[ICL][ffmpeg-vaapi][VP8 encode] ffmpeg exits with "Output file is empty, nothing was encoded"

[ykku16github]

201811081026_vp8_320x180_100kbps_30fps.txt

The attached stdout was captured by running the following ffmpeg command:
ffmpeg -hwaccel vaapi -vaapi_device /dev/dri/renderD128 -f rawvideo -pix_fmt nv12 -s:v 320x180 -r 30 -i tulip2-320x180-55be7124b3aec1b72bfb57f433297193.yuv -vf 'format=nv12,hwupload' -c:v vp8_vaapi -b:v 100k -maxrate 100k -y -r 30 -vstats -v debug output.webm 2>&1 | tee 201811081026_vp8_320x180_100kbps_30fps.txt

If needed, the input file can be downloaded from:
http://commondatastorage.googleapis.com/chromiumos-test-assets-public/tulip2/tulip2-320x180-55be7124b3aec1b72bfb57f433297193.yuv

[ykku16github]

For every frame that gets encoded, ffmpeg prints the following:

[vp8_vaapi @ 0x27dee40] Output buffer: 32717 bytes (status 00000001).
[vp8_vaapi @ 0x27dee40] Output buffer: 0 bytes (status 00000000).

This is printed by the for-loop in:
https://github.com/FFmpeg/FFmpeg/blob/70463b702697ef8be4ec4d88969b4fce5b4e7a7e/libavcodec/vaapi_encode.c#L517

This is because vaMapBuffer() returned 2 packets, caused by the following code in iHD:

media-driver/media_driver/linux/common/codec/ddi/media_ddi_encode_vp8.cpp

Line 244 in f3824c8

pFindTheLastEntry->next = pVACodedBufferSegmentForStatusReport;

It's not clear to me whether the proper fix should be in ffmpeg or in iHD. Any thoughts?

[Tianhaol]

This issue can be reproduced on our side.

[eero-t]

Issue title is misleading. This issue isn't ICL specific, it happens also e.g. on KBL.

[zhoub]

I have this fixed in FFmpeg as workaround.

zhoub/FFmpeg@493e507

[wangyan-intel]

This is ffmpeg issue.

[eero-t]

This is ffmpeg issue.

There was a comment that it's an issue between media-driver and FFmpeg, and it's not clear which should be fixed.

You would need to make sure there's a bug reported for FFmpeg (link please!) and it's been accepted as FFmpeg issue, before closing this.

[wangyan-intel]

Media driver will return 2 buffers. One is coded data buffer, another is some additional suggestion info for future encoding. So ffmpeg should ignore the 2nd buffer if it doesn't care theses suggested info.