[FFmpeg-devel] [PATCH 5/6] avcodec/h264: Avoid using gray gap frames as references

[Michael Niedermayer]

On Tue, Nov 21, 2023 at 09:27:59AM -0300, James Almer wrote:
> On 11/14/2023 2:20 PM, Michael Niedermayer wrote:
> > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> > ---
> >   libavcodec/h264_refs.c | 11 +++++++++++
> >   libavcodec/h264dec.c   |  1 +
> >   libavcodec/h264dec.h   |  1 +
> >   3 files changed, 13 insertions(+)
> > 
> > diff --git a/libavcodec/h264_refs.c b/libavcodec/h264_refs.c
> > index 92778e737a5..9bc7b20988f 100644
> > --- a/libavcodec/h264_refs.c
> > +++ b/libavcodec/h264_refs.c
> > @@ -410,6 +410,17 @@ int ff_h264_build_ref_list(H264Context *h, H264SliceContext *sl)
> >                   else
> >                       return -1;
> >               }
> > +            if (h->noref_gray>0 && sl->ref_list[list][index].parent->gray && h->non_gray) {
> > +                for (int j=0; j<sl->list_count; j++) {
> > +                    int list2 = (list+j)&1;
> > +                    if (h->default_ref[list2].parent && !h->default_ref[list2].parent->gray
> > +                        && !(!FIELD_PICTURE(h) && (h->default_ref[list2].reference&3) != 3)) {
> > +                        sl->ref_list[list][index] = h->default_ref[list2];
> > +                        av_log(h, AV_LOG_DEBUG, "replacement of gray gap frame\n");
> > +                        break;
> > +                    }
> > +                }
> > +            }
> >               av_assert0(av_buffer_get_ref_count(sl->ref_list[list][index].parent->f->buf[0]) > 0);
> >           }
> >       }
> > diff --git a/libavcodec/h264dec.c b/libavcodec/h264dec.c
> > index 7ea55db75dd..b48821db244 100644
> > --- a/libavcodec/h264dec.c
> > +++ b/libavcodec/h264dec.c
> > @@ -1091,6 +1091,7 @@ static const AVOption h264_options[] = {
> >       { "nal_length_size", "nal_length_size", OFFSET(nal_length_size), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 4, VDX },
> >       { "enable_er", "Enable error resilience on damaged frames (unsafe)", OFFSET(enable_er), AV_OPT_TYPE_BOOL, { .i64 = -1 }, -1, 1, VD },
> >       { "x264_build", "Assume this x264 version if no x264 version found in any SEI", OFFSET(x264_build), AV_OPT_TYPE_INT, {.i64 = -1}, -1, INT_MAX, VD },
> > +    { "noref_gray", "Avoid using gray gap frames as references", OFFSET(noref_gray), AV_OPT_TYPE_INT, {.i64 = 1}, -1, 1, VD },
> 
> Should be AV_OPT_TYPE_BOOL, and there's no point allowing -1. That's only
> useful for example when used with external modules as "use the default from
> the external library".

I was thinking that we may want to choose this depending on the detected
encoder when i wrote it. But as is, true it makes no sense ATM

I will change it

thx

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

Many things microsoft did are stupid, but not doing something just because
microsoft did it is even more stupid. If everything ms did were stupid they
would be bankrupt already.
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