[music-dsp] time stretching

roumbaba roumbaba at gmail.com
Thu Jun 10 20:20:33 EDT 2010


Hi all,

Does anyone know if any of these algorithms actually do work in real- 
time on the iphone (or other embedded devices)? For example   
dspdimension's site writes that their Dirac runs "...near-realtime  
(preview mode) on the iPhone." It makes sense since it seems to be  
wavelets based. Anyone had experience with other algorithms on the  
iphone? With what footprint (CPU/memory?)

Thanks,

Baba

On 10 juin 10, at 11:15, Nils Pipenbrinck wrote:

> Well-
>
> There is also the fine tutorial (with code) of DspDimension:
>
> One link with a good overview:
>
>  http://www.dspdimension.com/admin/time-pitch-overview/
>
> and:
>
>  http://www.dspdimension.com/admin/pitch-shifting-using-the-ft/
>
> (which is about pitch shifting, but time-stretching and pitch-shifting
> are so closely related that I treat them as the same).
>
>
> The code from the last link, smbpitchshift.c is great. It's not
> optimized, but written for clarity. I use this code (with some
> optimizations) for shifts in the cent range. +-100 cents (aka. micro
> pitch shifts to thicken up my guitar sound)
>
> From the quality point of view I couldn't be happier. Worth checking
> out, even if you want to go beyond the cent-range.
>
>
> Cheers,
>  Nils
>
>
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