docs/media/gpu/vdatest_usage.md

# Using the Video Decode/Encode Accelerator Unittests Manually

VDAtest (or `video_decode_accelerator_unittest`) and VEAtest (or
`video_encode_accelerator_unittest`) are unit tests that embeds the Chrome video
decoding/encoding stack without requiring the whole browser, meaning they can
work in a headless environment. They includes a variety of tests to validate the
decoding and encoding stacks with h264, vp8 and vp9.

Running these tests manually can be very useful when bringing up a new codec, or
in order to make sure that new code does not break hardware decoding and/or
encoding. This document is a walk though the prerequisites for running these
programs, as well as their most common options.

## Prerequisites

The required kernel drivers should be loaded, and there should exist a
`/dev/video-dec0` symbolic link pointing to the decoder device node (e.g.
`/dev/video-dec0` → `/dev/video0`). Similarly, a `/dev/video-enc0` symbolic
link should point to the encoder device node.

The unittests can be built by specifying the `video_decode_accelerator_unittest`
and `video_encode_accelerator_unittest` targets to `ninja`. If you are building
for an ARM board that is not yet supported by the
[simplechrome](https://chromium.googlesource.com/chromiumos/docs/+/master/simple_chrome_workflow.md)
workflow, use `arm-generic` as the board. It should work across all ARM targets.

For unlisted Intel boards, any other Intel target (preferably with the same
chipset) should be usable with libva. AMD targets can use `amd64-generic`.

## Basic VDA usage

The `media/test/data` folder in Chromium's source tree contains files with
encoded video data (`test-25fps.h264`, `test-25fps.vp8` and `test-25fps.vp9`).
Each of these files also has a `.md5` counterpart, which contains the md5
checksums of valid thumbnails.

Running the VDAtest can be done as follows:

    ./video_decode_accelerator_unittest --disable_rendering --single-process-tests --test_video_data=test_video

Where test_video is of the form

    filename:width:height:numframes:numfragments:minFPSwithRender:minFPSnoRender:profile

The correct value of test_video for each test file follows:

* __H264__: `test-25fps.h264:320:240:250:258:35:150:1`
* __VP8__: `test-25fps.vp8:320:240:250:250:35:150:11`
* __VP9__: `test-25fps.vp9:320:240:250:250:35:150:12`

So in order to run all h264 tests, one would invoke

    ./video_decode_accelerator_unittest --disable_rendering --single-process-tests --test_video_data=test-25fps.h264:320:240:250:258:35:150:1

## Test filtering options

`./video_decode_accelerator_unittest --help` will list all valid options.

The list of available tests can be retrieved using the `--gtest_list_tests`
option.

By default, all tests are run, which can be a bit too much, especially when
bringing up a new codec. The `--gtest_filter` option can be used to specify a
pattern of test names to run. For instance, to only run the
`TestDecodeTimeMedian` test, one can specify
`--gtest_filter="*TestDecodeTimeMedian*"`.

So the complete command line to test vp9 decoding with the
`TestDecodeTimeMedian` test only (a good starting point for bringup) would be

    ./video_decode_accelerator_unittest --disable_rendering --single-process-tests --test_video_data=test-25fps.vp9:320:240:250:250:35:150:12 --gtest_filter="*TestDecodeTimeMedian*"

## Verbosity options

The `--vmodule` options allows to specify a set of source files that should be
more verbose about what they are doing. For basic usage, a useful set of vmodule
options could be:

    --vmodule=*/media/gpu/*=4

## Testing performance

Use the `--disable_rendering --rendering_fps=0 --gtest_filter="DecodeVariations/*/0"`
options to max the decoder output and measure its performance.

## Testing parallel decoding

Use `--gtest_filter="ResourceExhaustion*/0"` to run 3 decoders in parallel, and
`--gtest_filter="ResourceExhaustion*/1"` to run 4 decoders in parallel.

## Wrap-up

Using all these options together, we can invoke VDAtest in the following way for
a verbose H264 decoding test:

    ./video_decode_accelerator_unittest --single-process-tests --disable_rendering --gtest_filter="*TestDecodeTimeMedian*" --vmodule=*/media/gpu/*=4 --test_video_data=test-25fps.h264:320:240:250:258:35:150:1

## Basic VEA usage

The VEA works in a similar fashion to the VDA, taking raw YUV files in I420
format as input and producing e.g. a H.264 Annex-B byte stream. Sample raw YUV
files can be found at the following locations:

* [1080 Crowd YUV](http://commondatastorage.googleapis.com/chromiumos-test-assets-public/crowd/crowd1080-96f60dd6ff87ba8b129301a0f36efc58.yuv)
* [320x180 Bear YUV](http://commondatastorage.googleapis.com/chromiumos-test-assets-public/bear/bear-320x180-c60a86c52ba93fa7c5ae4bb3156dfc2a.yuv)

It is recommended to rename these files after downloading them to e.g.
`crowd1080.yuv` and `bear-320x180.yuv`.

The VEA can then be tested as follows:

    ./video_encode_accelerator_unittest --single-process-tests --disable_flush --gtest_filter=SimpleEncode/VideoEncodeAcceleratorTest.TestSimpleEncode/0 --test_stream_data=bear-320x180.yuv:320:180:1:bear.mp4:100000:30

for the `bear` file, and

    ./video_encode_accelerator_unittest --single-process-tests --disable_flush --gtest_filter=SimpleEncode/VideoEncodeAcceleratorTest.TestSimpleEncode/0 --test_stream_data=crowd1080.yuv:1920:1080:1:crowd.mp4:4000000:30

for the larger `crowd` file. These commands will put the encoded output into
`bear.mp4` and `crowd.mp4` respectively. They can then be copied on the host and
played with `mplayer -fps 25`.

## Source code

The VDAtest's source code can be consulted here: [https://cs.chromium.org/chromium/src/media/gpu/video_decode_accelerator_unittest.cc](https://cs.chromium.org/chromium/src/media/gpu/video_decode_accelerator_unittest.cc).

V4L2 support: [https://cs.chromium.org/chromium/src/media/gpu/v4l2/](https://cs.chromium.org/chromium/src/media/gpu/v4l2/).

VAAPI support: [https://cs.chromium.org/chromium/src/media/gpu/vaapi/](https://cs.chromium.org/chromium/src/media/gpu/vaapi/).