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121 lines
3.9 KiB
121 lines
3.9 KiB
#ifndef _BASIC_PITCH_H_
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#define _BASIC_PITCH_H_
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#include <Arduino.h>
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#include "Audio.h"
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#define BASIC_PITCH_BUF_BITS (12)
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#define BASIC_PITCH_BUF_SIZE (1<<BASIC_PITCH_BUF_BITS)
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#define BASIC_PITCH_BUF_SIZE_HALF (1<<(BASIC_PITCH_BUF_BITS-1))
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#define BASIC_PITCH_BUF_MASK (BASIC_PITCH_BUF_SIZE-1)
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#define BASIC_PITCH_BUF_FRAC_MASK ((1<<(32-BASIC_PITCH_BUF_BITS))-1)
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#define BASIC_PITCH_XFADE_BITS (10)
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#define BASIC_PITCH_XFADE_LEN (1<<BASIC_PITCH_XFADE_BITS)
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#define BASIC_PITCH_XFADE_LEN_HALF (BASIC_PITCH_XFADE_LEN>>1)
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#define BASIC_PITCH_XFADE_MASK (BASIC_PITCH_XFADE_LEN-1)
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extern "C" {
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extern const float AudioWaveformFader_f32[]; // crossfade waveform
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extern const float music_intevals[]; // semitone intervals -1oct to +2oct
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}
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class AudioBasicPitch
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{
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public:
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bool init()
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{
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outFilter.init(hp_f, (float *)&hp_gain, lp_f, &lp_gain);
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bf = (float *)malloc(BASIC_PITCH_BUF_SIZE*sizeof(float)); // allocate buffer
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if (!bf) return false;
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reset();
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return true;
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}
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void setPitch(float ratio)
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{
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readAdder = (float)pitchDelta0 * ratio;
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}
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void setPitchSemintone(int8_t s)
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{
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s = constrain(s, -12, +24); // limit to the predefined range
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setPitch(music_intevals[s + 12]);
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}
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void setTone(float t)
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{
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//lp_f = constrain(t, 0.01f, 1.0f);
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lp_gain = constrain(t, 0.0f, 1.0f);
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}
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inline float process(float newSample)
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{
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uint32_t idx1, idx2;
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uint32_t delta, delta_acc;
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float k_frac, delta_frac, s_n, s_half, xf0, xf1;
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bf[writeAddr] = newSample; // write new sample
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readAddr = readAddr + readAdder; // update read pointer, readAdder controls the pitch
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// bypass mode is at mix = 0 or if no pitch change
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if (mix == 0.0f || readAdder == pitchDelta0)
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{
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writeAddr = (writeAddr + 1) & BASIC_PITCH_BUF_MASK;
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return newSample;
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}
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// sample end
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idx1 = (readAddr >> (32-BASIC_PITCH_BUF_BITS)) & BASIC_PITCH_BUF_MASK; // index of the last sample
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k_frac = (float)(readAddr & BASIC_PITCH_BUF_FRAC_MASK) / (float)BASIC_PITCH_BUF_FRAC_MASK; // fractional part
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s_n = bf[idx1] * (1.0f-k_frac);
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s_n += bf[(idx1 + 1) & BASIC_PITCH_BUF_MASK] * k_frac; // interpolated sample
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// sample half
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idx2 = ((readAddr + 0x80000000) >> (32-BASIC_PITCH_BUF_BITS)) & BASIC_PITCH_BUF_MASK;
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k_frac = (float)((readAddr+0x80000000) & BASIC_PITCH_BUF_FRAC_MASK) / (float)BASIC_PITCH_BUF_FRAC_MASK;
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s_half = bf[idx2] * (1.0f - k_frac);
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s_half += bf[(idx2 + 1) & BASIC_PITCH_BUF_MASK] * k_frac;
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delta_acc = readAddr - (writeAddr<<(32-BASIC_PITCH_BUF_BITS)); // distance between the write and read pointer
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delta = (delta_acc >> (32-9)) & 0x1FF; // 9 bit value = 2x fade table length (fade in + fade out)
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delta_frac = (float)(delta_acc & ((1<<23)-1)) / (float)((1<<23)-1); // fractional part for the xfade curve
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idx2 = delta&0xFF;
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xf0 = AudioWaveformFader_f32[idx2];
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xf1 = AudioWaveformFader_f32[idx2+1];
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k_frac = xf0 * (1.0f-delta_frac) + xf1 * delta_frac; // interpolated smooth crossfade coeff.
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if (delta > 0xFF) k_frac = 1.0f-k_frac; // invert the curve for the fade out part
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s_n = s_n * k_frac + s_half * (1.0f - k_frac); // crossfade the last and mid sample
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writeAddr = (writeAddr + 1) & BASIC_PITCH_BUF_MASK; // update the write pointer
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s_n = outFilter.process(s_n); // apply output lowpass
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return (s_n * mix + newSample * (1.0f-mix)); // do dry/wet mix
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}
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void setMix(float mixRatio)
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{
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mix = constrain(mixRatio, 0.0f, 1.0f);
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}
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void reset()
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{
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memset(bf, 0, BASIC_PITCH_BUF_SIZE*sizeof(float));
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readAddr = 0;
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writeAddr = 0;
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readAdder = pitchDelta0;
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mix = 1.0f;
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}
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private:
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float *bf;
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float mix;
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uint32_t readAddr;
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uint32_t readAdder;
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uint16_t writeAddr;
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static const uint32_t pitchDelta0 = BASIC_PITCH_BUF_FRAC_MASK+1;
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AudioFilterShelvingLPHP outFilter;
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static constexpr float hp_f = 0.003f;
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const float hp_gain = 0.0f;
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static constexpr float lp_f = 0.26f;
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float lp_gain = 1.0f;
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};
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#endif // _BASIC_PITCH_H_
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