diff --git a/MicroMDAEPiano.ino b/MicroMDAEPiano.ino index 8fe21d0..d8aba98 100644 --- a/MicroMDAEPiano.ino +++ b/MicroMDAEPiano.ino @@ -57,29 +57,31 @@ AudioAmplifier inverter; AudioEffectModulatedDelay modchorus_r; AudioEffectModulatedDelay modchorus_l; AudioSynthWaveform modulator; +AudioFilterBiquad modulator_filter; AudioConnection patchCord0(queue_r, peak_r); AudioConnection patchCord1(queue_l, peak_l); AudioConnection patchCord2(queue_r, freeverb_r); AudioConnection patchCord3(queue_l, freeverb_l); AudioConnection patchCord4(queue_r, 0, modchorus_r, 0); AudioConnection patchCord5(queue_l, 0, modchorus_l, 0); -AudioConnection patchCord6(modulator, 0, modchorus_r, 1); -AudioConnection patchCord7(modulator, inverter); -AudioConnection patchCord8(inverter, 0, modchorus_l, 1); -AudioConnection patchCord9(queue_r, 0, mixer_r, 0); -AudioConnection patchCord10(queue_l, 0, mixer_l, 0); -AudioConnection patchCord11(modchorus_r, 0, mixer_r, 2); -AudioConnection patchCord12(modchorus_l, 0, mixer_l, 2); -AudioConnection patchCord13(freeverb_r, 0, mixer_r, 1); -AudioConnection patchCord14(freeverb_l, 0, mixer_l, 1); -AudioConnection patchCord15(mixer_r, volume_r); -AudioConnection patchCord16(mixer_l, volume_l); +AudioConnection patchCord6(modulator, modulator_filter); +AudioConnection patchCord7(modulator_filter, 0, modchorus_r, 1); +AudioConnection patchCord8(modulator_filter, inverter); +AudioConnection patchCord9(inverter, 0, modchorus_l, 1); +AudioConnection patchCord10(queue_r, 0, mixer_r, 0); +AudioConnection patchCord11(queue_l, 0, mixer_l, 0); +AudioConnection patchCord12(modchorus_r, 0, mixer_r, 2); +AudioConnection patchCord13(modchorus_l, 0, mixer_l, 2); +AudioConnection patchCord14(freeverb_r, 0, mixer_r, 1); +AudioConnection patchCord15(freeverb_l, 0, mixer_l, 1); +AudioConnection patchCord16(mixer_r, volume_r); +AudioConnection patchCord17(mixer_l, volume_l); AudioOutputUSB usb1; -AudioConnection patchCord17(volume_r, 0, usb1, 0); -AudioConnection patchCord18(volume_l, 0, usb1, 1); +AudioConnection patchCord18(volume_r, 0, usb1, 0); +AudioConnection patchCord19(volume_l, 0, usb1, 1); AudioOutputI2S i2s1; -AudioConnection patchCord19(volume_r, 0, i2s1, 0); -AudioConnection patchCord20(volume_l, 0, i2s1, 1); +AudioConnection patchCord20(volume_r, 0, i2s1, 0); +AudioConnection patchCord21(volume_l, 0, i2s1, 1); AudioControlSGTL5000 sgtl5000_1; // Objects @@ -226,6 +228,7 @@ void setup() modulator.begin(CHORUS_WAVEFORM); modulator.phase(0); modulator.offset(0.0); + modulator_filter.setLowpass(0, CHORUS_MODULATOR_FILTER_FRQ, CHORUS_MODULATOR_FILTER_Q); inverter.gain(-1.0); // change phase for second moduleated delay // internal mixing of original signal(0), reverb(1) and chorus(2) diff --git a/config.h b/config.h index 5cb6ea7..6b39c84 100644 --- a/config.h +++ b/config.h @@ -26,6 +26,7 @@ #include "midinotes.h" #include +#include "spline.h" // ATTENTION! For better latency you have to redefine AUDIO_BLOCK_SAMPLES from // 128 to 64 in /cores/teensy3/AudioStream.h @@ -56,10 +57,12 @@ #define REDUCE_LOUDNESS 0 #define USE_XFADE_DATA 1 // CHORUS parameters -#define INTERPOLATION_WINDOW_SIZE 5 // use only odd numbers!!! -#define INTERPOLATE_MODE 11 -#define CHORUS_WAVEFORM WAVEFORM_TRIANGLE // WAVEFORM_SINE WAVEFORM_TRIANGLE WAVEFORM_SAWTOOTH WAVEFORM_SAWTOOTH_REVERSE #define CHORUS_DELAY_LENGTH_SAMPLES (15*AUDIO_BLOCK_SAMPLES) // one AUDIO_BLOCK_SAMPLES = 2.902ms; you need doubled length, e.g. delay point is 20ms, so you need up to 40ms delay! +#define CHORUS_WAVEFORM WAVEFORM_TRIANGLE // WAVEFORM_SINE WAVEFORM_TRIANGLE WAVEFORM_SAWTOOTH WAVEFORM_SAWTOOTH_REVERSE +#define CHORUS_MODULATOR_FILTER_FRQ 1000 +#define CHORUS_MODULATOR_FILTER_Q 0.7 +#define CHORUS_INTERPOLATION_MODE Catmull +#define CHORUS_INTERPOLATION_WINDOW_SIZE 11 //************************************************************************************************* //* DEBUG OUTPUT SETTINGS diff --git a/effect_modulated_delay.cpp b/effect_modulated_delay.cpp index f1cad50..3e2a21a 100644 --- a/effect_modulated_delay.cpp +++ b/effect_modulated_delay.cpp @@ -25,6 +25,7 @@ #include #include "limits.h" #include "effect_modulated_delay.h" +#include "spline.h" #include "config.h" /******************************************************************/ @@ -57,12 +58,6 @@ boolean AudioEffectModulatedDelay::begin(short *delayline, int d_length) _delayline = delayline; _delay_length = _max_delay_length = d_length; - // init filter - filter.numStages = 1; - filter.pState = filter_state; - filter.pCoeffs = filter_coeffs; - calcModFilterCoeff(500.0); - return (true); } @@ -80,16 +75,19 @@ void AudioEffectModulatedDelay::update(void) if (block && modulation) { int16_t *bp; - float *mp; + int16_t *mp; float mod_idx; float mod_number; float mod_fraction; +#ifdef CHORUS_INTERPOLATION_MODE + int8_t j; + float x[CHORUS_INTERPOLATION_WINDOW_SIZE]; + float y[CHORUS_INTERPOLATION_WINDOW_SIZE]; + Spline spline(x, y, CHORUS_INTERPOLATION_WINDOW_SIZE, CHORUS_INTERPOLATION_MODE); +#endif - // (Filter implementation: https://web.fhnw.ch/technik/projekte/eit/Fruehling2016/MuelZum/html/parametric__equalizer__example_8c_source.html) - arm_q15_to_float(modulation->data, modulation_f32, AUDIO_BLOCK_SAMPLES); - arm_biquad_cascade_df1_f32(&filter, modulation_f32, modulation_f32, AUDIO_BLOCK_SAMPLES); bp = block->data; - mp = modulation_f32; + mp = modulation->data; for (uint16_t i = 0; i < AUDIO_BLOCK_SAMPLES; i++) { @@ -102,7 +100,23 @@ void AudioEffectModulatedDelay::update(void) // The index is located around the half of the delay length multiplied by the current amount of the modulator mod_idx = *mp * float(_delay_length >> 1); mod_fraction = modff(mod_idx, &mod_number); - +#ifdef CHORUS_INTERPOLATION_MODE + // Spline interpolation + // Generate a an array with the size of CHORUS_INTERPOLATION_WINDOW_SIZE of x/y values around mod_idx for interpolation + uint8_t c = 0; + int16_t c_mod_idx = _circ_idx - int(round(mod_idx)); // This is the pointer to the value in the circular buffer at the current modulation index + for (j = (CHORUS_INTERPOLATION_WINDOW_SIZE / -2); j <= (CHORUS_INTERPOLATION_WINDOW_SIZE / 2); j++) + { + int16_t jc_mod_idx = (c_mod_idx + j) % _delay_length; // The modulation index pointer plus the value of the current window pointer + if (jc_mod_idx < 0) // check for negative offsets and correct them + y[c] = float(_delayline[_delay_length + jc_mod_idx]); + else + y[c] = float(_delayline[jc_mod_idx]); + x[c] = float(j); + c++; + } + *bp = int(round(spline.value(mod_fraction))); // use spline interpolated value +#else // Simple interpolation int16_t c_mod_idx = (_circ_idx + int(round(mod_idx))) % _delay_length; float value1, value2; @@ -118,16 +132,7 @@ void AudioEffectModulatedDelay::update(void) value2 = _delayline[c_mod_idx]; } *bp = int(round(mod_fraction * value1 + (1.0 - mod_fraction) * value2)); - -#ifdef DEBUG - float m = (value2 - value1) / (SHRT_MAX >> 1); - if (m > 1.0 || m < -1.0) - { - Serial.print(F("WARNING m=")); - Serial.println(m, 4); - } #endif - bp++; // next audio data mp++; // next modulation data _circ_idx++; // next circular buffer index @@ -148,40 +153,3 @@ void AudioEffectModulatedDelay::setDelay(float milliseconds) { _delay_length = min(AUDIO_SAMPLE_RATE * milliseconds / 500, _max_delay_length); } - -void AudioEffectModulatedDelay::calcModFilterCoeff(float32_t cFrq) -{ - const float sqrt2 = 1.4142135623730950488; - - float QcRaw = (2 * PI * cFrq) / AUDIO_SAMPLE_RATE_EXACT; // Find cutoff frequency in [0..PI] - float QcWarp = tan(QcRaw); // Warp cutoff frequency - - float gain = 1 / (1 + sqrt2 / QcWarp + 2 / (QcWarp * QcWarp)); - filter_coeffs[2] = (1 - sqrt2 / QcWarp + 2 / (QcWarp * QcWarp)) * gain; - filter_coeffs[1] = (2 - 2 * 2 / (QcWarp * QcWarp)) * gain; - filter_coeffs[0] = 1; - filter_coeffs[3] = 1 * gain; - filter_coeffs[4] = 2 * gain; - - /* - // 1.1kHz 2nd order Butterworth lowpass filter coefficients - // calculated with Iowa IIR FIlter Designer 6.5 - float32_t b0 = 0.072959657268266670; - float32_t b1 = 0.072959657268266670; - float32_t b2 = 0.0; - float32_t a0 = 1.000000000000000000; - float32_t a1 = -0.854080685463466605; - float32_t a2 = 0.0; - - // Normalize so a0 = 1 - filter_coeffs[0] = b0 / a0; - filter_coeffs[1] = b1 / a0; - filter_coeffs[2] = b2 / a0; - filter_coeffs[3] = -a1 / a0; - filter_coeffs[4] = -a2 / a0; */ -} - -void AudioEffectModulatedDelay::setModFilter(float cFrq) -{ - calcModFilterCoeff(cFrq); -} diff --git a/effect_modulated_delay.h b/effect_modulated_delay.h index c4a2373..ed05478 100644 --- a/effect_modulated_delay.h +++ b/effect_modulated_delay.h @@ -45,22 +45,13 @@ class AudioEffectModulatedDelay : boolean begin(short *delayline, int delay_length); virtual void update(void); virtual void setDelay(float milliseconds); - virtual void setModFilter(float cFrq); private: - virtual void calcModFilterCoeff(float32_t cFrq); - audio_block_t *inputQueueArray[2]; int16_t *_delayline; uint16_t _circ_idx; uint16_t _max_delay_length; uint16_t _delay_length; - - // filter data - arm_biquad_casd_df1_inst_f32 filter; - float32_t modulation_f32[AUDIO_BLOCK_SAMPLES]; - float32_t filter_coeffs[5]; - float32_t filter_state[4]; }; #endif diff --git a/spline.cpp b/spline.cpp new file mode 100644 index 0000000..913c647 --- /dev/null +++ b/spline.cpp @@ -0,0 +1,111 @@ +// From: https://raw.githubusercontent.com/kerinin/arduino-splines/master/spline.cpp +#include "Arduino.h" +#include "spline.h" +#include + +Spline::Spline(void) { + _prev_point = 0; +} + +Spline::Spline( float x[], float y[], int numPoints, int degree ) +{ + setPoints(x,y,numPoints); + setDegree(degree); + _prev_point = 0; +} + +Spline::Spline( float x[], float y[], float m[], int numPoints ) +{ + setPoints(x,y,m,numPoints); + setDegree(Hermite); + _prev_point = 0; +} + +void Spline::setPoints( float x[], float y[], int numPoints ) { + _x = x; + _y = y; + _length = numPoints; +} + +void Spline::setPoints( float x[], float y[], float m[], int numPoints ) { + _x = x; + _y = y; + _m = m; + _length = numPoints; +} + +void Spline::setDegree( int degree ){ + _degree = degree; +} + +float Spline::value( float x ) +{ + if( _x[0] > x ) { + return _y[0]; + } + else if ( _x[_length-1] < x ) { + return _y[_length-1]; + } + else { + for(int i = 0; i < _length; i++ ) + { + int index = ( i + _prev_point ) % _length; + + if( _x[index] == x ) { + _prev_point = index; + return _y[index]; + } else if( (_x[index] < x) && (x < _x[index+1]) ) { + _prev_point = index; + return calc( x, index ); + } + } + } +} + +float Spline::calc( float x, int i ) +{ + switch( _degree ) { + case 0: + return _y[i]; + case 1: + if( _x[i] == _x[i+1] ) { + // Avoids division by 0 + return _y[i]; + } else { + return _y[i] + (_y[i+1] - _y[i]) * ( x - _x[i]) / ( _x[i+1] - _x[i] ); + } + case Hermite: + return hermite( ((x-_x[i]) / (_x[i+1]-_x[i])), _y[i], _y[i+1], _m[i], _m[i+1], _x[i], _x[i+1] ); + case Catmull: + if( i == 0 ) { + // x prior to spline start - first point used to determine tangent + return _y[1]; + } else if( i == _length-2 ) { + // x after spline end - last point used to determine tangent + return _y[_length-2]; + } else { + float t = (x-_x[i]) / (_x[i+1]-_x[i]); + float m0 = (i==0 ? 0 : catmull_tangent(i) ); + float m1 = (i==_length-1 ? 0 : catmull_tangent(i+1) ); + return hermite( t, _y[i], _y[i+1], m0, m1, _x[i], _x[i+1]); + } + } +} + +float Spline::hermite( float t, float p0, float p1, float m0, float m1, float x0, float x1 ) { + return (hermite_00(t)*p0) + (hermite_10(t)*(x1-x0)*m0) + (hermite_01(t)*p1) + (hermite_11(t)*(x1-x0)*m1); +} +float Spline::hermite_00( float t ) { return (2*pow(t,3)) - (3*pow(t,2)) + 1;} +float Spline::hermite_10( float t ) { return pow(t,3) - (2*pow(t,2)) + t; } +float Spline::hermite_01( float t ) { return (3*pow(t,2)) - (2*pow(t,3)); } +float Spline::hermite_11( float t ) { return pow(t,3) - pow(t,2); } + +float Spline::catmull_tangent( int i ) +{ + if( _x[i+1] == _x[i-1] ) { + // Avoids division by 0 + return 0; + } else { + return (_y[i+1] - _y[i-1]) / (_x[i+1] - _x[i-1]); + } +} diff --git a/spline.h b/spline.h new file mode 100644 index 0000000..0382de9 --- /dev/null +++ b/spline.h @@ -0,0 +1,43 @@ +// From https://raw.githubusercontent.com/kerinin/arduino-splines/master/spline.h +/* + Library for 1-d splines + Copyright Ryan Michael + Licensed under the LGPLv3 +*/ +#ifndef spline_h +#define spline_h + +#include "Arduino.h" + +#define Hermite 10 +#define Catmull 11 + +class Spline +{ + public: + Spline( void ); + Spline( float x[], float y[], int numPoints, int degree = 1 ); + Spline( float x[], float y[], float m[], int numPoints ); + float value( float x ); + void setPoints( float x[], float y[], int numPoints ); + void setPoints( float x[], float y[], float m[], int numPoints ); + void setDegree( int degree ); + + private: + float calc( float, int); + float* _x; + float* _y; + float* _m; + int _degree; + int _length; + int _prev_point; + + float hermite( float t, float p0, float p1, float m0, float m1, float x0, float x1 ); + float hermite_00( float t ); + float hermite_10( float t ); + float hermite_01( float t ); + float hermite_11( float t ); + float catmull_tangent( int i ); +}; + +#endif