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TOPIC: Looped sample tuning bug

Looped sample tuning bug 2 years 6 months ago #2

  • Michael
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First of all, your english is fine! B)

I think tuning for short loops doesn't work due to lack of information which can be read from it's harmonics. You have to find the pitch manually - then switching on the sinus-sound can help you do it.
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Looped sample tuning bug 6 months 3 days ago #3

  • Davy
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Hi Roland, you are right: if the loop is too short then the Fourier transform and the autocorrelation have not enough data.
In that case I automatically increase the range around the small loop = > will be in version 2.3

If the sample itself is too small however, a manual tuning will be required as mentioned by Michael.
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Looped sample tuning bug 6 months 3 days ago #4

  • Roland
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I think it would be a better idea to duplicate the looped segment as many times as needed to make the FFT
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Looped sample tuning bug 6 months 3 days ago #5

  • bottrop
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i would like very much to see you duplicate a looped segment. call me when you start with it.
regards bottrop
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Looped sample tuning bug 5 months 2 weeks ago #6

  • Davy
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The case you are speaking is when we have a very short loop in a sample and the problem if we duplicate this portion several times is that both the autocorrelation and the Fourier transform will tend to give a resulting frequency equal to the loop length.

For example if we select a loop comprising 224 points with a sample rate of 44100 (as shown in your example), the length will be 5.08 ms and we will have a perfect correlation (since we duplicate the portion) at the frequency equal to 196.875 Hz.
If we add un single point, a loop comprising 225 points will have a length of 5.10 ms and the perfect correlation will be 196 Hz. The difference between 196.875 Hz and 196 Hz is 8 cents of a semitone.

All this to say that the result will be too sensitive to the number of points included in the small loop.
I may not be aware of all mathematical tools but based on the small loop we provide, extending both limits (start and end) provides a simple and better base to study the harmonic content.
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Looped sample tuning bug 5 months 2 weeks ago #7

  • Roland
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You are right, but if we have a sample with a short loop, the soundfont player will still duplicate this loop as many times as needed to make the sound. Hearable frequency will be very dependent on the number of points in the loop, so the correlation measurements will be perfectly valid. Also, knowing the frequency of the looped sample will make it easier to adjust the loop length.
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