[FFmpeg-devel] soundtouch filter?

[Pavel Koshevoy]

Hi,

Is anyone working on an audio tempo filter?  There are two use cases I 
am interested in.  The first is to speed up playback, because some 
people prefer to watch their movies at a faster rate (1.5x nominal) to 
save time.  The second is to slow down audio to accommodate slow video 
decoding on older hardware, so as to avoid stuttering audio during playback.

I could implement this feature in my player outside of the avfilter 
chain, but I think it would be more useful for everybody if this was an 
avfilter.  Am I on the right track?

I am thinking of using the soundtouch library for actual audio 
processing, so the filter would be a wrapper for soundtouch.  The number 
of audio samples going in and coming out of the filter would be scaled 
according to the playback rate setting, and the timestamps (if any) 
would be changed as well.  Is this going to be a problem for the current 
avfilter architecture?  If someone could give me a few pointers on where 
to begin that would really help.

Thank you,
     Pavel.