[FFmpeg-devel] Handling CODEC_FLAG2_CHUNKS type H264 content.

Dale Curtis dalecurtis at chromium.org
Wed Sep 24 20:55:38 CEST 2014


Some Chrome users ( http://crbug.com/415542 ) are encountering content
which requires CODEC_FLAG2_CHUNKS to decode without the following error:

http://git.videolan.org/?p=ffmpeg.git;a=blob;f=libavcodec/h264.c;hb=HEAD#l1917

We haven't enabled this flag globally in the past since it disables frame
level threading:

http://git.videolan.org/?p=ffmpeg.git;a=blob;f=libavcodec/pthread.c;hb=HEAD#l46

I have a couple questions on handling this type of content:

- Is the error returned truly an error or a warning? Ignoring it reveals
decoding continues okay; though I have no idea if this is always true for
chunked content.

- Chrome currently only uses 2 threads for video decoding. I'll run the
numbers soon, but generally, is frame level threading expected to be
beneficial with only two threads?

Thanks in advance!

- dale


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