[FFmpeg-devel] [PATCH] pthreads: export the delay that was previously exported by mangling has_b_frames through AVCodecContext.delay

[Michael Niedermayer]

On Wed, Nov 09, 2011 at 08:19:37PM +0100, Reimar Döffinger wrote:
> On Wed, Nov 09, 2011 at 08:09:14PM +0100, Michael Niedermayer wrote:
> > On Wed, Nov 09, 2011 at 08:05:26PM +0100, Reimar Döffinger wrote:
> > > On Wed, Nov 09, 2011 at 07:06:08PM +0100, Michael Niedermayer wrote:
> > > > Hi
> > > > 
> > > > patch below maybe usefull to applications which want to know the
> > > > thread count used in frame multitherading.
> > > > mplayer & mplayer2 fall in this category possibly.
> > > 
> > > I don't think mplayer2 is (generally) affected actually.
> > > 
> > > > From bd352d408af3928d9c53f4cea6a44a0797542cf1 Mon Sep 17 00:00:00 2001
> > > > From: Michael Niedermayer <michaelni at gmx.at>
> > > > Date: Wed, 9 Nov 2011 18:32:38 +0100
> > > > Subject: [PATCH] pthreads: export the delay that was previously exported by mangling has_b_frames through
> > > >  AVCodecContext.delay which was previously unused for decoders and fits better.
> > > > 
> > > > Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
> > > > ---
> > > >  libavcodec/pthread.c |    1 +
> > > >  libavcodec/version.h |    2 +-
> > > >  2 files changed, 2 insertions(+), 1 deletions(-)
> > > > 
> > > > diff --git a/libavcodec/pthread.c b/libavcodec/pthread.c
> > > > index 4a44cea..04181e2 100644
> > > > --- a/libavcodec/pthread.c
> > > > +++ b/libavcodec/pthread.c
> > > > @@ -363,6 +363,7 @@ static int update_context_from_thread(AVCodecContext *dst, AVCodecContext *src,
> > > >      }
> > > >  
> > > >      if (for_user) {
> > > > +        dst->delay         = src->thread_count - 1;
> > > 
> > > Well, if set like this it should probably include a change to the
> > > description that for decode it is the delay added due to decoding
> > > _beyond_ the reorder delay.
> > 
> > I can set it to anything that people prefer but this way
> > delay + has_b_frames would give the old value for both ffmpeg and
> > libav.
> 
> No, I think this way is better for this reason and it's logical enough.
> I just realized that IMO the description even for encode is impossible
> to understand.
> Not sure if it is completely correct, but this would be my suggestion
> for the updated text:

>      * Encoding: Number of frames decode delay inherent in the chosen encoding
>      * method (e.g. reorder delay).

this isnt correct
the value is the delay you get from encoder+reference decoder compared
to passing things through directly


>      * Decoding: Number of frames delay above the inherent delay, e.g. due to
>      * frame multi-threaded decoding. Combined with has_b_frames this should
>      * give the total decode delay.
>      * - encoding: Set by libavcodec.
>      * - decoding: Set by libavcodec.
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-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Everything should be made as simple as possible, but not simpler.
-- Albert Einstein
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