Dooho Yi
91f92c0e6c
migration from 'smp_v1p0' dev. for 'sampler' -> skip irrelavant note msg. and keep playing
98 lines
3.9 KiB
C++
98 lines
3.9 KiB
C++
/* Audio Library for Teensy 3.X
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* Copyright (c) 2014, Jonathan Payne (jon@jonnypayne.com)
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* Based on Effect_Fade by Paul Stoffregen
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* Also samplerate reduction based on Pete Brown's bitcrusher here:
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* http://10rem.net/blog/2013/01/13/a-simple-bitcrusher-and-sample-rate-reducer-in-cplusplus-for-a-windows-store-app
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*
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* Development of this audio library was funded by PJRC.COM, LLC by sales of
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* Teensy and Audio Adaptor boards. Please support PJRC's efforts to develop
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* open source software by purchasing Teensy or other PJRC products.
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*
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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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*
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* The above copyright notice, development funding notice, and this permission
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* notice shall be included in all copies or substantial portions of the Software.
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*
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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 "effect_bitcrusher.h"
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void AudioEffectBitcrusher::update(void)
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{
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audio_block_t *block;
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uint32_t i;
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uint32_t sampleSquidge, sampleSqueeze; //squidge is bitdepth, squeeze is for samplerate
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if (crushBits == 16 && sampleStep <= 1) {
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// nothing to do. Output is sent through clean, then exit the function
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block = receiveReadOnly();
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if (!block) return;
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transmit(block);
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release(block);
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return;
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}
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// start of processing functions. Could be more elegant based on external
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// functions but left like this to enable code optimisation later.
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block = receiveWritable();
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if (!block) return;
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if (sampleStep <= 1) { //no sample rate mods, just crush the bitdepth.
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for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
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// shift bits right to cut off fine detail sampleSquidge is a
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// uint32 so sign extension will not occur, fills with zeroes.
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sampleSquidge = block->data[i] >> (16-crushBits);
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// shift bits left again to regain the volume level.
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// fills with zeroes.
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block->data[i] = sampleSquidge << (16-crushBits);
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}
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} else if (crushBits == 16) { //bitcrusher not being used, samplerate mods only.
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i=0;
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while (i < AUDIO_BLOCK_SAMPLES) {
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// save the root sample. this will pick up a root
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// sample every _sampleStep_ samples.
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sampleSqueeze = block->data[i];
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for (int j = 0; j < sampleStep && i < AUDIO_BLOCK_SAMPLES; j++) {
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// for each repeated sample, paste in the current
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// root sample, then move onto the next step.
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block->data[i] = sampleSqueeze;
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i++;
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}
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}
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} else { //both being used. crush those bits and mash those samples.
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i=0;
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while (i < AUDIO_BLOCK_SAMPLES) {
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// save the root sample. this will pick up a root sample
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// every _sampleStep_ samples.
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sampleSqueeze = block->data[i];
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for (int j = 0; j < sampleStep && i < AUDIO_BLOCK_SAMPLES; j++) {
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// shift bits right to cut off fine detail sampleSquidge
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// is a uint32 so sign extension will not occur, fills
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// with zeroes.
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sampleSquidge = sampleSqueeze >> (16-crushBits);
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// shift bits left again to regain the volume level.
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// fills with zeroes. paste into buffer sample +
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// sampleStep offset.
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block->data[i] = sampleSquidge << (16-crushBits);
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i++;
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}
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}
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}
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transmit(block);
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release(block);
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}
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