[FFmpeg-devel] [PATCH] [2/??] [3/3] Filter graphs - Parser for a graph description

[vmrsss]

Hi Vitor,

On 19 Mar 2008, at 18:48, Vitor Sessak wrote:
> In a way, this is a problem. Now, the parsing of the filters are
> separated of the initialization (but that may change before hitting
> SVN). But to parse something like
>
> split, nop*rotate, picInPic
>
> There is no way to see the difference between
>
> (in1) ---> split ---> rotate ------+
>               |                   picinPic ----> out
>               ------> nop    ------+
>
> and
>
> (in1) -----+   +------> rotate
>            split
> (in2) -----+   +------> nop ------>   picinPic ----> out
>
> without knowing beforehand how many inputs and outputs each filter  
> has.

Unfortunately, I am not sure I can parse your second graph above, but  
in general yes, absolutely, without knowing the number of inputs and  
outputs of a filter (let's call it its type), you can't parse a  
syntactic form correctly. This is irrespective of the language you  
pick, I'd expect. But yo know the type for the atomic filters in  
libavfilter, and from that you can infer all the rest.