[FFmpeg-devel] soundtouch filter?

[Pavel Koshevoy]

On 05/15/2012 10:13 AM, Michael Niedermayer wrote:
> On Tue, May 15, 2012 at 12:30:32AM -0600, Pavel Koshevoy wrote:
>> On 4/29/12 2:56 PM, Pavel Koshevoy wrote:
<snip>
>> The filter files are here: 
>> http://apprenticevideo.svn.sourceforge.net/viewvc/apprenticevideo/trunk/apprenticevideo/yaeAudioTempoFilter.h 
>> http://apprenticevideo.svn.sourceforge.net/viewvc/apprenticevideo/trunk/apprenticevideo/yaeAudioFragment.h 
>> So, is it worth trying to wrap it as an avfilter and add it to ffmpeg? 
> sure it would be very welcome but keep in mind ffmpeg is C not C++


Understood.  I began porting my code to C today.

I have some concerns regarding timestamps.  In my opinion this filter should not 
change the timestamps.  In my player I added an extra field to the decoded frame 
for tempo value.  This way the audio/video renderers still sync according to the 
decoded PTS, and can adjust the frame duration and sleep according to current 
frame tempo.  I don't see any other easy way of preserving a/v sync while 
allowing the user to tweak tempo continuously during playback.

This brings me to my next point.  Is AVFilter::process_command the appropriate 
interface for updating the tempo parameter during playback?

Thank you,
     Pavel.