[vlc-devel] New audio resampler

Laurent Aimar fenrir at via.ecp.fr
Sat Feb 14 15:16:44 CET 2009


On Fri, Feb 13, 2009, "Bc. Michal Hromádko" wrote:
> Hello developers,
> last year I finished my bachelor project. I implemented PSOLA method to 
> dynamicly change the speed of speach. I also modified VLC to use the 
> PSOLA method as a resampler. It worked pretty good. All resamplers in 
> VLC changes base tone of the speech. 
 It depends when it is used. If it is used while playing faster/slower yes, if
it is used to convert to the format that the audio card support no.

> When user wants to play his video 
> faster, he gets funny smurf voices. It can be undone by reimplementing 
> my "PSOLA resampler". So my question is: Shud I (we) start to work on 
> it? Sorry for my English.

 In 1.0, a special module is tried instead of a resampler to provide correct audio
while playing faster/slower, if found the audio will be correct (ie no tone change).
 The current implementation is done by modules/audio_filter/scaletempo.c
So basically the functionnality is already there (not by default in 0.9).

 BUT the quality of this module is not great at all, specially when doing more
than 1.5x or less than 0.6x
 If your algorithm would provide a better quality, a plugin implementing it will be
welcome :)
 Now, there is a lot of restriction on what an audio plugin in VLC can actually
do, so if you want to give it a try, I think it would be best to tell us what
your plugin would need in order to give you advices (like amount of latency, or ...).



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