[FFmpeg-devel] [PATCH][RFC] avcodec: disallow hwaccel with frame threads
nfxjfg at googlemail.com
Wed Jan 20 09:50:10 CET 2016
On Wed, 20 Jan 2016 00:42:18 +0000
Andy Furniss <adf.lists at gmail.com> wrote:
> Hendrik Leppkes wrote:
> >>> I do not agree that it should be a warning. As outlined in the
> >>> commit message and this thread, there are serious flaws with
> >>> frame threading and hwaccel.
> >> I'm fine with it being an error, but since it is an API change, it
> >> should follow the usual deprecation period to allow downstream
> >> users time to fix it. Meanwhile it can be a warning so that people
> >> notice the problem.
> > Its fundamentally broken, and making it a warning would re-introduce
> > known crashes. So no.
> So are the flaws in ffmpeg or particular drivers?
> It does seem a shame perf wise, I've been testing my AMD UVD decode
> recently and for 500 UHD frames in a really high bitrate h264 file it's
> like -
> ffmpeg threaded = 16 sec.
> ffmpeg single thread = 20 sec.
With or without hwaccel?
> gstreamer vaapi 14 sec.
> gstreamer omx 10 sec.
> the omx is a faster as the others do nv12 -> I420 on cpu (AFAICT)
> Maybe -threads 1 hurts perf by limiting the format conversion as well?
> Is there a way to get whatever the h/w spits out (nv12) directly? Trying
> to ask for nv12 seemed to get a double conversion.
Both vdpau and vaapi can retrieve image data as nv12.
More information about the ffmpeg-devel