[FFmpeg-devel] [PATCH 0/2] colorkey vf, int math conversion, libavfilter questions

Carl Eugen Hoyos cehoyos at ag.or.at
Thu Apr 30 01:52:40 CEST 2015

Timo Rothenpieler <timo <at> rothenpieler.org> writes:

> The other issue is the pixel format conversions done 
> by this filter. It seems like libavfilter expects a 
> filter to be able to convert from any of its input 
> formats to any of its output formats.

>From a user's perspective, I don't think this is 
correct: The output format of a filter depends on its 
input format (if several are supported) and possibly 
on the used options.

> This isn't the case for this filter. The only 
> "conversion" it does is from BGR0 to BGRA, 0RGB to 
> ARGB, and so on, if the input format doesn't 
> already contain an alpha channel.

This sounds reasonable to me (again, from a user's 
perspective) and I think there must be other filters 
that act similarly.

Carl Eugen

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