[FFmpeg-devel] new filter infastructure stuff (Google Summer of Fun)

[mmh]

mark cox writes:
 > >
 > >
 > >
 > > On the audio stuff, I like that libaf stuff as it sits right now its
 > > not bad its fairly simple however its gpl and not lgpl.  It would be
 > > nice if there was an acceptable way to include it into ffmpeg before
 > > next years SOC.
 > 
 > 2 options:
 > A. get the authors  from the svn logs and email them to ask if they will
 > relicence as lgpl.
 > B. ffmpeg does not exclude gpl code. Include the code as is. with a libaf
 > configure option.

A is a pain, I guess B is the better option.  I'm thinking to put a
small wrapper in ffmpeg to handle option 'B' would be easiest approach.  I
don't think I would include dec_audio.c from libmpcodecs but a new
simplified mechanism which just envoked the filter chain itself.

  oafd = af_play (audio_filter_chain, iafd);

I guess that would get integrated roughly around here:

ffmpeg.c:1130:
        // preprocess audio (volume)
        if (ist->st->codec->codec_type == CODEC_TYPE_AUDIO) {

	    if (audio_filter_chain) {
	         iafd->audio = samples;
                 iafd->len   = data_size;
                 ...
	         oafd = af_play (audio_filter_chain, iafd);

		 if (!oafd) 
                    report error but continue?
                 else {
                    ...
		    memcpy (samples, oafd->audio, oafd->len);
                    ...
                 }
            }

            if (audio_volume != 256) {
                short *volp;
                volp = samples;
                for(i=0;i<(data_size / sizeof(short));i++) {
                    int v = ((*volp) * audio_volume + 128) >> 8;
                    if (v < -32768) v = -32768;
                    if (v >  32767) v = 32767;
                    *volp++ = v;
                }
            }
        }

Thoughts?

Thanks
Marc