Subject: Re: [linux-audio-dev] [ann] pvoc-0.1.0, caps-0.1.11
From: Tim Goetze (tim_AT_quitte.de)
Date: Wed Mar 24 2004 - 23:09:46 EET
[Jesse Chappell]
>Tim Goetze wrote on Wed, 24-Mar-2004:
>
> > [Jesse Chappell]
>
> > >The stretch program was not properly clamping the output from
> > >-1.0 -> 1.0 yielding to terrible cracks upon writing as 16bit
> > >wave files when the output is clipped. The fact that non-clipping
> > >(but very close to) input yielded clipping output is another issue,
> > >but not crucial.
> > >
> > >I've attached a patch that fixes the problem.
> >
> > applied, thanks.
>
>I just realized that you may not want to clamp if your output
>is a 32 bit float or double, as it is fully capable of handling
>the value as produced. For instance, if (well, when) we suck this
>algorithm into ardour we don't need to clamp, as our internal
>format is float.
true. i'll make it an option.
> > unfortunately, i can't come up with an algorithm giving the perfect
> > scale factor for the stretching algorithm. ideas welcome, of course.
>
>Hmm, this is a tough one.... even soundtouch doesn't get it right,
>and it doesn't have the same issues as the FFT approach....
maybe i'll come up with something when i find the time to really work
with the phase vocoder, which will probably give a bunch of insights.
too much to do right now to really dive into it (i feel that the pvoc
package is just scratching the surface).
tim
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