MicroMDAEPiano/effect_dynamics.cpp

/* Audio Library for Teensy 3.X
 * Dynamics Processor (Gate, Compressor & Limiter)
 * Copyright (c) 2017, Marc Paquette (marc@dacsystemes.com)
 * Based on analyse_rms & mixer objects by Paul Stoffregen
 *
 * Development of this audio library was funded by PJRC.COM, LLC by sales of
 * Teensy and Audio Adaptor boards.  Please support PJRC's efforts to develop
 * open source software by purchasing Teensy or other PJRC products.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice, development funding notice, and this permission
 * notice shall be included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "effect_dynamics.h"
#include "fast_log.h"
#include "utility/dspinst.h"
#include "utility/sqrt_integer.h"

static float analyse_rms(int16_t *data) {
	
	uint32_t *p = (uint32_t *)data;
	const uint32_t *end = p + AUDIO_BLOCK_SAMPLES / 2;
	int64_t sum = 0;
	do {
		uint32_t n1 = *p++;
		uint32_t n2 = *p++;
		uint32_t n3 = *p++;
		uint32_t n4 = *p++;
		sum = multiply_accumulate_16tx16t_add_16bx16b(sum, n1, n1);
		sum = multiply_accumulate_16tx16t_add_16bx16b(sum, n2, n2);
		sum = multiply_accumulate_16tx16t_add_16bx16b(sum, n3, n3);
		sum = multiply_accumulate_16tx16t_add_16bx16b(sum, n4, n4);
		
	} while (p < end);
	
	int32_t meansq = sum / AUDIO_BLOCK_SAMPLES;
	return sqrt_uint32(meansq) / 32767.0f;
}

static void applyGain(int16_t *data, int32_t mult1, int32_t mult2) {
	
	uint32_t *p = (uint32_t *)data;
	const uint32_t *end = p + AUDIO_BLOCK_SAMPLES / 2;
	int32_t inc = (mult2 - mult1) / (AUDIO_BLOCK_SAMPLES / 2);
	
	do {
		uint32_t tmp32 = *p; // read 2 samples from *data
		int32_t val1 = signed_multiply_32x16b(mult1, tmp32);
		mult1 += inc;
		int32_t val2 = signed_multiply_32x16t(mult1, tmp32);
		mult1 += inc;
		val1 = signed_saturate_rshift(val1, 16, 0);
		val2 = signed_saturate_rshift(val2, 16, 0);
		*p++ = pack_16b_16b(val2, val1);
	} while (p < end);
}

void AudioEffectDynamics::update(void) {

	audio_block_t *block;
	
	block = receiveWritable(0);

	if (!block) return;
	
	if (!gateEnabled && !compEnabled && !limiterEnabled) {
		
		//Transmit & release
		transmit(block);
		release(block);
		return;
	}
	
	//Analyze received block
	float rms = analyse_rms(block->data);
	
	//Compute block RMS level in Db
	float inputdb = MIN_DB;
	if (rms > 0) inputdb = unitToDb(rms);
	
	//Gate
	if (gateEnabled) {
		if (inputdb >= gateThresholdOpen) gatedb = (aGateAttack * gatedb) + (aOneMinusGateAttack * MAX_DB);
		else if (inputdb < gateThresholdClose) gatedb = (aGateRelease * gatedb) + (aOneMinusGateRelease * MIN_DB);
	}
	else gatedb = MAX_DB;

	//Compressor
	if (compEnabled) {
		float attdb = MAX_DB; //Below knee
		if (inputdb >= aLowKnee) {
			if(inputdb <= aHighKnee) {
				//Knee transition
				float knee = inputdb - aLowKnee;
				attdb = aKneeRatio * knee * knee * aTwoKneeWidth;
			}
			else {
				//Above knee
				attdb = compThreshold + ((inputdb - compThreshold) * compRatio) - inputdb;
			}
		}
		if (attdb <= compdb) compdb = (aCompAttack * compdb) + (aOneMinusCompAttack * attdb);
		else compdb = (aCompRelease * compdb) + (aOneMinusCompRelease * attdb);
	}
	else compdb = MAX_DB;

	//Brickwall Limiter
	if (limiterEnabled) {
		float outdb = inputdb + compdb + makeupdb;
		if (outdb >= limitThreshold) limitdb = (aLimitAttack * limitdb) + (aOneMinusLimitAttack * (limitThreshold - outdb));
		else limitdb *= aLimitRelease;
	}
	else limitdb = MAX_DB;

	//Compute linear gain
	float totalGain = gatedb + compdb + makeupdb + limitdb;
	int32_t mult = dbToUnit(totalGain) * 65536.0f;

	//Apply gain to block
	applyGain(block->data, last_mult, mult);
	last_mult = mult;
	
	//Transmit & release
	transmit(block);
	release(block);
}