wanmay
/
yaw-audio
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Change timbre of shepard tone: overtones are now nearly harmonic

This commit is contained in:
yaw-man 2022-09-14 19:05:04 -04:00
parent a629a65194
commit 18acf9eb95
1 changed files with 11 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
src/yaw-shepard/synth.cpp
View File

@ -40,13 +40,13 @@ void Synth::process(float* output, const uint32_t frames)
phase += hz * sampleInterval; phase += hz * sampleInterval;
phase = frac(phase); phase = frac(phase);
//Don't bother rendering anything over the Nyquist rate. //Anti-aliasing: don't bother rendering anything over the Nyquist rate.
if( hz > hzNyq ) break; if( hz > hzNyq ) break;
output[i] += getAmplitude(hz) * (phase > 0.5); // * sin(2.0 * M_PI * phase); output[i] += getAmplitude(hz) * sin(2.0 * M_PI * phase);
//Remember phase, move to higher overtone. //Remember phase, move to higher overtone.
phases[(voice + idxFund) & VOICE_MASK] = phase; phases[(voice + idxFund) & VOICE_MASK] = phase;
hz *= ratio; hz *= ratio * (voice + 1.0) / (voice + 2.0);
} }
output[i] *= volume / static_cast<double>(NUM_VOICES); output[i] *= volume / static_cast<double>(NUM_VOICES);
@ -60,8 +60,8 @@ void Synth::process(float* output, const uint32_t frames)
&& getAmplitude(hzFund) < MIN_VOLUME) && getAmplitude(hzFund) < MIN_VOLUME)
{ {
++idxFund; ++idxFund;
hz *= ratio; hz *= 2.0 * ratio;
hzFund *= ratio; hzFund *= 2.0 * ratio;
} }
} }
@ -72,8 +72,8 @@ void Synth::process(float* output, const uint32_t frames)
&& getAmplitude(hzFund) > MIN_VOLUME) && getAmplitude(hzFund) > MIN_VOLUME)
{ {
--idxFund; --idxFund;
hz /= ratio; hz /= 2.0 * ratio;
hzFund /= ratio; hzFund /= 2.0 * ratio;
} }
} }
} }
@ -93,10 +93,10 @@ void Synth::setFrequencyShift(double in){
} }
static constexpr double minRatio = 1.0; static constexpr double minRatio = 1.0;
static constexpr double maxRatio = 3.0; static constexpr double maxRatio = 1.05;
//Slew to given ratio. //Slew to given inharmonicity ratio.
//0 : next voice is one fifth above previous voice. //0 : next voice is exactly harmonic.
//1 : next voice is one octave above previous voice. //1 : next voice is 5% inharmonic.
void Synth::setTargetRatio(double in){ void Synth::setTargetRatio(double in){
targetRatio = minRatio + in * (maxRatio - minRatio); targetRatio = minRatio + in * (maxRatio - minRatio);
} }