[FFmpeg-devel] [PATCH] lavfi: add audio eval signal source

Michael Niedermayer michaelni at gmx.at
Sat Oct 15 19:25:24 CEST 2011


On Sat, Oct 15, 2011 at 01:37:59AM +0200, Stefano Sabatini wrote:
> On date Thursday 2011-10-13 10:04:34 +0200, Nicolas George encoded:
> > Le duodi 22 vendémiaire, an CCXX, Stefano Sabatini a écrit :
> [...]
> > > +    int64_t chlayouts[] = { AV_CH_LAYOUT_MONO, -1 };
> > 
> > As Michael said, the possibility to generate several channels would be cool.
> > OTOH, it could be left to a separate amerge filter: (n channels, p channels)
> > -> n+p channels.
> 
> Yes I like this idea, and I wanted to implement it but I'm still
> thinking what should be the better syntax for it.  Ideally:
> 
> expr1:expr2:...:exprN:opts
> 
> but then there is no easy way to understand what is an expression and
> what not (the options are of the form {key=val}+).
> 
> I could suppose that the first time I found ident= then I found the
> options string, but this assumption won't be correct if we extend the
> expression syntax, for example to make them accept things of the
> kind: x=10; 2*x+x^x
> 
> (in that case it would be impossible to distinguish a key=val
> form from an expression).
> 
> Considered alternatives:
> expr1\:expr2\:...\:exprN:opts
> 
> but this would require a double level of escaping, since the filter
> args are fetched with av_get_token(), same for:
> expr1,expr2,...,exprN:opts
> 
> Maybe:
> expr1|expr2|...|exprN:opts
> 
> where I use '|' to separate expressions (and I assume the | is never
> part of an expression).
> 
> Other alternative:
> c1=expr1:c2=expr2:...:cN=exprN:opts
> 
> but this would be way too verbose and clunky for my taste.
> 

> Suggestions are welcome.

expr1:expr2:...:exprN::opts


[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Those who are too smart to engage in politics are punished by being
governed by those who are dumber. -- Plato 
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