[FFmpeg-devel] [PATCH] libavfilter/qsvvpp: Use different alignment for YUV420P format

[Chen, Wenbin]

> On 11/29/2022 5:07 AM, wenbin.chen-at-intel.com at ffmpeg.org wrote:
> > From: Wenbin Chen <wenbin.chen at intel.com>
> >
> > When process yuv420 frames, FFmpeg use same alignment on Y/U/V
> > planes. VPL and MSDK use Y plane's pitch / 2 as U/V planes's
> > pitch, which make U/V planes 16-bytes aligned. We need to set
> > a separate alignment to meet runtime's behaviour.
> >
> > Now the commandline works fine:
> > ffmpeg -f rawvideo -pix_fmt yuv420p -s:v 3082x1884 \
> > -i ./3082x1884.yuv -vf 'vpp_qsv=w=2466:h=1508' -f rawvideo \
> > -pix_fmt yuv420p 2466_1508.yuv
> >
> > Signed-off-by: Wenbin Chen <wenbin.chen at intel.com>
> > ---
> >   libavfilter/qsvvpp.c | 12 +++++++++---
> >   1 file changed, 9 insertions(+), 3 deletions(-)
> >
> > diff --git a/libavfilter/qsvvpp.c b/libavfilter/qsvvpp.c
> > index 8428ee89ab..ad09114cb7 100644
> > --- a/libavfilter/qsvvpp.c
> > +++ b/libavfilter/qsvvpp.c
> > @@ -408,9 +408,15 @@ static QSVFrame *submit_frame(QSVVPPContext
> *s, AVFilterLink *inlink, AVFrame *p
> >       } else {
> >           /* make a copy if the input is not padded as libmfx requires */
> >           if (picref->height & 31 || picref->linesize[0] & 31) {
> > -            qsv_frame->frame = ff_get_video_buffer(inlink,
> > -                                                   FFALIGN(inlink->w, 32),
> > -                                                   FFALIGN(inlink->h, 32));
> > +            /* When process YUV420 frames, FFmpeg uses same alignment on
> Y/U/V
> > +             * planes. VPL and MSDK use Y plane's pitch / 2 as U/V planes's
> > +             * pitch, which makes U/V planes 16-bytes aligned. We need to set
> a
> > +             * separate alignment to meet runtime's behaviour.
> > +             */
> > +            qsv_frame->frame = ff_default_get_video_buffer2(inlink,
> 
> I think the proper way to do this is by setting a custom AVFilterPad
> get_buffer.video() callback, which will be called instead of
> ff_default_get_video_buffer() (Which uses an automatically chosen
> alignment at runtime) by ff_get_video_buffer().
> 
> See other filters like vf_pad, vf_transpose_vaapi, etc.

Thanks for your advice. I will try it.
> 
> > +                                                FFALIGN(inlink->w, 32),
> > +                                                FFALIGN(inlink->h, 32),
> > +                                                16);
> >               if (!qsv_frame->frame)
> >                   return NULL;
> >
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