[FFmpeg-devel] [PATCH v4] libavfilter/vf_cover_rect: support for cover image with more pixel format and different width and height

[Lance Wang]

On Sun, Jun 16, 2019 at 3:26 PM Michael Niedermayer <michael at niedermayer.cc>
wrote:

> On Sun, Jun 16, 2019 at 07:11:27AM +0800, Lance Wang wrote:
> > On Sun, Jun 16, 2019 at 6:20 AM Michael Niedermayer
> <michael at niedermayer.cc>
> > wrote:
> >
> > > On Fri, Jun 14, 2019 at 11:52:47PM +0800, Lance Wang wrote:
> > > > On Fri, Jun 14, 2019 at 5:31 PM Michael Niedermayer
> > > <michael at niedermayer.cc>
> > > > wrote:
> [...]
> > >
> > > >
> > > >
> > > > >
> > > > >
> > > > > > +        if (!cover->match_frame || (w !=
> cover->match_frame->width
> > > || h
> > > > > != cover->match_frame->height
> > > > > > +                    || in_format !=
> cover->match_frame->format)) {
> > > > > > +            if (cover->match_frame)
> > > > > > +                av_freep(&cover->match_frame->data[0]);
> > > > > > +            else if (!(cover->match_frame = av_frame_alloc()))
> > > > > > +                return AVERROR(ENOMEM);
> > > > > > +
> > > > >
> > > > > > +            if ((ret = ff_scale_image(cover->match_frame->data,
> > > > > cover->match_frame->linesize,
> > > > > > +                            w, h, in_format,
> > > cover->cover_frame->data,
> > > > > cover->cover_frame->linesize,
> > > > > > +                            cover->cover_frame->width,
> > > > > cover->cover_frame->height,
> > > > > > +                            cover->cover_frame->format, ctx)) <
> 0)
> > > > > > +                return AVERROR(ENOMEM);
> > > > >
> > > > > This sort of reimplements the scale filter and it
> > > > > doesnt consider some parameters like AVCOL_RANGE*
> > > > >
> > > >
> > > > the ff_scale_image is implemented and used by other alike place,  I
> try
> > > to
> > > > reuse the function anyway.
> > > > If we need other parameters for scale, we may improve the function
> later,
> > > > now it's OK for my testing as
> > > > the cover image is logo mostly.
> > >
> > > I think one could argue that the scale filter should be used for
> converting
> > > this way the cover image would become one externally vissible input.
> (which
> > > then subsequently also could change over time and not just be a static
> > > image ...)
> > >
> > >
> > For now, the code is simple and prefer to use it.  How about to improve
> all
> > other function which use ff_scale_image in future.
>
> if you add no new ff_scale_image(), sure theres no need to clean it up
> but if you add more bad code, no thats not ok IMO.
>
>
OK,  if not use ff_scale_image function, what's better recommended to reuse
the vf_scale complete function simply?



> Thanks
>
> [...]
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> Asymptotically faster algorithms should always be preferred if you have
> asymptotical amounts of data
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