Hi Hans, how are you measuring the delays?
Cheers, Maxi El vie, 20 nov 2020 a las 15:25, i...@hansroels.be (<i...@hansroels.be>) escribió: > Hello, > > Hopefully people with more knowledge of audio processing can answer the > following questions. Background: I make patches in which the microphone > input is modified by different kinds of pitch-shifting, I would like to > compensate the delays caused by these pitch-shifts and thus avoid > artefacts. > > 1) How much delay does a pitch-shifter based on a variable delay (the > classic rotating-tape-head style) produce? as in G09.pitchshift.pd in the > audio.examples folder. I did a quick test with a one-sample-audio-trigger > going immediately to the first channel of a recording patch in Pd and > simultaneously going to a variable delay pitchshift (pp.pitchshift~ from > AudioLab), routed into the second channel of the recorder. The delays are > quite large and vary between 30 and 80 milliseconds, there seems to be no > relation with the amount of pitch-shift. In the pitch-shifting patch I also > notice that the delay varies between zero and the window size. Is there a > way/patch to calculate and compensate for this delay? (for example, if you > want to combine the original with the pitch-shifted signal in a patch). Or > is this impossible because the delay is variable... > > 2) I'd like to know the delay in ms with FFT processing if you have a 1024 > sample window with overlap factor of 4, for example, in a pitch-shifting > vocoder? I found this info on a MAx/MSP mailing list, is it correct?: "The > I/ O delay is equal to the window size minus the hop size (e.g., for a > 1024-sample FFT window with an overlap factor of 4, the hop size is equal > to 256, and the overall delay from input to output is 768 samples)"; at > 44100 sampling rate this is around 17ms delay (for a window of 1024 > samples, overlap 4). > > 3) Conclusion: any pitch-shifting technique introduces tens of > milliseconds delay? (Pitch-shifting based on granular synthesis is not a > solution, I think it also requires a buffer of at least 50ms.) > > Hans > -- > _______________________________________________ > Pd-list@lists.iem.at mailing list > UNSUBSCRIBE and account-management -> > https://lists.puredata.info/listinfo/pd-list > -- Maximiliano Estudies *VDT Referat Beschallung* +49 176 36784771 omslo.com maxiestudies.com
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