[FFmpeg-soc] libavfilter review

[Bobby Bingham]

On Fri, 17 Aug 2007 21:10:15 +0200
Michael Niedermayer <michaelni at gmx.at> wrote:

> the query_formats system is very flexible, it takes a AVFilterLink
> so a filter could have a fixed list of supported input pix_fmts and
> make the output query_formats depend on the input pix_fmt or the
> other was around well i dont think the other way around would work
> but how should the user know that?
> and whats the sense of this overly flexible system if it doesnt work
> with anything but the obvious simple supported output pix_fmt depends
> upon input formats, it would be alot clearer if query_formats would
> take a list/array of input pix_fmts as argument (or a array or
> pix_fmt, flags pairs) where the flags could indicate if the pix_fmt
> can be provided without colorspace conversation, but maybe thats not
> really usefull and a simpler prefer first possible format in the list
> system would work equally well
> 
> 
> also what happens in the following case:
> src -> filter -> destination
> 
> src supports formats A and C
> destination supports formats B anc C
> and the filter supports A,B,C inputs and output=input
> 
> if i understood the code correctly this would fail
> 

I think I've got an idea which will be less absurdly flexible, and will
support graphs like your example without requiring conversion.  The
only thing is that I might need to set the restriction that all the
inputs of a filter must always be operating on the same colorspace, and
similar for outputs.

This of course doesn't affect all those filters with only simple inputs
and outputs.  And I expect most filter authors would only support this
case anyway.  But before I start coding it, I want to check if such a
restriction would be acceptable.

-- 
Bobby Bingham
Never trust atoms.  Or anything made of atoms.
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