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188 lines
6.5 KiB
188 lines
6.5 KiB
/* Audio Library for Teensy 3.X
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Copyright (c) 2014, Pete (El Supremo)
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Copyright (c) 2019, Holger Wirtz
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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THE SOFTWARE.
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*/
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#include <Arduino.h>
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#include <Audio.h>
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#include "arm_math.h"
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#include "effect_modulated_delay.h"
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#include "config.h"
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extern config_t configuration;
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/******************************************************************/
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// Based on; A u d i o E f f e c t D e l a y
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// Written by Pete (El Supremo) Jan 2014
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// 140529 - change to handle mono stream - change modify() to voices()
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// 140219 - correct storage class (not static)
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// 190527 - added modulation input (by Holger Wirtz)
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boolean AudioEffectModulatedDelay::begin(short *delayline, int d_length)
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{
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#if 0
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Serial.print(F("AudioEffectModulatedDelay.begin(Chorus delay line length = "));
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Serial.print(d_length);
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Serial.println(F(")"));
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#endif
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_delayline = NULL;
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_delay_length = 0;
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_delay_offset = 0.0;
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_cb_index = 0;
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if (delayline == NULL) {
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return (false);
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}
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if (d_length < 10) {
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return (false);
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}
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_delayline = delayline;
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_delay_length = d_length;
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set_modulator_filter_coeffs(1.0, configuration.chorus_frequency / 10, 1.0); // gain, center frerquency
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modulator_filter_data = {1, &modulator_filter_state, modulator_filter_coeffs};
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return (true);
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}
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void AudioEffectModulatedDelay::set_modulator_filter_coeffs(float gain, float fc, float width)
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{
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// modulator filter
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// coefficients calculated with "IOWA Hills IIR Filter Designer 6.5", http://www.iowahills.com/8DownloadPage.html
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// Example: https://web.fhnw.ch/technik/projekte/eit/Fruehling2016/MuelZum/html/parametric_equalizer_example_8c-example.html
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/* float32_t A = sqrt(powf(10, gain / 20.0f));
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float32_t w0 = 2.0f * PI * fc / ((float32_t)AUDIO_SAMPLE_RATE_EXACT);
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float32_t cosw0 = cosf(w0);
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float32_t sinw0 = sinf(w0);
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float32_t alpha = sinw0 / (2.0f * width);
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float32_t a0 = 1.0f + alpha / A;
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modulator_filter_coeffs[0] = (1.0f + alpha * A) / a0; // b0
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modulator_filter_coeffs[1] = (-2.0f * cosw0) / a0; // b1
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modulator_filter_coeffs[2] = (1.0f - alpha * A) / a0; // b2
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modulator_filter_coeffs[3] = -(2.0f * cosw0) / -a0; // -a1
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modulator_filter_coeffs[4] = (1.0f - alpha / A) / -a0; // -a2 */
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// OmegaC = 0.1, SR = 44117.64706, Fc = 2.21 kHz, N=2
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modulator_filter_coeffs[0] = 0.020727217357494492; // b0
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modulator_filter_coeffs[1] = 0.020727217357494492; // b1
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modulator_filter_coeffs[2] = 0.020727217357494492; // b2
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modulator_filter_coeffs[3] = 1.563046149664217620; // -a1
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modulator_filter_coeffs[4] = -0.642749223719756180; // -a2
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}
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void AudioEffectModulatedDelay::update(void)
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{
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audio_block_t *block;
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audio_block_t *modulation;
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if (_delayline == NULL)
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return;
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block = receiveWritable(0);
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modulation = receiveReadOnly(1);
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if (block && modulation)
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{
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int16_t *bp;
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int16_t cb_mod_index_neighbor;
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float *mp;
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float mod_index;
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float mod_number;
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float mod_fraction;
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float modulation_f32[AUDIO_BLOCK_SAMPLES];
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bp = block->data;
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arm_q15_to_float(modulation->data, modulation_f32, AUDIO_BLOCK_SAMPLES);
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//arm_biquad_cascade_df1_f32(&modulator_filter_data, modulation_f32, modulation_f32, AUDIO_BLOCK_SAMPLES);
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mp = modulation_f32;
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for (uint16_t i = 0; i < AUDIO_BLOCK_SAMPLES; i++)
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{
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// write data into circular buffer (delayline)
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if (_cb_index >= _delay_length)
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_cb_index = 0;
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_delayline[_cb_index] = *bp;
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// Calculate the modulation-index as a floating point number for interpolation
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mod_index = *mp * (1 - MODULATION_MAX_FACTOR) * _delay_length; // "(1 - MODULATION_MAX_FACTOR) * _delay_length" means: maximum bytes of modulation allowed by given delay length
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mod_fraction = modff(mod_index, &mod_number); // split float of mod_index into integer (= mod_number) and fraction part
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// calculate modulation index into circular buffer
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cb_mod_index = (_cb_index - (_delay_offset + int(mod_index)));
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if (cb_mod_index >= _delay_length)
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cb_mod_index -= _delay_length;
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if (cb_mod_index < 0) // check for negative offsets and correct them
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cb_mod_index += _delay_length;
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if (*mp < 0.0)
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{
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if (cb_mod_index == 0)
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cb_mod_index_neighbor = _delay_length;
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else
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cb_mod_index_neighbor = cb_mod_index - 1;
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}
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else
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{
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if (cb_mod_index == _delay_length)
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cb_mod_index_neighbor = 0;
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else
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cb_mod_index_neighbor = cb_mod_index + 1;
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}
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if (*mp < 0.0)
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*bp = round(float(_delayline[cb_mod_index]) * mod_fraction + float(_delayline[cb_mod_index_neighbor]) * (1.0 - mod_fraction));
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else
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*bp = round(float(_delayline[cb_mod_index_neighbor]) * mod_fraction + float(_delayline[cb_mod_index]) * (1.0 - mod_fraction));
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// push the pointers forward
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bp++; // next audio data
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mp++; // next modulation data
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_cb_index++; // next circular buffer index
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}
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}
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if (modulation)
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release(modulation);
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if (block)
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{
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transmit(block, 0);
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release(block);
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}
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}
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float AudioEffectModulatedDelay::offset(float offset_value) // in ms
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{
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uint16_t offset_frames = (offset_value / 1000) * AUDIO_SAMPLE_RATE;
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if (offset_frames > _delay_length * MODULATION_MAX_FACTOR)
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_delay_offset = _delay_length * MODULATION_MAX_FACTOR;
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else if (offset_frames <= _delay_length * (1 - MODULATION_MAX_FACTOR))
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_delay_offset = _delay_length * (1 - MODULATION_MAX_FACTOR);
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else
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_delay_offset = offset_frames;
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return (offset_frames / AUDIO_SAMPLE_RATE * 1000);
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}
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