Re: [FFmpeg-devel] [PATCH 2/2] avformat/mov: Support parsing of still AVIF Alpha Channel

[Vignesh Venkatasubramanian <vigneshv-at-google.com@ffmpeg.org>]

On Tue, Jul 5, 2022 at 9:54 AM Anton Khirnov <anton@khirnov.net> wrote:
>
> Quoting Vignesh Venkatasubramanian (2022-07-02 23:15:35)
> > > As for encoding, not fully sure how it should be integrated, if any
> > > encoders actually at this moment do proper alpha coding, or do all API
> > > clients have to separately encode with one context the primary image,
> > > and the alpha with another?
> >
> > I am not sure about other codecs, but in the case of AVIF/AV1, the
> > encoder does not understand/support alpha channels. The only way to do
> > it is to use two separate encoders.
>
> Can this not be handled in our encoder wrapper?
>

By encoder wrapper, you mean codec wrappers in libavcodec like
libaomenc.c right ? Yes, it is possible to do this in the encoder
wrapper by keeping multiple instances of the encoder. But each encoder
wrapper has to be updated to support it. AV1, for example, has three
different encoders that can be used as of today (aom, rav1e and
svt-av1).

> We should strive as much as possible to shield our callers from
> codec-specific implementation details.
>
> --
> Anton Khirnov
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-- 
Vignesh
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