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Code Issues Releases Wiki Activity

further fix regarding bug 309, from off-list discussion with Steve

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v.audacity 2013-06-02 00:26:16 +00:00
parent 7aeb4396b7
commit 44c03e7de8
1 changed files with 7 additions and 11 deletions
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18
src/PitchName.cpp
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@ -31,16 +31,7 @@
double FreqToMIDInoteNumber(double freq) double FreqToMIDInoteNumber(double freq)
{ {
// Make the calculation relative to A440 (A4), note number 69. // Make the calculation relative to A440 (A4), note number 69.
double dCalc = 69.0 + (12.0 * (log(freq / 440.0) / log(2.0))); return (69.0 + (12.0 * (log(freq / 440.0) / log(2.0))));
//vvv For freq values in the range (0.0, ~8.2), that calculation
// produces negative dCalc, and as close in frequency as they are,
// their modulo 12 results are different.
// Also, not clear that any of those frequencies is a "pitch",
// so pending further discussion, just enforce a floor.
// MIDI numbers are non-negative.
if (dCalc < 0.0)
dCalc = 0.0;
return dCalc;
} }
// PitchIndex returns the [0,11] index for a double pitchNum, // PitchIndex returns the [0,11] index for a double pitchNum,
@ -48,7 +39,12 @@ double FreqToMIDInoteNumber(double freq)
// of the integer part of (pitchNum + 0.5), so 0=C, 1=C#, etc. // of the integer part of (pitchNum + 0.5), so 0=C, 1=C#, etc.
unsigned int PitchIndex(double pitchNum) unsigned int PitchIndex(double pitchNum)
{ {
return ((int)(pitchNum + 0.5) % 12); int nPitchIndex = ((int)(pitchNum + 0.5) % 12);
// MIDI numbers (pitchNum) can be negative.
// Because of the modulo, we know we're within 12 of positive.
if (nPitchIndex < 0)
nPitchIndex += 12;
return nPitchIndex;
} }