[FFmpeg-devel] [PATCH v2 1/1] avcodec/vpp_qsv: Copy side data from input to output frame

[Anton Khirnov]

Quoting Soft Works (2021-12-07 10:03:28)
> 
> 
> > -----Original Message-----
> > From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of Anton
> > Khirnov
> > Sent: Tuesday, December 7, 2021 9:08 AM
> > To: FFmpeg development discussions and patches <ffmpeg-devel at ffmpeg.org>
> > Subject: Re: [FFmpeg-devel] [PATCH v2 1/1] avcodec/vpp_qsv: Copy side data
> > from input to output frame
> > 
> > Quoting Soft Works (2021-12-03 09:51:13)
> > > > I'm concerned that this behavior will become hardcoded into this new API
> > > > and we won't be able to get rid of it in the future.
> > >
> > > I understand your concern from an abstract point of view. But the point
> > > about which you want to be concerned has already happened 7 years ago
> > > and now there exist more than 200 usages of av_frame_copy_props(), all
> > > of which are possibly expecting the special treatment of PANSCAN.
> > > That makes me wonder, whether there might be any practical use for
> > > a function av_frame_copy_side_data() that behaves differently?
> > 
> > I suspect the overwhelming majority of these calls are done between the
> > frames with the same resolution, so the relevant code is not executed.
> > The places where it does matter should be quite few.
> > 
> > And more generally, there's a lot of stuff in our codebase that
> > shouldn't be there. We shouldn't give up on improving things just
> > because they have been around for a long time.
> 
> I'm totally with you. I mean, I've gone over 4 patch versions just for improving
> the documentation of the linesize[] parameter ;-)
> 
> You didn't quote the other part where I said that it might more sense to
> investigate the PANSCAN story directly.
> Anyway, I think the solution with the flags is good now.

I had nothing to add there. You are correct, the reason that code was
added should be investigated and we should find a better solution to the
problem. But that's for whenever somebody feels motivated enough to do
it.

-- 
Anton Khirnov