);
+	buf->flags = (__u32) s2flags_buffer(json_object_get_string(flags_obj));
+
+	json_object *field_obj;
+	json_object_object_get_ex(buf_obj, "field", &field_obj);
+	buf->field = (__u32) s2val(json_object_get_string(field_obj), v4l2_field_val_def);
+
+	json_object *timestamp_obj;
+	json_object_object_get_ex(buf_obj, "timestamp", &timestamp_obj);
+
+	struct timeval tv = {};
+	json_object *tv_sec_obj;
+	json_object_object_get_ex(timestamp_obj, "tv_sec", &tv_sec_obj);
+	tv.tv_sec = json_object_get_int64(tv_sec_obj);
+	json_object *tv_usec_obj;
+	json_object_object_get_ex(timestamp_obj, "tv_usec", &tv_usec_obj);
+	tv.tv_usec = json_object_get_int64(tv_usec_obj);
+	buf->timestamp = tv;
+
+	json_object *sequence_obj;
+	json_object_object_get_ex(buf_obj, "sequence", &sequence_obj);
+	buf->sequence = (__u32) json_object_get_uint64(sequence_obj);
+
+	json_object *memory_obj;
+	json_object_object_get_ex(buf_obj, "memory", &memory_obj);
+	buf->memory = s2val(json_object_get_string(memory_obj), v4l2_memory_val_def);
+
+	json_object *length_obj;
+	json_object_object_get_ex(buf_obj, "length", &length_obj);
+	buf->length = (__u32) json_object_get_uint64(length_obj);
+
+	json_object *m_obj;
+	json_object_object_get_ex(buf_obj, "m", &m_obj);
+
+	if (buf->type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE ||
+	    buf->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE) {
+		json_object *planes_obj;
+		json_object_object_get_ex(m_obj, "planes", &planes_obj);
+		 /* TODO add planes > 0 */
+		json_object *plane_obj = json_object_array_get_idx(planes_obj, 0);
+		buf->m.planes = retrace_v4l2_plane(plane_obj, buf->memory);
+	}
+
+	if (buf->type == V4L2_BUF_TYPE_VIDEO_CAPTURE ||
+	    buf->type == V4L2_BUF_TYPE_VIDEO_OUTPUT) {
+		if (buf->memory == V4L2_MEMORY_MMAP) {
+			json_object *offset_obj;
+			json_object_object_get_ex(m_obj, "offset", &offset_obj);
+			buf->m.offset = (__u32) json_object_get_uint64(offset_obj);
+		}
+	}
+
+	if (buf->flags & V4L2_BUF_FLAG_REQUEST_FD) {
+		json_object *request_fd_obj;
+		json_object_object_get_ex(buf_obj, "request_fd", &request_fd_obj);
+		buf->request_fd = (__s32) get_fd_retrace_from_fd_trace(json_object_get_int(request_fd_obj));
+		if (buf->request_fd < 0) {
+			fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+			fprintf(stderr, "bad or missing file descriptor\n");
+		}
+	}
+
+	return buf;
+}
+
+void retrace_vidioc_querybuf(int fd_retrace, json_object *ioctl_args_user)
+{
+	struct v4l2_buffer *buf = retrace_v4l2_buffer(ioctl_args_user);
+
+	ioctl(fd_retrace, VIDIOC_QUERYBUF, buf);
+
+	if (buf->memory == V4L2_MEMORY_MMAP) {
+		__u32 offset = 0;
+		if ((buf->type == V4L2_BUF_TYPE_VIDEO_CAPTURE) ||
+		    (buf->type == V4L2_BUF_TYPE_VIDEO_OUTPUT))
+			offset = buf->m.offset;
+		if ((buf->type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE) ||
+		    (buf->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE))
+			offset = buf->m.planes->m.mem_offset;
+		if (!get_buffer_fd_retrace(buf->type, buf->index))
+			add_buffer_retrace(fd_retrace, buf->type, buf->index, offset);
+	}
+
+	if (buf->type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE ||
+	    buf->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE) {
+		if (buf->m.planes != nullptr) {
+			free(buf->m.planes);
+		}
+	}
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0)) {
+		fprintf(stderr, "%s, index: %d, fd: %d, ",
+		        buftype2s(buf->type).c_str(), buf->index, fd_retrace);
+		perror("VIDIOC_QUERYBUF");
+		if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+			fprintf(stderr, "%s:%s:%d\n", __FILE__, __func__, __LINE__);
+			print_context();
+		}
+	}
+
+	if (buf)
+		free(buf);
+}
+
+void retrace_vidioc_qbuf(int fd_retrace, json_object *ioctl_args_user)
+{
+	struct v4l2_buffer *ptr = retrace_v4l2_buffer(ioctl_args_user);
+
+	ioctl(fd_retrace, VIDIOC_QBUF, ptr);
+
+	if (ptr->type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE ||
+	    ptr->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE) {
+		if (ptr->m.planes != nullptr) {
+			free(ptr->m.planes);
+		}
+	}
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0)) {
+		fprintf(stderr, "%s, index: %d, fd: %d, ",
+		        buftype2s(ptr->type).c_str(), ptr->index, fd_retrace);
+		perror("VIDIOC_QBUF");
+		if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+			fprintf(stderr, "%s:%s:%d\n", __FILE__, __func__, __LINE__);
+			print_context();
+		}
+	}
+
+	if (ptr)
+		free(ptr);
+}
+
+void retrace_vidioc_dqbuf(int fd_retrace, json_object *ioctl_args_user)
+{
+	struct v4l2_buffer *buf = retrace_v4l2_buffer(ioctl_args_user);
+
+	struct pollfd *pfds = (struct pollfd *) calloc(1, sizeof(struct pollfd));
+	if (pfds == NULL)
+		exit(EXIT_FAILURE);
+	pfds[0].fd = fd_retrace;
+	pfds[0].events = POLLIN;
+	poll(pfds, 1, 5000);
+	free(pfds);
+
+	ioctl(fd_retrace, VIDIOC_DQBUF, buf);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0)) {
+		fprintf(stderr, "%s, index: %d, fd: %d, ",
+		        buftype2s(buf->type).c_str(), buf->index, fd_retrace);
+		perror("VIDIOC_DQBUF");
+		if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+			fprintf(stderr, "%s:%s:%d\n", __FILE__, __func__, __LINE__);
+			print_context();
+		}
+	}
+
+	if (buf->type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE ||
+	    buf->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE) {
+		if (buf->m.planes != nullptr) {
+			free(buf->m.planes);
+		}
+	}
+
+	if (buf)
+		free(buf);
+}
+
+void retrace_vidioc_prepare_buf(int fd_retrace, json_object *ioctl_args_user)
+{
+	struct v4l2_buffer *buf = retrace_v4l2_buffer(ioctl_args_user);
+
+	ioctl(fd_retrace, VIDIOC_PREPARE_BUF, buf);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0)) {
+		fprintf(stderr, "%s, index: %d, fd: %d, ",
+		        buftype2s(buf->type).c_str(), buf->index, fd_retrace);
+		perror("VIDIOC_PREPARE_BUF");
+		if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+			fprintf(stderr, "%s:%s:%d\n", __FILE__, __func__, __LINE__);
+			print_context();
+		}
+	}
+
+	if (buf->type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE ||
+	    buf->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE) {
+		if (buf->m.planes != nullptr) {
+			free(buf->m.planes);
+		}
+	}
+
+	if (buf)
+		free(buf);
+}
+
+void retrace_vidioc_create_bufs(int fd_retrace, json_object *ioctl_args)
+{
+	struct v4l2_create_buffers *ptr = retrace_v4l2_create_buffers_gen(ioctl_args);
+	ioctl(fd_retrace, VIDIOC_CREATE_BUFS, ptr);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0)) {
+		perror("VIDIOC_CREATE_BUFS");
+		if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+			fprintf(stderr, "%s:%s:%d\n", __FILE__, __func__, __LINE__);
+			print_context();
+		}
+	}
+
+	if (ptr)
+		free(ptr);
+}
+
+void retrace_vidioc_expbuf(int fd_retrace, json_object *ioctl_args_user, json_object *ioctl_args_driver)
+{
+	struct v4l2_exportbuffer *ptr = retrace_v4l2_exportbuffer_gen(ioctl_args_user);
+	ioctl(fd_retrace, VIDIOC_EXPBUF, ptr);
+
+	int buf_fd_retrace = ptr->fd;
+
+	/*
+	 * If a buffer was previously added to the retrace context using the video device
+	 * file descriptor, replace the video fd with the more specific buffer fd from EXPBUF.
+	 */
+	int fd_found_in_retrace_context = get_buffer_fd_retrace(ptr->type, ptr->index);
+	if (fd_found_in_retrace_context)
+		remove_buffer_retrace(fd_found_in_retrace_context);
+
+	add_buffer_retrace(buf_fd_retrace, ptr->type, ptr->index);
+
+	/* Retrace again to associate the original fd with the current buffer fd. */
+	memset(ptr, 0, sizeof(v4l2_exportbuffer));
+	ptr = retrace_v4l2_exportbuffer_gen(ioctl_args_driver);
+	int buf_fd_trace = ptr->fd;
+	add_fd(buf_fd_trace, buf_fd_retrace);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0))
+		perror("VIDIOC_EXPBUF");
+
+	if (ptr)
+		free(ptr);
+}
+
+void retrace_vidioc_streamon(int fd_retrace, json_object *ioctl_args)
+{
+	json_object *type_obj;
+	json_object_object_get_ex(ioctl_args, "type", &type_obj);
+	v4l2_buf_type buf_type = (v4l2_buf_type) s2val(json_object_get_string(type_obj),
+	                                               v4l2_buf_type_val_def);
+
+	ioctl(fd_retrace, VIDIOC_STREAMON, &buf_type);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0)) {
+		fprintf(stderr, "%s, ", buftype2s(buf_type).c_str());
+		perror("VIDIOC_STREAMON");
+	}
+}
+
+void retrace_vidioc_streamoff(int fd_retrace, json_object *ioctl_args)
+{
+	json_object *type_obj;
+	json_object_object_get_ex(ioctl_args, "type", &type_obj);
+	v4l2_buf_type buf_type = (v4l2_buf_type) s2val(json_object_get_string(type_obj),
+	                                               v4l2_buf_type_val_def);
+
+	ioctl(fd_retrace, VIDIOC_STREAMOFF, &buf_type);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0)) {
+		fprintf(stderr, "%s, ", buftype2s(buf_type).c_str());
+		perror("VIDIOC_STREAMOFF");
+	}
+}
+
+void retrace_vidioc_try_fmt(int fd_retrace, json_object *ioctl_args)
+{
+	struct v4l2_format *ptr = retrace_v4l2_format_gen(ioctl_args);
+	ioctl(fd_retrace, VIDIOC_TRY_FMT, ptr);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0))
+		perror("VIDIOC_TRY_FMT");
+
+	if (ptr)
+		free(ptr);
+}
+
+void retrace_vidioc_g_fmt(int fd_retrace, json_object *ioctl_args)
+{
+	struct v4l2_format *ptr = retrace_v4l2_format_gen(ioctl_args);
+	ioctl(fd_retrace, VIDIOC_G_FMT, ptr);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0))
+		perror("VIDIOC_G_FMT");
+
+	if (ptr)
+		free(ptr);
+}
+
+void retrace_vidioc_s_fmt(int fd_retrace, json_object *ioctl_args_user)
+{
+	struct v4l2_format *ptr = retrace_v4l2_format_gen(ioctl_args_user);
+
+	ioctl(fd_retrace, VIDIOC_S_FMT, ptr);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0)) {
+		perror("VIDIOC_S_FMT");
+	}
+
+	if (ptr)
+		free(ptr);
+}
+
+struct v4l2_streamparm *retrace_v4l2_streamparm(json_object *parent_obj, std::string key_name = "")
+{
+	struct v4l2_streamparm *p = (struct v4l2_streamparm *) calloc(1, sizeof(v4l2_streamparm));
+
+	json_object *v4l2_streamparm_obj;
+	json_object_object_get_ex(parent_obj, "v4l2_streamparm", &v4l2_streamparm_obj);
+
+	json_object *type_obj;
+	if (json_object_object_get_ex(v4l2_streamparm_obj, "type", &type_obj))
+		p->type = (__u32) s2val(json_object_get_string(type_obj), v4l2_buf_type_val_def);
+
+	if ((p->type == V4L2_BUF_TYPE_VIDEO_CAPTURE) || (p->type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE))
+		p->parm.capture = *retrace_v4l2_captureparm_gen(v4l2_streamparm_obj);
+
+	if ((p->type == V4L2_BUF_TYPE_VIDEO_OUTPUT) || (p->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE))
+		p->parm.output = *retrace_v4l2_outputparm_gen(v4l2_streamparm_obj);
+
+	return p;
+}
+
+void retrace_vidioc_g_parm (int fd_retrace, json_object *ioctl_args)
+{
+	struct v4l2_streamparm *ptr = retrace_v4l2_streamparm(ioctl_args);
+	ioctl(fd_retrace, VIDIOC_G_PARM, ptr);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0))
+		perror("VIDIOC_G_PARM");
+
+	if (ptr)
+		free(ptr);
+}
+
+void retrace_vidioc_s_parm (int fd_retrace, json_object *ioctl_args)
+{
+	struct v4l2_streamparm *ptr = retrace_v4l2_streamparm(ioctl_args);
+	ioctl(fd_retrace, VIDIOC_S_PARM, ptr);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0))
+		perror("VIDIOC_S_PARM");
+
+	if (ptr)
+		free(ptr);
+}
+
+void retrace_vidioc_queryctrl(int fd_retrace, json_object *ioctl_args)
+{
+	struct v4l2_queryctrl *ptr = retrace_v4l2_queryctrl_gen(ioctl_args);
+	ioctl(fd_retrace, VIDIOC_QUERYCTRL, ptr);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0))
+		perror("VIDIOC_QUERYCTRL");
+
+	if (ptr)
+		free(ptr);
+}
+
+void retrace_vidioc_g_control(int fd_retrace, json_object *ioctl_args)
+{
+	struct v4l2_control *ptr = retrace_v4l2_control_gen(ioctl_args);
+	ioctl(fd_retrace, VIDIOC_G_CTRL, ptr);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0))
+		perror("VIDIOC_G_CTRL");
+
+	if (ptr)
+		free(ptr);
+}
+
+void retrace_vidioc_s_control(int fd_retrace, json_object *ioctl_args)
+{
+	struct v4l2_control *ptr = retrace_v4l2_control_gen(ioctl_args);
+	ioctl(fd_retrace, VIDIOC_S_CTRL, ptr);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0))
+		perror("VIDIOC_S_CTRL");
+
+	if (ptr)
+		free(ptr);
+}
+
+void retrace_vidioc_g_crop(int fd_retrace, json_object *ioctl_args)
+{
+	struct v4l2_crop *ptr = retrace_v4l2_crop_gen(ioctl_args);
+	ioctl(fd_retrace, VIDIOC_G_CROP, ptr);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0))
+		perror("VIDIOC_G_CROP");
+
+	if (ptr)
+		free(ptr);
+}
+
+void retrace_vidioc_s_crop(int fd_retrace, json_object *ioctl_args)
+{
+	struct v4l2_crop *ptr = retrace_v4l2_crop_gen(ioctl_args);
+	ioctl(fd_retrace, VIDIOC_S_CROP, ptr);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0))
+		perror("VIDIOC_S_CROP");
+
+	if (ptr)
+		free(ptr);
+}
+
+int retrace_v4l2_ext_control_value(json_object *ctrl_obj, const val_def *def)
+{
+	__s32 value = -1;
+
+	json_object *value_obj;
+	if (json_object_object_get_ex(ctrl_obj, "value", &value_obj))
+		value = (__s32) s2val(json_object_get_string(value_obj), def);
+
+	return value;
+}
+
+__u32 *retrace_v4l2_dynamic_array(json_object *v4l2_ext_control_obj)
+{
+	__u32 elems = 0;
+	json_object *elems_obj;
+	if (json_object_object_get_ex(v4l2_ext_control_obj, "elems", &elems_obj))
+		elems = (__u32) json_object_get_int64(elems_obj);
+
+	__u32 *ptr = static_cast<__u32 *>(calloc(elems, sizeof(__u32)));
+
+	json_object *p_u32_obj;
+	if (json_object_object_get_ex(v4l2_ext_control_obj, "p_u32", &p_u32_obj)) {
+		for (size_t i = 0; i < elems; i++) {
+			if (json_object_array_get_idx(p_u32_obj, i))
+				ptr[i] = (__u32) json_object_get_int64(json_object_array_get_idx(p_u32_obj, i));
+		}
+	}
+
+	return ptr;
+}
+
+struct v4l2_ext_control *retrace_v4l2_ext_control(json_object *parent_obj, int ctrl_idx)
+{
+	struct v4l2_ext_control *p = (struct v4l2_ext_control *) calloc(1, sizeof(v4l2_ext_control));
+
+	json_object *v4l2_ext_control_obj = json_object_array_get_idx(parent_obj, ctrl_idx);
+	if (!v4l2_ext_control_obj)
+		return p;
+
+	json_object *id_obj;
+	if (json_object_object_get_ex(v4l2_ext_control_obj, "id", &id_obj))
+		p->id = s2val(json_object_get_string(id_obj), control_val_def);
+
+	json_object *size_obj;
+	if (json_object_object_get_ex(v4l2_ext_control_obj, "size", &size_obj))
+		p->size = json_object_get_int64(size_obj);
+
+	switch (p->id) {
+	case V4L2_CID_STATELESS_H264_DECODE_MODE:
+		p->value = retrace_v4l2_ext_control_value(v4l2_ext_control_obj,
+		                                          v4l2_stateless_h264_decode_mode_val_def);
+		break;
+	case V4L2_CID_STATELESS_H264_START_CODE:
+		p->value = retrace_v4l2_ext_control_value(v4l2_ext_control_obj,
+		                                          v4l2_stateless_h264_start_code_val_def);
+		break;
+	case V4L2_CID_STATELESS_HEVC_DECODE_MODE:
+		p->value = retrace_v4l2_ext_control_value(v4l2_ext_control_obj,
+		                                          v4l2_stateless_hevc_decode_mode_val_def);
+		break;
+	case V4L2_CID_STATELESS_HEVC_START_CODE:
+		p->value = retrace_v4l2_ext_control_value(v4l2_ext_control_obj,
+		                                          v4l2_stateless_hevc_start_code_val_def);
+		break;
+	default:
+		break;
+	}
+
+	/* Don't retrace pointers that were not traced because they were null. */
+	if (p->size == 0)
+		return p;
+
+	switch (p->id) {
+	case V4L2_CID_STATELESS_VP8_FRAME:
+		p->ptr = retrace_v4l2_ctrl_vp8_frame_gen(v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_H264_SPS:
+		p->ptr = retrace_v4l2_ctrl_h264_sps_gen(v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_H264_PPS:
+		p->ptr = retrace_v4l2_ctrl_h264_pps_gen(v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_H264_SCALING_MATRIX:
+		p->ptr = retrace_v4l2_ctrl_h264_scaling_matrix_gen(v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_H264_PRED_WEIGHTS:
+		p->ptr = retrace_v4l2_ctrl_h264_pred_weights_gen(v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_H264_SLICE_PARAMS:
+		p->ptr = retrace_v4l2_ctrl_h264_slice_params_gen(v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_H264_DECODE_PARAMS:
+		p->ptr = retrace_v4l2_ctrl_h264_decode_params_gen(v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_FWHT_PARAMS:
+		p->ptr = retrace_v4l2_ctrl_fwht_params_gen(v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_VP9_FRAME:
+		p->ptr = retrace_v4l2_ctrl_vp9_frame_gen(v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_VP9_COMPRESSED_HDR:
+		p->ptr = retrace_v4l2_ctrl_vp9_compressed_hdr_gen(v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_HEVC_SPS:
+		p->ptr = retrace_v4l2_ctrl_hevc_sps_gen(v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_HEVC_PPS:
+		p->ptr = retrace_v4l2_ctrl_hevc_pps_gen(v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_HEVC_SLICE_PARAMS:
+		p->ptr = retrace_v4l2_ctrl_hevc_slice_params_gen(v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_HEVC_SCALING_MATRIX:
+		p->ptr = retrace_v4l2_ctrl_hevc_scaling_matrix_gen(v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_HEVC_DECODE_PARAMS:
+		p->ptr = retrace_v4l2_ctrl_hevc_decode_params_gen(v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_HEVC_ENTRY_POINT_OFFSETS:
+		p->p_u32 = retrace_v4l2_dynamic_array(v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_MPEG2_SEQUENCE:
+		p->ptr = retrace_v4l2_ctrl_mpeg2_sequence_gen(v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_MPEG2_PICTURE:
+		p->ptr = retrace_v4l2_ctrl_mpeg2_picture_gen(v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_MPEG2_QUANTISATION:
+		p->ptr = retrace_v4l2_ctrl_mpeg2_quantisation_gen(v4l2_ext_control_obj);
+		break;
+	default:
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "warning: cannot retrace control: %s\n",
+		        val2s(p->id, control_val_def).c_str());
+		break;
+	}
+
+	return p;
+}
+
+struct v4l2_ext_controls *retrace_v4l2_ext_controls(json_object *parent_obj)
+{
+	struct v4l2_ext_controls *p = (struct v4l2_ext_controls *) calloc(1, sizeof(v4l2_ext_controls));
+
+	json_object *v4l2_ext_controls_obj;
+	json_object_object_get_ex(parent_obj, "v4l2_ext_controls", &v4l2_ext_controls_obj);
+
+	json_object *which_obj;
+	if (json_object_object_get_ex(v4l2_ext_controls_obj, "which", &which_obj))
+		p->which = (__u32) s2val(json_object_get_string(which_obj), which_val_def);
+
+	json_object *count_obj;
+	if (json_object_object_get_ex(v4l2_ext_controls_obj, "count", &count_obj))
+		p->count = (__u32) json_object_get_int64(count_obj);
+
+	json_object *error_idx_obj;
+	if (json_object_object_get_ex(v4l2_ext_controls_obj, "error_idx", &error_idx_obj))
+		p->error_idx = (__u32) json_object_get_int64(error_idx_obj);
+
+	/* request_fd is only valid for V4L2_CTRL_WHICH_REQUEST_VAL */
+	if (p->which == V4L2_CTRL_WHICH_REQUEST_VAL) {
+		json_object *request_fd_obj;
+		if (json_object_object_get_ex(v4l2_ext_controls_obj, "request_fd", &request_fd_obj)) {
+
+			int request_fd_trace = json_object_get_int(request_fd_obj);
+			int request_fd_retrace = get_fd_retrace_from_fd_trace(request_fd_trace);
+			if (request_fd_retrace < 0) {
+				fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+				fprintf(stderr, "bad file descriptor\n");
+				return p;
+			} else {
+				p->request_fd = (__s32) request_fd_retrace;
+			}
+		}
+	}
+
+	json_object *controls_obj;
+	if (json_object_object_get_ex(v4l2_ext_controls_obj, "controls", &controls_obj)) {
+
+		p->controls = (struct v4l2_ext_control *) calloc(p->count, sizeof(v4l2_ext_control));
+
+		for (__u32 i = 0; i < p->count; i++) {
+			void *temp = retrace_v4l2_ext_control(controls_obj, i);
+			if (temp != nullptr) {
+				p->controls[i] = *(static_cast<struct v4l2_ext_control*>(temp));
+			}
+		}
+	}
+
+	return p;
+}
+
+void retrace_vidioc_try_ext_ctrls(int fd_retrace, json_object *ioctl_args)
+{
+	struct v4l2_ext_controls *ptr = retrace_v4l2_ext_controls(ioctl_args);
+	ioctl(fd_retrace, VIDIOC_TRY_EXT_CTRLS, ptr);
+
+	if (ptr)
+		free(ptr);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0))
+		perror("VIDIOC_TRY_EXT_CTRLS");
+}
+
+void retrace_vidioc_g_ext_ctrls(int fd_retrace, json_object *ioctl_args)
+{
+	struct v4l2_ext_controls *ptr = retrace_v4l2_ext_controls(ioctl_args);
+	ioctl(fd_retrace, VIDIOC_G_EXT_CTRLS, ptr);
+
+	if (ptr)
+		free(ptr);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0))
+		perror("VIDIOC_G_EXT_CTRLS");
+}
+
+void retrace_vidioc_s_ext_ctrls(int fd_retrace, json_object *ioctl_args)
+{
+	struct v4l2_ext_controls *ptr = retrace_v4l2_ext_controls(ioctl_args);
+	ioctl(fd_retrace, VIDIOC_S_EXT_CTRLS, ptr);
+
+	if (ptr)
+		free(ptr);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0)) {
+		perror("VIDIOC_S_EXT_CTRLS");
+		if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+			fprintf(stderr, "%s:%s:%d\n", __FILE__, __func__, __LINE__);
+			print_context();
+		}
+	}
+}
+
+void retrace_vidioc_try_encoder_cmd(int fd_retrace, json_object *ioctl_args)
+{
+	struct v4l2_encoder_cmd *ptr = retrace_v4l2_encoder_cmd_gen(ioctl_args);
+
+	ioctl(fd_retrace, VIDIOC_TRY_ENCODER_CMD, ptr);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0))
+		perror("VIDIOC_TRY_ENCODER_CMD");
+
+	if (ptr)
+		free(ptr);
+}
+
+void retrace_vidioc_encoder_cmd(int fd_retrace, json_object *ioctl_args)
+{
+	struct v4l2_encoder_cmd *ptr = retrace_v4l2_encoder_cmd_gen(ioctl_args);
+
+	ioctl(fd_retrace, VIDIOC_ENCODER_CMD, ptr);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0))
+		perror("VIDIOC_ENCODER_CMD");
+
+	if (ptr)
+		free(ptr);
+}
+
+void retrace_vidioc_g_selection(int fd_retrace, json_object *ioctl_args)
+{
+	struct v4l2_selection *ptr = retrace_v4l2_selection_gen(ioctl_args);
+
+	ioctl(fd_retrace, VIDIOC_G_SELECTION, ptr);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0))
+		perror("VIDIOC_G_SELECTION");
+
+	if (ptr)
+		free(ptr);
+
+}
+
+void retrace_vidioc_s_selection(int fd_retrace, json_object *ioctl_args)
+{
+	struct v4l2_selection *ptr = retrace_v4l2_selection_gen(ioctl_args);
+
+	ioctl(fd_retrace, VIDIOC_S_SELECTION, ptr);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0))
+		perror("VIDIOC_S_SELECTION");
+
+	if (ptr)
+		free(ptr);
+}
+
+struct v4l2_decoder_cmd *retrace_v4l2_decoder_cmd(json_object *parent_obj)
+{
+	struct v4l2_decoder_cmd *p = (struct v4l2_decoder_cmd *) calloc(1, sizeof(v4l2_decoder_cmd));
+
+	json_object *v4l2_decoder_cmd_obj;
+	json_object_object_get_ex(parent_obj, "v4l2_decoder_cmd", &v4l2_decoder_cmd_obj);
+
+	json_object *cmd_obj;
+	if (json_object_object_get_ex(v4l2_decoder_cmd_obj, "cmd", &cmd_obj))
+		p->cmd = (__u32) s2val(json_object_get_string(cmd_obj), decoder_cmd_val_def);
+	else
+		p->cmd = 0xBAD; /* Since V4L2_DEC_CMD_START is 0 and p->cmd is unsigned */
+
+	std::string flags;
+	json_object *flags_obj;
+	if (json_object_object_get_ex(v4l2_decoder_cmd_obj, "flags", &flags_obj))
+		flags = json_object_get_string(flags_obj);
+
+	switch (p->cmd) {
+	case V4L2_DEC_CMD_START: {
+		if (flags == "V4L2_DEC_CMD_START_MUTE_AUDIO")
+			p->flags = V4L2_DEC_CMD_START_MUTE_AUDIO;
+
+		json_object *start_obj;
+		json_object_object_get_ex(v4l2_decoder_cmd_obj, "start", &start_obj);
+
+		json_object *speed_obj;
+		if (json_object_object_get_ex(start_obj, "speed", &speed_obj))
+			p->start.speed = json_object_get_int(speed_obj);
+
+		std::string format;
+		json_object *format_obj;
+		if (json_object_object_get_ex(start_obj, "format", &format_obj))
+			format = json_object_get_string(format_obj);
+
+		if (format == "V4L2_DEC_START_FMT_GOP")
+			p->start.format = V4L2_DEC_START_FMT_GOP;
+		else if (format == "V4L2_DEC_START_FMT_NONE")
+			p->start.format = V4L2_DEC_START_FMT_NONE;
+		break;
+	}
+	case V4L2_DEC_CMD_STOP: {
+		if (flags == "V4L2_DEC_CMD_STOP_TO_BLACK")
+			p->flags = V4L2_DEC_CMD_STOP_TO_BLACK;
+		else if (flags == "V4L2_DEC_CMD_STOP_IMMEDIATELY")
+			p->flags = V4L2_DEC_CMD_STOP_IMMEDIATELY;
+
+		json_object *stop_obj;
+		json_object_object_get_ex(v4l2_decoder_cmd_obj, "stop", &stop_obj);
+
+		json_object *pts_obj;
+		if (json_object_object_get_ex(stop_obj, "pts", &pts_obj))
+			p->stop.pts = (__u64) json_object_get_uint64(pts_obj);
+		break;
+	}
+	case V4L2_DEC_CMD_PAUSE: {
+		if (flags == "V4L2_DEC_CMD_PAUSE_TO_BLACK")
+			p->flags = V4L2_DEC_CMD_PAUSE_TO_BLACK;
+		break;
+	}
+	default:
+		break;
+	}
+
+	return p;
+}
+
+void retrace_vidioc_try_decoder_cmd(int fd_retrace, json_object *ioctl_args)
+{
+	struct v4l2_decoder_cmd *ptr = retrace_v4l2_decoder_cmd(ioctl_args);
+
+	ioctl(fd_retrace, VIDIOC_TRY_DECODER_CMD, ptr);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0))
+		perror("VIDIOC_TRY_DECODER_CMD");
+
+	if (ptr)
+		free (ptr);
+}
+
+void retrace_vidioc_decoder_cmd(int fd_retrace, json_object *ioctl_args)
+{
+	struct v4l2_decoder_cmd *ptr = retrace_v4l2_decoder_cmd(ioctl_args);
+
+	ioctl(fd_retrace, VIDIOC_DECODER_CMD, ptr);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0))
+		perror("VIDIOC_DECODER_CMD");
+
+	if (ptr)
+		free (ptr);
+}
+
+void retrace_vidioc_query_ext_ctrl(int fd_retrace, json_object *ioctl_args)
+{
+	struct v4l2_query_ext_ctrl *ptr = retrace_v4l2_query_ext_ctrl_gen(ioctl_args);
+
+	ioctl(fd_retrace, VIDIOC_QUERY_EXT_CTRL, ptr);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE"))
+		perror("VIDIOC_QUERY_EXT_CTRL");
+
+	if (ptr)
+		free(ptr);
+}
+
+void retrace_vidioc_enum_fmt(int fd_retrace, json_object *ioctl_args)
+{
+	struct v4l2_fmtdesc *ptr = retrace_v4l2_fmtdesc_gen(ioctl_args);
+
+	ioctl(fd_retrace, VIDIOC_ENUM_FMT, ptr);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE"))
+		perror("VIDIOC_ENUM_FMT");
+
+	if (ptr)
+		free(ptr);
+}
+
+void retrace_vidioc_querycap(int fd_retrace, json_object *ioctl_args)
+{
+	struct v4l2_capability *ptr = retrace_v4l2_capability_gen(ioctl_args);
+
+	ioctl(fd_retrace, VIDIOC_QUERYCAP, ptr);
+
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") || (errno != 0))
+		perror("VIDIOC_QUERYCAP");
+
+	if (ptr)
+		free(ptr);
+}
+
+void retrace_media_ioc_request_alloc(int fd_retrace, json_object *ioctl_args)
+{
+	/* Get the original request file descriptor from the original trace file. */
+	json_object *request_fd_trace_obj;
+	json_object_object_get_ex(ioctl_args, "request_fd", &request_fd_trace_obj);
+	int request_fd_trace = json_object_get_int(request_fd_trace_obj);
+
+	/* Allocate a request in the retrace context. */
+	__s32 request_fd_retrace = 0;
+	ioctl(fd_retrace, MEDIA_IOC_REQUEST_ALLOC, &request_fd_retrace);
+
+	/* Associate the original request file descriptor with the current request file descriptor. */
+	add_fd(request_fd_trace, request_fd_retrace);
+}
+
+void retrace_ioctl(json_object *syscall_obj)
+{
+	long cmd = 0;
+	int fd_retrace = 0;
+
+	json_object *fd_trace_obj;
+	json_object_object_get_ex(syscall_obj, "fd", &fd_trace_obj);
+	fd_retrace = get_fd_retrace_from_fd_trace(json_object_get_int(fd_trace_obj));
+	if (fd_retrace < 0) {
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "bad file descriptor\n");
+		return;
+	}
+
+	json_object *cmd_obj;
+	json_object_object_get_ex(syscall_obj, "ioctl", &cmd_obj);
+	cmd = s2val(json_object_get_string(cmd_obj), ioctl_val_def);
+
+	json_object *ioctl_args_user;
+	json_object_object_get_ex(syscall_obj, "from_userspace", &ioctl_args_user);
+
+	json_object *ioctl_args_driver;
+	json_object_object_get_ex(syscall_obj, "from_driver", &ioctl_args_driver);
+
+	switch (cmd) {
+	case VIDIOC_QUERYCAP:
+		retrace_vidioc_querycap(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_ENUM_FMT:
+		retrace_vidioc_enum_fmt(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_TRY_FMT:
+		retrace_vidioc_try_fmt(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_G_FMT:
+		retrace_vidioc_g_fmt(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_S_FMT:
+		retrace_vidioc_s_fmt(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_REQBUFS:
+		retrace_vidioc_reqbufs(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_QUERYBUF:
+		retrace_vidioc_querybuf(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_QBUF:
+		retrace_vidioc_qbuf(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_EXPBUF:
+		retrace_vidioc_expbuf(fd_retrace, ioctl_args_user, ioctl_args_driver);
+		break;
+	case VIDIOC_DQBUF:
+		retrace_vidioc_dqbuf(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_STREAMON:
+		retrace_vidioc_streamon(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_STREAMOFF:
+		retrace_vidioc_streamoff(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_G_PARM:
+		retrace_vidioc_g_parm(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_S_PARM:
+		retrace_vidioc_s_parm(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_G_CTRL:
+		retrace_vidioc_g_control(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_S_CTRL:
+		retrace_vidioc_s_control(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_QUERYCTRL:
+		retrace_vidioc_queryctrl(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_G_CROP:
+		retrace_vidioc_g_crop(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_S_CROP:
+		retrace_vidioc_s_crop(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_G_EXT_CTRLS:
+		retrace_vidioc_g_ext_ctrls(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_TRY_EXT_CTRLS:
+		retrace_vidioc_try_ext_ctrls(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_S_EXT_CTRLS:
+		retrace_vidioc_s_ext_ctrls(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_TRY_ENCODER_CMD:
+		retrace_vidioc_try_encoder_cmd(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_ENCODER_CMD:
+		retrace_vidioc_encoder_cmd(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_CREATE_BUFS:
+		retrace_vidioc_create_bufs(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_G_SELECTION:
+		retrace_vidioc_g_selection(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_S_SELECTION:
+		retrace_vidioc_s_selection(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_PREPARE_BUF:
+		retrace_vidioc_prepare_buf(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_TRY_DECODER_CMD:
+		retrace_vidioc_try_decoder_cmd(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_DECODER_CMD:
+		retrace_vidioc_decoder_cmd(fd_retrace, ioctl_args_user);
+		break;
+	case VIDIOC_QUERY_EXT_CTRL:
+		retrace_vidioc_query_ext_ctrl(fd_retrace, ioctl_args_user);
+		break;
+	case MEDIA_IOC_REQUEST_ALLOC:
+		retrace_media_ioc_request_alloc(fd_retrace, ioctl_args_driver);
+		break;
+	case MEDIA_REQUEST_IOC_QUEUE:
+		ioctl(fd_retrace, MEDIA_REQUEST_IOC_QUEUE);
+		break;
+	case MEDIA_REQUEST_IOC_REINIT:
+		ioctl(fd_retrace, MEDIA_REQUEST_IOC_REINIT);
+		break;
+	default:
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "warning: \'%s\' will not be retraced.\n", json_object_get_string(cmd_obj));
+		break;
+	}
+}
+
+void retrace_mem(json_object *mem_obj)
+{
+	json_object *type_obj;
+	json_object_object_get_ex(mem_obj, "mem_dump", &type_obj);
+	v4l2_buf_type type = (v4l2_buf_type) s2val(json_object_get_string(type_obj),
+	                                           v4l2_buf_type_val_def);
+	json_object *bytesused_obj;
+	json_object_object_get_ex(mem_obj, "bytesused", &bytesused_obj);
+	int bytesused = json_object_get_int64(bytesused_obj);
+	if (!bytesused)
+		return;
+
+	json_object *offset_obj;
+	json_object_object_get_ex(mem_obj, "offset", &offset_obj);
+	__u32 offset = json_object_get_int64(offset_obj);
+
+	json_object *address_obj;
+	json_object_object_get_ex(mem_obj, "address", &address_obj);
+	long buffer_address_trace = json_object_get_int64(address_obj);
+
+	long buffer_address_retrace = get_retrace_address_from_trace_address(buffer_address_trace);
+
+	unsigned char *buffer_pointer = (unsigned char *) buffer_address_retrace;
+
+	/* Get the encoded data from the json file and write it to output buffer memory. */
+	if (type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE || type == V4L2_BUF_TYPE_VIDEO_OUTPUT)
+		write_to_output_buffer(buffer_pointer, bytesused, mem_obj);
+
+	if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "%s, bytesused: %d, offset: %d, addr: %ld\n",
+		        buftype2s(type).c_str(), bytesused, offset, buffer_address_retrace);
+		print_context();
+	}
+}
+
+void retrace_object(json_object *jobj)
+{
+	errno = 0;
+	json_object *temp_obj;
+	if (json_object_object_get_ex(jobj, "ioctl", &temp_obj)) {
+		retrace_ioctl(jobj);
+		return;
+	}
+
+	if (json_object_object_get_ex(jobj, "open", &temp_obj)) {
+		retrace_open(jobj, false);
+		return;
+	}
+
+	if (json_object_object_get_ex(jobj, "open64", &temp_obj)) {
+		retrace_open(jobj, true);
+		return;
+	}
+
+	if (json_object_object_get_ex(jobj, "close", &temp_obj)) {
+		retrace_close(jobj);
+		return;
+	}
+
+	if (json_object_object_get_ex(jobj, "mmap", &temp_obj)) {
+		retrace_mmap(jobj, false);
+		return;
+	}
+
+	if (json_object_object_get_ex(jobj, "mmap64", &temp_obj)) {
+		retrace_mmap(jobj, true);
+		return;
+	}
+
+	if (json_object_object_get_ex(jobj, "munmap", &temp_obj)) {
+		retrace_munmap(jobj);
+		return;
+	}
+
+	if (json_object_object_get_ex(jobj, "mem_dump", &temp_obj)) {
+		retrace_mem(jobj);
+		return;
+	}
+
+	if (json_object_object_get_ex(jobj, "package_version", &temp_obj)) {
+		compare_program_versions(jobj);
+		return;
+	}
+
+	if (json_object_object_get_ex(jobj, "Trace", &temp_obj)) {
+		return;
+	}
+
+	fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+	fprintf(stderr, "warning: unexpected JSON object in trace file.\n");
+}
+
+void retrace_array(json_object *root_array_obj)
+{
+	json_object *jobj;
+	struct array_list *al = json_object_get_array(root_array_obj);
+	size_t json_objects_in_file = array_list_length(al);
+
+	if (json_objects_in_file < 3) {
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "warning: trace file may be empty.\n");
+	}
+
+	for (size_t i = 0; i < json_objects_in_file; i++) {
+		jobj = (json_object *) array_list_get_idx(al, i);
+		retrace_object(jobj);
+	}
+}
+
+int retracer (std::string trace_filename)
+{
+	FILE *trace_file = fopen(trace_filename.c_str(), "r");
+	if (trace_file == NULL) {
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "Trace file error: \'%s\'\n", trace_filename.c_str());
+		return 1;
+	}
+	fclose(trace_file);
+
+	fprintf(stderr, "Retracing: %s\n", trace_filename.c_str());
+
+	json_object *root_array_obj = json_object_from_file(trace_filename.c_str());
+
+	if (root_array_obj == nullptr) {
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "cannot get JSON-object from file: %s\n", trace_filename.c_str());
+		return 1;
+	}
+
+	retrace_array(root_array_obj);
+	json_object_put(root_array_obj);
+
+	return 0;
+}
diff --git a/utils/v4l2-tracer/retrace.h b/utils/v4l2-tracer/retrace.h
new file mode 100644
index 00000000..a4cef1f0
--- /dev/null
+++ b/utils/v4l2-tracer/retrace.h
@@ -0,0 +1,41 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2022 Collabora Ltd.
+ */
+
+#ifndef RETRACE_H
+#define RETRACE_H
+
+#include "v4l2-tracer-common.h"
+#include "retrace-gen.h"
+
+struct buffer_retrace {
+	int fd;
+	__u32 type;
+	__u32 index;
+	__u32 offset;
+	long address_trace;
+	long address_retrace;
+};
+
+struct retrace_context {
+	/* Key is a file descriptor from the trace, value is the corresponding fd in the retrace. */
+	std::unordered_map<int, int> retrace_fds;
+	/* List of output and capture buffers being retraced. */
+	std::list<struct buffer_retrace> buffers;
+};
+
+bool buffer_in_retrace_context(int fd, __u32 offset = 0);
+int get_buffer_fd_retrace(__u32 type, __u32 index);
+void add_buffer_retrace(int fd, __u32 type, __u32 index, __u32 offset = 0);
+void remove_buffer_retrace(int fd);
+void set_buffer_address_retrace(int fd, __u32 offset, long address_trace, long address_retrace);
+long get_retrace_address_from_trace_address(long address_trace);
+void add_fd(int fd_trace, int fd_retrace);
+int get_fd_retrace_from_fd_trace(int fd_trace);
+std::string get_path_retrace_from_path_trace(std::string path_trace, json_object *jobj);
+void write_to_output_buffer(unsigned char *buffer_pointer, int bytesused, json_object *mem_obj);
+void compare_program_versions(json_object *v4l2_tracer_info_obj);
+void print_context(void);
+
+#endif
diff --git a/utils/v4l2-tracer/trace-helper.cpp b/utils/v4l2-tracer/trace-helper.cpp
new file mode 100644
index 00000000..ccf88c5d
--- /dev/null
+++ b/utils/v4l2-tracer/trace-helper.cpp
@@ -0,0 +1,503 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2022 Collabora Ltd.
+ */
+
+#include <math.h>
+#include "trace.h"
+
+struct trace_context ctx_trace = {};
+
+bool is_video_or_media_device(const char *path)
+{
+	std::string dev_path_video = "/dev/video";
+	std::string dev_path_media = "/dev/media";
+	if (strncmp(path, dev_path_video.c_str(), dev_path_video.length()) &&
+	    strncmp(path, dev_path_media.c_str(), dev_path_media.length()))
+		return false;
+	return true;
+}
+
+void add_device(int fd, std::string path)
+{
+	if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "fd: %d, path: %s\n", fd, path.c_str());
+	}
+	std::pair<int, std::string> new_pair = std::make_pair(fd, path);
+	ctx_trace.devices.insert(new_pair);
+}
+
+std::string get_device(int fd)
+{
+	std::string path;
+	std::unordered_map<int, std::string>::const_iterator it;
+	it = ctx_trace.devices.find(fd);
+	if (it != ctx_trace.devices.end())
+		path = it->second;
+	return path;
+}
+
+void print_devices(void)
+{
+	if (ctx_trace.devices.size())
+		fprintf(stderr, "Devices:\n");
+	for (auto &device_pair : ctx_trace.devices)
+		fprintf(stderr, "fd: %d, path: %s\n", device_pair.first, device_pair.second.c_str());
+}
+
+void print_decode_order(void)
+{
+	fprintf(stderr, "Decode order: ");
+	for (auto &num : ctx_trace.decode_order)
+		fprintf(stderr, "%ld, ",  num);
+	fprintf(stderr, ".\n");
+}
+
+void set_decode_order(long decode_order)
+{
+	if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "%ld\n", decode_order);
+	}
+
+	std::list<long>::iterator it;
+	it = find(ctx_trace.decode_order.begin(), ctx_trace.decode_order.end(), decode_order);
+	if (it == ctx_trace.decode_order.end())
+		ctx_trace.decode_order.push_front(decode_order);
+
+	if (getenv("V4L2_TRACER_OPTION_DEBUG"))
+		print_decode_order();
+}
+
+long get_decode_order(void)
+{
+	long decode_order = 0;
+	if (!ctx_trace.decode_order.empty())
+		decode_order = ctx_trace.decode_order.front();
+	return decode_order;
+}
+
+void add_buffer_trace(int fd, __u32 type, __u32 index, __u32 offset = 0)
+{
+	struct buffer_trace buf = {};
+	buf.fd = fd;
+	buf.type = type;
+	buf.index = index;
+	buf.offset = offset;
+	buf.display_order = -1;
+	ctx_trace.buffers.push_front(buf);
+}
+
+void remove_buffer_trace(int fd)
+{
+	for (auto it = ctx_trace.buffers.begin(); it != ctx_trace.buffers.end(); ++it) {
+		if (it->fd == fd) {
+			ctx_trace.buffers.erase(it);
+			break;
+		}
+	}
+}
+
+bool buffer_in_trace_context(int fd, __u32 offset)
+{
+	bool buffer_in_trace_context = false;
+	for (auto &b : ctx_trace.buffers) {
+		if ((b.fd == fd) && (b.offset == offset)) {
+			buffer_in_trace_context = true;
+			break;
+		}
+	}
+	return buffer_in_trace_context;
+}
+
+int get_buffer_fd_trace(__u32 type, __u32 index)
+{
+	int fd = 0;
+	for (auto &b : ctx_trace.buffers) {
+		if ((b.type == type) && (b.index == index)) {
+			fd = b.fd;
+			break;
+		}
+	}
+	return fd;
+}
+
+__u32 get_buffer_type_trace(int fd, __u32 offset)
+{
+	__u32 type = 0;
+	for (auto &b : ctx_trace.buffers) {
+		if ((b.fd == fd) && (b.offset == offset)) {
+			type = b.type;
+			break;
+		}
+	}
+	return type;
+}
+
+int get_buffer_index_trace(int fd, __u32 offset)
+{
+	int index = -1;
+	for (auto &b : ctx_trace.buffers) {
+		if ((b.fd == fd) && (b.offset == offset)) {
+			index = b.index;
+			break;
+		}
+	}
+	return index;
+}
+
+__u32 get_buffer_offset_trace(__u32 type, __u32 index)
+{
+	__u32 offset = 0;
+	for (auto &b : ctx_trace.buffers) {
+		if ((b.type == type) && (b.index == index)) {
+			offset = b.offset;
+			break;
+		}
+	}
+	return offset;
+}
+
+void set_buffer_bytesused_trace(int fd, __u32 offset, __u32 bytesused)
+{
+	for (auto &b : ctx_trace.buffers) {
+		if ((b.fd == fd) && (b.offset == offset)) {
+			b.bytesused = bytesused;
+			break;
+		}
+	}
+}
+
+long get_buffer_bytesused_trace(int fd, __u32 offset)
+{
+	long bytesused = 0;
+	for (auto &b : ctx_trace.buffers) {
+		if ((b.fd == fd) && (b.offset == offset)) {
+			bytesused = b.bytesused;
+			break;
+		}
+	}
+	return bytesused;
+}
+
+void set_buffer_display_order(int fd, __u32 offset, long display_order)
+{
+	if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "%ld\n", display_order);
+	}
+	for (auto &b : ctx_trace.buffers) {
+		if ((b.fd == fd) && (b.offset == offset)) {
+			b.display_order = display_order;
+			break;
+		}
+	}
+}
+
+void set_buffer_address_trace(int fd, __u32 offset, unsigned long address)
+{
+	for (auto &b : ctx_trace.buffers) {
+		if ((b.fd == fd) && (b.offset == offset)) {
+			b.address = address;
+			break;
+		}
+	}
+}
+
+unsigned long get_buffer_address_trace(int fd, __u32 offset)
+{
+	unsigned long address = 0;
+	for (auto &b : ctx_trace.buffers) {
+		if ((b.fd == fd) && (b.offset == offset)) {
+			address = b.address;
+			break;
+		}
+	}
+	return address;
+}
+
+bool buffer_is_mapped(unsigned long buffer_address)
+{
+	bool ret = false;
+	for (auto &b : ctx_trace.buffers) {
+		if (b.address == buffer_address) {
+			ret = true;
+			break;
+		}
+	}
+	return ret;
+}
+
+void print_buffers_trace(void)
+{
+	for (auto &b : ctx_trace.buffers) {
+		fprintf(stderr, "fd: %d, %s, index: %d, display_order: %ld, bytesused: %d, ",
+		        b.fd, buftype2s(b.type).c_str(), b.index, b.display_order, b.bytesused);
+		fprintf(stderr, "address: %lu, offset: %u \n",  b.address, b.offset);
+	}
+}
+
+unsigned get_expected_length_trace()
+{
+	/*
+	 * TODO: this assumes that the stride is equal to the real width and that the
+	 * padding follows the end of the chroma plane. It could be improved by
+	 * following the model in v4l2-ctl-streaming.cpp read_write_padded_frame()
+	 */
+	unsigned expected_length = ctx_trace.width * ctx_trace.height;
+	if (ctx_trace.pixelformat == V4L2_PIX_FMT_NV12 || ctx_trace.pixelformat == V4L2_PIX_FMT_YUV420) {
+		expected_length *= 3;
+		expected_length /= 2;
+		expected_length += (expected_length % 2);
+	}
+	return expected_length;
+}
+
+void s_ext_ctrls_setup(struct v4l2_ext_controls *ext_controls)
+{
+	if (ext_controls->which != V4L2_CTRL_WHICH_REQUEST_VAL)
+		return;
+
+	if (getenv("V4L2_TRACER_OPTION_DEBUG"))
+		fprintf(stderr, "%s:%s:%d\n", __FILE__, __func__, __LINE__);
+
+	/*
+	 * Since userspace sends H264 frames out of order, get information
+	 * about the correct display order of each frame so that v4l2-tracer
+	 * can write the decoded frames to a file.
+	 */
+	for (__u32 i = 0; i < ext_controls->count; i++) {
+		struct v4l2_ext_control ctrl = ext_controls->controls[i];
+
+		switch (ctrl.id) {
+		case V4L2_CID_STATELESS_H264_SPS: {
+			ctx_trace.max_pic_order_cnt_lsb = pow(2, ctrl.p_h264_sps->log2_max_pic_order_cnt_lsb_minus4 + 4);
+			break;
+		}
+		case V4L2_CID_STATELESS_H264_DECODE_PARAMS: {
+			long pic_order_cnt_msb;
+			int max = ctx_trace.max_pic_order_cnt_lsb;
+			long prev_pic_order_cnt_msb = get_decode_order();
+			int prev_pic_order_cnt_lsb = ctx_trace.pic_order_cnt_lsb;
+			int pic_order_cnt_lsb = ctrl.p_h264_decode_params->pic_order_cnt_lsb;
+
+			if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+				fprintf(stderr, "%s:%s:%d\n", __FILE__, __func__, __LINE__);
+				fprintf(stderr, "\tprev_pic_order_cnt_lsb: %d\n", prev_pic_order_cnt_lsb);
+				fprintf(stderr, "\tprev_pic_order_cnt_msb: %ld\n", prev_pic_order_cnt_msb);
+				fprintf(stderr, "\tpic_order_cnt_lsb: %d\n", pic_order_cnt_lsb);
+			}
+
+			/* The first frame. */
+			if (prev_pic_order_cnt_msb == 0)
+				pic_order_cnt_msb = 0;
+
+			/*
+			 * TODO: improve the displaying of decoded frames following H264 specification
+			 * 8.2.1.1. For now, dump all the previously decoded frames when an IDR_PIC is
+			 * received to avoid losing frames although this will still sometimes result
+			 * in frames out of order.
+			 */
+			if (ctrl.p_h264_decode_params->flags & V4L2_H264_DECODE_PARAM_FLAG_IDR_PIC) {
+				if (ctx_trace.compressed_frame_count)
+					trace_mem_decoded();
+			}
+
+			/*
+			 * When pic_order_cnt_lsb wraps around to zero, adjust the total count using
+			 * max to keep the correct display order.
+			 */
+			if ((pic_order_cnt_lsb < prev_pic_order_cnt_lsb) &&
+				((prev_pic_order_cnt_lsb - pic_order_cnt_lsb) >= (max / 2))) {
+				pic_order_cnt_msb = prev_pic_order_cnt_msb + max;
+			} else if ((pic_order_cnt_lsb > prev_pic_order_cnt_lsb) &&
+				((pic_order_cnt_lsb - prev_pic_order_cnt_lsb) > (max / 2))) {
+				pic_order_cnt_msb = prev_pic_order_cnt_msb - max;
+			} else {
+				pic_order_cnt_msb = prev_pic_order_cnt_msb + (pic_order_cnt_lsb - prev_pic_order_cnt_lsb);
+			}
+
+			if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+				fprintf(stderr, "%s:%s:%d\n", __FILE__, __func__, __LINE__);
+				fprintf(stderr, "\tpic_order_cnt_msb: %ld\n", pic_order_cnt_msb);
+			}
+			ctx_trace.pic_order_cnt_lsb = pic_order_cnt_lsb;
+			set_decode_order(pic_order_cnt_msb);
+			break;
+		}
+		default:
+			break;
+		}
+	}
+}
+
+void qbuf_setup(struct v4l2_buffer *buf)
+{
+	if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "%s, index: %d\n", buftype2s(buf->type).c_str(), buf->index);
+	}
+
+	int buf_fd = get_buffer_fd_trace(buf->type, buf->index);
+	__u32 buf_offset = get_buffer_offset_trace(buf->type, buf->index);
+
+	__u32 bytesused = 0;
+	if (buf->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE ||
+	    buf->type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE)
+		bytesused = buf->m.planes[0].bytesused;
+	if (buf->type == V4L2_BUF_TYPE_VIDEO_OUTPUT || buf->type == V4L2_BUF_TYPE_VIDEO_CAPTURE)
+		bytesused = buf->bytesused;
+	set_buffer_bytesused_trace(buf_fd, buf_offset, bytesused);
+
+	/* The output buffer should have compressed data just before it is queued, so trace it. */
+	if (buf->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE ||
+	    buf->type == V4L2_BUF_TYPE_VIDEO_OUTPUT) {
+		trace_mem_encoded(buf_fd, buf_offset);
+		ctx_trace.compressed_frame_count = ctx_trace.compressed_frame_count + 1;
+	}
+
+	if (buf->type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE ||
+	    buf->type == V4L2_BUF_TYPE_VIDEO_CAPTURE) {
+
+		/* If the capture buffer is queued for reuse, trace it before it is reused. */
+		if (ctx_trace.compressed_frame_count)
+			trace_mem_decoded();
+
+		/* H264 sets display order in controls, otherwise display just in the order queued. */
+		if (ctx_trace.compression_format != V4L2_PIX_FMT_H264_SLICE)
+			set_decode_order(get_decode_order() + 1);
+
+		set_buffer_display_order(buf_fd, buf_offset, get_decode_order());
+
+		if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+			fprintf(stderr, "%s:%s:%d\n", __FILE__, __func__, __LINE__);
+			print_decode_order();
+			print_buffers_trace();
+		}
+	}
+}
+
+void streamoff_cleanup(v4l2_buf_type buf_type)
+{
+
+	if (getenv("V4L2_TRACER_OPTION_DEBUG"))
+		fprintf(stderr, "%s:%s:%d\n", __FILE__, __func__, __LINE__);
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE") ||
+	    getenv("V4L2_TRACER_OPTION_WRITE_DECODED_TO_YUV_FILE")) {
+		fprintf(stderr, "VIDIOC_STREAMOFF: %s\n", buftype2s(buf_type).c_str());
+		fprintf(stderr, "%s, %s %s, width: %d, height: %d\n",
+		        val2s(ctx_trace.compression_format, v4l2_pix_fmt_val_def).c_str(),
+		        val2s(ctx_trace.pixelformat, v4l2_pix_fmt_val_def).c_str(),
+		        fcc2s(ctx_trace.pixelformat).c_str(), ctx_trace.width, ctx_trace.height);
+	}
+
+	/*
+	 * Before turning off the stream, trace any remaining capture buffers that were missed
+	 * because they were not queued for reuse.
+	 */
+	if (buf_type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE ||
+	    buf_type == V4L2_BUF_TYPE_VIDEO_CAPTURE) {
+		if (ctx_trace.compressed_frame_count)
+			trace_mem_decoded();
+	}
+}
+
+void g_fmt_setup_trace(struct v4l2_format *format)
+{
+	if (format->type == V4L2_BUF_TYPE_VIDEO_CAPTURE) {
+		ctx_trace.width = format->fmt.pix.width;
+		ctx_trace.height = format->fmt.pix.height;
+		ctx_trace.pixelformat = format->fmt.pix.pixelformat;
+	}
+	if (format->type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE) {
+		ctx_trace.width = format->fmt.pix_mp.width;
+		ctx_trace.height = format->fmt.pix_mp.height;
+		ctx_trace.pixelformat = format->fmt.pix_mp.pixelformat;
+	}
+	if (format->type == V4L2_BUF_TYPE_VIDEO_OUTPUT)
+		ctx_trace.compression_format = format->fmt.pix.pixelformat;
+	if (format->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE)
+		ctx_trace.compression_format = format->fmt.pix_mp.pixelformat;
+}
+
+void s_fmt_setup(struct v4l2_format *format)
+{
+	if (format->type == V4L2_BUF_TYPE_VIDEO_OUTPUT)
+		ctx_trace.compression_format = format->fmt.pix.pixelformat;
+	if (format->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE)
+		ctx_trace.compression_format = format->fmt.pix_mp.pixelformat;
+}
+
+void expbuf_setup(struct v4l2_exportbuffer *export_buffer)
+{
+	__u32 type = export_buffer->type;
+	__u32 index = export_buffer->index;
+	int fd_found_in_trace_context = get_buffer_fd_trace(type, index);
+
+	/* If the buffer was already added to the trace context don't add it again. */
+	if (fd_found_in_trace_context == export_buffer->fd)
+		return;
+
+	/*
+	 * If a buffer was previously added to the trace context using the video device
+	 * file descriptor, replace the video fd with the more specific buffer fd from EXPBUF.
+	 */
+	if (fd_found_in_trace_context)
+		remove_buffer_trace(fd_found_in_trace_context);
+
+	add_buffer_trace(export_buffer->fd, type, index);
+}
+
+void querybuf_setup(int fd, struct v4l2_buffer *buf)
+{
+	/* If the buffer was already added to the trace context don't add it again. */
+	if (get_buffer_fd_trace(buf->type, buf->index))
+		return;
+
+	if (buf->memory == V4L2_MEMORY_MMAP) {
+		__u32 offset = 0;
+		if ((buf->type == V4L2_BUF_TYPE_VIDEO_CAPTURE) ||
+		    (buf->type == V4L2_BUF_TYPE_VIDEO_OUTPUT))
+			offset = buf->m.offset;
+		if ((buf->type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE) ||
+		    (buf->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE))
+			offset = buf->m.planes->m.mem_offset;
+		add_buffer_trace(fd, buf->type, buf->index, offset);
+	}
+}
+
+void query_ext_ctrl_setup(int fd, struct v4l2_query_ext_ctrl *p)
+{
+	if (p->flags & (V4L2_CTRL_FLAG_HAS_PAYLOAD|V4L2_CTRL_FLAG_DYNAMIC_ARRAY)) {
+		if (p->id == V4L2_CID_STATELESS_HEVC_ENTRY_POINT_OFFSETS)
+			ctx_trace.elems = p->elems;
+	}
+}
+
+void write_json_object_to_json_file(json_object *jobj)
+{
+	std::string json_str;
+	if (getenv("V4L2_TRACER_OPTION_COMPACT_PRINT"))
+		json_str = json_object_to_json_string_ext(jobj, JSON_C_TO_STRING_PLAIN);
+	else
+		json_str = json_object_to_json_string_ext(jobj, JSON_C_TO_STRING_PRETTY);
+
+	if (!ctx_trace.trace_file) {
+		ctx_trace.trace_filename = getenv("TRACE_ID");
+		ctx_trace.trace_filename += ".json";
+		ctx_trace.trace_file = fopen(ctx_trace.trace_filename.c_str(), "a");
+	}
+
+	fwrite(json_str.c_str(), sizeof(char), json_str.length(), ctx_trace.trace_file);
+	fputs(",\n", ctx_trace.trace_file);
+	fflush(ctx_trace.trace_file);
+}
+
+void close_json_file(void)
+{
+	if (ctx_trace.trace_file) {
+		fclose(ctx_trace.trace_file);
+		ctx_trace.trace_file = 0;
+	}
+}
diff --git a/utils/v4l2-tracer/trace.cpp b/utils/v4l2-tracer/trace.cpp
new file mode 100644
index 00000000..f0bd7002
--- /dev/null
+++ b/utils/v4l2-tracer/trace.cpp
@@ -0,0 +1,588 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2022 Collabora Ltd.
+ */
+
+#include "trace.h"
+
+extern struct trace_context ctx_trace;
+
+void trace_open(int fd, const char *path, int oflag, mode_t mode, bool is_open64)
+{
+	json_object *open_obj = json_object_new_object();
+	json_object_object_add(open_obj, "fd", json_object_new_int(fd));
+
+	json_object *open_args = json_object_new_object();
+	json_object_object_add(open_args, "path", json_object_new_string(path));
+	json_object_object_add(open_args, "oflag",
+	                       json_object_new_string(val2s(oflag, open_val_def).c_str()));
+	json_object_object_add(open_args, "mode", json_object_new_string(number2s_oct(mode).c_str()));
+	if (is_open64)
+		json_object_object_add(open_obj, "open64", open_args);
+	else
+		json_object_object_add(open_obj, "open", open_args);
+
+	/* Add additional topology information about device. */
+	std::string path_str = path;
+	bool is_media = path_str.find("media") != path_str.npos;
+	bool is_video = path_str.find("video") != path_str.npos;
+
+	int media_fd = -1;
+	if (is_media)
+		media_fd = fd;
+
+	std::string driver;
+	if (is_video) {
+		struct v4l2_capability cap = {};
+		setenv("V4L2_TRACER_PAUSE_TRACE", "true", 0);
+		ioctl(fd, VIDIOC_QUERYCAP, &cap);
+		unsetenv("V4L2_TRACER_PAUSE_TRACE");
+
+		std::string path_media = get_path_media(reinterpret_cast<const char *>(cap.driver));
+
+		setenv("V4L2_TRACER_PAUSE_TRACE", "true", 0);
+		media_fd = open(path_media.c_str(), O_RDONLY);
+		unsetenv("V4L2_TRACER_PAUSE_TRACE");
+	}
+
+	struct media_device_info info = {};
+	ioctl(media_fd, MEDIA_IOC_DEVICE_INFO, &info);
+
+	json_object_object_add(open_obj, "driver", json_object_new_string(info.driver));
+	json_object_object_add(open_obj, "bus_info", json_object_new_string(info.bus_info));
+
+	if (is_video) {
+		std::list<std::string> linked_entities = get_linked_entities(media_fd, path_str);
+		json_object *linked_entities_obj = json_object_new_array();
+		for (auto &name : linked_entities)
+			json_object_array_add(linked_entities_obj, json_object_new_string(name.c_str()));
+		json_object_object_add(open_obj, "linked_entities", linked_entities_obj);
+		setenv("V4L2_TRACER_PAUSE_TRACE", "true", 0);
+		close(media_fd);
+		unsetenv("V4L2_TRACER_PAUSE_TRACE");
+	}
+
+	write_json_object_to_json_file(open_obj);
+	json_object_put(open_obj);
+}
+
+void trace_mmap(void *addr, size_t len, int prot, int flags, int fildes, off_t off, unsigned long buf_address, bool is_mmap64)
+{
+	json_object *mmap_obj = json_object_new_object();
+
+	if (errno)
+		json_object_object_add(mmap_obj, "errno", json_object_new_string(strerrorname_np(errno)));
+
+	json_object *mmap_args = json_object_new_object();
+	json_object_object_add(mmap_args, "addr", json_object_new_int64((int64_t)addr));
+	json_object_object_add(mmap_args, "len", json_object_new_uint64(len));
+	json_object_object_add(mmap_args, "prot", json_object_new_int(prot));
+	json_object_object_add(mmap_args, "flags", json_object_new_string(number2s(flags).c_str()));
+	json_object_object_add(mmap_args, "fildes", json_object_new_int(fildes));
+	json_object_object_add(mmap_args, "off", json_object_new_int64(off));
+
+	if (is_mmap64)
+		json_object_object_add(mmap_obj, "mmap64", mmap_args);
+	else
+		json_object_object_add(mmap_obj, "mmap", mmap_args);
+
+	json_object_object_add(mmap_obj, "buffer_address", json_object_new_uint64(buf_address));
+
+	write_json_object_to_json_file(mmap_obj);
+	json_object_put(mmap_obj);
+}
+
+json_object *trace_buffer(unsigned char *buffer_pointer, __u32 bytesused)
+{
+	char buf[5];
+	std::string s;
+	int byte_count_per_line = 0;
+	json_object *mem_array_obj = json_object_new_array();
+
+	for (__u32 i = 0; i < bytesused; i++) {
+		memset(buf, 0, sizeof(buf));
+		/* Each byte e.g. D9 will write a string of two characters "D9". */
+		sprintf(buf, "%02x", buffer_pointer[i]);
+		s += buf;
+		byte_count_per_line++;
+
+		/*  Add a newline every 32 bytes. */
+		if (byte_count_per_line == 32) {
+			byte_count_per_line = 0;
+			json_object_array_add(mem_array_obj, json_object_new_string(s.c_str()));
+			s.clear();
+		} else if (!getenv("V4L2_TRACER_OPTION_COMPACT_PRINT")) {
+			/* Add a space every two bytes e.g. "012A 4001" */
+			s += " ";
+		}
+	}
+
+	/* Trace the last line if it was less than a full line. */
+	if (byte_count_per_line)
+		json_object_array_add(mem_array_obj, json_object_new_string(s.c_str()));
+
+	return mem_array_obj;
+}
+
+void trace_mem(int fd, __u32 offset, __u32 type, int index, __u32 bytesused, unsigned long start)
+{
+	json_object *mem_obj = json_object_new_object();
+	json_object_object_add(mem_obj, "mem_dump",
+	                       json_object_new_string(val2s(type, v4l2_buf_type_val_def).c_str()));
+	json_object_object_add(mem_obj, "fd", json_object_new_int(fd));
+	json_object_object_add(mem_obj, "offset", json_object_new_uint64(offset));
+	json_object_object_add(mem_obj, "index", json_object_new_int(index));
+	json_object_object_add(mem_obj, "bytesused", json_object_new_uint64(bytesused));
+	json_object_object_add(mem_obj, "address", json_object_new_uint64(start));
+
+	if ((type == V4L2_BUF_TYPE_VIDEO_OUTPUT || type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE) ||
+	    (getenv("V4L2_TRACER_OPTION_WRITE_DECODED_TO_JSON_FILE"))) {
+		json_object *mem_array_obj = trace_buffer((unsigned char*) start, bytesused);
+		json_object_object_add(mem_obj, "mem_array", mem_array_obj);
+	}
+
+	write_json_object_to_json_file(mem_obj);
+
+	json_object_put(mem_obj);
+}
+
+void trace_mem_encoded(int fd, __u32 offset)
+{
+	int index;
+	__u32 type;
+	__u32 bytesused;
+	unsigned long start = get_buffer_address_trace(fd, offset);
+
+	if (!start)
+		return;
+
+	bytesused = get_buffer_bytesused_trace(fd, offset);
+	type = get_buffer_type_trace(fd, offset);
+	index = get_buffer_index_trace(fd, offset);
+	trace_mem(fd, offset, type, index, bytesused, start);
+}
+
+void trace_mem_decoded(void)
+{
+	int displayed_count = 0;
+	unsigned expected_length = get_expected_length_trace();
+
+	while (!ctx_trace.decode_order.empty()) {
+		std::list<buffer_trace>::iterator it;
+		long next_frame_to_be_displayed = *std::min_element(ctx_trace.decode_order.begin(),
+		                                                    ctx_trace.decode_order.end());
+		for (it = ctx_trace.buffers.begin(); it != ctx_trace.buffers.end(); ++it) {
+			if (it->display_order != next_frame_to_be_displayed)
+				continue;
+			if (!it->address)
+				break;
+			if (it->bytesused < expected_length)
+				break;
+			if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+				fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+				fprintf(stderr, "displaying: %ld, %s, index: %d\n",
+				        it->display_order, buftype2s(it->type).c_str(), it->index);
+			}
+			displayed_count++;
+
+			if (getenv("V4L2_TRACER_OPTION_WRITE_DECODED_TO_YUV_FILE")) {
+				std::string filename = getenv("TRACE_ID");
+				filename +=  ".yuv";
+				FILE *fp = fopen(filename.c_str(), "a");
+				unsigned char *buffer_pointer = (unsigned char*) it->address;
+				for (__u32 i = 0; i < expected_length; i++)
+					fwrite(&buffer_pointer[i], sizeof(unsigned char), 1, fp);
+				fclose(fp);
+			}
+			trace_mem(it->fd, it->offset, it->type, it->index, it->bytesused, it->address);
+			ctx_trace.decode_order.remove(next_frame_to_be_displayed);
+			it->display_order = -1;
+			break;
+		}
+		if (!it->address || it == ctx_trace.buffers.end() || it->bytesused < expected_length)
+			break;
+	}
+	ctx_trace.compressed_frame_count = ctx_trace.compressed_frame_count - displayed_count;
+}
+
+json_object *trace_v4l2_plane(struct v4l2_plane *p, __u32 memory)
+{
+	json_object *plane_obj = json_object_new_object();
+
+	json_object_object_add(plane_obj, "bytesused", json_object_new_int64(p->bytesused));
+	json_object_object_add(plane_obj, "length", json_object_new_int64(p->length));
+
+	json_object *m_obj = json_object_new_object();
+
+	if (memory == V4L2_MEMORY_MMAP)
+		json_object_object_add(m_obj, "mem_offset", json_object_new_int64(p->m.mem_offset));
+	json_object_object_add(plane_obj, "m", m_obj);
+
+	json_object_object_add(plane_obj, "data_offset", json_object_new_int64(p->data_offset));
+
+	return plane_obj;
+}
+
+void trace_v4l2_buffer(void *arg, json_object *ioctl_args)
+{
+	json_object *buf_obj = json_object_new_object();
+	struct v4l2_buffer *buf = static_cast<struct v4l2_buffer*>(arg);
+
+	json_object_object_add(buf_obj, "index", json_object_new_uint64(buf->index));
+	json_object_object_add(buf_obj, "type",
+	                       json_object_new_string(val2s(buf->type, v4l2_buf_type_val_def).c_str()));
+	json_object_object_add(buf_obj, "bytesused", json_object_new_uint64(buf->bytesused));
+	json_object_object_add(buf_obj, "flags", json_object_new_string(fl2s_buffer(buf->flags).c_str()));
+	json_object_object_add(buf_obj, "field",
+	                       json_object_new_string(val2s(buf->field, v4l2_field_val_def).c_str()));
+	json_object *timestamp_obj = json_object_new_object();
+	json_object_object_add(timestamp_obj, "tv_sec", json_object_new_int64(buf->timestamp.tv_sec));
+	json_object_object_add(timestamp_obj, "tv_usec",
+	                       json_object_new_int64(buf->timestamp.tv_usec));
+	json_object_object_add(buf_obj, "timestamp", timestamp_obj);
+	json_object_object_add(buf_obj, "timestamp_ns",
+	                       json_object_new_uint64(v4l2_timeval_to_ns(&buf->timestamp)));
+
+	json_object_object_add(buf_obj, "sequence", json_object_new_uint64(buf->sequence));
+	json_object_object_add(buf_obj, "memory",
+	                       json_object_new_string(val2s(buf->memory, v4l2_memory_val_def).c_str()));
+
+	json_object *m_obj = json_object_new_object();
+	if (buf->type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE ||
+	    buf->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE) {
+		json_object *planes_obj = json_object_new_array();
+		/* TODO add planes > 0 */
+		json_object_array_add(planes_obj, trace_v4l2_plane(buf->m.planes, buf->memory));
+		json_object_object_add(m_obj, "planes", planes_obj);
+	}
+
+	if (buf->type == V4L2_BUF_TYPE_VIDEO_CAPTURE ||
+	    buf->type == V4L2_BUF_TYPE_VIDEO_OUTPUT) {
+		if (buf->memory == V4L2_MEMORY_MMAP)
+			json_object_object_add(m_obj, "offset", json_object_new_uint64(buf->m.offset));
+	}
+	json_object_object_add(buf_obj, "m", m_obj);
+	json_object_object_add(buf_obj, "length", json_object_new_uint64(buf->length));
+
+	if (buf->flags & V4L2_BUF_FLAG_REQUEST_FD)
+		json_object_object_add(buf_obj, "request_fd", json_object_new_int(buf->request_fd));
+
+	json_object_object_add(ioctl_args, "v4l2_buffer", buf_obj);
+}
+
+void trace_vidioc_stream(void *arg, json_object *ioctl_args)
+{
+	v4l2_buf_type buf_type = *(static_cast<v4l2_buf_type*>(arg));
+	json_object_object_add(ioctl_args, "type",
+	                       json_object_new_string(val2s(buf_type, v4l2_buf_type_val_def).c_str()));
+}
+
+void trace_v4l2_streamparm(void *arg, json_object *ioctl_args)
+{
+	json_object *v4l2_streamparm_obj = json_object_new_object();
+	struct v4l2_streamparm *streamparm = static_cast<struct v4l2_streamparm*>(arg);
+
+	json_object_object_add(v4l2_streamparm_obj, "type",
+	                       json_object_new_string(val2s(streamparm->type, v4l2_buf_type_val_def).c_str()));
+
+	if ((streamparm->type == V4L2_BUF_TYPE_VIDEO_CAPTURE) ||
+	    (streamparm->type == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE))
+		trace_v4l2_captureparm_gen(&streamparm->parm, v4l2_streamparm_obj);
+
+	if ((streamparm->type == V4L2_BUF_TYPE_VIDEO_OUTPUT) ||
+	    (streamparm->type == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE))
+		trace_v4l2_outputparm_gen(&streamparm->parm, v4l2_streamparm_obj);
+
+	json_object_object_add(ioctl_args, "v4l2_streamparm", v4l2_streamparm_obj);
+}
+
+void trace_v4l2_ext_control(void *arg, json_object *parent_obj, std::string key_name = "")
+{
+	json_object *v4l2_ext_control_obj = json_object_new_object();
+	struct v4l2_ext_control *p = static_cast<struct v4l2_ext_control*>(arg);
+
+	json_object_object_add(v4l2_ext_control_obj, "id",
+	                       json_object_new_string(val2s(p->id, control_val_def).c_str()));
+	json_object_object_add(v4l2_ext_control_obj, "size", json_object_new_uint64(p->size));
+
+	/* trace controls of type V4L2_CTRL_TYPE_MENU */
+	switch (p->id) {
+	case V4L2_CID_STATELESS_H264_DECODE_MODE: {
+		json_object_object_add(v4l2_ext_control_obj, "value",
+		                       json_object_new_string(val2s(p->value, v4l2_stateless_h264_decode_mode_val_def).c_str()));
+		json_object_array_add(parent_obj, v4l2_ext_control_obj);
+		return;
+	}
+	case V4L2_CID_STATELESS_H264_START_CODE: {
+		json_object_object_add(v4l2_ext_control_obj, "value",
+		                       json_object_new_string(val2s(p->value, v4l2_stateless_h264_start_code_val_def).c_str()));
+		json_object_array_add(parent_obj, v4l2_ext_control_obj);
+		return;
+	}
+	case V4L2_CID_STATELESS_HEVC_DECODE_MODE: {
+		json_object_object_add(v4l2_ext_control_obj, "value",
+		                       json_object_new_string(val2s(p->value, v4l2_stateless_hevc_decode_mode_val_def).c_str()));
+		json_object_array_add(parent_obj, v4l2_ext_control_obj);
+		return;
+	}
+	case V4L2_CID_STATELESS_HEVC_START_CODE: {
+		json_object_object_add(v4l2_ext_control_obj, "value",
+		                       json_object_new_string(val2s(p->value, v4l2_stateless_hevc_start_code_val_def).c_str()));
+		json_object_array_add(parent_obj, v4l2_ext_control_obj);
+		return;
+	}
+	default:
+		break;
+	}
+
+	if (p->ptr == nullptr) {
+		json_object_array_add(parent_obj, v4l2_ext_control_obj);
+		return;
+	}
+
+	switch (p->id) {
+	case V4L2_CID_STATELESS_VP8_FRAME:
+		trace_v4l2_ctrl_vp8_frame_gen(p->p_vp8_frame, v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_H264_SPS:
+		trace_v4l2_ctrl_h264_sps_gen(p->p_h264_sps, v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_H264_PPS:
+		trace_v4l2_ctrl_h264_pps_gen(p->p_h264_pps, v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_H264_SCALING_MATRIX:
+		trace_v4l2_ctrl_h264_scaling_matrix_gen(p->p_h264_scaling_matrix, v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_H264_PRED_WEIGHTS:
+		trace_v4l2_ctrl_h264_pred_weights_gen(p->p_h264_pred_weights, v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_H264_SLICE_PARAMS:
+		trace_v4l2_ctrl_h264_slice_params_gen(p->p_h264_slice_params, v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_H264_DECODE_PARAMS:
+		trace_v4l2_ctrl_h264_decode_params_gen(p->p_h264_decode_params, v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_FWHT_PARAMS:
+		trace_v4l2_ctrl_fwht_params_gen(p->p_fwht_params, v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_VP9_FRAME:
+		trace_v4l2_ctrl_vp9_frame_gen(p->p_vp9_frame, v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_VP9_COMPRESSED_HDR:
+		trace_v4l2_ctrl_vp9_compressed_hdr_gen(p->p_vp9_compressed_hdr_probs, v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_HEVC_SPS:
+		trace_v4l2_ctrl_hevc_sps_gen(p->p_hevc_sps, v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_HEVC_PPS:
+		trace_v4l2_ctrl_hevc_pps_gen(p->p_hevc_pps, v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_HEVC_SLICE_PARAMS:
+		trace_v4l2_ctrl_hevc_slice_params_gen(p->p_hevc_slice_params, v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_HEVC_SCALING_MATRIX:
+		trace_v4l2_ctrl_hevc_scaling_matrix_gen(p->p_hevc_scaling_matrix, v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_HEVC_DECODE_PARAMS:
+		trace_v4l2_ctrl_hevc_decode_params_gen(p->p_hevc_decode_params, v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_HEVC_ENTRY_POINT_OFFSETS: {
+		/* V4L2_CTRL_TYPE_U32, V4L2_CTRL_FLAG_DYNAMIC_ARRAY */
+		__u32 elems = ctx_trace.elems;
+		json_object_object_add(v4l2_ext_control_obj, "elems", json_object_new_int64(elems));
+		json_object *hevc_entry_point_offsets_obj = json_object_new_array();
+		for (__u32 i = 0; i < elems; i++)
+			json_object_array_add(hevc_entry_point_offsets_obj, json_object_new_int64(p->p_u32[i]));
+		json_object_object_add(v4l2_ext_control_obj, "p_u32", hevc_entry_point_offsets_obj);
+		break;
+	}
+	case V4L2_CID_STATELESS_MPEG2_SEQUENCE:
+		trace_v4l2_ctrl_mpeg2_sequence_gen(p->p_mpeg2_sequence, v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_MPEG2_PICTURE:
+		trace_v4l2_ctrl_mpeg2_picture_gen(p->p_mpeg2_picture, v4l2_ext_control_obj);
+		break;
+	case V4L2_CID_STATELESS_MPEG2_QUANTISATION:
+		trace_v4l2_ctrl_mpeg2_quantisation_gen(p->p_mpeg2_quantisation, v4l2_ext_control_obj);
+		break;
+	default:
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "warning: cannot trace control: %s\n", val2s(p->id, control_val_def).c_str());
+		break;
+	}
+
+	json_object_array_add(parent_obj, v4l2_ext_control_obj);
+}
+
+void trace_v4l2_ext_controls(void *arg, json_object *ioctl_args)
+{
+	json_object *ext_controls_obj = json_object_new_object();
+	struct v4l2_ext_controls *ext_controls = static_cast<struct v4l2_ext_controls*>(arg);
+
+	json_object_object_add(ext_controls_obj, "which",
+	                       json_object_new_string(val2s(ext_controls->which, which_val_def).c_str()));
+
+	json_object_object_add(ext_controls_obj, "count", json_object_new_int64(ext_controls->count));
+
+	/* error_idx is defined only if the ioctl returned an error  */
+	if (errno)
+		json_object_object_add(ext_controls_obj, "error_idx",
+		                       json_object_new_uint64(ext_controls->error_idx));
+
+	/* request_fd is only valid when "which" == V4L2_CTRL_WHICH_REQUEST_VAL */
+	if (ext_controls->which == V4L2_CTRL_WHICH_REQUEST_VAL)
+		json_object_object_add(ext_controls_obj, "request_fd",
+		                       json_object_new_int(ext_controls->request_fd));
+
+	json_object *controls_obj = json_object_new_array();
+	for (__u32 i = 0; i < ext_controls->count; i++) {
+		if ((void *) ext_controls->controls == nullptr)
+			break;
+		trace_v4l2_ext_control((void *) &ext_controls->controls[i], controls_obj);
+	}
+	json_object_object_add(ext_controls_obj, "controls", controls_obj);
+
+	json_object_object_add(ioctl_args, "v4l2_ext_controls", ext_controls_obj);
+}
+
+void trace_v4l2_decoder_cmd(void *arg, json_object *ioctl_args)
+{
+	json_object *v4l2_decoder_cmd_obj = json_object_new_object();
+	struct v4l2_decoder_cmd *p = static_cast<struct v4l2_decoder_cmd*>(arg);
+
+	json_object_object_add(v4l2_decoder_cmd_obj, "cmd",
+	                       json_object_new_string(val2s(p->cmd, decoder_cmd_val_def).c_str()));
+
+	std::string flags;
+
+	switch (p->cmd) {
+	case V4L2_DEC_CMD_START: {
+		/*  This command has one flag: V4L2_DEC_CMD_START_MUTE_AUDIO. */
+		if (p->flags == V4L2_DEC_CMD_START_MUTE_AUDIO)
+			flags = "V4L2_DEC_CMD_START_MUTE_AUDIO";
+
+		/* struct start */
+		json_object *start_obj = json_object_new_object();
+		json_object_object_add(start_obj, "speed", json_object_new_int(p->start.speed));
+
+		std::string format;
+		/* possible values V4L2_DEC_START_FMT_NONE, V4L2_DEC_START_FMT_GOP */
+		if (p->start.format == V4L2_DEC_START_FMT_GOP)
+			format = "V4L2_DEC_START_FMT_GOP";
+		else if (p->start.format == V4L2_DEC_START_FMT_NONE)
+			format = "V4L2_DEC_START_FMT_NONE";
+		json_object_object_add(start_obj, "format", json_object_new_string(format.c_str()));
+
+		json_object_object_add(v4l2_decoder_cmd_obj, "start", start_obj);
+		break;
+	}
+	case V4L2_DEC_CMD_STOP: {
+		/*  This command has two flags */
+		if (p->flags == V4L2_DEC_CMD_STOP_TO_BLACK)
+			flags = "V4L2_DEC_CMD_STOP_TO_BLACK";
+		else if (p->flags == V4L2_DEC_CMD_STOP_IMMEDIATELY)
+			flags = "V4L2_DEC_CMD_STOP_IMMEDIATELY";
+
+		json_object *stop_obj = json_object_new_object();
+		json_object_object_add(stop_obj, "pts", json_object_new_uint64(p->stop.pts));
+
+		json_object_object_add(v4l2_decoder_cmd_obj, "stop", stop_obj);
+		break;
+	}
+
+	case V4L2_DEC_CMD_PAUSE: {
+		if (p->flags == V4L2_DEC_CMD_PAUSE_TO_BLACK)
+			flags = "V4L2_DEC_CMD_PAUSE_TO_BLACK";
+		break;
+	}
+	case V4L2_DEC_CMD_RESUME:
+	case V4L2_DEC_CMD_FLUSH:
+	default:
+		break;
+	}
+	json_object_object_add(v4l2_decoder_cmd_obj, "flags", json_object_new_string(flags.c_str()));
+
+	json_object_object_add(ioctl_args, "v4l2_decoder_cmd", v4l2_decoder_cmd_obj);
+}
+
+json_object *trace_ioctl_args(unsigned long cmd, void *arg)
+{
+	json_object *ioctl_args = json_object_new_object();
+
+	switch (cmd) {
+	case VIDIOC_QUERYCAP:
+		trace_v4l2_capability_gen(arg, ioctl_args);
+		break;
+	case VIDIOC_ENUM_FMT:
+		trace_v4l2_fmtdesc_gen(arg, ioctl_args);
+		break;
+	case VIDIOC_G_FMT:
+	case VIDIOC_TRY_FMT:
+	case VIDIOC_S_FMT:
+		trace_v4l2_format_gen(arg, ioctl_args);
+		break;
+	case VIDIOC_REQBUFS:
+		trace_v4l2_requestbuffers_gen(arg, ioctl_args);
+		break;
+	case VIDIOC_PREPARE_BUF:
+	case VIDIOC_QUERYBUF:
+	case VIDIOC_QBUF:
+	case VIDIOC_DQBUF:
+		trace_v4l2_buffer(arg, ioctl_args);
+		break;
+	case VIDIOC_EXPBUF:
+		trace_v4l2_exportbuffer_gen(arg, ioctl_args);
+		break;
+	case VIDIOC_STREAMON:
+	case VIDIOC_STREAMOFF:
+		trace_vidioc_stream(arg, ioctl_args);
+		break;
+	case VIDIOC_G_PARM:
+	case VIDIOC_S_PARM:
+		trace_v4l2_streamparm(arg, ioctl_args);
+		break;
+	case VIDIOC_G_CTRL:
+	case VIDIOC_S_CTRL:
+		trace_v4l2_control_gen(arg, ioctl_args);
+		break;
+	case VIDIOC_QUERYCTRL:
+		trace_v4l2_queryctrl_gen(arg, ioctl_args);
+		break;
+	case VIDIOC_G_CROP:
+	case VIDIOC_S_CROP:
+		trace_v4l2_crop_gen(arg, ioctl_args);
+		break;
+	case VIDIOC_G_EXT_CTRLS:
+	case VIDIOC_TRY_EXT_CTRLS:
+	case VIDIOC_S_EXT_CTRLS:
+		trace_v4l2_ext_controls(arg, ioctl_args);
+		break;
+	case VIDIOC_TRY_ENCODER_CMD:
+	case VIDIOC_ENCODER_CMD:
+		trace_v4l2_encoder_cmd_gen(arg, ioctl_args);
+		break;
+	case VIDIOC_CREATE_BUFS:
+		trace_v4l2_create_buffers_gen(arg, ioctl_args);
+		break;
+	case VIDIOC_G_SELECTION:
+	case VIDIOC_S_SELECTION:
+		trace_v4l2_selection_gen(arg, ioctl_args);
+		break;
+	case VIDIOC_TRY_DECODER_CMD:
+	case VIDIOC_DECODER_CMD:
+		trace_v4l2_decoder_cmd(arg, ioctl_args);
+		break;
+	case VIDIOC_QUERY_EXT_CTRL:
+		trace_v4l2_query_ext_ctrl_gen(arg, ioctl_args);
+		break;
+	case MEDIA_IOC_REQUEST_ALLOC: {
+		__s32 *request_fd = static_cast<__s32*>(arg);
+		json_object_object_add(ioctl_args, "request_fd", json_object_new_int(*request_fd));
+		break;
+	}
+	default:
+		break;
+	}
+
+	return ioctl_args;
+}
diff --git a/utils/v4l2-tracer/trace.h b/utils/v4l2-tracer/trace.h
new file mode 100644
index 00000000..7fa0a22a
--- /dev/null
+++ b/utils/v4l2-tracer/trace.h
@@ -0,0 +1,73 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2022 Collabora Ltd.
+ */
+
+#ifndef TRACE_H
+#define TRACE_H
+
+#include "v4l2-tracer-common.h"
+#include "trace-gen.h"
+
+struct buffer_trace {
+	int fd;
+	__u32 type;
+	__u32 index;
+	__u32 offset;
+	__u32 bytesused;
+	long display_order;
+	unsigned long address;
+};
+
+struct trace_context {
+	__u32 elems;
+	__u32 width;
+	__u32 height;
+	FILE *trace_file;
+	__u32 pixelformat;
+	int pic_order_cnt_lsb;
+	int max_pic_order_cnt_lsb;
+	pthread_mutex_t lock;
+	std::string media_device;
+	__u32 compression_format;
+	std::string trace_filename;
+	int compressed_frame_count;
+	std::list<long> decode_order;
+	std::list<struct buffer_trace> buffers;
+	std::unordered_map<int, std::string> devices; /* key:fd, value: path of the device */
+};
+
+void trace_open(int fd, const char *path, int oflag, mode_t mode, bool is_open64);
+void trace_mmap(void *addr, size_t len, int prot, int flags, int fildes, off_t off, unsigned long buf_address, bool is_mmap64);
+void trace_mem(int fd, __u32 offset, __u32 type, int index, __u32 bytesused, unsigned long start);
+void trace_mem_encoded(int fd, __u32 offset);
+void trace_mem_decoded(void);
+json_object *trace_ioctl_args(unsigned long cmd, void *arg);
+
+bool is_video_or_media_device(const char *path);
+void add_device(int fd, std::string path);
+std::string get_device(int fd);
+void print_devices(void);
+
+bool buffer_in_trace_context(int fd, __u32 offset = 0);
+__u32 get_buffer_type_trace(int fd, __u32 offset = 0);
+int get_buffer_index_trace(int fd, __u32 offset);
+long get_buffer_bytesused_trace(int fd, __u32 offset);
+void set_buffer_address_trace(int fd, __u32 offset, unsigned long address);
+unsigned long get_buffer_address_trace(int fd, __u32 offset);
+bool buffer_is_mapped(unsigned long buffer_address);
+
+unsigned get_expected_length_trace(void);
+void s_ext_ctrls_setup(struct v4l2_ext_controls *ext_controls);
+void qbuf_setup(struct v4l2_buffer *buf);
+void streamoff_cleanup(v4l2_buf_type buf_type);
+void g_fmt_setup_trace(struct v4l2_format *format);
+void s_fmt_setup(struct v4l2_format *format);
+void expbuf_setup(struct v4l2_exportbuffer *export_buffer);
+void querybuf_setup(int fd, struct v4l2_buffer *buf);
+void query_ext_ctrl_setup(int fd, struct v4l2_query_ext_ctrl *p);
+
+void write_json_object_to_json_file(json_object *jobj);
+void close_json_file(void);
+
+#endif
diff --git a/utils/v4l2-tracer/v4l2-tracer-common.cpp b/utils/v4l2-tracer/v4l2-tracer-common.cpp
new file mode 100644
index 00000000..4d6adcd3
--- /dev/null
+++ b/utils/v4l2-tracer/v4l2-tracer-common.cpp
@@ -0,0 +1,453 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2022 Collabora Ltd.
+ */
+
+#include <sstream>
+#include <iostream>
+#include <iomanip>
+#include "v4l2-tracer-common.h"
+
+void print_v4l2_tracer_info(void)
+{
+	fprintf(stderr, "v4l2-tracer %s%s\n", PACKAGE_VERSION, STRING(GIT_COMMIT_CNT));
+	if (strlen(STRING(GIT_SHA)))
+		fprintf(stderr, "v4l2-tracer SHA: '%s' %s\n", STRING(GIT_SHA), STRING(GIT_COMMIT_DATE));
+}
+
+void print_usage(void)
+{
+	print_v4l2_tracer_info();
+	fprintf(stderr, "Usage:\n\tv4l2-tracer [options] trace <tracee>\n"
+	        "\tv4l2-tracer [options] retrace <trace_file>.json\n"
+	        "\tv4l2-tracer clean <trace_file>.json\n\n"
+
+	        "\tCommon options:\n"
+	        "\t\t-c, --compact     Write minimal whitespace in JSON file.\n"
+	        "\t\t-g, --debug       Turn on verbose reporting plus additional debug info.\n"
+	        "\t\t-h, --help        Display this message.\n"
+	        "\t\t-r  --raw         Write decoded video frame data to JSON file.\n"
+	        "\t\t-v, --verbose     Turn on verbose reporting.\n"
+	        "\t\t-y, --yuv         Write decoded video frame data to yuv file.\n\n"
+
+	        "\tRetrace options:\n"
+	        "\t\t-d, --video_device <dev>   Retrace with a specific video device.\n"
+	        "\t\t                           <dev> must be a digit corresponding to\n"
+	        "\t\t                           /dev/video<dev> \n\n"
+	        "\t\t-m, --media_device <dev>   Retrace with a specific media device.\n"
+	        "\t\t                           <dev> must be a digit corresponding to\n"
+	        "\t\t                           /dev/media<dev> \n\n");
+}
+
+void add_separator(std::string &s)
+{
+	if (!s.empty())
+		s += "|";
+}
+
+void clean_string(size_t idx, std::string substring_to_erase, std::string &s)
+{
+	std::string temp = substring_to_erase + '|';
+	if (s.find(temp) != s.npos)
+		s.erase(idx, temp.length());
+	else
+		s.erase(idx, substring_to_erase.length());
+}
+
+std::string ver2s(unsigned int version)
+{
+	char buf[16];
+	sprintf(buf, "%d.%d.%d", version >> 16, (version >> 8) & 0xff, version & 0xff);
+	return buf;
+}
+
+/* Convert a number to an octal string. If num is 0, return an empty string. */
+std::string number2s_oct(long num)
+{
+	std::stringstream ss;
+	ss << std::setfill ('0') << std::setw(5) << std::oct << num;
+	return ss.str();
+}
+
+/* Convert a number to a hex string. If num is 0, return an empty string. */
+std::string number2s(long num)
+{
+	if (!num)
+		return "";
+	std::stringstream ss;
+	ss << std::hex << num;
+	return "0x" + ss.str();
+}
+
+std::string val2s(long val, const val_def *def)
+{
+	std::string s;
+	if (def == nullptr)
+		return number2s(val);
+
+	while ((def->val != -1) && (def->val != val))
+		def++;
+
+	if (def->val == val)
+		return def->str;
+
+	return number2s(val);
+}
+
+std::string fl2s(unsigned val, const flag_def *def)
+{
+	std::string s;
+
+	if (def == nullptr)
+		return number2s(val);
+
+	while (def->flag) {
+		if (val & def->flag) {
+			add_separator(s);
+			s += def->str;
+			val &= ~def->flag;
+		}
+		def++;
+	}
+	if (val) {
+		add_separator(s);
+		s += number2s(val);
+	}
+
+	return s;
+}
+
+std::string fl2s_buffer(__u32 flags)
+{
+	std::string s;
+
+	switch (flags & V4L2_BUF_FLAG_TIMESTAMP_MASK) {
+	case V4L2_BUF_FLAG_TIMESTAMP_UNKNOWN:
+		s += "V4L2_BUF_FLAG_TIMESTAMP_UNKNOWN";
+		flags &= ~V4L2_BUF_FLAG_TIMESTAMP_UNKNOWN;
+		break;
+	case V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC:
+		s += "V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC";
+		flags &= ~V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
+		break;
+	case V4L2_BUF_FLAG_TIMESTAMP_COPY:
+		s += "V4L2_BUF_FLAG_TIMESTAMP_COPY";
+		flags &= ~V4L2_BUF_FLAG_TIMESTAMP_COPY;
+		break;
+	default:
+		break;
+	}
+
+	/* Since V4L2_BUF_FLAG_TSTAMP_SRC_EOF == 0, at least this flag will always be added. */
+	add_separator(s);
+	switch (flags & V4L2_BUF_FLAG_TSTAMP_SRC_MASK) {
+	case V4L2_BUF_FLAG_TSTAMP_SRC_EOF:
+		s += "V4L2_BUF_FLAG_TSTAMP_SRC_EOF";
+		flags &= ~V4L2_BUF_FLAG_TSTAMP_SRC_EOF;
+		break;
+	case V4L2_BUF_FLAG_TSTAMP_SRC_SOE:
+		s += "V4L2_BUF_FLAG_TSTAMP_SRC_SOE";
+		flags &= ~V4L2_BUF_FLAG_TSTAMP_SRC_SOE;
+		break;
+	default:
+		break;
+	}
+
+	if (flags) {
+		add_separator(s);
+		const unsigned ts_mask = V4L2_BUF_FLAG_TIMESTAMP_MASK | V4L2_BUF_FLAG_TSTAMP_SRC_MASK;
+		s += fl2s(flags & ~ts_mask, v4l2_buf_flag_def);
+	}
+
+	return s;
+}
+
+std::string fl2s_fwht(__u32 flags)
+{
+	std::string s;
+	switch (flags & V4L2_FWHT_FL_PIXENC_MSK) {
+	case V4L2_FWHT_FL_PIXENC_YUV:
+		s += "V4L2_FWHT_FL_PIXENC_YUV";
+		flags &= ~V4L2_FWHT_FL_PIXENC_YUV;
+		break;
+	case V4L2_FWHT_FL_PIXENC_RGB:
+		s += "V4L2_FWHT_FL_PIXENC_RGB";
+		flags &= ~V4L2_FWHT_FL_PIXENC_RGB;
+		break;
+	case V4L2_FWHT_FL_PIXENC_HSV:
+		s += "V4L2_FWHT_FL_PIXENC_HSV";
+		flags &= ~V4L2_FWHT_FL_PIXENC_HSV;
+		break;
+	default:
+		break;
+	}
+	add_separator(s);
+	s += fl2s(flags, v4l2_ctrl_fwht_params_flag_def);
+	return s;
+}
+
+long s2number(std::string s)
+{
+	long num = 0;
+	if (s.empty())
+		return num;
+	try {
+		num = std::stoul(s, nullptr, 0); /* base is auto-detected */
+	} catch (std::invalid_argument& ia) {
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "string \'%s\' is invalid\n", s.c_str());
+	} catch (std::out_of_range& oor) {
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "string \'%s\' is out of range\n", s.c_str());
+	}
+	return num;
+}
+
+long s2val(std::string s, const val_def *def)
+{
+	if (s.empty())
+		return 0;
+
+	if (def == nullptr)
+		return s2number(s);
+
+	while ((def->val != -1) && (def->str != s))
+		def++;
+
+	if (def->str == s)
+		return def->val;
+
+	return s2number(s);
+}
+
+unsigned long s2flags(std::string s, const flag_def *def)
+{
+	size_t idx;
+	unsigned long flags = 0;
+
+	if (def == nullptr)
+		return s2number(s);
+
+	while (def->flag) {
+		idx = s.find(def->str);
+		if (idx == s.npos) {
+			def++;
+			continue;
+		}
+		/* Stop false substring matches e.g. in V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS */
+		std::string check = def->str;
+		if (check.length() != s.length()) {
+			idx = s.find(check + '|');
+			if (idx == s.npos) {
+				def++;
+				continue;
+			}
+		}
+		flags += def->flag;
+		clean_string(idx, def->str, s);
+		def++;
+	}
+	if (!s.empty())
+		flags += s2number(s);
+
+	return flags;
+}
+
+unsigned long s2flags_buffer(std::string s)
+{
+	size_t idx = 0;
+	unsigned long flags = 0;
+
+	idx = s.find("V4L2_BUF_FLAG_TIMESTAMP_COPY");
+	if (idx != s.npos) {
+		flags += V4L2_BUF_FLAG_TIMESTAMP_COPY;
+		clean_string(idx, "V4L2_BUF_FLAG_TIMESTAMP_COPY", s);
+	}
+	idx = s.find("V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC");
+	if (idx != s.npos) {
+		flags += V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
+		clean_string(idx, "V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC", s);
+	}
+	idx = s.find("V4L2_BUF_FLAG_TIMESTAMP_UNKNOWN");
+	if (idx != s.npos) {
+		flags += V4L2_BUF_FLAG_TIMESTAMP_UNKNOWN;
+		clean_string(idx, "V4L2_BUF_FLAG_TIMESTAMP_UNKNOWN", s);
+	}
+	idx = s.find("V4L2_BUF_FLAG_TSTAMP_SRC_SOE");
+	if (idx != s.npos) {
+		flags += V4L2_BUF_FLAG_TSTAMP_SRC_SOE;
+		clean_string(idx, "V4L2_BUF_FLAG_TSTAMP_SRC_SOE", s);
+	}
+	idx = s.find("V4L2_BUF_FLAG_TSTAMP_SRC_EOF");
+	if (idx != s.npos) {
+		flags += V4L2_BUF_FLAG_TSTAMP_SRC_EOF;
+		clean_string(idx, "V4L2_BUF_FLAG_TSTAMP_SRC_EOF", s);
+	}
+	if (!s.empty())
+		flags += s2flags(s, v4l2_buf_flag_def);
+	return flags;
+}
+
+unsigned long s2flags_fwht(std::string s)
+{
+	size_t idx = 0;
+	unsigned long flags = 0;
+	idx = s.find("V4L2_FWHT_FL_PIXENC_YUV");
+	if (idx != s.npos) {
+		flags += V4L2_FWHT_FL_PIXENC_YUV;
+		clean_string(idx, "V4L2_FWHT_FL_PIXENC_YUV", s);
+	}
+	idx = s.find("V4L2_FWHT_FL_PIXENC_RGB");
+	if (idx != s.npos) {
+		flags += V4L2_FWHT_FL_PIXENC_RGB;
+		clean_string(idx, "V4L2_FWHT_FL_PIXENC_RGB", s);
+	}
+	idx = s.find("V4L2_FWHT_FL_PIXENC_HSV");
+	if (idx != s.npos) {
+		flags += V4L2_FWHT_FL_PIXENC_HSV;
+		clean_string(idx, "V4L2_FWHT_FL_PIXENC_HSV", s);
+	}
+	if (!s.empty())
+		flags += s2flags(s, v4l2_ctrl_fwht_params_flag_def);
+	return flags;
+}
+
+std::string get_path_media(std::string driver)
+{
+	struct dirent *ep;
+	std::string path_media;
+	DIR *dp = opendir("/dev");
+	if (dp == nullptr)
+		return path_media;
+
+	while ((ep = readdir(dp))) {
+		const char *name = ep->d_name;
+		if (memcmp(name, "media", 5) || !isdigit(name[5]))
+			continue;
+
+		std::string media_devname = std::string("/dev/") + name;
+		setenv("V4L2_TRACER_PAUSE_TRACE", "true", 0);
+		int media_fd = open(media_devname.c_str(), O_RDONLY);
+		unsetenv("V4L2_TRACER_PAUSE_TRACE");
+		if (media_fd < 0)
+			continue;
+
+		struct media_device_info info = {};
+		if (ioctl(media_fd, MEDIA_IOC_DEVICE_INFO, &info) || info.driver != driver) {
+			setenv("V4L2_TRACER_PAUSE_TRACE", "true", 0);
+			close(media_fd);
+			unsetenv("V4L2_TRACER_PAUSE_TRACE");
+			continue;
+		} else {
+			path_media = media_devname;
+			setenv("V4L2_TRACER_PAUSE_TRACE", "true", 0);
+			close(media_fd);
+			unsetenv("V4L2_TRACER_PAUSE_TRACE");
+			break;
+		}
+	}
+	closedir(dp);
+	return path_media;
+}
+
+std::string get_path_video(int media_fd, std::list<std::string> linked_entities)
+{
+	int err = 0;
+	std::string path_video;
+	struct media_v2_topology topology = {};
+
+	err = ioctl(media_fd, MEDIA_IOC_G_TOPOLOGY, &topology);
+	if (err < 0)
+		return path_video;
+
+	auto ifaces = new media_v2_interface[topology.num_interfaces];
+	topology.ptr_interfaces = (uintptr_t)ifaces;
+	auto links = new media_v2_link[topology.num_links];
+	topology.ptr_links = (uintptr_t)links;
+	auto ents = new media_v2_entity[topology.num_entities];
+	topology.ptr_entities = (uintptr_t)ents;
+
+	err = ioctl(media_fd, MEDIA_IOC_G_TOPOLOGY, &topology);
+	if (err < 0) {
+		delete [] ifaces;
+		delete [] links;
+		delete [] ents;
+		return path_video;
+	}
+
+	for (auto &name : linked_entities) {
+		/* Find an entity listed in the video device's linked_entities. */
+		for (__u32 i = 0; i < topology.num_entities; i++) {
+			if (ents[i].name != name)
+				continue;
+			/* Find the first link connected to that entity. */
+			for (__u32 j = 0; j < topology.num_links; j++) {
+				if (links[j].sink_id != ents[i].id)
+					continue;
+				/* Find the interface connected to that link. */
+				for (__u32 k = 0; k < topology.num_interfaces; k++) {
+					if (ifaces[k].id != links[j].source_id)
+						continue;
+					std::string video_devname = mi_media_get_device(ifaces[k].devnode.major,
+					                                                ifaces[k].devnode.minor);
+					if (!video_devname.empty()) {
+						path_video = video_devname;
+						break;
+					}
+				}
+			}
+		}
+	}
+	return path_video;
+}
+
+std::list<std::string> get_linked_entities(int media_fd, std::string path_video)
+{
+	int err = 0;
+	std::list<std::string> linked_entities;
+	struct media_v2_topology topology = {};
+
+	err = ioctl(media_fd, MEDIA_IOC_G_TOPOLOGY, &topology);
+	if (err < 0)
+		return linked_entities;
+
+	auto ifaces = new media_v2_interface[topology.num_interfaces];
+	topology.ptr_interfaces = (uintptr_t)ifaces;
+	auto links = new media_v2_link[topology.num_links];
+	topology.ptr_links = (uintptr_t)links;
+	auto ents = new media_v2_entity[topology.num_entities];
+	topology.ptr_entities = (uintptr_t)ents;
+
+	err = ioctl(media_fd, MEDIA_IOC_G_TOPOLOGY, &topology);
+	if (err < 0) {
+		delete [] ifaces;
+		delete [] links;
+		delete [] ents;
+		return linked_entities;
+	}
+
+	/* find the interface corresponding to the path_video */
+	for (__u32 i = 0; i < topology.num_interfaces; i++) {
+		if (path_video != mi_media_get_device(ifaces[i].devnode.major, ifaces[i].devnode.minor))
+			continue;
+		/* find the links from that interface */
+		for (__u32 j = 0; j < topology.num_links; j++) {
+			if (links[j].source_id != ifaces[i].id)
+				continue;
+			/* find the entities connected by that link to the interface */
+			for (__u32 k = 0; k < topology.num_entities; k++) {
+				if (ents[k].id != links[j].sink_id)
+					continue;
+				linked_entities.push_back(ents[k].name);
+			}
+		}
+		if (linked_entities.size())
+			break;
+	}
+
+	delete [] ents;
+	delete [] links;
+	delete [] ifaces;
+
+	return linked_entities;
+}
diff --git a/utils/v4l2-tracer/v4l2-tracer-common.h b/utils/v4l2-tracer/v4l2-tracer-common.h
new file mode 100644
index 00000000..45544062
--- /dev/null
+++ b/utils/v4l2-tracer/v4l2-tracer-common.h
@@ -0,0 +1,82 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2022 Collabora Ltd.
+ */
+
+#ifndef V4L2_TRACER_COMMON_H
+#define V4L2_TRACER_COMMON_H
+
+#include <json.h>
+#include <poll.h>
+#include <stdio.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <dirent.h>
+#include <unistd.h>
+#include <getopt.h>
+#include <pthread.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <linux/media.h>
+#include <linux/videodev2.h>
+#include <list>
+#include <vector>
+#include <algorithm>
+#include <stdexcept>
+#include <unordered_map>
+#include "v4l2-info.h"
+#include "codec-fwht.h"
+#include "media-info.h"
+#include "config.h"
+
+#define STR(x) #x
+#define STRING(x) STR(x)
+
+struct val_def {
+	long val;
+	const char *str;
+};
+
+void print_v4l2_tracer_info(void);
+void print_usage(void);
+
+std::string ver2s(unsigned int version);
+std::string number2s_oct(long num);
+std::string number2s(long num);
+std::string val2s(long val, const val_def *def);
+std::string fl2s(unsigned val, const flag_def *def);
+std::string fl2s_buffer(__u32 flags);
+std::string fl2s_fwht(__u32 flags);
+
+long s2number(std::string s);
+long s2val(std::string s, const val_def *def);
+long s2ioctl(std::string s);
+unsigned long s2flags(std::string s, const flag_def *def);
+unsigned long s2flags_buffer(std::string s);
+unsigned long s2flags_fwht(std::string s);
+
+std::string which2s(unsigned long which);
+
+std::string get_path_media(std::string driver);
+std::string get_path_video(int media_fd, std::list<std::string> linked_entities);
+std::list<std::string> get_linked_entities(int media_fd, std::string path_video);
+
+#include "v4l2-tracer-info-gen.h"
+
+constexpr val_def which_val_def[] = {
+	{ V4L2_CTRL_WHICH_CUR_VAL,	"V4L2_CTRL_WHICH_CUR_VAL" },
+	{ V4L2_CTRL_WHICH_DEF_VAL,	"V4L2_CTRL_WHICH_DEF_VAL" },
+	{ V4L2_CTRL_WHICH_REQUEST_VAL,	"V4L2_CTRL_WHICH_REQUEST_VAL" },
+	{ -1, "" }
+};
+
+constexpr val_def open_val_def[] = {
+	{ O_RDONLY,	"O_RDONLY" },
+	{ O_WRONLY,	"O_WRONLY" },
+	{ O_RDWR,	"O_RDWR" },
+	{ -1, "" }
+};
+
+#endif
diff --git a/utils/v4l2-tracer/v4l2-tracer-gen.pl b/utils/v4l2-tracer/v4l2-tracer-gen.pl
new file mode 100755
index 00000000..595e5b04
--- /dev/null
+++ b/utils/v4l2-tracer/v4l2-tracer-gen.pl
@@ -0,0 +1,840 @@
+#!/usr/bin/perl
+# SPDX-License-Identifier: GPL-2.0-only */
+# Copyright 2022 Collabora Ltd.
+
+sub convert_type_to_json_type {
+	my $type = shift;
+	if ($type eq __u8 || $type eq char || $type eq __u16 || $type eq __s8 || $type eq __s16 || $type eq __s32 || $type eq 'int') {
+		return "int";
+	}
+	if ($type eq __u32 || $type eq __le32 || $type eq __s64) {
+		return "int64";
+	}
+
+	# unsigned appears just twice in videodev2.h and in both cases it is 'unsigned long'
+	if ($type eq __u64 || $type eq 'v4l2_std_id' || $type eq 'unsigned') {
+		return "uint64";
+	}
+	if ($type eq struct || $type eq union || $type eq void) {
+		return;
+	}
+	print "v4l2_tracer: error: couldn't convert \'$type\' to json_object type.\n";
+	return;
+}
+
+sub get_index_letter {
+	my $index = shift;
+	if ($index eq 0) {return "i";}
+	if ($index eq 1) {return "j";}
+	if ($index eq 2) {return "k";}
+	if ($index eq 3) {return "l";}
+	if ($index eq 4) {return "m";}
+	if ($index eq 5) {return "n";}
+	if ($index eq 6) {return "o";} # "p" is saved for pointer
+	if ($index eq 8) {return "q";}
+	return "z";
+}
+
+$flag_func_name;
+
+sub flag_gen {
+	my $flag_type = shift;
+
+	if ($flag_type =~ /fwht/) {
+		$flag_func_name = v4l2_ctrl_fwht_params_;
+	} elsif ($flag_type =~ /vp8_loop_filter/) {
+		$flag_func_name = v4l2_vp8_loop_filter_;
+	} else {
+		($flag_func_name) = ($_) =~ /#define (\w+_)FL.+/;
+		$flag_func_name = lc $flag_func_name;
+	}
+
+	printf $fh_common_info_h "constexpr flag_def %sflag_def[] = {\n", $flag_func_name;
+
+	($flag) = ($_) =~ /#define\s+(\w+)\s+.+/;
+	printf $fh_common_info_h "\t{ $flag, \"$flag\" },\n"; # get the first flag
+
+	while (<>) {
+		next if ($_ =~ /^\/?\s?\*.*/); # skip comments between flags if any
+		next if $_ =~ /^\s*$/; # skip blank lines between flags if any
+		last if ((grep {!/^#define\s+\w+_FL/} $_) && (grep {!/^#define V4L2_VP8_LF/} $_));
+		($flag) = ($_) =~ /#\s*define\s+(\w+)\s+.+/;
+
+		# don't include flags that are masks
+		next if ($flag_func_name eq v4l2_buf_) && ($flag =~ /.*TIMESTAMP.*/ || $flag =~ /.*TSTAMP.*/);
+		next if ($flag_func_name eq v4l2_ctrl_fwht_params_) && ($flag =~ /.*COMPONENTS.*/ || $flag =~ /.*PIXENC.*/);
+		next if ($flag =~ /.*MEDIA_LNK_FL_LINK_TYPE.*/);
+		next if ($flag =~ /.*MEDIA_ENT_ID_FLAG_NEXT.*/);
+
+		printf $fh_common_info_h "\t{ $flag, \"$flag\" },\n";
+	}
+	printf $fh_common_info_h "\t{ 0, \"\" }\n};\n\n";
+}
+
+sub enum_gen {
+	($enum_name) = ($_) =~ /enum (\w+) {/;
+	printf $fh_common_info_h "constexpr val_def %s_val_def[] = {\n", $enum_name;
+	while (<>) {
+		last if $_ =~ /};/;
+		($name) = ($_) =~ /\s+(\w+)\s?.*/;
+		next if ($name ne uc $name); # skip comments that don't start with *
+		next if ($_ =~ /^\s*\/?\s?\*.*/); # skip comments
+		next if $name =~ /^\s*$/;  # skip blank lines
+		printf $fh_common_info_h "\t{ %s,\t\"%s\" },\n", $name, $name;
+	}
+	printf $fh_common_info_h "\t{ -1, \"\" }\n};\n\n";
+}
+
+sub clean_up_line {
+	my $line = shift;
+	chomp($line);
+	$line =~ s/^\s+//; # remove leading whitespace
+	$line =~ s/.*\# define.*//; # zero out line if it has defines inside a structure (e.g. v4l2_jpegcompression)
+	$line =~ s/^\s*\/?\s?\*.*//; # zero out line if it has comments where the line starts with start with /* / * or just *
+	$line =~ s/\s*\/\*.*//; # remove comments at the end of a line following a member
+	$line =~ s/\*\/$//; # zero out line if it has comments that begin without any slashs or asterisks but end with */
+	# zero out lines that don't have a ; or { because they are comments but without any identifying slashes or asteriks
+	if ($line !~ /.*[\;|\{].*/) {
+		$line =~ s/.*//;
+	}
+	$line =~ s/.*reserved.*//; # zero out lines with reserved members, they will segfault on retracing
+	$line =~ s/.*raw_data.*//;
+	# don't remove semi-colon at end because some functions will look for it
+	return $line;
+}
+
+sub get_val_def_name {
+	my @params = @_;
+	my $member = @params[0];
+	my $struct_name = @params[1];
+
+	$val_def_name = "";
+	if ($member =~ /type/) {
+		if ($struct_name =~ /.*fmt|format|buf|parm|crop|selection|vbi.*/) {
+			$val_def_name = "v4l2_buf_type_val_def";
+		} elsif ($struct_name =~ /ctrl$/) {
+			$val_def_name = "v4l2_ctrl_type_val_def";
+		} else {
+			$val_def_name = "nullptr"; # will print as hex string
+		}
+	}
+	if ($member =~ /pixelformat/) {
+		$val_def_name = "v4l2_pix_fmt_val_def";
+	}
+	if ($member =~ /cmd/) {
+		if ($struct_name =~ /v4l2_decoder_cmd/) {
+			$val_def_name = "decoder_cmd_val_def";
+		}
+		if ($struct_name =~ /v4l2_encoder_cmd/) {
+			$val_def_name = "encoder_cmd_val_def";
+		}
+	}
+	if ($member =~ /memory/) {
+		$val_def_name = "v4l2_memory_val_def";
+	}
+	if ($member =~ /field/) {
+		if ($struct_name =~ /.*pix|buffer.*/) {
+			$val_def_name = "v4l2_field_val_def";
+		} else {
+			$val_def_name = "nullptr"; # will print as hex string
+		}
+	}
+	if ($member =~ /^id$/) {
+		if ($struct_name =~ /.*control|query.*/) {
+			$val_def_name = "control_val_def";
+		} else {
+			$val_def_name = "nullptr"; # will print as hex string
+		}
+	}
+	if ($member =~ /capability|outputmode|capturemode/) {
+		if ($struct_name =~ /.*v4l2_captureparm|v4l2_outputparm.*/) {
+		$val_def_name = "streamparm_val_def";
+		}
+	}
+	if ($member =~ /colorspace/) {
+		$val_def_name = "v4l2_colorspace_val_def";
+	}
+	if ($member =~ /ycbcr_enc/) {
+		$val_def_name = "v4l2_ycbcr_encoding_val_def";
+	}
+	if ($member =~ /quantization/) {
+		$val_def_name = "v4l2_quantization_val_def";
+	}
+	if ($member =~ /xfer_func/) {
+		$val_def_name = "v4l2_xfer_func_val_def";
+	}
+
+	return $val_def_name;
+}
+
+sub get_flag_def_name {
+	my @params = @_;
+	my $member = @params[0];
+	my $struct_name = @params[1];
+
+	$flag_def_name = "";
+	if ($member =~ /flags/) {
+		if ($struct_name =~ /buffers$/) {
+			$flag_def_name = "v4l2_memory_flag_def";
+		} elsif ($struct_name =~ /.*pix_format.*/) {
+			$flag_def_name = "v4l2_pix_fmt_flag_def";
+		} elsif ($struct_name =~ /.*ctrl$/) {
+			$flag_def_name = "v4l2_ctrl_flag_def";
+		} elsif ($struct_name =~ /.*fmtdesc$/) {
+			$flag_def_name = "v4l2_fmt_flag_def";
+		} elsif ($struct_name =~ /.*selection$/) {
+			$flag_def_name = "v4l2_sel_flag_def";
+		} else {
+			$flag_def_name = "nullptr"
+		}
+	}
+
+	if ($member =~ /.*cap.*/) {
+		# v4l2_requestbuffers, v4l2_create_buffers
+		if ($struct_name =~ /buffers$/) {
+			$flag_def_name = "v4l2_buf_cap_flag_def";
+		}
+		# v4l2_capability
+		if ($struct_name =~ /capability$/) {
+			$flag_def_name = "v4l2_cap_flag_def";
+		}
+	}
+
+	return $flag_def_name;
+}
+
+# trace a struct nested in another struct in videodev2.h
+sub handle_struct {
+	printf $fh_trace_cpp "\t//$line\n";
+	printf $fh_retrace_cpp "\t//$line\n";
+
+	# this is a multi-lined nested struct so iterate through it
+	if ($line !~ /.*;$/) {
+		$suppress_struct = true;
+		return;
+	}
+
+	# don't trace struct pointers
+	if ($line =~ /\*/) {
+		return;
+	}
+	# don't trace struct arrays
+	if ($line =~ /\[/) {
+		return;
+	}
+
+	my ($struct_tag) = ($line) =~ /\s*struct (\w+)\s+.*/;
+
+	# structs defined outside of videodev2.h
+	if ($struct_tag =~ /v4l2_ctrl|timeval|timespec/) {
+		return;
+	}
+
+	my ($struct_var) = ($line) =~ /(\w+)\;$/;
+	printf $fh_trace_cpp "\ttrace_%s_gen(&p->%s, %s_obj, \"%s\");\n", $struct_tag, $struct_var, $struct_name, $struct_var;
+	printf $fh_retrace_cpp "\tp->$struct_var = *retrace_%s_gen(%s_obj, \"%s\");\n\n", $struct_tag, $struct_name, $struct_var;
+}
+
+# trace a union in videodev2.h
+sub handle_union {
+	my @params = @_;
+	my $struct_name = @params[0];
+
+	$in_union = true;
+	$suppress_union = true;
+	printf $fh_trace_cpp "\t//union\n";
+	printf $fh_retrace_cpp "\t//union\n";
+
+	if ($struct_name =~ /^v4l2_pix_format/) {
+		$suppress_union = false;
+	}
+
+	if ($struct_name =~ /^v4l2_format$/) {
+		printf $fh_trace_cpp "\tswitch (p->type) {\n";
+		printf $fh_trace_cpp "\tcase V4L2_BUF_TYPE_VIDEO_CAPTURE:\n\tcase V4L2_BUF_TYPE_VIDEO_OUTPUT:\n";
+		printf $fh_trace_cpp "\t\ttrace_v4l2_pix_format_gen(&p->fmt.pix, %s_obj);\n\t\tbreak;\n", $struct_name;
+		printf $fh_trace_cpp "\tcase V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE:\n\tcase V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE:\n";
+		printf $fh_trace_cpp "\t\ttrace_v4l2_pix_format_mplane_gen(&p->fmt.pix, %s_obj);\n\t\tbreak;\n", $struct_name;
+		printf $fh_trace_cpp "\tdefault:\n\t\tbreak;\n\t}\n";
+
+		printf $fh_retrace_cpp "\tswitch (p->type) {\n";
+		printf $fh_retrace_cpp "\tcase V4L2_BUF_TYPE_VIDEO_CAPTURE:\n\tcase V4L2_BUF_TYPE_VIDEO_OUTPUT:\n";
+		printf $fh_retrace_cpp "\t\tp->fmt.pix = *retrace_v4l2_pix_format_gen(%s_obj);\n\t\tbreak;\n", $struct_name;
+		printf $fh_retrace_cpp "\tcase V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE:\n\tcase V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE:\n";
+		printf $fh_retrace_cpp "\t\tp->fmt.pix_mp = *retrace_v4l2_pix_format_mplane_gen(%s_obj);\n\t\tbreak;\n", $struct_name;
+		printf $fh_retrace_cpp "\tdefault:\n\t\tbreak;\n\t}\n";
+	}
+
+	return $suppress_union;
+}
+
+# generate functions for structs in videodev2.h
+sub struct_gen {
+	($struct_name) = ($_) =~ /struct (\w+) {/;
+
+	# it's not being used and was generating a warning
+	if ($struct_name =~ /v4l2_mpeg_vbi_ITV0/) {
+		return;
+	}
+	printf $fh_trace_cpp "void trace_%s_gen(void *arg, json_object *parent_obj, std::string key_name = \"\")\n{\n", $struct_name;
+	printf $fh_trace_h "void trace_%s_gen(void *arg, json_object *parent_obj, std::string key_name = \"\");\n", $struct_name;
+	printf $fh_trace_cpp "\tjson_object *%s_obj = json_object_new_object();\n", $struct_name;
+	printf $fh_trace_cpp "\tstruct %s *p = static_cast<struct %s*>(arg);\n\n", $struct_name, $struct_name;
+
+	printf $fh_retrace_h "struct %s *retrace_%s_gen(json_object *parent_obj, std::string key_name = \"\");\n", $struct_name, $struct_name;
+	printf $fh_retrace_cpp "struct %s *retrace_%s_gen(json_object *parent_obj, std::string key_name = \"\")\n{\n", $struct_name, $struct_name;
+
+	printf $fh_retrace_cpp "\tstruct %s *p = (struct %s *) calloc(1, sizeof(%s));\n\n", $struct_name, $struct_name, $struct_name;
+	printf $fh_retrace_cpp "\tjson_object *%s_obj;\n", $struct_name;
+	printf $fh_retrace_cpp "\tif (key_name.empty())\n";
+	printf $fh_retrace_cpp "\t\tjson_object_object_get_ex(parent_obj, \"%s\", &%s_obj);\n", $struct_name, $struct_name;
+	printf $fh_retrace_cpp "\telse\n";
+	printf $fh_retrace_cpp "\t\tjson_object_object_get_ex(parent_obj, key_name.c_str(), &%s_obj);\n\n", $struct_name;
+
+	$suppress_union = false;
+	$suppress_struct = false;
+	while ($line = <>) {
+		chomp($line);
+		$member = "";
+		if ($line =~ /}.*;/) {
+			if ($suppress_struct eq true) {
+				printf $fh_trace_cpp "\t//end of struct $line\n";
+				printf $fh_retrace_cpp "\t//end of struct $line\n";
+				$suppress_struct = false;
+				next;
+			} elsif ($in_union eq true) {
+				if ($suppress_union eq true) {
+					$suppress_union = false; # end of union
+				}
+				printf $fh_trace_cpp "\t//end of union $line\n";
+				printf $fh_retrace_cpp "\t//end of union $line\n";
+				$in_union = false;
+				next;
+			} else {
+				last;
+			}
+		}
+		last if $line =~ /^} __attribute__.*/;
+
+		$line = clean_up_line($line);
+		next if $line =~ /^\s*$/; # ignore blank lines
+
+		@words = split /[\s\[]/, $line; # split on whitespace and also'[' to get char arrays
+		@words = grep  {/^\D/} @words; # remove values that start with digit from inside []
+		@words = grep  {!/\]/} @words; # remove values with brackets e.g. V4L2_H264_REF_LIST_LEN]
+
+		($type) = $words[0];
+
+		# unions inside the struct
+		if ($type eq 'union') {
+			handle_union($struct_name);
+			next;
+		}
+		# suppress anything inside a union including structs nested inside a union
+		if ($suppress_union eq true) {
+			printf $fh_trace_cpp "\t//$line\n";
+			printf $fh_retrace_cpp "\t//$line\n";
+			next;
+		}
+
+		# struct members inside the struct
+		if ($type eq 'struct') {
+			handle_struct();
+			next;
+		}
+		if ($suppress_struct eq true) {
+			printf $fh_trace_cpp "\t//$line\n";
+			printf $fh_retrace_cpp "\t//$line\n";
+			next;
+		}
+
+		$json_type = convert_type_to_json_type($type);
+
+		($member) = $words[scalar @words - 1];
+		$member =~ s/;//; # remove the ;
+
+		if ($member =~ /service_lines/) {
+			printf $fh_trace_cpp "\t//$line\n";
+			printf $fh_retrace_cpp "\t//$line\n";
+			next;
+		}
+
+		# Don't trace members that are pointers
+		if ($member =~ /\*/) {
+			printf $fh_trace_cpp "\t//$line\n";
+			printf $fh_retrace_cpp "\t//$line\n";
+			next;
+		}
+
+		if ($line =~ /dims\[V4L2_CTRL_MAX_DIMS\]/) {
+			printf $fh_trace_cpp "\t\/\* $line \*\/\n"; # add comment
+			printf $fh_trace_cpp "\tjson_object *dims_obj = json_object_new_array();\n";
+			printf $fh_trace_cpp "\tfor (int i = 0; i < (std::min((int) p->nr_of_dims, V4L2_CTRL_MAX_DIMS)); i++) {\n";
+			printf $fh_trace_cpp "\t\tjson_object_array_add(dims_obj, json_object_new_int64(p->dims[i]));\n\t}\n";
+			printf $fh_trace_cpp "\tjson_object_object_add(%s_obj, \"$member\", dims_obj);\n", $struct_name;
+
+			printf $fh_retrace_cpp "\t\/\* $line \*\/\n"; # add comment
+			printf $fh_retrace_cpp "\tjson_object *dims_obj;\n";
+			printf $fh_retrace_cpp "\tif (json_object_object_get_ex(%s_obj, \"$member\", &%s_obj)) {\n", $struct_name, $member;
+			printf $fh_retrace_cpp "\t\tfor (int i = 0; i < (std::min((int) p->nr_of_dims, V4L2_CTRL_MAX_DIMS)); i++) {\n";
+			printf $fh_retrace_cpp "\t\t\tif (json_object_array_get_idx(dims_obj, i))\n";
+			printf $fh_retrace_cpp "\t\t\t\tp->dims[i] = (__u32) json_object_get_int64(json_object_array_get_idx(dims_obj, i));\n\t\t}\n\t}\n";
+			next;
+		}
+
+		printf $fh_retrace_cpp "\tjson_object *%s_obj;\n", $member;
+
+		# struct v4l2_pix_format
+		if ($member =~ /priv/) {
+			printf $fh_trace_cpp "\tif (p->priv == V4L2_PIX_FMT_PRIV_MAGIC)\n";
+			printf $fh_trace_cpp "\t\tjson_object_object_add(%s_obj, \"%s\", json_object_new_string(\"V4L2_PIX_FMT_PRIV_MAGIC\"));\n", $struct_name, $member;
+			printf $fh_trace_cpp "\telse\n";
+			printf $fh_trace_cpp "\t\tjson_object_object_add(%s_obj, \"%s\", json_object_new_string(\"\"));\n", $struct_name, $member;
+
+			printf $fh_retrace_cpp "\tif (json_object_object_get_ex(%s_obj, \"$member\", &%s_obj)) {\n", $struct_name, $member;
+			printf $fh_retrace_cpp "\t\tif (!json_object_get_string(priv_obj))\n\t\t\treturn p;\n";
+			printf $fh_retrace_cpp "\t\tstd::string priv_str = json_object_get_string(priv_obj);\n";
+			printf $fh_retrace_cpp "\t\tif (!priv_str.empty())\n";
+			printf $fh_retrace_cpp "\t\t\tp->priv = V4L2_PIX_FMT_PRIV_MAGIC;\n\t}\n";
+			next;
+		}
+
+		printf $fh_trace_cpp "\tjson_object_object_add(%s_obj, \"%s\", json_object_new_", $struct_name, $member;
+		printf $fh_retrace_cpp "\tif (json_object_object_get_ex(%s_obj, \"$member\", &%s_obj))\n", $struct_name, $member;
+
+		# Convert char array members to string
+		if ($line =~ /.*\[.*/) {
+			if ($member =~ /.*name|driver|card|bus_info|description|model|magic|serial|userbits|APP_data|COM_data|linemask|data|start|count|raw|.*/) {
+				printf $fh_trace_cpp "string(reinterpret_cast<const char *>(p->$member)));\n";
+
+				my @char_array_size = ($line) =~ /\[(\w+)\]/g;
+				printf $fh_retrace_cpp "\t\tmemcpy(p->$member, json_object_get_string(%s_obj), @char_array_size);\n\n", $member;
+				next;
+			}
+		}
+
+		# special strings
+		if ($member =~ /version/) {
+			printf $fh_trace_cpp "string(ver2s(p->$member).c_str()));\n";
+			printf $fh_retrace_cpp "\t\tmemset(&p->$member, 0, sizeof(p->$member));\n\n"; # driver can fill in version
+			next;
+		}
+
+		printf $fh_retrace_cpp "\t\tp->$member = ";
+
+		if ($struct_name =~ /^v4l2_buffer$/) {
+			if ($member =~ /flags/) {
+				printf $fh_trace_cpp "string(fl2s_buffer(p->$member).c_str()));\n";
+				printf $fh_retrace_cpp "(%s) s2flags_buffer(json_object_get_string(%s_obj));\n\n", $type, $member, $flag_def_name;
+				next;
+			}
+		}
+
+		# strings
+		$val_def_name = get_val_def_name($member, $struct_name);
+		if ($val_def_name !~ /^\s*$/) {
+			printf $fh_trace_cpp "string(val2s(p->$member, %s).c_str()));\n", $val_def_name;
+			printf $fh_retrace_cpp "(%s) s2val(json_object_get_string(%s_obj), %s);\n", $type,  $member, $val_def_name;
+			next;
+		}
+
+		$flag_def_name = get_flag_def_name($member, $struct_name);
+		if ($flag_def_name !~ /^\s*$/) {
+			printf $fh_trace_cpp "string(fl2s(p->$member, %s).c_str()));\n", $flag_def_name;
+			printf $fh_retrace_cpp "(%s) s2flags(json_object_get_string(%s_obj), %s);\n\n", $type, $member, $flag_def_name;
+			next;
+		}
+
+		# integers
+		printf $fh_trace_cpp "$json_type(p->$member));\n";
+		printf $fh_retrace_cpp "(%s) json_object_get_%s(%s_obj);\n\n", $type, $json_type, $member;
+
+		# special treatment for v4l2_pix_format_mplane member plane_fmt[VIDEO_MAX_PLANES]
+		# it can only be traced after num_planes is known
+		if ($member =~ /num_planes/) {
+			printf $fh_trace_cpp "\tjson_object *plane_fmt_obj = json_object_new_array();\n";
+			printf $fh_trace_cpp "\tfor (int i = 0; i < (std::min((int) p->num_planes, VIDEO_MAX_PLANES)); i++) {\n";
+			printf $fh_trace_cpp "\t\tjson_object *element_obj = json_object_new_object();\n";
+			printf $fh_trace_cpp "\t\ttrace_v4l2_plane_pix_format_gen(&(p->plane_fmt[i]), element_obj);\n";
+			printf $fh_trace_cpp "\t\tjson_object *element_no_key_obj;\n";
+			printf $fh_trace_cpp "\t\tjson_object_object_get_ex(element_obj, \"v4l2_plane_pix_format\", &element_no_key_obj);\n";
+			printf $fh_trace_cpp "\t\tjson_object_array_add(plane_fmt_obj, element_no_key_obj);\n\t}\n";
+			printf $fh_trace_cpp "\tjson_object_object_add(v4l2_pix_format_mplane_obj, \"plane_fmt\", plane_fmt_obj);\n\n";
+
+			printf $fh_retrace_cpp "\tjson_object *plane_fmt_obj;\n";
+			printf $fh_retrace_cpp "\tif (json_object_object_get_ex(v4l2_pix_format_mplane_obj, \"plane_fmt\", &plane_fmt_obj)) {\n";
+			printf $fh_retrace_cpp "\t\tfor (int i = 0; i < (std::min((int) p->num_planes, VIDEO_MAX_PLANES)); i++) {\n";
+			printf $fh_retrace_cpp "\t\t\tif (json_object_array_get_idx(plane_fmt_obj, i)) {\n";
+			printf $fh_retrace_cpp "\t\t\t\tjson_object *element_obj = json_object_new_object();\n";
+			printf $fh_retrace_cpp "\t\t\t\tjson_object_object_add(element_obj, \"v4l2_plane_pix_format\", json_object_array_get_idx(plane_fmt_obj, i));\n";
+			printf $fh_retrace_cpp "\t\t\t\tp->plane_fmt[i] = *retrace_v4l2_plane_pix_format_gen(element_obj);\n";
+			printf $fh_retrace_cpp "\t\t\t}\n\t\t}\n\t}\n\n";
+		}
+	}
+
+	# The key name option allows a struct to be traced when it is nested inside another struct.
+	printf $fh_trace_cpp "\n\tif (key_name.empty())\n";
+	printf $fh_trace_cpp "\t\tjson_object_object_add(parent_obj, \"%s\", %s_obj);\n", $struct_name, $struct_name;
+	printf $fh_trace_cpp "\telse\n";
+	printf $fh_trace_cpp "\t\tjson_object_object_add(parent_obj, key_name.c_str(), %s_obj);\n", $struct_name;
+	printf $fh_trace_cpp "}\n\n";
+
+	printf $fh_retrace_cpp "\treturn p;\n}\n";
+}
+
+# generate functions for structs in v4l2-controls.h
+sub struct_gen_ctrl {
+	($struct_name) = ($_) =~ /struct (\w+) {/;
+
+	printf $fh_trace_h "void trace_%s_gen(void *ptr, json_object *parent_obj);\n", $struct_name;
+	printf $fh_trace_cpp "void trace_%s_gen(void *ptr, json_object *parent_obj)\n{\n", $struct_name;
+	printf $fh_trace_cpp "\tjson_object *%s_obj = json_object_new_object();\n", $struct_name;
+	printf $fh_trace_cpp "\tstruct %s *p = static_cast<struct %s*>(ptr);\n", $struct_name, $struct_name;
+
+	printf $fh_retrace_h "struct %s *retrace_%s_gen(json_object *ctrl_obj);\n", $struct_name, $struct_name;
+	printf $fh_retrace_cpp "struct %s *retrace_%s_gen(json_object *ctrl_obj)\n{\n", $struct_name, $struct_name;
+	printf $fh_retrace_cpp "\tstruct %s *p = (struct %s *) calloc(1, sizeof(%s));\n", $struct_name, $struct_name, $struct_name;
+	printf $fh_retrace_cpp "\tjson_object *%s_obj;\n", $struct_name;
+	# if a key value isn't found, assume it is retracing an element of an array
+	# e.g. in struct v4l2_ctrl_h264_pred_weights
+	printf $fh_retrace_cpp "\tif (!json_object_object_get_ex(ctrl_obj, \"%s\", &%s_obj))\n", $struct_name, $struct_name;
+	printf $fh_retrace_cpp "\t\t%s_obj = ctrl_obj;\n", $struct_name;
+
+	while ($line = <>) {
+		chomp($line);
+		last if $line =~ /};/;
+		$line = clean_up_line($line);
+		next if $line =~ /^\s*$/; # ignore blank lines
+		$line =~ s/;$//; # remove semi-colon at the end
+		@words = split /[\s\[]/, $line; # also split on '[' to avoid arrays
+		@words = grep  {/^\D/} @words; # remove values that start with digit from inside []
+		@words = grep  {!/\]/} @words; # remove values with brackets e.g. V4L2_H264_REF_LIST_LEN]
+
+		($type) = $words[0];
+		$json_type = convert_type_to_json_type($type);
+
+		($member) = $words[scalar @words - 1];
+
+		# generate members that are arrays
+		if ($line =~ /.*\[.*/) {
+			printf $fh_trace_cpp "\t\/\* %s \*\/\n", $line; # add comment
+			printf $fh_trace_cpp "\tjson_object *%s_obj = json_object_new_array();\n", $member;
+			printf $fh_retrace_cpp "\n\t\/\* %s \*\/\n", $line; # add comment
+
+			my @dimensions = ($line) =~ /\[(\w+)\]/g;
+			$dimensions_count = scalar @dimensions;
+
+			if ($dimensions_count > 1) {
+				printf $fh_retrace_cpp "\tint count_%s = 0;\n", $member;
+			}
+			printf $fh_retrace_cpp "\tjson_object *%s_obj;\n", $member;
+			printf $fh_retrace_cpp "\tif (json_object_object_get_ex(%s_obj, \"%s\", &%s_obj)) {\n", $struct_name, $member, $member;
+
+			for (my $idx = 0; $idx < $dimensions_count; $idx = $idx + 1) {
+				$size = $dimensions[$idx];
+				$index_letter = get_index_letter($idx);
+				printf $fh_trace_cpp "\t" x ($idx + 1);
+				printf $fh_trace_cpp "for (size_t %s = 0; %s < %s\; %s++) {\n", $index_letter, $index_letter, $size, $index_letter;
+
+				printf $fh_retrace_cpp "\t" x ($idx + 1);
+				printf $fh_retrace_cpp "\t";
+				printf $fh_retrace_cpp "for (size_t %s = 0; %s < %s\; %s++) {\n", $index_letter, $index_letter, $size, $index_letter;
+			}
+			printf $fh_trace_cpp "\t" x ($dimensions_count + 1);
+			printf $fh_retrace_cpp "\t" x ($dimensions_count + 1);
+			printf $fh_retrace_cpp "\t";
+
+			# handle arrays of structs
+			if ($type =~ /struct/) {
+				my $struct_name_nested = @words[1];
+				printf $fh_trace_cpp "json_object *element_obj = json_object_new_object();\n";
+				printf $fh_trace_cpp "\t" x ($dimensions_count + 1);
+				printf $fh_trace_cpp "trace_%s_gen(&(p->%s", $struct_name_nested, $member;
+				for (my $idx = 0; $idx < $dimensions_count; $idx = $idx + 1) {
+					printf $fh_trace_cpp "[%s]", get_index_letter($idx);
+				}
+				printf $fh_trace_cpp "), element_obj);\n";
+				printf $fh_trace_cpp "\t" x ($dimensions_count + 1);
+				printf $fh_trace_cpp "json_object *element_no_key_obj;\n";
+				printf $fh_trace_cpp "\t" x ($dimensions_count + 1);
+				printf $fh_trace_cpp "json_object_object_get_ex(element_obj, \"%s\", &element_no_key_obj);\n", $struct_name_nested;
+				printf $fh_trace_cpp "\t" x ($dimensions_count + 1);
+				printf $fh_trace_cpp "json_object_array_add(%s_obj, element_no_key_obj);\n", $member;
+
+				printf $fh_retrace_cpp "p->%s", $member;
+				for (my $idx = 0; $idx < $dimensions_count; $idx = $idx + 1) {
+					printf $fh_retrace_cpp "[%s]", get_index_letter($idx);
+				}
+				printf $fh_retrace_cpp " = *retrace_%s_gen(json_object_array_get_idx(%s_obj, ", $struct_name_nested, $member;
+				if ($dimensions_count > 1) {
+					printf $fh_retrace_cpp "count_%s++", $member;
+				} else {
+					printf $fh_retrace_cpp "i";
+				}
+				printf $fh_retrace_cpp "));\n";
+			} else {
+				# handle arrays of ints
+				printf $fh_trace_cpp "json_object_array_add(%s_obj, json_object_new_%s(p->%s", $member, $json_type, $member;
+				for (my $idx = 0; $idx < $dimensions_count; $idx = $idx + 1) {
+					printf $fh_trace_cpp "[%s]", get_index_letter($idx);
+				}
+				printf $fh_trace_cpp "));\n";
+
+				# add a check to avoid accessing a null array index
+				printf $fh_retrace_cpp "if (json_object_array_get_idx(%s_obj, ", $member;
+				if ($dimensions_count > 1) {
+					printf $fh_retrace_cpp "count_%s", $member;
+				} else {
+					printf $fh_retrace_cpp "i";
+				}
+				printf $fh_retrace_cpp "))\n";
+
+				printf $fh_retrace_cpp "\t" x ($dimensions_count + 1);
+				printf $fh_retrace_cpp "\t\t";
+				printf $fh_retrace_cpp "p->%s", $member;
+				for (my $idx = 0; $idx < $dimensions_count; $idx = $idx + 1) {
+					printf $fh_retrace_cpp "[%s]", get_index_letter($idx);
+				}
+
+				printf $fh_retrace_cpp " = ($type) json_object_get_%s(json_object_array_get_idx(%s_obj, ", $json_type, $member;
+				if ($dimensions_count > 1) {
+					printf $fh_retrace_cpp "count_%s++", $member;
+				} else {
+					printf $fh_retrace_cpp "i";
+				}
+				printf $fh_retrace_cpp "));\n";
+			}
+			# closing brackets for all array types
+			for (my $idx = $dimensions_count - 1; $idx >= 0 ; $idx = $idx - 1) {
+				printf $fh_trace_cpp "\t" x ($idx + 1);
+				printf $fh_trace_cpp "}\n";
+
+				printf $fh_retrace_cpp "\t" x ($idx + 1);
+				printf $fh_retrace_cpp "\t";
+				printf $fh_retrace_cpp "}\n";
+			}
+			printf $fh_retrace_cpp "\t}\n";
+			printf $fh_trace_cpp "\tjson_object_object_add(%s_obj, \"%s\", %s_obj);\n\n", $struct_name, $member, $member;
+		} elsif ($type =~ /struct/) {
+			# member that is a struct but not an array of structs
+			my $struct_name_nested = @words[1];
+			printf $fh_trace_cpp "\t\/\* %s \*\/\n", $line;
+			printf $fh_trace_cpp "\ttrace_%s_gen(&(p->%s), %s_obj);\n", $struct_name_nested, $member, $struct_name;
+
+			printf $fh_retrace_cpp "\t\/\* %s \*\/\n", $line;
+			printf $fh_retrace_cpp "\tjson_object *%s_obj;\n", $member;
+			printf $fh_retrace_cpp "\tjson_object_object_get_ex(%s_obj, \"%s\", &%s_obj);\n", $struct_name, $struct_name_nested, $member;
+			printf $fh_retrace_cpp "\tp->%s = \*retrace_%s_gen(%s_obj);\n\n", $member, $struct_name_nested, $member;
+		} else {
+			printf $fh_trace_cpp "\tjson_object_object_add(%s_obj, \"%s\", json_object_new_", $struct_name, $member;
+			printf $fh_retrace_cpp "\n\tjson_object *%s_obj;\n", $member;
+			printf $fh_retrace_cpp "\tif (json_object_object_get_ex(%s_obj, \"%s\", &%s_obj))\n", $struct_name, $member, $member;
+
+			# strings
+			if ($member =~ /flags/) {
+				if ($struct_name eq "v4l2_ctrl_fwht_params") {
+					printf $fh_trace_cpp "string(fl2s_fwht(p->$member).c_str()));\n";
+					printf $fh_retrace_cpp "\t\tp->%s = ($type) s2flags_fwht(json_object_get_string(%s_obj));\n", $member, $member, $flag_func_name;
+				} else {
+					printf $fh_trace_cpp "string(fl2s(p->$member, %sflag_def).c_str()));\n", $flag_func_name;
+					printf $fh_retrace_cpp "\t\tp->%s = ($type) s2flags(json_object_get_string(%s_obj), %sflag_def);\n", $member, $member, $flag_func_name;
+				}
+				next;
+			}
+
+			# Add members with a single string value (e.g. enums, #define)
+			$val_def_name = get_val_def_name($member, $struct_name);
+			if ($val_def_name !~ /^\s*$/) {
+				printf $fh_trace_cpp "string(val2s(p->$member, %s).c_str()));\n", $val_def_name;
+				printf $fh_retrace_cpp "\t\tp->%s = ($type) s2val(json_object_get_string(%s_obj), $val_def_name);\n", $member, $member;
+				next;
+			}
+
+			# integers
+			printf $fh_trace_cpp "%s(p->%s));\n", $json_type, $member;
+			printf $fh_retrace_cpp "\t\tp->%s = ($type) json_object_get_%s(%s_obj);\n", $member, $json_type, $member;
+		}
+	}
+	printf $fh_trace_cpp "\tjson_object_object_add(parent_obj, \"%s\", %s_obj);\n", $struct_name, $struct_name;
+	printf $fh_trace_cpp "}\n\n";
+
+	printf $fh_retrace_cpp "\n\treturn p;\n";
+	printf $fh_retrace_cpp "}\n\n";
+}
+
+open($fh_trace_cpp, '>', 'trace-gen.cpp') or die "Could not open trace-gen.cpp for writing";
+printf $fh_trace_cpp "/* SPDX-License-Identifier: GPL-2.0-only */\n/*\n * Copyright 2022 Collabora Ltd.\n */\n\n";
+printf $fh_trace_cpp "#include \"v4l2-tracer-common.h\"\n\n";
+
+open($fh_trace_h, '>', 'trace-gen.h') or die "Could not open trace-gen.h for writing";
+printf $fh_trace_h "/* SPDX-License-Identifier: GPL-2.0-only */\n/*\n * Copyright 2022 Collabora Ltd.\n */\n\n";
+printf $fh_trace_h "\#ifndef TRACE_GEN_H\n";
+printf $fh_trace_h "\#define TRACE_GEN_H\n\n";
+
+open($fh_retrace_cpp, '>', 'retrace-gen.cpp') or die "Could not open retrace-gen.cpp for writing";
+printf $fh_retrace_cpp "/* SPDX-License-Identifier: GPL-2.0-only */\n/*\n * Copyright 2022 Collabora Ltd.\n */\n\n";
+printf $fh_retrace_cpp "#include \"v4l2-tracer-common.h\"\n\n";
+
+open($fh_retrace_h, '>', 'retrace-gen.h') or die "Could not open retrace-gen.h for writing";
+printf $fh_retrace_h "/* SPDX-License-Identifier: GPL-2.0-only */\n/*\n * Copyright 2022 Collabora Ltd.\n */\n\n";
+printf $fh_retrace_h "\#ifndef RETRACE_GEN_H\n";
+printf $fh_retrace_h "\#define RETRACE_GEN_H\n\n";
+
+open($fh_common_info_h, '>', 'v4l2-tracer-info-gen.h') or die "Could not open v4l2-tracer-info-gen.h for writing";
+printf $fh_common_info_h "/* SPDX-License-Identifier: GPL-2.0-only */\n/*\n * Copyright 2022 Collabora Ltd.\n */\n\n";
+printf $fh_common_info_h "\#ifndef V4L2_TRACER_INFO_GEN_H\n";
+printf $fh_common_info_h "\#define V4L2_TRACER_INFO_GEN_H\n\n";
+printf $fh_common_info_h "#include \"v4l2-tracer-common.h\"\n\n";
+
+$in_v4l2_controls = true;
+
+while (<>) {
+	if (grep {/#define __LINUX_VIDEODEV2_H/} $_) {
+		$in_v4l2_controls = false;
+	}
+
+	if (grep {/^#define.+FWHT_FL_.+/} $_) {
+		flag_gen("fwht");
+	} elsif (grep {/^#define V4L2_VP8_LF.*/} $_) {
+		flag_gen("vp8_loop_filter");
+	} elsif (grep {/^#define.+_FL_.+/} $_) {  #use to get media flags
+		flag_gen();
+	} elsif (grep {/^#define.+_FLAG_.+/} $_) {
+		flag_gen();
+	}
+
+	if ($in_v4l2_controls eq true) {
+		if (grep {/^struct/} $_) {
+			struct_gen_ctrl();
+		}
+	} else {
+		if (grep {/^struct/} $_) {
+			struct_gen();
+		}
+	}
+
+	if (grep {/^enum/} $_) {
+		enum_gen();
+	}
+
+	if (grep {/^#define (V4L2_CID\w*)\s*.*/} $_) {
+		push (@controls, $_);
+	}
+
+	if (grep {/^\/\* Control classes \*\//} $_) {
+		printf $fh_common_info_h "constexpr val_def ctrlclass_val_def[] = {\n";
+		while (<>) {
+			last if $_ =~ /^\s*$/; # last if blank line
+			($ctrl_class) = ($_) =~ /#define\s*(\w+)\s+.*/;
+			printf $fh_common_info_h "\t{ %s,\t\"%s\" },\n", $ctrl_class, $ctrl_class;
+		}
+		printf $fh_common_info_h "\t{ -1, \"\" }\n};\n\n";
+	}
+
+	if (grep {/\/\* Values for 'capabilities' field \*\//} $_) {
+		printf $fh_common_info_h "constexpr flag_def v4l2_cap_flag_def[] = {\n";
+		while (<>) {
+			last if $_ =~ /.*V I D E O   I M A G E   F O R M A T.*/;
+			next if ($_ =~ /^\/?\s?\*.*/); # skip comments
+			next if $_ =~ /^\s*$/; # skip blank lines
+			($cap) = ($_) =~ /#define\s+(\w+)\s+.+/;
+			printf $fh_common_info_h "\t{ $cap, \"$cap\" },\n"
+		}
+		printf $fh_common_info_h "\t{ 0, \"\" }\n};\n\n";
+	}
+
+	if (grep {/\*      Pixel format         FOURCC                          depth  Description  \*\//} $_) {
+		printf $fh_common_info_h "constexpr val_def v4l2_pix_fmt_val_def[] = {\n";
+		while (<>) {
+			last if $_ =~ /.*SDR formats - used only for Software Defined Radio devices.*/;
+			next if ($_ =~ /^\s*\/\*.*/); # skip comments
+			next if $_ =~ /^\s*$/; # skip blank lines
+			($pixfmt) = ($_) =~ /#define (\w+)\s+.*/;
+			printf $fh_common_info_h "\t{ %s,\t\"%s\" },\n", $pixfmt, $pixfmt;
+		}
+		printf $fh_common_info_h "\t{ -1, \"\" }\n};\n\n";
+	}
+
+	if (grep {/^#define V4L2_BUF_CAP_SUPPORTS_MMAP.*/} $_) {
+		printf $fh_common_info_h "constexpr flag_def v4l2_buf_cap_flag_def[] = {\n";
+		($buf_cap) = ($_) =~ /#define (\w+)\s+.*/;
+		printf $fh_common_info_h "\t{ %s,\t\"%s\" },\n", $buf_cap, $buf_cap;
+		while (<>) {
+			last if $_ =~ /^\s*$/; # blank line
+			($buf_cap) = ($_) =~ /#define (\w+)\s+.*/;
+			printf $fh_common_info_h "\t{ %s,\t\"%s\" },\n", $buf_cap, $buf_cap;
+		}
+		printf $fh_common_info_h "\t{ 0, \"\" }\n};\n\n";
+	}
+
+	if (grep {/.*Flags for 'capability' and 'capturemode' fields.*/} $_) {
+		printf $fh_common_info_h "constexpr val_def streamparm_val_def[] = {\n";
+		while (<>) {
+			last if $_ =~ /^\s*$/; # blank line
+			($streamparm) = ($_) =~ /^#define\s*(\w+)\s*/;
+			printf $fh_common_info_h "\t{ %s,\t\"%s\" },\n", $streamparm, $streamparm;
+		}
+		printf $fh_common_info_h "\t{ -1, \"\" }\n};\n\n";
+	}
+
+	if (grep {/.*V4L2_ENC_CMD_START.*/} $_) {
+		printf $fh_common_info_h "constexpr val_def encoder_cmd_val_def[] = {\n";
+		($enc_cmd) = ($_) =~ /^#define\s*(\w+)\s*/;
+		printf $fh_common_info_h "\t{ %s,\t\"%s\" },\n", $enc_cmd, $enc_cmd;
+		while (<>) {
+			last if $_ =~ /^\s*$/; # blank line
+			($enc_cmd) = ($_) =~ /^#define\s*(\w+)\s*/;
+			printf $fh_common_info_h "\t{ %s,\t\"%s\" },\n", $enc_cmd, $enc_cmd;
+		}
+		printf $fh_common_info_h "\t{ -1, \"\" }\n};\n\n";
+	}
+
+	if (grep {/.*Decoder commands.*/} $_) {
+		printf $fh_common_info_h "constexpr val_def decoder_cmd_val_def[] = {\n";
+		while (<>) {
+			last if $_ =~ /^\s*$/; # blank line
+			($dec_cmd) = ($_) =~ /^#define\s*(\w+)\s*/;
+			printf $fh_common_info_h "\t{ %s,\t\"%s\" },\n", $dec_cmd, $dec_cmd;
+		}
+		printf $fh_common_info_h "\t{ -1, \"\" }\n};\n\n";
+	}
+
+	if (grep {/^#define\s+(VIDIOC_\w*)\s*.*/} $_) {
+		push (@ioctls, $_);
+	}
+
+	if (grep {/^#define\s+(MEDIA_IOC\w*)\s*.*/} $_) {
+		push (@ioctls, $_);
+	}
+
+	if (grep {/^#define\s+(MEDIA_REQUEST_IOC\w*)\s*.*/} $_) {
+		push (@ioctls, $_);
+	}
+}
+
+printf $fh_common_info_h "constexpr val_def control_val_def[] = {\n";
+foreach (@controls) {
+	($control) = ($_) =~ /^#define\s*(\w+)\s*/;
+	next if ($control =~ /BASE$/);
+	printf $fh_common_info_h "\t{ %s,\t\"%s\" },\n", $control, $control;
+}
+printf $fh_common_info_h "\t{ -1, \"\" }\n};\n";
+
+printf $fh_common_info_h "constexpr val_def ioctl_val_def[] = {\n";
+foreach (@ioctls) {
+	($ioctl) = ($_) =~ /^#define\s*(\w+)\s*/;
+	printf $fh_common_info_h "\t{ %s,\t\"%s\" },\n", $ioctl, $ioctl;
+}
+printf $fh_common_info_h "\t{ -1, \"\" }\n};\n";
+
+
+printf $fh_trace_h "\n#endif\n";
+close $fh_trace_h;
+close $fh_trace_cpp;
+
+printf $fh_retrace_h "\n#endif\n";
+close $fh_retrace_h;
+close $fh_retrace_cpp;
+
+printf $fh_common_info_h "\n#endif\n";
+close $fh_common_info_h;
diff --git a/utils/v4l2-tracer/v4l2-tracer.1.in b/utils/v4l2-tracer/v4l2-tracer.1.in
new file mode 100644
index 00000000..13942eba
--- /dev/null
+++ b/utils/v4l2-tracer/v4l2-tracer.1.in
@@ -0,0 +1,111 @@
+.TH "V4L2-TRACER" "1" "November 2022" "v4l-utils @PACKAGE_VERSION@" "User Commands"
+.SH NAME
+v4l2-tracer - An application to trace and replay stateless video decoding.
+.SH SYNOPSIS
+\fBv4l2-tracer \fR[options] \fBtrace\fR <\fItracee\fR>
+.RS
+.RE
+\fBv4l2-tracer \fR[options] \fBretrace\fR  <\fItrace_file\fR>\fB.json\fR
+.RS
+.RE
+\fBv4l2-tracer clean\fR  <\fIfile\fR>\fB.json\fR
+.RS
+.RE
+
+.SH DESCRIPTION
+The v4l2-tracer utility traces, records and replays userspace applications
+that implement the v4l2 memory-to-memory stateless video decoder interface.
+.SS Trace
+Trace system calls and video frame data passed by userspace application <\fItracee\fR> to kernel driver.
+All stateless codec controls in user-space API can be traced. Outputs a JSON-formatted trace file.
+.SS Retrace
+Read the JSON-formatted <\fItrace_file\fR>\fB.json\fR. Replay the same system calls and pass the same video frame data to kernel driver.
+Outputs a JSON-formatted retrace file.
+
+.SS Clean
+Remove lines with irrelevant differences (e.g. file descriptors and memory addresses) from JSON files.
+Outputs a clean copy, not necessarily still in JSON-format.
+
+.SH OPTIONS
+.SS Common Options
+.TP
+\fB\-c\fR, \fB\-\-compact\fR
+Write minimal whitespace in JSON file.
+.TP
+\fB\-g\fR, \fB\-\-debug\fR
+Turn on verbose reporting plus additional debug info.
+.TP
+\fB\-h\fR, \fB\-\-help\fR
+Display this message.
+.TP
+\fB\-r\fR, \fB\-\-raw\fR
+Write decoded video frame data to JSON file.
+.TP
+\fB\-v\fR, \fB\-\-verbose\fR
+Turn on verbose reporting.
+.TP
+\fB\-y\fR, \fB\-\-yuv\fR
+Write decoded video frame data to yuv file.
+
+.SS Retrace Options
+.TP
+\fB\-d\fR, \fB\-\-device\fR <\fIdev\fR>
+Use a different video device than specified in the trace file.
+.RS
+<\fIdev\fR> must be a digit corresponding to an existing /dev/video<\fIdev\fR>
+.RE
+.TP
+\fB\-m\fR, \fB\-\-media\fR <\fIdev\fR>
+Use a different media device than specified in the trace file.
+.RS
+<\fIdev\fR> must be a digit corresponding to an existing /dev/media<\fIdev\fR>
+.RE
+
+.SH EXIT STATUS
+On success, it returns 0. Otherwise, it will return 1 or an error code.
+
+.SH EXAMPLE
+.TP
+Trace an application decoding VP8 video:
+.EX
+\fIv4l2-tracer trace gst-launch-1.0 -- filesrc location=test-25fps.vp8 ! parsebin ! v4l2slvp8dec ! videocodectestsink\fR
+.EE
+.TP
+A trace file is generated:
+.EE
+\fI71827_trace.json\fR
+.TP
+Retrace the trace file:
+.EX
+\fIv4l2-tracer retrace 71827_trace.json\fR
+.EE
+.TP
+Specify device nodes if retracing on a different driver:
+.EX
+\fIv4l2-tracer -d0 -m0 retrace 71827_trace.json\fR
+.EE
+.TP
+A retrace file is generated:
+.EE
+\fI71827_trace_retrace.json\fR
+.EX
+.TP
+Remove file descriptors and addresses (optional):
+.EX
+\fIv4l2-tracer clean 71827_trace.json\fR
+.EE
+.EX
+\fIv4l2-tracer clean 71827_trace_retrace.json\fR
+.EE
+.TP
+Clean files are generated for comparison:
+.EX
+\fIclean_71827_trace.json\fR
+.EE
+.EE
+\fIclean_71827_trace_retrace.json\fR
+.EX
+
+.SH BUGS
+Bug reports or questions about this utility should be sent to the
+linux-media@vger.kernel.org mailinglist.
diff --git a/utils/v4l2-tracer/v4l2-tracer.cpp b/utils/v4l2-tracer/v4l2-tracer.cpp
new file mode 100644
index 00000000..114bcce4
--- /dev/null
+++ b/utils/v4l2-tracer/v4l2-tracer.cpp
@@ -0,0 +1,412 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2022 Collabora Ltd.
+ */
+
+#include <time.h>
+#include <sys/wait.h>
+#include <climits>
+#include "v4l2-tracer-common.h"
+
+int tracer(int argc, char *argv[], bool retrace = false);
+int retracer(std::string trace_filename);
+
+enum Options {
+	V4l2TracerOptCompactPrint = 'c',
+	V4l2TracerOptSetVideoDevice = 'd',
+	V4l2TracerOptDebug = 'g',
+	V4l2TracerOptHelp = 'h',
+	V4l2TracerOptSetMediaDevice = 'm',
+	V4l2TracerOptWriteDecodedToJson = 'r',
+	V4l2TracerOptVerbose = 'v',
+	V4l2TracerOptWriteDecodedToYUVFile = 'y',
+};
+
+static struct option long_options[] = {
+	{ "compact", no_argument, nullptr, V4l2TracerOptCompactPrint },
+	{ "video_device", required_argument, nullptr, V4l2TracerOptSetVideoDevice },
+	{ "debug", no_argument, nullptr, V4l2TracerOptDebug },
+	{ "help", no_argument, nullptr, V4l2TracerOptHelp },
+	{ "media_device", required_argument, nullptr, V4l2TracerOptSetMediaDevice },
+	{ "raw", no_argument, nullptr, V4l2TracerOptWriteDecodedToJson },
+	{ "verbose", no_argument, nullptr, V4l2TracerOptVerbose },
+	{ "yuv", no_argument, nullptr, V4l2TracerOptWriteDecodedToYUVFile },
+	{ nullptr, 0, nullptr, 0 }
+};
+
+char short_options[] = {
+	V4l2TracerOptCompactPrint,
+	V4l2TracerOptSetVideoDevice, ':',
+	V4l2TracerOptDebug,
+	V4l2TracerOptHelp,
+	V4l2TracerOptSetMediaDevice, ':',
+	V4l2TracerOptWriteDecodedToJson,
+	V4l2TracerOptVerbose,
+	V4l2TracerOptWriteDecodedToYUVFile
+};
+
+int get_options(int argc, char *argv[])
+{
+	int ch;
+
+	do {
+		/* If there are no commands after the valid options, return err. */
+		if (optind == argc) {
+			print_usage();
+			return -1;
+		}
+
+		/* Avoid reading the tracee's options. */
+		if ((strcmp(argv[optind], "trace") == 0) || (strcmp(argv[optind], "retrace") == 0))
+			return 0;
+
+		ch = getopt_long(argc, argv, short_options, long_options, NULL);
+		switch (ch) {
+		case V4l2TracerOptCompactPrint: {
+			setenv("V4L2_TRACER_OPTION_COMPACT_PRINT", "true", 0);
+			break;
+		}
+		case V4l2TracerOptSetVideoDevice: {
+			std::string device_num = optarg;
+			try {
+				std::stoi(device_num, nullptr, 0);
+			} catch (std::exception& e) {
+				fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+				fprintf(stderr, "can't convert <dev> \'%s\' to integer\n", device_num.c_str());
+				return -1;
+			}
+			if (device_num[0] >= '0' && device_num[0] <= '9' && device_num.length() <= 3) {
+				std::string path_video = "/dev/video";
+				path_video += optarg;
+				setenv("V4L2_TRACER_OPTION_SET_VIDEO_DEVICE", path_video.c_str(), 0);
+			} else {
+				fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+				fprintf(stderr, "cannot use device number\'%s\'\n", device_num.c_str());
+				return -1;
+			}
+			break;
+		}
+		case V4l2TracerOptDebug:
+			setenv("V4L2_TRACER_OPTION_VERBOSE", "true", 0);
+			setenv("V4L2_TRACER_OPTION_DEBUG", "true", 0);
+			break;
+		case V4l2TracerOptHelp:
+			print_usage();
+			return -1;
+		case V4l2TracerOptSetMediaDevice: {
+			std::string device_num = optarg;
+			try {
+				std::stoi(device_num, nullptr, 0);
+			} catch (std::exception& e) {
+				fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+				fprintf(stderr, "can't convert <dev> \'%s\' to integer\n", device_num.c_str());
+				return -1;
+			}
+			if (device_num[0] >= '0' && device_num[0] <= '9' && device_num.length() <= 3) {
+				std::string path_media = "/dev/media";
+				path_media += optarg;
+				setenv("V4L2_TRACER_OPTION_SET_MEDIA_DEVICE", path_media.c_str(), 0);
+			} else {
+				fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+				fprintf(stderr, "cannot use device number\'%s\'\n", device_num.c_str());
+				return -1;
+			}
+			break;
+		}
+		case V4l2TracerOptWriteDecodedToJson:
+			setenv("V4L2_TRACER_OPTION_WRITE_DECODED_TO_JSON_FILE", "true", 0);
+			break;
+		case V4l2TracerOptVerbose:
+			setenv("V4L2_TRACER_OPTION_VERBOSE", "true", 0);
+			break;
+		case V4l2TracerOptWriteDecodedToYUVFile:
+			setenv("V4L2_TRACER_OPTION_WRITE_DECODED_TO_YUV_FILE", "true", 0);
+			break;
+		default:
+			break;
+		}
+
+		/* invalid option */
+		if (optopt > 0) {
+			print_usage();
+			return -1;
+		}
+
+	} while (ch != -1);
+
+	return 0;
+}
+
+int clean(std::string trace_filename)
+{
+	FILE *trace_file = fopen(trace_filename.c_str(), "r");
+	if (trace_file == NULL) {
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "cannot open \'%s\'\n", trace_filename.c_str());
+		return 1;
+	}
+
+	fprintf(stderr, "Cleaning: %s\n", trace_filename.c_str());
+
+	std::string clean_filename = "clean_" + trace_filename;
+	FILE *clean_file = fopen(clean_filename.c_str(), "w");
+	if (clean_file == NULL) {
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "cannot open \'%s\'\n", clean_filename.c_str());
+		return 1;
+	}
+
+	std::string line;
+	char buf[SHRT_MAX];
+	int count_total = 0;
+	int count_lines_removed = 0;
+
+	while (fgets(buf, SHRT_MAX, trace_file) != nullptr) {
+		line = buf;
+		count_total++;
+		if (line.find("fd") != line.npos) {
+			count_lines_removed++;
+			continue;
+		}
+		if (line.find("address") != line.npos) {
+			count_lines_removed++;
+			continue;
+		}
+		if (line.find("fildes") != line.npos) {
+			count_lines_removed++;
+			continue;
+		}
+		if (line.find("\"start\"") != line.npos) {
+			count_lines_removed++;
+			continue;
+		}
+		if (line.find("\"name\"") != line.npos) {
+			count_lines_removed++;
+			continue;
+		}
+
+		fputs(buf, clean_file);
+	}
+
+	fclose(trace_file);
+	fclose(clean_file);
+	fprintf(stderr, "Removed %d lines of %d total lines: %s\n",
+	        count_lines_removed, count_total, clean_filename.c_str());
+
+	return 0;
+}
+
+int tracer(int argc, char *argv[], bool retrace)
+{
+	char *exec[argc];
+	int exec_index = 0;
+
+	char retrace_command[] = "__retrace";
+
+	if (retrace) {
+		std::string trace_file = argv[optind];
+		if (trace_file.find(".json") == trace_file.npos) {
+			fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+			fprintf(stderr, "Trace file \'%s\' must have .json file extension\n",
+			        trace_file.c_str());
+			print_usage();
+			return -1;
+		}
+	}
+
+	/* Get the application to be traced. */
+	if (retrace) {
+		exec[exec_index++] = argv[0]; /* tracee is v4l2-tracer, local or installed */
+		exec[exec_index++] = retrace_command;
+		exec[exec_index++] = argv[optind]; /* json file to be retraced */
+	} else {
+		while (optind < argc)
+			exec[exec_index++] = argv[optind++];
+	}
+	exec[exec_index] = nullptr;
+
+	/* Create a unique trace filename and open a file. */
+	std::string trace_id;
+	if (retrace) {
+		std::string json_file_name = argv[optind];
+		trace_id = json_file_name.substr(0, json_file_name.find(".json"));
+		trace_id += "_retrace";
+	} else {
+		trace_id = std::to_string(time(nullptr));
+		trace_id = trace_id.substr(5, trace_id.npos) + "_trace";
+	}
+	setenv("TRACE_ID", trace_id.c_str(), 0);
+	std::string trace_filename = trace_id + ".json";
+	FILE *trace_file = fopen(trace_filename.c_str(), "w");
+	if (trace_file == nullptr) {
+		fprintf(stderr, "Could not open trace file: %s\n", trace_filename.c_str());
+		perror("");
+		return errno;
+	}
+
+	/* Open the json array.*/
+	fputs("[\n", trace_file);
+
+	/* Add v4l-utils package and git info to the top of the trace file. */
+	std::string json_str;
+	json_object *v4l2_tracer_info_obj = json_object_new_object();
+	json_object_object_add(v4l2_tracer_info_obj, "package_version",
+	                       json_object_new_string(PACKAGE_VERSION));
+	std::string git_commit_cnt = STRING(GIT_COMMIT_CNT);
+	git_commit_cnt = git_commit_cnt.erase(0, 1); /* remove the hyphen in front of git_commit_cnt */
+	json_object_object_add(v4l2_tracer_info_obj, "git_commit_cnt",
+	                       json_object_new_string(git_commit_cnt.c_str()));
+	json_object_object_add(v4l2_tracer_info_obj, "git_sha",
+	                       json_object_new_string(STRING(GIT_SHA)));
+	json_object_object_add(v4l2_tracer_info_obj, "git_commit_date",
+	                       json_object_new_string(STRING(GIT_COMMIT_DATE)));
+	json_str = json_object_to_json_string(v4l2_tracer_info_obj);
+	fwrite(json_str.c_str(), sizeof(char), json_str.length(), trace_file);
+	fputs(",\n", trace_file);
+	json_object_put(v4l2_tracer_info_obj);
+
+	/* Add v4l2-tracer command line to the top of the trace file. */
+	json_object *tracee_obj = json_object_new_object();
+	std::string tracee;
+	for (int i = 0; i < argc; i++) {
+		tracee += argv[i];
+		tracee += " ";
+	}
+	json_object_object_add(tracee_obj, "Trace", json_object_new_string(tracee.c_str()));
+	const time_t t = time(nullptr);
+	json_object_object_add(tracee_obj, "Timestamp", json_object_new_string(ctime(&t)));
+
+	json_str = json_object_to_json_string(tracee_obj);
+	fwrite(json_str.c_str(), sizeof(char), json_str.length(), trace_file);
+	fputs(",\n", trace_file);
+	json_object_put(tracee_obj);
+	fclose(trace_file);
+
+	/*
+	 * Preload the libv4l2tracer library. If the program is installed, load the library
+	 * from its installed location, otherwise load it locally. If it's loaded locally,
+	 * use ./configure --disable-dyn-libv4l.
+	 */
+	std::string libv4l2tracer_path;
+	std::string program = argv[0];
+	std::size_t idx = program.rfind("/v4l2-tracer");
+	if (idx != program.npos) {
+		libv4l2tracer_path = program.replace(program.begin() + idx + 1, program.end(), ".libs");
+		DIR *dp = opendir(libv4l2tracer_path.c_str());
+		if (dp == nullptr)
+			libv4l2tracer_path = program.replace(program.begin() + idx, program.end(), "./.libs");
+		closedir(dp);
+	} else {
+		libv4l2tracer_path = STRING(LIBTRACER_PATH);
+	}
+	libv4l2tracer_path += "/libv4l2tracer.so";
+	if (getenv("V4L2_TRACER_OPTION_VERBOSE"))
+		fprintf(stderr, "Loading libv4l2tracer: %s\n", libv4l2tracer_path.c_str());
+	setenv("LD_PRELOAD", libv4l2tracer_path.c_str(), 0);
+
+	if (fork() == 0) {
+
+		if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+			fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+			fprintf(stderr, "tracee: ");
+			for (int i = 0; i < exec_index; i++)
+				fprintf(stderr,"%s ", exec[i]);
+			fprintf(stderr, "\n");
+		}
+
+		execvpe(exec[0], (char* const*) exec, environ);
+
+		fprintf(stderr, "%s:%s:%d: ", __FILE__, __func__, __LINE__);
+		fprintf(stderr, "could not execute application \'%s\'", exec[0]);
+		perror(" ");
+		return errno;
+	}
+
+	int exec_result;
+	wait(&exec_result);
+
+	if (WEXITSTATUS(exec_result)) {
+		fprintf(stderr, "Trace error: %s\n", trace_filename.c_str());
+
+		trace_file = fopen(trace_filename.c_str(), "a");
+		fseek(trace_file, 0L, SEEK_END);
+		fputs("\n]\n", trace_file);
+		fclose(trace_file);
+
+		exit(EXIT_FAILURE);
+	}
+
+	/* Close the json-array and the trace file. */
+	trace_file = fopen(trace_filename.c_str(), "a");
+	fseek(trace_file, 0L, SEEK_END);
+	fputs("\n]\n", trace_file);
+	fclose(trace_file);
+
+	if (retrace)
+		fprintf(stderr, "Retrace complete: ");
+	else
+		fprintf(stderr, "Trace complete: ");
+	fprintf(stderr, "%s", trace_filename.c_str());
+	fprintf(stderr, "\n");
+
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	int ret = -1;
+
+	if (argc <= 1) {
+		print_usage();
+		return ret;
+	}
+
+	ret = get_options(argc, argv);
+
+	if (ret < 0) {
+		if (getenv("V4L2_TRACER_OPTION_DEBUG"))
+			fprintf(stderr, "%s:%s:%d\n", __FILE__, __func__, __LINE__);
+		return ret;
+	}
+
+	if (optind == argc) {
+		if (getenv("V4L2_TRACER_OPTION_DEBUG"))
+			fprintf(stderr, "%s:%s:%d\n", __FILE__, __func__, __LINE__);
+		print_usage();
+		return ret;
+	}
+
+	std::string command = argv[optind++];
+
+	if (optind == argc) {
+		if (getenv("V4L2_TRACER_OPTION_DEBUG"))
+			fprintf(stderr, "%s:%s:%d\n", __FILE__, __func__, __LINE__);
+		print_usage();
+		return ret;
+	}
+
+	if (command == "trace") {
+		ret = tracer(argc, argv);
+	} else if (command == "retrace") {
+		ret = tracer(argc, argv, true);
+	} else if (command == "__retrace") {
+		/*
+		 * This command is meant to be used only internally to allow
+		 * v4l2-tracer to recursively trace itself during a retrace.
+		 */
+		ret = retracer(argv[optind]);
+	} else if (command == "clean") {
+		ret = clean (argv[optind]);
+	} else {
+		if (getenv("V4L2_TRACER_OPTION_DEBUG")) {
+			fprintf(stderr, "%s:%s:%d\n", __FILE__, __func__, __LINE__);
+			fprintf(stderr, "tracee: ");
+			for (int i = 0; i < argc; i++)
+				fprintf(stderr,"%s ", argv[i]);
+			fprintf(stderr, "\n");
+		}
+		print_usage();
+	}
+
+	return ret;
+}
