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Generalize noteNumberToFrequency to use any periodic tuning #26

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Generalize noteNumberToFrequency to use any periodic tuning #26

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fe39341
Generalize noteNumberToFrequency for any tuning
ellapollack May 16, 2020
5e8de22
Fix comment
ellapollack May 16, 2020
922b9e3
EDO -> TET
ellapollack May 16, 2020
e54c61e
Merge branch 'master' of https://github.com/soul-lang/SOUL into patch-1
ellapollack May 25, 2020
355c41d
Documentation
ellapollack May 26, 2020
a9ffe4a
Fixed `noteNumberToFrequency` wrapping "bug"
ellapollack Jun 25, 2020
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18 changes: 15 additions & 3 deletions source/modules/soul_core/library/soul_library_audio_utils.h
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Original file line number Diff line number Diff line change
Expand Up @@ -35,11 +35,23 @@ namespace soul
float32 gainTodB (float32 gain) { return gain > 0 ? log10 (gain) * 20.0f : -100.0f; }
float64 gainTodB (float64 gain) { return gain > 0 ? log10 (gain) * 20.0 : -100.0; }

/** Converts a MIDI note (usually in the range 0-127) to a frequency in Hz. */
/** Converts a MIDI note (usually in the range 0-127) to a frequency in Hz using a periodic tuning.

@param note a note number
@param rootNote the note number at which the scale begins
@param rootFrequency the frequency at which the scale begins
@param scale the frequency interval of each scale degree (`scale[-1]` is used as the period)
*/
float32 noteNumberToFrequency (int note, int rootNote, float32 rootFrequency, float32[] scale)
{
note -= rootNote + 1;
return scale.at(note) * rootFrequency * pow(scale[-1], float32((note-wrap(note, scale.size)) / scale.size));
}
/** Converts a MIDI note (usually in the range 0-127) to a frequency in Hz using A440 12-TET tuning. */
float32 noteNumberToFrequency (int note) { return 440.0f * pow (2.0f, (note - 69) * (1.0f / 12.0f)); }
/** Converts a MIDI note (usually in the range 0-127) to a frequency in Hz. */
/** Converts a MIDI note (usually in the range 0-127) to a frequency in Hz using A440 12-TET tuning. */
float32 noteNumberToFrequency (float32 note) { return 440.0f * pow (2.0f, (note - 69.0f) * (1.0f / 12.0f)); }
/** Converts a frequency in Hz to an equivalent MIDI note number. */
/** Converts a frequency in Hz to an equivalent MIDI note number using A440 12-TET tuning. */
float32 frequencyToNoteNumber (float32 frequency) { return 69.0f + (12.0f / log (2.0f)) * log (frequency * (1.0f / 440.0f)); }

/** Returns the ratio by which a sample's playback must be sped-up in order to map
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