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Clarify formant methods

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Geraint 2025-04-29 15:42:15 +01:00
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README.md
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@ -124,9 +124,20 @@ Using `.seek()`/`.flush()` like this, you can perform an exact time-stretch on a
### Formant compensation
The two methods `.setFormantFactor()` and `.setFormantSemitones()` can specify a scaling-factor for the formants. They both have an optional `compensatePitch` flag, and enabling this . when performing formant correction/shifting.
```cpp
stretch.setFormantFactor(1.2); // up ~3 semitones
The formant correction is not a sharp as monophonic algorithms (such such as PSOLA). It also needs you to give it a rough estimate of fundamental frequency (relative to Nyquist) using `.setFormantBase()`.
stretch.setTransposeSemitones(3);
```
Both of those methods both have an optional `compensatePitch` flag. Enabling this adjust for the pitch-shift (or non-linear map) when correcting/shifting formants.
The formant correction is not a sharp as monophonic algorithms (such such as PSOLA). It also needs you to give it a rough estimate of fundamental frequency (relative to Nyquist):
```cpp
// if 200Hz is the middle-register of the instrument
stretch.setFormantBase(200/sampleRate);
```
## Compiling