[FFmpeg-devel] [PATCH]lavf/webpenc: Do not set alpha flag for yuv420p

Carl Eugen Hoyos cehoyos at ag.or.at
Tue Apr 12 21:53:13 CEST 2016

wm4 <nfxjfg <at> googlemail.com> writes:

> > -                flags |= 2 + 16;
> > +                flags |= 2;
> > +                if (st->codecpar->format != AV_PIX_FMT_YUV420P)
> > +                    flags |= 16; // stream may contain transparency 
> > information

> The pixel format shouldn't be required to be set in this muxer.

I am sorry, I don't understand the word "should" in this 
sentence: Do you mean the webp specification is bad or 
that the muxer should use a different information to 
find out if the frames may contain transparency?
Or that the ticket is invalid or that I misunderstand it?

> It's generally not needed.

If it is not needed, why is it available?

> It also means that if the user doesn't set it,
> everything will apparently work well, but it 
> will be flagged as alpha.

The webp format afaict needs the information, if the 
user prefers not to set it, what is the solution?

> When will you learn to send properly formatted 
> patches (git format-patch)?

Is this related to the patch?
Or do you want to commit my patches (this is not necessary)?

Carl Eugen

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