"old school" pitch shifting
Moderator: frank
"old school" pitch shifting
hello everybody, first, I'm a begginer, so sorry for this question:
I was checking the website of a famous VST plugin maker, and found this:
"Modern pitch-shifters use sophisticated mathematical algorithms to transform music and vocals as naturally as possible. The original old school devices (like Eventide's classic H910 Harmonizer) used a resample and cross-fade technique that introduced audible 'glitches' in the pitch-shifted audio."
is this (the old school one) the same approach you use to take to get pitch shifting in the FV1, so the same described on the knowledge base page, or is something different and more "rude"?
thanks everyone!
I was checking the website of a famous VST plugin maker, and found this:
"Modern pitch-shifters use sophisticated mathematical algorithms to transform music and vocals as naturally as possible. The original old school devices (like Eventide's classic H910 Harmonizer) used a resample and cross-fade technique that introduced audible 'glitches' in the pitch-shifted audio."
is this (the old school one) the same approach you use to take to get pitch shifting in the FV1, so the same described on the knowledge base page, or is something different and more "rude"?
thanks everyone!
FV-1 basically does the old school technique because it is designed to do it real time. If you are pitch shifting a file on a computer then using advanced techniques will give better results but the techniques are much slower and more complex so not realistic to do real time.
Frank Thomson
Experimental Noize
Experimental Noize
many thanks
I believe every real time effect we use for guitar or other use the same technique then?
I didn't understand very well the explaination of Pitch Transp. vs Pitch Shift on the website (that's my fault, I'm not english), but is Pitch shift not more than a pitch trasp. like the one described here http://www.spinsemi.com/knowledge_base/ ... nsposition, but using an increment instead of a factor? that's the only difference?
I believe every real time effect we use for guitar or other use the same technique then?
I didn't understand very well the explaination of Pitch Transp. vs Pitch Shift on the website (that's my fault, I'm not english), but is Pitch shift not more than a pitch trasp. like the one described here http://www.spinsemi.com/knowledge_base/ ... nsposition, but using an increment instead of a factor? that's the only difference?
Yes, we are really doing a pitch transpose. We are basically multiplying by a factor rather than adding an increment. For example, in transposing we may want to transpose up by an octave, so all frequencies are multiplied by 2. Therefor 1Khz becomes 2KHz (1KHz * 2), 3KHz becomes 6KHz (3KHz * 2), etc. This is nice and musical because the ratio between signals is maintained.
In shifting, a constant value is added to the frequency. If we want to shift by 1KHz we add 1KHz to all frequencies so 1KHz becomes 2KHz, 3KHz becomes 4KHz, etc. This is not musical because the ratio between signals is not maintained but it can have desirable effects like slightly shifting a persons voice by a small increment.
So while we tend to say "pitch shifting" we typical mean "pitch transposing".
In shifting, a constant value is added to the frequency. If we want to shift by 1KHz we add 1KHz to all frequencies so 1KHz becomes 2KHz, 3KHz becomes 4KHz, etc. This is not musical because the ratio between signals is not maintained but it can have desirable effects like slightly shifting a persons voice by a small increment.
So while we tend to say "pitch shifting" we typical mean "pitch transposing".
Frank Thomson
Experimental Noize
Experimental Noize
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Frank can respond with a deeper answer probably, but it has to do with the speed of the LFOs which do the pitch bending and crossfading. If the LFOs oscillate at a frequency related to the pitch you're playing, you can sometimes get a periodic cancellation which sounds like wobbling or chirping.
But it's not really a hard line between "polyphonic" and "monophonic" - The Whammy gets warbly, and so does the FV1 pitch transpose program, but in fact so do the HOG and POG - I've used both and gotten these warbly sounds in both. So you can minimize the phase cancellations to an extent, and get less "glitchy" but there's no technique, except for maybe fourier transform which is not possible in the FV1, which would completely remove warbling.
But it's not really a hard line between "polyphonic" and "monophonic" - The Whammy gets warbly, and so does the FV1 pitch transpose program, but in fact so do the HOG and POG - I've used both and gotten these warbly sounds in both. So you can minimize the phase cancellations to an extent, and get less "glitchy" but there's no technique, except for maybe fourier transform which is not possible in the FV1, which would completely remove warbling.
yes sure,
I found it here
http://valhalladsp.wordpress.com/2010/0 ... glitching/
and I read that in other parts too that I don't remember right now
I found it here
http://valhalladsp.wordpress.com/2010/0 ... glitching/
and I read that in other parts too that I don't remember right now
OK, I'm familiar with that process. Never tried to do it in the FV-1, it is a complex thing to do to so may be too complex for the FV-1.
Frank Thomson
Experimental Noize
Experimental Noize
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I tried doing some simple auto-correlation on the FV-1. I couldn't get it to work. Theoretically, you could use the JAM instruction to get things to reset, but the problem is figuring out the proper reset point. The early de-glitching pitch shifters used dedicated auto-correlation boards for computing the correct splicing points.
Today, you can use FFTs (accelerated by vector libraries) to compute the autocorrelation for splicing in pitch shifters. Or, you can use the same FFTs for phase vocoding pitch shifting, which seems to produce "better" results. Of course, plenty of people like the artifacts of the old school "glitchy" pitch shifters.
Sean Costello
Today, you can use FFTs (accelerated by vector libraries) to compute the autocorrelation for splicing in pitch shifters. Or, you can use the same FFTs for phase vocoding pitch shifting, which seems to produce "better" results. Of course, plenty of people like the artifacts of the old school "glitchy" pitch shifters.
Sean Costello
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- Joined: Mon Sep 11, 2006 10:04 pm
I am fairly certain that the HOG and POG use FFTs for their pitch shifting. Probably phase vocoder, maybe phase locked vocoder as described by Puckette. My MicroPOG sounds very smooth, but it isn't perfect. I've never heard perfect polyphonic pitch shifting, and it may not be possible.livingston wrote: But it's not really a hard line between "polyphonic" and "monophonic" - The Whammy gets warbly, and so does the FV1 pitch transpose program, but in fact so do the HOG and POG - I've used both and gotten these warbly sounds in both. So you can minimize the phase cancellations to an extent, and get less "glitchy" but there's no technique, except for maybe fourier transform which is not possible in the FV1, which would completely remove warbling.