[vlc-devel] libav* private options

[Rafaël Carré]

Hi, this patch serie adds private options for avformat mux/demux
Other modules (switcher, avcodec, avio) are trivial to implement, i just felt lazy.

Example with mp3 muxer "id3v2_version" option:

% cvlc in.mp3 --sout "#std{access=file,dst=out.mp3,mux=avformat{mux=mp3}}"
% eyeD3 out.mp3|grep ID3
ID3 v2.4:

% cvlc in.mp3 --sout "#std{access=file,dst=out.mp3,mux=avformat{mux=mp3,options={id3v2_version=3}}}"
% eyeD3 out.mp3|grep ID3
ID3 v2.3:


I expect to be able to remove quite a few options, especially from avcodec, 
since they would be duplicated with private options.

I would've committed it directly, but I noticed that avcodec/avformat etc still 
use "-ffmpeg" prefix, renaming them properly breaks compatibility with scripts.

Apparently we used to have support for renaming options but not anymore?