mirror of
https://github.com/f4exb/sdrangel.git
synced 2024-11-25 09:18:54 -05:00
324 lines
12 KiB
C++
324 lines
12 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
|
|
// Copyright (C) 2019-2020 Edouard Griffiths, F4EXB <f4exb06@gmail.com> //
|
|
// //
|
|
// Audio compressor based on sndfilter by Sean Connelly (@voidqk) //
|
|
// https://github.com/voidqk/sndfilter //
|
|
// //
|
|
// Sample by sample interface to facilitate integration in SDRangel modulators. //
|
|
// Uses mono samples (just floats) //
|
|
// //
|
|
// This program is free software; you can redistribute it and/or modify //
|
|
// it under the terms of the GNU General Public License as published by //
|
|
// the Free Software Foundation as version 3 of the License, or //
|
|
// (at your option) any later version. //
|
|
// //
|
|
// This program is distributed in the hope that it will be useful, //
|
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of //
|
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the //
|
|
// GNU General Public License V3 for more details. //
|
|
// //
|
|
// You should have received a copy of the GNU General Public License //
|
|
// along with this program. If not, see <http://www.gnu.org/licenses/>. //
|
|
///////////////////////////////////////////////////////////////////////////////////
|
|
|
|
#include <algorithm>
|
|
#include "audiocompressorsnd.h"
|
|
|
|
|
|
AudioCompressorSnd::AudioCompressorSnd()
|
|
{
|
|
m_sampleIndex = 0;
|
|
std::fill(m_processedBuffer, m_processedBuffer+AUDIOCOMPRESSORSND_SF_COMPRESSOR_CHUNKSIZE, 0.0f);
|
|
}
|
|
|
|
AudioCompressorSnd::~AudioCompressorSnd()
|
|
{}
|
|
|
|
void AudioCompressorSnd::initState()
|
|
{
|
|
m_compressorState.sf_advancecomp(
|
|
m_rate,
|
|
m_pregain,
|
|
m_threshold,
|
|
m_knee,
|
|
m_ratio,
|
|
m_attack,
|
|
m_release,
|
|
m_predelay,
|
|
m_releasezone1,
|
|
m_releasezone2,
|
|
m_releasezone3,
|
|
m_releasezone4,
|
|
m_postgain,
|
|
m_wet
|
|
);
|
|
}
|
|
|
|
float AudioCompressorSnd::compress(float sample)
|
|
{
|
|
float compressedSample;
|
|
|
|
if (m_sampleIndex >= AUDIOCOMPRESSORSND_SF_COMPRESSOR_CHUNKSIZE)
|
|
{
|
|
sf_compressor_process(&m_compressorState, AUDIOCOMPRESSORSND_SF_COMPRESSOR_CHUNKSIZE, m_storageBuffer, m_processedBuffer);
|
|
m_sampleIndex = 0;
|
|
}
|
|
|
|
compressedSample = m_processedBuffer[m_sampleIndex];
|
|
m_storageBuffer[m_sampleIndex] = sample;
|
|
m_sampleIndex++;
|
|
|
|
return compressedSample;
|
|
}
|
|
|
|
// populate the compressor state with advanced parameters
|
|
void AudioCompressorSnd::CompressorState::sf_advancecomp(
|
|
// these parameters are the same as the simple version above:
|
|
int rate, float pregain, float threshold, float knee, float ratio, float attack, float release,
|
|
// these are the advanced parameters:
|
|
float predelay, // seconds, length of the predelay buffer [0 to 1]
|
|
float releasezone1, // release zones should be increasing between 0 and 1, and are a fraction
|
|
float releasezone2, // of the release time depending on the input dB -- these parameters define
|
|
float releasezone3, // the adaptive release curve, which is discussed in further detail in the
|
|
float releasezone4, // demo: adaptive-release-curve.html
|
|
float postgain, // dB, amount of gain to apply after compression [0 to 100]
|
|
float wet) // amount to apply the effect [0 completely dry to 1 completely wet]
|
|
{
|
|
// setup the predelay buffer
|
|
int delaybufsize = rate * predelay;
|
|
|
|
if (delaybufsize < 1)
|
|
{
|
|
delaybufsize = 1;
|
|
}
|
|
else if (delaybufsize > AUDIOCOMPRESSORSND_SF_COMPRESSOR_MAXDELAY)
|
|
{
|
|
delaybufsize = AUDIOCOMPRESSORSND_SF_COMPRESSOR_MAXDELAY;
|
|
std::fill(delaybuf, delaybuf+delaybufsize, 0.0f);
|
|
}
|
|
|
|
// useful values
|
|
float linearpregain = db2lin(pregain);
|
|
float linearthreshold = db2lin(threshold);
|
|
float slope = 1.0f / ratio;
|
|
float attacksamples = rate * attack;
|
|
float attacksamplesinv = 1.0f / attacksamples;
|
|
float releasesamples = rate * release;
|
|
float satrelease = 0.0025f; // seconds
|
|
float satreleasesamplesinv = 1.0f / ((float)rate * satrelease);
|
|
float dry = 1.0f - wet;
|
|
|
|
// metering values (not used in core algorithm, but used to output a meter if desired)
|
|
float meterfalloff = 0.325f; // seconds
|
|
float meterrelease = 1.0f - expf(-1.0f / ((float)rate * meterfalloff));
|
|
|
|
// calculate knee curve parameters
|
|
float k = 5.0f; // initial guess
|
|
float kneedboffset = 0.0f;
|
|
float linearthresholdknee = 0.0f;
|
|
|
|
if (knee > 0.0f) // if a knee exists, search for a good k value
|
|
{
|
|
float xknee = db2lin(threshold + knee);
|
|
float mink = 0.1f;
|
|
float maxk = 10000.0f;
|
|
|
|
// search by comparing the knee slope at the current k guess, to the ideal slope
|
|
for (int i = 0; i < 15; i++)
|
|
{
|
|
if (kneeslope(xknee, k, linearthreshold) < slope) {
|
|
maxk = k;
|
|
} else {
|
|
mink = k;
|
|
}
|
|
|
|
k = sqrtf(mink * maxk);
|
|
}
|
|
|
|
kneedboffset = lin2db(kneecurve(xknee, k, linearthreshold));
|
|
linearthresholdknee = db2lin(threshold + knee);
|
|
}
|
|
|
|
// calculate a master gain based on what sounds good
|
|
float fulllevel = compcurve(1.0f, k, slope, linearthreshold, linearthresholdknee, threshold, knee, kneedboffset);
|
|
float mastergain = db2lin(postgain) * powf(1.0f / fulllevel, 0.6f);
|
|
|
|
// calculate the adaptive release curve parameters
|
|
// solve a,b,c,d in `y = a*x^3 + b*x^2 + c*x + d`
|
|
// interescting points (0, y1), (1, y2), (2, y3), (3, y4)
|
|
float y1 = releasesamples * releasezone1;
|
|
float y2 = releasesamples * releasezone2;
|
|
float y3 = releasesamples * releasezone3;
|
|
float y4 = releasesamples * releasezone4;
|
|
float a = (-y1 + 3.0f * y2 - 3.0f * y3 + y4) / 6.0f;
|
|
float b = y1 - 2.5f * y2 + 2.0f * y3 - 0.5f * y4;
|
|
float c = (-11.0f * y1 + 18.0f * y2 - 9.0f * y3 + 2.0f * y4) / 6.0f;
|
|
float d = y1;
|
|
|
|
// save everything
|
|
this->metergain = 1.0f; // large value overwritten immediately since it's always < 0
|
|
this->meterrelease = meterrelease;
|
|
this->threshold = threshold;
|
|
this->knee = knee;
|
|
this->wet = wet;
|
|
this->linearpregain = linearpregain;
|
|
this->linearthreshold = linearthreshold;
|
|
this->slope = slope;
|
|
this->attacksamplesinv = attacksamplesinv;
|
|
this->satreleasesamplesinv = satreleasesamplesinv;
|
|
this->dry = dry;
|
|
this->k = k;
|
|
this->kneedboffset = kneedboffset;
|
|
this->linearthresholdknee = linearthresholdknee;
|
|
this->mastergain = mastergain;
|
|
this->a = a;
|
|
this->b = b;
|
|
this->c = c;
|
|
this->d = d;
|
|
this->detectoravg = 0.0f;
|
|
this->compgain = 1.0f;
|
|
this->maxcompdiffdb = -1.0f;
|
|
this->delaybufsize = delaybufsize;
|
|
this->delaywritepos = 0;
|
|
this->delayreadpos = delaybufsize > 1 ? 1 : 0;
|
|
}
|
|
|
|
void AudioCompressorSnd::sf_compressor_process(AudioCompressorSnd::CompressorState *state, int size, float *input, float *output)
|
|
{
|
|
// pull out the state into local variables
|
|
float metergain = state->metergain;
|
|
float meterrelease = state->meterrelease;
|
|
float threshold = state->threshold;
|
|
float knee = state->knee;
|
|
float linearpregain = state->linearpregain;
|
|
float linearthreshold = state->linearthreshold;
|
|
float slope = state->slope;
|
|
float attacksamplesinv = state->attacksamplesinv;
|
|
float satreleasesamplesinv = state->satreleasesamplesinv;
|
|
float wet = state->wet;
|
|
float dry = state->dry;
|
|
float k = state->k;
|
|
float kneedboffset = state->kneedboffset;
|
|
float linearthresholdknee = state->linearthresholdknee;
|
|
float mastergain = state->mastergain;
|
|
float a = state->a;
|
|
float b = state->b;
|
|
float c = state->c;
|
|
float d = state->d;
|
|
float detectoravg = state->detectoravg;
|
|
float compgain = state->compgain;
|
|
float maxcompdiffdb = state->maxcompdiffdb;
|
|
int delaybufsize = state->delaybufsize;
|
|
int delaywritepos = state->delaywritepos;
|
|
int delayreadpos = state->delayreadpos;
|
|
float *delaybuf = state->delaybuf;
|
|
|
|
int samplesperchunk = AUDIOCOMPRESSORSND_SF_COMPRESSOR_SPU;
|
|
int chunks = size / samplesperchunk;
|
|
float ang90 = (float)M_PI * 0.5f;
|
|
float ang90inv = 2.0f / (float)M_PI;
|
|
int samplepos = 0;
|
|
float spacingdb = AUDIOCOMPRESSORSND_SF_COMPRESSOR_SPACINGDB;
|
|
|
|
for (int ch = 0; ch < chunks; ch++)
|
|
{
|
|
detectoravg = fixf(detectoravg, 1.0f);
|
|
float desiredgain = detectoravg;
|
|
float scaleddesiredgain = asinf(desiredgain) * ang90inv;
|
|
float compdiffdb = lin2db(compgain / scaleddesiredgain);
|
|
|
|
// calculate envelope rate based on whether we're attacking or releasing
|
|
float enveloperate;
|
|
if (compdiffdb < 0.0f)
|
|
{ // compgain < scaleddesiredgain, so we're releasing
|
|
compdiffdb = fixf(compdiffdb, -1.0f);
|
|
maxcompdiffdb = -1; // reset for a future attack mode
|
|
// apply the adaptive release curve
|
|
// scale compdiffdb between 0-3
|
|
float x = (clampf(compdiffdb, -12.0f, 0.0f) + 12.0f) * 0.25f;
|
|
float releasesamples = adaptivereleasecurve(x, a, b, c, d);
|
|
enveloperate = db2lin(spacingdb / releasesamples);
|
|
}
|
|
else
|
|
{ // compresorgain > scaleddesiredgain, so we're attacking
|
|
compdiffdb = fixf(compdiffdb, 1.0f);
|
|
if (maxcompdiffdb == -1 || maxcompdiffdb < compdiffdb)
|
|
maxcompdiffdb = compdiffdb;
|
|
float attenuate = maxcompdiffdb;
|
|
if (attenuate < 0.5f)
|
|
attenuate = 0.5f;
|
|
enveloperate = 1.0f - powf(0.25f / attenuate, attacksamplesinv);
|
|
}
|
|
|
|
// process the chunk
|
|
for (int chi = 0; chi < samplesperchunk; chi++, samplepos++,
|
|
delayreadpos = (delayreadpos + 1) % delaybufsize,
|
|
delaywritepos = (delaywritepos + 1) % delaybufsize)
|
|
{
|
|
|
|
float inputL = input[samplepos] * linearpregain;
|
|
delaybuf[delaywritepos] = inputL;
|
|
|
|
inputL = absf(inputL);
|
|
float inputmax = inputL;
|
|
|
|
float attenuation;
|
|
if (inputmax < 0.0001f)
|
|
attenuation = 1.0f;
|
|
else
|
|
{
|
|
float inputcomp = compcurve(inputmax, k, slope, linearthreshold,
|
|
linearthresholdknee, threshold, knee, kneedboffset);
|
|
attenuation = inputcomp / inputmax;
|
|
}
|
|
|
|
float rate;
|
|
if (attenuation > detectoravg)
|
|
{ // if releasing
|
|
float attenuationdb = -lin2db(attenuation);
|
|
if (attenuationdb < 2.0f)
|
|
attenuationdb = 2.0f;
|
|
float dbpersample = attenuationdb * satreleasesamplesinv;
|
|
rate = db2lin(dbpersample) - 1.0f;
|
|
}
|
|
else
|
|
rate = 1.0f;
|
|
|
|
detectoravg += (attenuation - detectoravg) * rate;
|
|
if (detectoravg > 1.0f)
|
|
detectoravg = 1.0f;
|
|
detectoravg = fixf(detectoravg, 1.0f);
|
|
|
|
if (enveloperate < 1) // attack, reduce gain
|
|
compgain += (scaleddesiredgain - compgain) * enveloperate;
|
|
else
|
|
{ // release, increase gain
|
|
compgain *= enveloperate;
|
|
if (compgain > 1.0f)
|
|
compgain = 1.0f;
|
|
}
|
|
|
|
// the final gain value!
|
|
float premixgain = sinf(ang90 * compgain);
|
|
float gain = dry + wet * mastergain * premixgain;
|
|
|
|
// calculate metering (not used in core algo, but used to output a meter if desired)
|
|
float premixgaindb = lin2db(premixgain);
|
|
if (premixgaindb < metergain)
|
|
metergain = premixgaindb; // spike immediately
|
|
else
|
|
metergain += (premixgaindb - metergain) * meterrelease; // fall slowly
|
|
|
|
// apply the gain
|
|
output[samplepos] = delaybuf[delayreadpos] * gain;
|
|
}
|
|
}
|
|
|
|
state->metergain = metergain;
|
|
state->detectoravg = detectoravg;
|
|
state->compgain = compgain;
|
|
state->maxcompdiffdb = maxcompdiffdb;
|
|
state->delaywritepos = delaywritepos;
|
|
state->delayreadpos = delayreadpos;
|
|
}
|