Provided by: v4l-utils_1.10.0-1_amd64 
NAME
v4l2-compliance - An application to test video4linux drivers
SYNOPSIS
v4l2-compliance [-h] [-d <dev>] [-r <dev>] [-V <dev>] [-S <dev>] [-e <dev>] [-s <count>]
[-f] [-a] [-c color=<color>,skip=<skip>,perc=<perc>] [-n] [-T] [-v] [-w]
DESCRIPTION
The v4l2-compliance tool is used to test video4linux devices, either video, vbi, radio or
swradio, both input and output. It attempts to test almost all aspects of a V4L2 device
and it covers almost all V4L2 ioctls. It has very good support for video capture and
output, VBI capture and output and (software) radio tuning and transmitting.
The support for memory-to-memory devices is limited at the moment.
If you have questions about v4l2-compliance then mail those to the linux-
media@vger.kernel.org mailinglist.
When testing a driver always compile the utility from the latest source code from the git
repository (http://git.linuxtv.org/cgit.cgi/v4l-utils.git/). The version supplied by linux
distributions is almost certainly too old.
In addition, if a test fails then it will output the source and line where the failure
occured, so you often need access to the source code to see what that test is all about.
Note that v4l2-compliance not only tests for compliance against the V4L2 API, but also
whether the driver is using all the correct frameworks. These frameworks often
automatically provide ioctls that are strictly speaking optional, but that come for free
if you use those frameworks. By requiring their presence the v4l2-compliance utility will
enforce their use.
If you want to submit a new V4L2 driver, then that driver must pass the v4l2-compliance
tests without fails. The best method of using this tool to test your driver is to first
test without any streaming options and fix any failures from the first reported failure to
the last. Sometimes earlier failures can generate later failures, so just start fixing
them in order and test again after each fix.
Next test your driver with the -s option to do the basic streaming tests. This requires
that there is a valid input or output.
Whenever you run v4l2-compliance it will save the current driver state and restore it
after all tests are done (including when you press Ctrl-C). All the streaming tests are
performed using the saved configuration. This makes it possible to prepare for the
streaming tests by configuring the device before calling v4l2-compliance.
Finally you should test your driver using the -f and -c options to verify that all video
pixel formats are correctly supported. You need to perform all three streaming tests for
all inputs and outputs. You can use the -a option to automate that if that is possible for
your hardware.
If your driver passes all tests, then your can be confident that your driver is in very
good shape!
OPTIONS
-d, --device=<dev>
Use device <dev> as the video device. If <dev> is a number, then /dev/video<dev> is
used.
-V, --vbi-device=<dev>
Use device <dev> as the vbi device. If <dev> is a number, then /dev/vbi<dev> is
used.
-r, --radio-device=<dev>
Use device <dev> as the radio device. If <dev> is a number, then /dev/radio<dev> is
used.
-S, --sdr-device=<dev>
Use device <dev> as the SDR device. If <dev> is a number, then /dev/swradio<dev> is
used.
-e, --exp-buf-device=<dev>
Use device <dev> as the video device used to export DMABUFfers for doing DMABUF
streaming tests. If <dev> is a number, then /dev/video<dev> is used. If this option
is not specified, then the DMABUF streaming tests will be skipped.
-s, --streaming=<count>
Enable the streaming tests. Set <count> to the number of frames to stream (default
60). This requires that before v4l2-compliance is called the device has been
configured with a valid input (or output) and frequency (when the device has a
tuner). For DMABUF testing --expbuf-device needs to be set as well.
The configuration of the driver at the time v4l2-compliance was called will be used
for the streaming tests.
-f, --stream-all-formats
Test whether all available formats can be streamed. This attempts to stream using
MMAP mode or read/write (if V4L2_MEMORY_MMAP is not available) for one second for
all formats, at all sizes, at all intervals and with all field values. In addition,
if the driver supports scaling, cropping or composing it will test that as well in
various combinations. If the driver supports a lot of combinations then this test
can take a long time.
The configuration of the driver at the time v4l2-compliance was called will be used
for the streaming tests.
-c, --stream-all-color=color=red|green|blue,skip=<skip>,perc=<perc>
For all supported, non-compressed formats stream <skip + 1> frames. For the last
frame go over all pixels and calculate which of the R, G and B color components of
a pixel has the highest value and count that as a red, green or blue pixel. The
test succeeds if at least perc percent of the frame has the given color. This
requires that a valid and predominantly red, green or blue video signal is present
on the input(s). If skip is not specified, then just capture the first frame. A
non-zero skip value is useful if it takes a few frames for the device to calibrate.
If perc is not specified, then this defaults to 90%.
Most signal generators are able to generate pure red, blue or green video. For
cameras you can print a completely red, green or blue picture and hold it before
the camera.
The goal of this test is to determine if all pixel formats will interpret the red,
green and blue colors correctly and that no color components are swapped.
The configuration of the driver at the time v4l2-compliance was called will be used
for the streaming tests.
-a, --stream-all-io
Do the -s, -c and -f streaming tests for all inputs or outputs instead of just the
current input or output. This requires that a valid video signal is present on all
inputs or that all outputs are hooked up.
-n, --no-warnings
Turn off warning messages. They are still counted in the summary, but you won't see
them.
-T, --trace
Trace all called ioctls.
-v, --verbose
Turn on verbose reporting.
-w, --wrapper
Use the libv4l2 wrapper library for all V4L2 device accesses. Note that doing this
will cause some tests to fail because the libv4l2 library isn't fully V4L2
compliant. By default v4l2-compliance will bypass libv4l2 and access the V4L2
devices directly.
-h, --help
Prints the help message.
EXIT STATUS
On success, it returns 0. Otherwise, it will return the error code.
BUGS
This is a work in progress, and every so often it turns out that some tests done by
v4l2-compliance are too strict or plain wrong. If you suspect that might be the case, then
report such bugs to the linux-media@vger.kernel.org mailinglist.