[vlc-devel] New audio resampler

"Bc. Michal Hromádko" n17r0m4nc3r at gmail.com
Sat Feb 14 16:49:47 CET 2009

Laurent Aimar napsal(a):
> Hi,
> 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 :)
It depends on type of the pitch detection algorithm. I can try to use 
several types and maybe I could provide a better quality.
>  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 ...).
At this time I don't exactly know what my plugin would need. I'll do 
some research .
> Regards,

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