Holger Wirtz
5 years ago
parent
94c5d375df
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be8f93b976
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/* Audio Library for Teensy 3.X
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* Dynamics Processor (Gate, Compressor & Limiter) |
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* Copyright (c) 2017, Marc Paquette (marc@dacsystemes.com) |
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* Based on analyse_rms & mixer objects by Paul Stoffregen |
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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 "effect_dynamics.h" |
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#include "fast_log.h" |
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#include "utility/dspinst.h" |
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#include "utility/sqrt_integer.h" |
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static float analyse_rms(int16_t *data) { |
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uint32_t *p = (uint32_t *)data; |
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const uint32_t *end = p + AUDIO_BLOCK_SAMPLES / 2; |
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int64_t sum = 0; |
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do { |
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uint32_t n1 = *p++; |
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uint32_t n2 = *p++; |
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uint32_t n3 = *p++; |
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uint32_t n4 = *p++; |
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sum = multiply_accumulate_16tx16t_add_16bx16b(sum, n1, n1); |
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sum = multiply_accumulate_16tx16t_add_16bx16b(sum, n2, n2); |
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sum = multiply_accumulate_16tx16t_add_16bx16b(sum, n3, n3); |
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sum = multiply_accumulate_16tx16t_add_16bx16b(sum, n4, n4); |
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} while (p < end); |
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int32_t meansq = sum / AUDIO_BLOCK_SAMPLES; |
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return sqrt_uint32(meansq) / 32767.0f; |
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} |
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static void applyGain(int16_t *data, int32_t mult1, int32_t mult2) { |
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uint32_t *p = (uint32_t *)data; |
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const uint32_t *end = p + AUDIO_BLOCK_SAMPLES / 2; |
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int32_t inc = (mult2 - mult1) / (AUDIO_BLOCK_SAMPLES / 2); |
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do { |
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uint32_t tmp32 = *p; // read 2 samples from *data
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int32_t val1 = signed_multiply_32x16b(mult1, tmp32); |
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mult1 += inc; |
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int32_t val2 = signed_multiply_32x16t(mult1, tmp32); |
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mult1 += inc; |
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val1 = signed_saturate_rshift(val1, 16, 0); |
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val2 = signed_saturate_rshift(val2, 16, 0); |
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*p++ = pack_16b_16b(val2, val1); |
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} while (p < end); |
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} |
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void AudioEffectDynamics::update(void) { |
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audio_block_t *block; |
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block = receiveWritable(0); |
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if (!block) return; |
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if (!gateEnabled && !compEnabled && !limiterEnabled) { |
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//Transmit & release
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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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//Analyze received block
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float rms = analyse_rms(block->data); |
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//Compute block RMS level in Db
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float inputdb = MIN_DB; |
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if (rms > 0) inputdb = unitToDb(rms); |
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//Gate
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if (gateEnabled) { |
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if (inputdb >= gateThresholdOpen) gatedb = (aGateAttack * gatedb) + (aOneMinusGateAttack * MAX_DB); |
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else if (inputdb < gateThresholdClose) gatedb = (aGateRelease * gatedb) + (aOneMinusGateRelease * MIN_DB); |
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} |
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else gatedb = MAX_DB; |
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//Compressor
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if (compEnabled) { |
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float attdb = MAX_DB; //Below knee
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if (inputdb >= aLowKnee) { |
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if(inputdb <= aHighKnee) { |
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//Knee transition
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float knee = inputdb - aLowKnee; |
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attdb = aKneeRatio * knee * knee * aTwoKneeWidth; |
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} |
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else { |
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//Above knee
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attdb = compThreshold + ((inputdb - compThreshold) * compRatio) - inputdb; |
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} |
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} |
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if (attdb <= compdb) compdb = (aCompAttack * compdb) + (aOneMinusCompAttack * attdb); |
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else compdb = (aCompRelease * compdb) + (aOneMinusCompRelease * attdb); |
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} |
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else compdb = MAX_DB; |
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//Brickwall Limiter
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if (limiterEnabled) { |
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float outdb = inputdb + compdb + makeupdb; |
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if (outdb >= limitThreshold) limitdb = (aLimitAttack * limitdb) + (aOneMinusLimitAttack * (limitThreshold - outdb)); |
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else limitdb *= aLimitRelease; |
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} |
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else limitdb = MAX_DB; |
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//Compute linear gain
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float totalGain = gatedb + compdb + makeupdb + limitdb; |
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int32_t mult = dbToUnit(totalGain) * 65536.0f; |
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//Apply gain to block
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applyGain(block->data, last_mult, mult); |
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last_mult = mult; |
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//Transmit & release
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transmit(block); |
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release(block); |
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} |
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@ -0,0 +1,196 @@ |
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/* Audio Library for Teensy 3.X
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* Dynamics Processor (Gate, Compressor & Limiter) |
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* Copyright (c) 2018, Marc Paquette (marc@dacsystemes.com) |
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* Based on analyse_rms, effect_envelope & mixer objects by Paul Stoffregen |
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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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#ifndef effect_dynamics_h_ |
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#define effect_dynamics_h_ |
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#include "Arduino.h" |
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#include "AudioStream.h" |
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#define MIN_DB -110.0f |
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#define MAX_DB 0.0f |
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#define MIN_T 0.03f //Roughly 1 block
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#define MAX_T 4.00f |
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#define RATIO_OFF 1.0f |
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#define RATIO_INFINITY 60.0f |
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class AudioEffectDynamics : public AudioStream |
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{ |
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public: |
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AudioEffectDynamics(void) : AudioStream(1, inputQueueArray) { |
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gate(); |
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compression(); |
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limit(); |
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autoMakeupGain(); |
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} |
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//Sets the gate parameters.
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//threshold is in dbFS
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//attack & release are in seconds
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void gate(float threshold = -50.0f, float attack = MIN_T, float release = 0.3f, float hysterisis = 6.0f) { |
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gateEnabled = threshold > MIN_DB; |
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gateThresholdOpen = constrain(threshold, MIN_DB, MAX_DB); |
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gateThresholdClose = gateThresholdOpen - constrain(hysterisis, 0.0f, 6.0f); |
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float gateAttackTime = constrain(attack, MIN_T, MAX_T); |
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float gateReleaseTime = constrain(release, MIN_T, MAX_T); |
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aGateAttack = timeToAlpha(gateAttackTime); |
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aOneMinusGateAttack = 1.0f - aGateAttack; |
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aGateRelease = timeToAlpha(gateReleaseTime); |
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aOneMinusGateRelease = 1.0f - aGateRelease; |
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gatedb = MIN_DB; |
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} |
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//Sets the compression parameters.
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//threshold & kneeWidth are in db(FS)
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//attack and release are in seconds
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//ratio is expressed as x:1 i.e. 1 for no compression, 60 for brickwall limiting
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//Set kneeWidth to 0 for hard knee
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void compression(float threshold = -40.0f, float attack = MIN_T, float release = 0.5f, float ratio = 35.0f, float kneeWidth = 6.0f) { |
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compEnabled = threshold < MAX_DB; |
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compThreshold = constrain(threshold, MIN_DB, MAX_DB); |
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float compAttackTime = constrain(attack, MIN_T, MAX_T); |
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float compReleaseTime = constrain(release, MIN_T, MAX_T); |
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compRatio = 1.0f / constrain(abs(ratio), RATIO_OFF, RATIO_INFINITY); |
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float compKneeWidth = constrain(abs(kneeWidth), 0.0f, 32.0f); |
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computeMakeupGain(); |
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aCompAttack = timeToAlpha(compAttackTime); |
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aOneMinusCompAttack = 1.0f - aCompAttack; |
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aCompRelease = timeToAlpha(compReleaseTime); |
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aOneMinusCompRelease = 1.0f - aCompRelease; |
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aHalfKneeWidth = compKneeWidth / 2.0f; |
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aTwoKneeWidth = 1.0f / (compKneeWidth * 2.0f); |
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aKneeRatio = compRatio - 1.0f; |
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aLowKnee = compThreshold - aHalfKneeWidth; |
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aHighKnee = compThreshold + aHalfKneeWidth; |
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compdb = MIN_DB; |
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} |
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//Sets the hard limiter parameters
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//threshold is in dbFS
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//attack & release are in seconds
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void limit(float threshold = -3.0f, float attack = MIN_T, float release = MIN_T) { |
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limiterEnabled = threshold < MAX_DB; |
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limitThreshold = constrain(threshold, MIN_DB, MAX_DB); |
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float limitAttackTime = constrain(attack, MIN_T, MAX_T); |
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float limitReleaseTime = constrain(release, MIN_T, MAX_T);
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computeMakeupGain(); |
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aLimitAttack = timeToAlpha(limitAttackTime); |
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aOneMinusLimitAttack = 1.0f - aLimitAttack; |
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aLimitRelease = timeToAlpha(limitReleaseTime); |
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limitdb = MIN_DB; |
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} |
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//Enables automatic makeup gain setting
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//headroom is in dbFS
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void autoMakeupGain(float headroom = 6.0f) { |
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mgAutoEnabled = true; |
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mgHeadroom = constrain(headroom, 0.0f, 60.0f); |
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computeMakeupGain(); |
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} |
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//Sets a fixed makeup gain value.
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//gain is in dbFS
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void makeupGain(float gain = 0.0f) { |
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mgAutoEnabled = false; |
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makeupdb = constrain(gain, -12.0f, 24.0f); |
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} |
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private: |
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audio_block_t *inputQueueArray[1]; |
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bool gateEnabled = false; |
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float gateThresholdOpen; |
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float gateThresholdClose; |
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float gatedb; |
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bool compEnabled = false; |
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float compThreshold; |
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float compRatio; |
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float compdb; |
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bool limiterEnabled = false; |
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float limitThreshold; |
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float limitdb; |
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bool mgAutoEnabled; |
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float mgHeadroom; |
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float makeupdb; |
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float aGateAttack; |
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float aOneMinusGateAttack; |
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float aGateRelease; |
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float aOneMinusGateRelease; |
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float aHalfKneeWidth; |
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float aTwoKneeWidth; |
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float aKneeRatio; |
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float aLowKnee; |
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float aHighKnee; |
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float aCompAttack; |
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float aOneMinusCompAttack; |
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float aCompRelease; |
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float aOneMinusCompRelease; |
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float aLimitAttack; |
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float aOneMinusLimitAttack; |
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float aLimitRelease; |
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int32_t last_mult; |
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void computeMakeupGain() { |
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if (mgAutoEnabled) { |
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makeupdb = -compThreshold + (compThreshold * compRatio) + limitThreshold - mgHeadroom; |
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} |
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} |
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//Computes smoothing time constants for a 10% to 90% change
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float timeToAlpha(float time) { |
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return expf(-0.9542f / (((float)AUDIO_SAMPLE_RATE_EXACT / (float)AUDIO_BLOCK_SAMPLES) * time)); |
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} |
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virtual void update(void); |
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}; |
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#endif |
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@ -0,0 +1,50 @@ |
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/* ----------------------------------------------------------------------
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* https://community.arm.com/tools/f/discussions/4292/cmsis-dsp-new-functionality-proposal/22621#22621
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* Fast approximation to the log2() function. It uses a two step |
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* process. First, it decomposes the floating-point number into |
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* a fractional component F and an exponent E. The fraction component |
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* is used in a polynomial approximation and then the exponent added |
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* to the result. A 3rd order polynomial is used and the result |
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* when computing db20() is accurate to 7.984884e-003 dB. |
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** ------------------------------------------------------------------- */ |
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float log2f_approx_coeff[4] = {1.23149591368684f, -4.11852516267426f, 6.02197014179219f, -3.13396450166353f}; |
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float log2f_approx(float X) |
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{ |
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float *C = &log2f_approx_coeff[0]; |
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float Y; |
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float F; |
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int E; |
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// This is the approximation to log2()
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F = frexpf(fabsf(X), &E); |
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// Y = C[0]*F*F*F + C[1]*F*F + C[2]*F + C[3] + E;
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Y = *C++; |
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Y *= F; |
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Y += (*C++); |
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Y *= F; |
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Y += (*C++); |
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Y *= F; |
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Y += (*C++); |
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Y += E; |
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return(Y); |
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} |
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// https://codingforspeed.com/using-faster-exponential-approximation/
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inline float expf_approx(float x) { |
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x = 1.0f + x / 1024; |
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x *= x; x *= x; x *= x; x *= x; |
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x *= x; x *= x; x *= x; x *= x; |
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x *= x; x *= x; |
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return x; |
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} |
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inline float unitToDb(float unit) { |
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return 6.02f * log2f_approx(unit); |
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} |
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inline float dbToUnit(float db) { |
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return expf_approx(db * 2.302585092994046f * 0.05f); |
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} |
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