You should have a search for papers by Jean Laroche and Mark Dolson, such
as "About This Phasiness Business" for some good information on phase
vocoder processing. They address time scale modification mostly in that
specific paper, but many of the insights apply in general, and you will
find
Am 28.10.2018 um 22:28 schrieb gm:
I am thinking now that resetting the phase to the original when the
amplitude exceeds the previous value
is probably wrong too, because the phase should be different when
shifted to a different bin
if you want to preserve the waveshape
I am not sure about
there had been a mistake in my structure which caused the phase to be
set to zero
now it sounds more like the original when there is no pitch shift applied
(which is a good indicator that there is something wrong when it does not)
Am 28.10.2018 um 18:05 schrieb Scott Cotton:
- you need two up to 200 tap FIR filters for a spectral envelope
on an ERB scale (or similar) at this FFT size (you can
precalculate this
offline though)
Could you explain more about this? What exactly are you doing with
ERB and
On Sun, 28 Oct 2018 at 16:47, gm wrote:
> to sum it up, assumptions:
>
> - for the phase vocoder approach you need an FFT size of 4096 @ 44.1 kHz
> SR and
> - 8 or rather 16 overlaps at this FFT size and SR for a decent quality
>
The coincides with what I've played with. But the FFT size is
to sum it up, assumptions:
- for the phase vocoder approach you need an FFT size of 4096 @ 44.1 kHz
SR and
- 8 or rather 16 overlaps at this FFT size and SR for a decent quality
- you need two up to 200 tap FIR filters for a spectral envelope
on an ERB scale (or similar) at this FFT size (you
Am 28.10.2018 um 10:46 schrieb Scott Cotton:
- the quantised pitch shift is only an approximation of a continuous
pitch shift because
the sinc shaped realisation of a pure sine wave in the quantised
frequency domain can occur
at different distances from the bin centers for different sine
Dear Peter,
There are numerous (academic) sources which cite phase vocoding as a
"solved problem" when used
in conjunction with transient detection and phase locking. I don't
entirely agree with that assessment.
Phase vocoders often have limitations around the following
1. integer vs real/float
Dear Scott,
* Scott Cotton [2018-10-28 10:49]:
> I don't know if you're "doing it the right way", however, pitch shift by
> bin shifting has
> the following problems:
>
> -edge effects (using windowing can help)
> - pitch shift up puts some frequencies above nyquist limit, they need to be
>
I don't know if you're "doing it the right way", however, pitch shift by
bin shifting has
the following problems:
-edge effects (using windowing can help)
- pitch shift up puts some frequencies above nyquist limit, they need to be
elided
- the quantised pitch shift is only an approximation of a
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