[FFmpeg-devel] [PATCH 1/3] avcodec/h264, videotoolbox: pass SPS changes into the VT decoder

[Michael Niedermayer]

On Fri, Feb 17, 2017 at 07:02:10AM +0100, wm4 wrote:
> On Thu, 16 Feb 2017 10:29:36 -0800
> Aman Gupta <ffmpeg at tmm1.net> wrote:
> 
> > From: Aman Gupta <aman at tmm1.net>
> > 
> > This fixes playback of h264 streams with SPS changes. One such sample
> > is available at http://tmm1.s3.amazonaws.com/videotoolbox/spschange.ts.
> > It switches mid-stream from level 4.0 to level 3.2.
> > 
> > Previously, playing this sample with the VT hwaccel on iOS would crash.
> > After this patch, it plays back as expected.
> > 
> > On macOS however, feeding in new SPS into an existing decompression
> > session does not always work, so this patch is only a partial fix.
> > ---
> >  libavcodec/h264dec.c | 7 +++++++
> >  1 file changed, 7 insertions(+)
> > 
> > diff --git a/libavcodec/h264dec.c b/libavcodec/h264dec.c
> > index 41c0964..e521c52 100644
> > --- a/libavcodec/h264dec.c
> > +++ b/libavcodec/h264dec.c
> > @@ -740,6 +740,13 @@ FF_ENABLE_DEPRECATION_WARNINGS
> >              break;
> >          case H264_NAL_SPS: {
> >              GetBitContext tmp_gb = nal->gb;
> > +            if (avctx->hwaccel && avctx->hwaccel->pix_fmt == AV_PIX_FMT_VIDEOTOOLBOX) {
> > +                ret = avctx->hwaccel->decode_slice(avctx,
> > +                                                   nal->data,
> > +                                                   nal->size);
> > +                if (ret < 0)
> > +                    goto end;
> > +            }
> >              if (ff_h264_decode_seq_parameter_set(&tmp_gb, avctx, &h->ps, 0) >= 0)
> >                  break;
> >              av_log(h->avctx, AV_LOG_DEBUG,
> 
> A bit ugly but ok IMHO. Maybe it would be better to add a new hwaccel
> callback here, even if it's used by VT only.
> 
> You should probably wait for approval by michaelni.

i dont really have an oppinion on hwaccel, thats not so much my
area
though i find special cases for specific hwaccel a bit ugly, i dont
object to it, just saying i would be in favor of not having special
cases if that is possible

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

During times of universal deceit, telling the truth becomes a
revolutionary act. -- George Orwell
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