The video decoder tests are a set of tests used to validate various video decoder implementations. Multiple scenarios are tested, and the resulting decoded frames are validated against known checksums. These tests run directly on top of the video decoder implementation, and don‘t require the full Chrome browser stack. They can be very useful when adding support for a new codec or platform, or to make sure code changes don’t break existing functionality. They are build on top of the GoogleTest framework.
The Tast framework provides an easy way to run the video decoder tests from a ChromeOS chroot. Test data is automatically deployed to the device being tested. To run all video decoder tests use:
tast run $HOST video.DecodeAccelH264* video.DecodeAccelVP*
Wildcards can be used to run specific sets of tests:
tast run $HOST video.DecodeAccelVP8*
tast run $HOST video.DecodeAccelVP92*
To run the video decoder tests manually the video_decode_accelerator_tests target needs to be built and deployed to the device being tested. Running the video decoder tests can be done by executing:
./video_decode_accelerator_tests [<video path>] [<video metadata path>]
Video Metadata: These videos also have an accompanying metadata .json file that needs to be deployed alongside the test video. They can also be found in the media/test/data folder (e.g. test-25fps.h264.json). If no metadata file is specified <video path>.json will be used. The video metadata file contains info about the video such as its codec profile, dimensions, number of frames and a list of md5 frame checksums to validate decoded frames. These frame checksums can be generated using ffmpeg, e.g.:
ffmpeg -i test-25fps.h264 -f framemd5 test-25fps.h264.frames.md5.
Multiple command line arguments can be given to the command:
-v enable verbose mode, e.g. -v=2. --vmodule enable verbose mode for the specified module, e.g. --vmodule=*media/gpu*=2. --disable_validator disable frame validation. --use_vd use the new VD-based video decoders, instead of the default VDA-based video decoders. --use_vd_vda use the new VD-based video decoders with a wrapper that translates to the VDA interface, used to test interaction with older components expecting the VDA interface. --output_frames write the selected video frames to disk, possible values are "all|corrupt". --output_format set the format of frames saved to disk, supported formats are "png" (default) and "yuv". --output_limit limit the number of frames saved to disk. --output_folder set the folder used to store frames, defaults to "<testname>" --gtest_help display the gtest help and exit. --help display this help and exit.
See the video decoder tests source code.