[FFmpeg-devel] [PATCH] libavfilter/vf_overlay_qsv: Use format of first input to set output format for overlay_qsv

Xiang, Haihao haihao.xiang at intel.com
Wed Dec 15 08:56:54 EET 2021


On Mon, 2021-12-13 at 09:40 +0000, Chen, Wenbin wrote:
> > > -----Original Message-----
> > > From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of
> > 
> > Wenbin Chen
> > > Sent: Friday, December 10, 2021 3:22 AM
> > > To: ffmpeg-devel at ffmpeg.org
> > > Cc: Wenbin Chen <wenbin.chen at intel.com>
> > > Subject: [FFmpeg-devel] [PATCH] libavfilter/vf_overlay_qsv: Use format of
> > > first input to set output format for overlay_qsv
> > > 
> > > overlay_qsv hard coded to use nv12 as output format. Now use the format
> > > of the first input to set output format. Now the following command
> > > works:
> > > 
> > > ffmpeg -hwaccel qsv -c:v hevc_qsv -i input_p010.265 -hwaccel qsv -c:v
> > > hevc_qsv \
> > > -i input2_p010.265 -filter_complex
> > 
> > "[0:v][1:v]overlay_qsv=x=0:y=0:alpha=255,
> > > \
> > > hwdownload,format=p010le" -f rawvideo -y output_p010.yuv
> > > 
> > > Signed-off-by: Wenbin Chen <wenbin.chen at intel.com>
> > > ---
> > >  libavfilter/vf_overlay_qsv.c | 2 ++
> > >  1 file changed, 2 insertions(+)
> > > 
> > > diff --git a/libavfilter/vf_overlay_qsv.c b/libavfilter/vf_overlay_qsv.c
> > > index 7e76b39aa9..d947a1faa1 100644
> > > --- a/libavfilter/vf_overlay_qsv.c
> > > +++ b/libavfilter/vf_overlay_qsv.c
> > > @@ -276,6 +276,7 @@ static int config_output(AVFilterLink *outlink)
> > >      int ret;
> > > 
> > >      av_log(ctx, AV_LOG_DEBUG, "Output is of %s.\n",
> > > av_get_pix_fmt_name(outlink->format));
> > > +    vpp->qsv_param.out_sw_format = in0->format;
> > >      if ((in0->format == AV_PIX_FMT_QSV && in1->format !=
> > 
> > AV_PIX_FMT_QSV) ||
> > >          (in0->format != AV_PIX_FMT_QSV && in1->format ==
> > 
> > AV_PIX_FMT_QSV)) {
> > >          av_log(ctx, AV_LOG_ERROR, "Mixing hardware and software pixel
> > > formats is not supported.\n");
> > > @@ -288,6 +289,7 @@ static int config_output(AVFilterLink *outlink)
> > >              av_log(ctx, AV_LOG_ERROR, "Inputs with different underlying
> > > QSV
> > > devices are forbidden.\n");
> > >              return AVERROR(EINVAL);
> > >          }
> > > +        vpp->qsv_param.out_sw_format = hw_frame0->sw_format;
> > >      }
> > > 
> > >      outlink->w          = vpp->var_values[VAR_MW];
> > > --
> > 
> > When you're already looking at that area:
> > 
> > Do you have any idea why it sets the output time_base to the reciprocal
> > input0 framerate?
> > I think it should rather set it to the same as the input0 time_base.
> > 
> > https://github.com/FFmpeg/FFmpeg/blob/4f44a218e53cd92e64ba10a935bc
> > 1e7583c3e218/libavfilter/vf_overlay_qsv.c#L293-L296
> > 
> > What do you think? (also @Haihao)
> > 
> > Thanks,
> > softworkz
> 
> I have no idea why it is set to the reciprocal input0 framerate.
> I agree with you. I think it should be set to in0->time_base.
> I tried and changing to "in0->time_base" also works fine.

Maybe the code was copied from other files. As soon as the PTS of the frames
passing through the output link uses the output time_base as unit, I think this
code may work too except the precision of the output time_base. The PTS of the
output frame from overlay_qsv uses the output time_base as unit:


https://github.com/FFmpeg/FFmpeg/blob/master/libavfilter/vf_overlay_qsv.c#L314-L315

I may submit a patch to set the output time_base to the input0 time_base if you
are thinking this is better. 

Thanks
Haihao



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