[FFmpeg-devel] On libavfilter: A Summary of Issues

Stefano Sabatini stefasab at gmail.com
Sun Oct 7 14:57:14 CEST 2012

On date Saturday 2012-10-06 21:34:05 -0600, Michael Bradshaw encoded:
> Thanks for that list. I summarizes many of my own thoughts.
> On Sat, Oct 6, 2012 at 5:38 PM, Derek Buitenhuis <derek.buitenhuis at gmail.com
> > wrote:
> > Is it supposed to be an extensible filtering framework that 3rd
> > party devs write filters for and use for a lot of video processing,
> > like Avisynth and VapourSynth? Is it supposed to be something to
> > mainly be used as a C API from others' applications? Just ffmpeg.c?
> >

> This one in particular gets me. I use the C API of libav* and rarely use
> the command line ffmpeg, but many of the libavfilter filters are quite
> useless in the C API. Take, for example, the silencedetect filter.
> Detecting silence is useful, and I would certainly use it, but all that
> filter does is print it out to the console. Is it meant to be useful only
> to ffmpeg.c (and even then... how useful is that?), or in the C API as
> well? In other words, the ability to get data *out* of libavfilter is
> severely lacking in the C API, so I'm not even sure if it's targeting the C
> API or not.

Right now that output is not very useful. Possible solutions:
1. extend outputting capabilities (e.g. define a logger via the opaque
structure), and 2. implement metadata injection, so you send the
statistics as metadata and the next filters can process it (e.g. by
sending commands to other filters).
FFmpeg = Fundamental and Friendly Mournful Problematic Elastic Ghost

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