Ok, heres a final idea, can't test any of this so it's pure science fiction:
-Take a much larger FFT spectrogramme offline, with really fine overlap
granularity.
-Take the cesptrum, identify regions/groups of transients by new peaks
in the cepstrum.
-Pick peaks in the spectrum, by
Original Message
Subject: Re: [music-dsp] pitch shifting in frequency domain Re: FFT for
realtime synthesis?
From: "gm"
Date: Mon, October 29, 2018 7:57 pm
To: music-dsp@music.co
Unfortunately I would have to stick with the "sliding" PD phase locking
structure from the book for now,
iterating through the spectrum to search for peaks and identify groups
will add too many frames of additional latency in Reaktor.
But for me this method unfortunately defintively gave
On Mon, 29 Oct 2018 at 20:09, gm wrote:
> That's understood.
>
> What is not completely understood by me is the technique in the paper, and
> the very much related technique from the book.
> How can this apply to arbitrary signals when it relies on sinusioids
> seperated by several bins?
>
For
in frequency domain Re: FFT for
realtime synthesis?
From: "gm"
Date: Mon, October 29, 2018 2:12 pm
To: music-dsp@music.columbia.edu
--
>
>
> Am 29.10.2018 um 05:43 schrieb Ethan Duni:
>> You should
That's understood.
What is not completely understood by me is the technique in the paper,
and the very much related technique from the book.
How can this apply to arbitrary signals when it relies on sinusioids
seperated by several bins?
Also it seems I dont understand where the artefacts in
On Mon, 29 Oct 2018 at 19:12, gm wrote:
>
>
> Am 29.10.2018 um 05:43 schrieb Ethan Duni:
> > 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
Am 29.10.2018 um 19:12 schrieb gm:
From the structure displayed in the book, he adds two neighbouring
complex numbered bins,
multiplied. That is, he multiplies their real and imaginary part
respectivly
and adds that to the values of the bin - (Fig 9.18 p. 293).
Unfortunately this is not
Am 29.10.2018 um 05:43 schrieb Ethan Duni:
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
Thanks for tip, I had a brief look at this paper before.
I think the issue it adresses is not the problem I encounter now.
But it might be interesting again at a later stage or if I return to the
time domain pitch shift.
This is how I do it now, it seems simple & correct but I am not 100%
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
Now I tried pitch shifting in the frequency domain instead of time
domain to get rid of one transform step, but it sounds bad and phasey etc.
I do it like this:
multiply phase difference with frequency factor and add to accumulated
phase,
and shift bins according to frequency factor
again
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