[FFmpeg-devel] [PATCH] libavutil: add clean aperture (CLAP) side data.

[Neil Birkbeck]

On Tue, Apr 28, 2020 at 3:18 AM Nicolas George <george at nsup.org> wrote:

> Andreas Rheinhardt (12020-04-28):
> > That's expected. The patch provided only provides the structure in which
> > the values are intended to be exported; it does not add any demuxing or
> > muxing capabilities for mov or mkv (as you can see from the fact that
> > none of these (de)muxers have been changed in the patch).
>
> Which is something I intended to comment on: adding code without users
> is rarely a good idea. I suggest we do not commit until at least one
> demuxer use it, preferably at least two. Otherwise, we may realize that
> “oh crap, it doesn't work” because of a tiny unforeseen detail.


Thanks for the feedback. I also have patches for the demux (MOV/MKV) and
mux (MOV/MKV).

As there is still the alternative of using the fields in the
AVCodecParameters/AVCodecContext, my intention was to keep the first patch
small to resolve discussion on that point.

I've included the patches, if you'd like to try test it, Kieren. I see on
your test file that there may be some slight rounding error making output
crop 704 not 703 (MKV file ends up with pixel_crop_{left,right} = 8).

/ffprobe ../testdata/clap.mov 2>&1 | grep -A1 "Side"
    Side data:
      Clean aperture:[width 41472/59 height:576/1 h_offset:0/1 v_offset:0/1]
./ffmpeg -i ../testdata/clap.mov  -vcodec copy -acodec copy /tmp/clap.mkv
./ffprobe /tmp/clap.mkv 2>&1 | grep -A1 "Side"
    Side data:
      Clean aperture:[width 704/1 height:576/1 h_offset:0/1 v_offset:0/1]
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