On Thu, Aug 18, 2016 at 7:50 AM, Moritz Barsnick <barsn...@gmx.net> wrote:
> On Wed, Aug 17, 2016 at 23:13:13 +0100, Mark Thompson wrote: > > > The test video was captured from a 3MP(2048x1536) camera. The commands > I > > > used: > > > - ffmpeg -c:v h264_qsv -async_depth 10 -i test.h264 -c:v rawvideo -f > null > > > /dev/null > > > - sample_decode h264 -i test.h264 > > > Both uses 100% cpu (a full core). ffmpeg got 170FPS. sample_decode got > > > 370FPS. > > > I think in both cases your speed bound must be on something other > > than the decode, because the hardware goes a lot faster than either > > of those for me. > > Don't explicitly convert to rawvideo, the null muxer recently defaults > to wrapped_avframe, which is a tad bit faster: > > $ ffmpeg -c:v h264_qsv -async_depth 10 -i test.h264 -f null /dev/null Right. rawvideo was causing the problem. However, even with this command. ffmpeg is still slow than sample_decode. 240fps VS 370fps. The interesting thing is that if I set async_depth to 1, both sample_decode and ffmpeg got only 100fps. > > Actually, you may want to rule out too much influence from the output > section of the chain by using "-c copy", if possible: > > $ ffmpeg -c:v h264_qsv -async_depth 10 -i test.h264 -c copy -f null > /dev/null > Well, ffmpeg is smart enough to figure out it doesn't need to do anything here and return immediately.. I don't think demuxer matters here, since samle_decode needs to demux too. > > In addition to this, do benchmark the demuxing/muxing overhead for > comparison, without HW decoding. (Yes this is a different demuxer, but > just in order to see.): > > $ ffmpeg -i test.h264 -c copy -f null /dev/null > > (And drop audio processing using "-an". Not applicable in this case.) > > Moritz > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel > _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
