mirror of
https://github.com/f4exb/sdrangel.git
synced 2024-11-29 19:28:47 -05:00
229 lines
8.9 KiB
C++
229 lines
8.9 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
|
|
// Copyright (C) 2019 F4EXB //
|
|
// written by Edouard Griffiths //
|
|
// //
|
|
// 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/>. //
|
|
///////////////////////////////////////////////////////////////////////////////////
|
|
|
|
#ifndef SDRBASE_AUDIO_AUDIOCOMPRESSORSND_H_
|
|
#define SDRBASE_AUDIO_AUDIOCOMPRESSORSND_H_
|
|
|
|
#include <cmath>
|
|
|
|
// maximum number of samples in the delay buffer
|
|
#define AUDIOCOMPRESSORSND_SF_COMPRESSOR_MAXDELAY 1024
|
|
|
|
// samples per update; the compressor works by dividing the input chunks into even smaller sizes,
|
|
// and performs heavier calculations after each mini-chunk to adjust the final envelope
|
|
#define AUDIOCOMPRESSORSND_SF_COMPRESSOR_SPU 32
|
|
|
|
// not sure what this does exactly, but it is part of the release curve
|
|
#define AUDIOCOMPRESSORSND_SF_COMPRESSOR_SPACINGDB 5.0f
|
|
|
|
// the "chunk" size as defined in original sndfilter library
|
|
#define AUDIOCOMPRESSORSND_SF_COMPRESSOR_CHUNKSIZE 128
|
|
|
|
#include "export.h"
|
|
|
|
class SDRBASE_API AudioCompressorSnd
|
|
{
|
|
public:
|
|
AudioCompressorSnd();
|
|
~AudioCompressorSnd();
|
|
|
|
void initDefault(int rate)
|
|
{
|
|
m_rate = rate;
|
|
m_pregain = 0.000f;
|
|
m_threshold = -24.000f;
|
|
m_knee = 30.000f;
|
|
m_ratio = 12.000f;
|
|
m_attack = 0.003f;
|
|
m_release = 0.250f;
|
|
m_predelay = 0.006f;
|
|
m_releasezone1 = 0.090f;
|
|
m_releasezone2 = 0.160f;
|
|
m_releasezone3 = 0.420f;
|
|
m_releasezone4 = 0.980f;
|
|
m_postgain = 0.000f;
|
|
m_wet = 1.000f;
|
|
initState();
|
|
}
|
|
|
|
void initSimple(
|
|
int rate, // input sample rate (samples per second)
|
|
float pregain, // dB, amount to boost the signal before applying compression [0 to 100]
|
|
float threshold, // dB, level where compression kicks in [-100 to 0]
|
|
float knee, // dB, width of the knee [0 to 40]
|
|
float ratio, // unitless, amount to inversely scale the output when applying comp [1 to 20]
|
|
float attack, // seconds, length of the attack phase [0 to 1]
|
|
float release // seconds, length of the release phase [0 to 1]
|
|
)
|
|
{
|
|
m_rate = rate;
|
|
m_pregain = pregain;
|
|
m_threshold = threshold;
|
|
m_knee = knee;
|
|
m_ratio = ratio;
|
|
m_attack = attack;
|
|
m_release = release;
|
|
m_predelay = 0.006f;
|
|
m_releasezone1 = 0.090f;
|
|
m_releasezone2 = 0.160f;
|
|
m_releasezone3 = 0.420f;
|
|
m_releasezone4 = 0.980f;
|
|
m_postgain = 0.000f;
|
|
m_wet = 1.000f;
|
|
initState();
|
|
}
|
|
|
|
void initState();
|
|
float compress(float sample);
|
|
|
|
float m_rate;
|
|
float m_pregain;
|
|
float m_threshold;
|
|
float m_knee;
|
|
float m_ratio;
|
|
float m_attack;
|
|
float m_release;
|
|
float m_predelay;
|
|
float m_releasezone1;
|
|
float m_releasezone2;
|
|
float m_releasezone3;
|
|
float m_releasezone4;
|
|
float m_postgain;
|
|
float m_wet;
|
|
|
|
private:
|
|
static inline float db2lin(float db){ // dB to linear
|
|
return powf(10.0f, 0.05f * db);
|
|
}
|
|
|
|
static inline float lin2db(float lin){ // linear to dB
|
|
return 20.0f * log10f(lin);
|
|
}
|
|
|
|
// for more information on the knee curve, check out the compressor-curve.html demo + source code
|
|
// included in this repo
|
|
static inline float kneecurve(float x, float k, float linearthreshold){
|
|
return linearthreshold + (1.0f - expf(-k * (x - linearthreshold))) / k;
|
|
}
|
|
|
|
static inline float kneeslope(float x, float k, float linearthreshold){
|
|
return k * x / ((k * linearthreshold + 1.0f) * expf(k * (x - linearthreshold)) - 1);
|
|
}
|
|
|
|
static inline float compcurve(float x, float k, float slope, float linearthreshold,
|
|
float linearthresholdknee, float threshold, float knee, float kneedboffset){
|
|
if (x < linearthreshold)
|
|
return x;
|
|
if (knee <= 0.0f) // no knee in curve
|
|
return db2lin(threshold + slope * (lin2db(x) - threshold));
|
|
if (x < linearthresholdknee)
|
|
return kneecurve(x, k, linearthreshold);
|
|
return db2lin(kneedboffset + slope * (lin2db(x) - threshold - knee));
|
|
}
|
|
|
|
// for more information on the adaptive release curve, check out adaptive-release-curve.html demo +
|
|
// source code included in this repo
|
|
static inline float adaptivereleasecurve(float x, float a, float b, float c, float d){
|
|
// a*x^3 + b*x^2 + c*x + d
|
|
float x2 = x * x;
|
|
return a * x2 * x + b * x2 + c * x + d;
|
|
}
|
|
|
|
static inline float clampf(float v, float min, float max){
|
|
return v < min ? min : (v > max ? max : v);
|
|
}
|
|
|
|
static inline float absf(float v){
|
|
return v < 0.0f ? -v : v;
|
|
}
|
|
|
|
static inline float fixf(float v, float def){
|
|
// fix NaN and infinity values that sneak in... not sure why this is needed, but it is
|
|
if (std::isnan(v) || std::isinf(v))
|
|
return def;
|
|
return v;
|
|
}
|
|
|
|
struct CompressorState
|
|
{ // sf_compressor_state_st
|
|
// user can read the metergain state variable after processing a chunk to see how much dB the
|
|
// compressor would have liked to compress the sample; the meter values aren't used to shape the
|
|
// sound in any way, only used for output if desired
|
|
float metergain;
|
|
|
|
// everything else shouldn't really be mucked with unless you read the algorithm and feel
|
|
// comfortable
|
|
float meterrelease;
|
|
float threshold;
|
|
float knee;
|
|
float linearpregain;
|
|
float linearthreshold;
|
|
float slope;
|
|
float attacksamplesinv;
|
|
float satreleasesamplesinv;
|
|
float wet;
|
|
float dry;
|
|
float k;
|
|
float kneedboffset;
|
|
float linearthresholdknee;
|
|
float mastergain;
|
|
float a; // adaptive release polynomial coefficients
|
|
float b;
|
|
float c;
|
|
float d;
|
|
float detectoravg;
|
|
float compgain;
|
|
float maxcompdiffdb;
|
|
int delaybufsize;
|
|
int delaywritepos;
|
|
int delayreadpos;
|
|
float delaybuf[AUDIOCOMPRESSORSND_SF_COMPRESSOR_MAXDELAY]; // predelay buffer
|
|
|
|
// populate the compressor state with advanced parameters
|
|
void 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]
|
|
);
|
|
};
|
|
|
|
static void sf_compressor_process(CompressorState *state, int size, float *input, float *output);
|
|
|
|
CompressorState m_compressorState;
|
|
float m_storageBuffer[AUDIOCOMPRESSORSND_SF_COMPRESSOR_CHUNKSIZE];
|
|
float m_processedBuffer[AUDIOCOMPRESSORSND_SF_COMPRESSOR_CHUNKSIZE];
|
|
int m_sampleIndex;
|
|
};
|
|
|
|
|
|
|
|
|
|
#endif // SDRBASE_AUDIO_AUDIOCOMPRESSORSND_H_
|