[FFmpeg-devel] mutlithreading in ffmpeg?

Reimar Döffinger Reimar.Doeffinger at gmx.de
Sat Mar 19 13:08:22 CET 2011

On Fri, Mar 18, 2011 at 05:33:04PM -0700, Thomas Worth wrote:
> On Fri, Mar 18, 2011 at 7:31 AM, Michael Niedermayer <michaelni at gmx.at> wrote:
> > On Thu, Mar 17, 2011 at 04:10:58PM -0700, Thomas Worth wrote:
> >> >> There is ffmpeg-mt for frame level multithreaded decoding.
> >> >> http://gitorious.org/ffmpeg/ffmpeg-mt
> >> >> It would be nice to see that integrated into mainline ffmpeg.
> >> >> Its quite effective, scales nicely to whatever number of cores you've got
> >> >> and not sensitive to what to tool was used to create the content.
> >> >
> >> > It will be integrated soon.
> >>
> >> Hopefully you guys can fix the seeking problem with the H.264 decoder
> >> before then... hint, hint ;-)
> >
> > which issue number on the bug tracker is that?
> I didn't file a bug report in case I was overlooking something.
> However, I've spent some time with this and I am pretty sure it's a
> problem with multi-threaded decoding. Anyway, I put together a simple
> page that explains it in case it's a problem with my code:
> http://rarevision.com/ffmpeg-mt/

Well, it is in sofar a problem with your code as it does not show any _bug_,
just some conspiciously inconsistent behaviour.
And even that is unsure since you do not show the full code, e.g. whether
you correctly flush after a seek.
But either way not immediately returning a decoded frame is _not_ a bug,
if your code in any way assumes this it is _broken_ and it will not
work correctly with some current and future (also hw-accelerated) codecs.

More information about the ffmpeg-devel mailing list