[FFmpeg-devel] [RFC] AVFilter Parser
Thu Mar 27 00:24:30 CET 2008
On 26 Mar 2008, at 18:55, Vitor Sessak wrote:
> Well, I think here you really underestimating the differences between
> the two syntaxes. This is not good, because it can seriously confuse
> someone who is trying to follow the discussion.
No, I don't think I do. Unfortunately we seem to have had a
communication difficulty: it is certainly not easy to discuss matters
like this my email. Please read below:
>> I am using the following syntactic elements because I find them
>> intuitive, but there is nothing special about them, just a matter of
>> - comma (,) for sequential composition --
>> F,G implies #outstream(F) = #instream(G)
> Well, this is a very big difference between my syntax and yours. In my
> syntax a comma compose two filters (not two streams) linking one or
> streams between them.
Where did I say streams? I wrote: comma is for sequential composition
of FILTERS. F and G are filters. The I wrote that writing F and G
implies that the number of output streams of F equals the number of
output streams of G. This is the same as you do...
>> - star (*) for parallel composition --
>> #instream(F*G) = #instreams(F) + #instream(G)
>> #outstream(F*G) = #outstreams(F) + #outstream(G)
> Same thing, in mine a star puts two filters (not streams) in parallel.
So does mine. And I added: the number of input (output) streams of F*G
is the sum of the number of input (output) streams for F plus the
number of input (output) streams of G.
>> ATOMIC_STREAM ::= all the streams in avfilter, eg crop, vflip,
>> scale, ...
> I'm not sure I understand what you call a stream. "crop" is a filter,
> with one input pad and one output pad. You can say that in a graph it
> gets an input stream and an output stream.
Oops, just a typo: I meant to write ATOMIC_FILTER of course, all the
filters defined in avfilter.
I'll reply to the rest of the questions in a separate messages.
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