[FFmpeg-devel] [PATCH] lavf/tee: add support for bitstream filtering

Stefano Sabatini stefasab at gmail.com
Mon Aug 5 12:23:54 CEST 2013

On date Thursday 2013-08-01 18:32:59 +0200, Stefano Sabatini encoded:
> On date Thursday 2013-08-01 14:36:21 +0200, Nicolas George encoded:
> > Le tridi 13 thermidor, an CCXXI, Stefano Sabatini a écrit :
> > > Changed to:
> > > dumo_extra+a,mp4toannexb+v.
> > 
> > I believe you missed my point: I meant:
> > 
> > bsfs:a=dump_extra,bsfs:v=mp4toannexb
> > 
> > But I realize that it is not possible as ':' is not an authorized option
> > character. "bsfs.a=dump_extra" would be possible, though.
> The problem is that such mechanism is awkward implementation-wise, I'd
> need to iterate the options and match all the options which look like
> bsfs.SPEC, store them and then open the filters after the various
> streams have been opened.

Elaborating more on this. I'd need to store the couples
specifiers+filters in a dictionary (this destroys the specification
order and is a bit more complicate to implement). I leave the design
choice to the maintainer.

> One problem is that you need to specify the option multiple times, for
> example:
> bsf.a=dump_extra:bsf.v=mp4toannexb
> with my proposed syntax:
> bsfs=dump_extra+a,mp4annexb+v
> which is shorter and IMO at least as much as readable, the only
> advantage of your syntax is that it *resembles* specific ffmpeg
> syntax, which I consider a marginal gain in this case.
> The other problem is that once the dictionary has been parsed, you
> lose the order of application of the filters, which could be
> practically relevant.
> (Note also that my syntax can be easily extended in case the need
> arise to support filter arguments: filter+spec=args).
> What we need is a specification format to set a sequence of bitstream
> filters, each one of which can be applied to a selected subset of
> streams. If such specification is not exploded in multiple options,
> that's better from my point of view.
FFmpeg = Formidable and Fancy Moronic Purposeless Elfic Guide

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