[FFmpeg-devel] [PATCH] avcodec/h264_slice: use the new SAR early when setting the decoder

[wm4]

On Tue, 24 Apr 2018 08:28:35 +0200
Hendrik Leppkes <h.leppkes at gmail.com> wrote:

> On Fri, Jan 19, 2018 at 1:01 PM, Steve Lhomme <robux4 at ycbcr.xyz> wrote:
> > If we don't do that get_format might not be called for a while and the proper
> > SAR not used.
> >
> > See the sample mentioned here: https://trac.videolan.org/vlc/ticket/19435
> > ---
> >  libavcodec/h264_slice.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/libavcodec/h264_slice.c b/libavcodec/h264_slice.c
> > index e6b7998834..319a37f5b6 100644
> > --- a/libavcodec/h264_slice.c
> > +++ b/libavcodec/h264_slice.c
> > @@ -1050,8 +1050,10 @@ static int h264_init_ps(H264Context *h, const H264SliceContext *sl, int first_sl
> >          || (non_j_pixfmt(h->avctx->pix_fmt) != non_j_pixfmt(get_pixel_format(h, 0))))
> >          must_reinit = 1;
> >
> > -    if (first_slice && av_cmp_q(sps->sar, h->avctx->sample_aspect_ratio))
> > +    if (first_slice && av_cmp_q(sps->sar, h->avctx->sample_aspect_ratio)) {
> >          must_reinit = 1;
> > +        ff_set_sar(h->avctx, sps->sar);
> > +    }
> >
> >      if (!h->setup_finished) {
> >          h->avctx->profile = ff_h264_get_profile(sps);
> > --
> > 2.14.2  
> 
> Why do we even do a get_format call for aspect ratio changes in the
> first place? It doesn't change the physical image properties, the
> format of image buffers etc remains the same, hwaccel decisions remain
> the same.. anyone know why this is?

Commit 5388f0b479c56179d566c49afd8765fefef4a18e.

https://ffmpeg.org/pipermail/ffmpeg-devel/2010-February/085931.html

I bet it's not a real reason anymore, but didn't try.