[FFmpeg-devel] [PATCH 1/6] avcodec/apng: Remove threading support

[Ronald S. Bultje]

Hi,

On Tue, Jun 2, 2015 at 1:42 PM, Donny Yang <work at kota.moe> wrote:

> On 3 June 2015 at 03:31, Paul B Mahol <onemda at gmail.com> wrote:
>
> > Dana 2. 6. 2015. 17:49 osoba "Donny Yang" <work at kota.moe> napisala je:
> > >
> > > Each frame depends on the previous frame any way, and it will
> > > cause bugs with frame disposal
> > >
> > > Signed-off-by: Donny Yang <work at kota.moe>
> > > ---
> > >  libavcodec/pngdec.c | 11 +----------
> > >  1 file changed, 1 insertion(+), 10 deletions(-)
> > >
> > > diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
> > > index 2512799..2ea3e8b 100644
> > > --- a/libavcodec/pngdec.c
> > > +++ b/libavcodec/pngdec.c
> > > @@ -1224,17 +1224,10 @@ static int update_thread_context(AVCodecContext
> > *dst, const AVCodecContext *src)
> > >      if (dst == src)
> > >          return 0;
> > >
> > > -    pdst->frame_id = psrc->frame_id;
> > > -
> > >      ff_thread_release_buffer(dst, &pdst->picture);
> > >      if (psrc->picture.f->data[0] &&
> > >          (ret = ff_thread_ref_frame(&pdst->picture, &psrc->picture)) <
> 0)
> > >          return ret;
> > > -    if (CONFIG_APNG_DECODER && dst->codec_id == AV_CODEC_ID_APNG) {
> > > -        ff_thread_release_buffer(dst, &pdst->last_picture);
> > > -        if (psrc->last_picture.f->data[0])
> > > -            return ff_thread_ref_frame(&pdst->last_picture,
> > &psrc->last_picture);
> > > -    }
> > >
> > >      return 0;
> > >  }
> > > @@ -1294,9 +1287,7 @@ AVCodec ff_apng_decoder = {
> > >      .init           = png_dec_init,
> > >      .close          = png_dec_end,
> > >      .decode         = decode_frame_apng,
> > > -    .init_thread_copy = ONLY_IF_THREADS_ENABLED(png_dec_init),
> > > -    .update_thread_context =
> > ONLY_IF_THREADS_ENABLED(update_thread_context),
> > > -    .capabilities   = CODEC_CAP_DR1 | CODEC_CAP_FRAME_THREADS /*|
> > CODEC_CAP_DRAW_HORIZ_BAND*/,
> > > +    .capabilities   = CODEC_CAP_DR1 /*| CODEC_CAP_DRAW_HORIZ_BAND*/,
> > >  };
> > >  #endif
> > >
> > > --
> > > 2.4.0
> > >
> >
> > Hmm, have you checked it is really broken now?
> >
>
> It wasn't broken originally, but breaks when I fix the frame disposing.
> More specifically, since each frame depends on the metadata of the previous
> frame as well as the frame itself, having it threaded would give
> inconsistent last-frame metadata, unless we wait for the frame before
> reading the next frame's metadata.


What is this metadata? I'm fairly confused over this.

Ronald