AudioCompressorSnd Class Reference

#include <audiocompressorsnd.h>

Collaboration diagram for AudioCompressorSnd:

Classes
struct	CompressorState

Public Member Functions
	AudioCompressorSnd ()
	~AudioCompressorSnd ()
void	initDefault (int rate)
void	initSimple (int rate, float pregain, float threshold, float knee, float ratio, float attack, float release)
void	initState ()
float	compress (float sample)

Public Attributes
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

Static Private Member Functions
static float	db2lin (float db)
static float	lin2db (float lin)
static float	kneecurve (float x, float k, float linearthreshold)
static float	kneeslope (float x, float k, float linearthreshold)
static float	compcurve (float x, float k, float slope, float linearthreshold, float linearthresholdknee, float threshold, float knee, float kneedboffset)
static float	adaptivereleasecurve (float x, float a, float b, float c, float d)
static float	clampf (float v, float min, float max)
static float	absf (float v)
static float	fixf (float v, float def)
static void	sf_compressor_process (CompressorState *state, int size, float *input, float *output)

Private Attributes
CompressorState	m_compressorState
float	m_storageBuffer [AUDIOCOMPRESSORSND_SF_COMPRESSOR_CHUNKSIZE]
float	m_processedBuffer [AUDIOCOMPRESSORSND_SF_COMPRESSOR_CHUNKSIZE]
int	m_sampleIndex

Detailed Description

Definition at line 46 of file audiocompressorsnd.h.

Constructor & Destructor Documentation

AudioCompressorSnd()

AudioCompressorSnd::AudioCompressorSnd

(

)

Definition at line 29 of file audiocompressorsnd.cpp.

References AUDIOCOMPRESSORSND_SF_COMPRESSOR_CHUNKSIZE, m_processedBuffer, and m_sampleIndex.

{
    m_sampleIndex = 0;
    std::fill(m_processedBuffer, m_processedBuffer+AUDIOCOMPRESSORSND_SF_COMPRESSOR_CHUNKSIZE, 0.0f);
}

~AudioCompressorSnd()

AudioCompressorSnd::~AudioCompressorSnd

(

)

Definition at line 35 of file audiocompressorsnd.cpp.

{}

Member Function Documentation

absf()

static float AudioCompressorSnd::absf ( float  v )

inlinestaticprivate

Definition at line 158 of file audiocompressorsnd.h.

Referenced by sf_compressor_process().

                                     {
        return v < 0.0f ? -v : v;
    }

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adaptivereleasecurve()

static float AudioCompressorSnd::adaptivereleasecurve ( float  x, float  a, float  b, float  c, float  d  )

inlinestaticprivate

Definition at line 148 of file audiocompressorsnd.h.

Referenced by sf_compressor_process().

                                                                                         {
        // a*x^3 + b*x^2 + c*x + d
        float x2 = x * x;
        return a * x2 * x + b * x2 + c * x + d;
    }

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clampf()

static float AudioCompressorSnd::clampf ( float  v, float  min, float  max  )

inlinestaticprivate

Definition at line 154 of file audiocompressorsnd.h.

References leansdr::max().

Referenced by sf_compressor_process().

                                                             {
        return v < min ? min : (v > max ? max : v);
    }

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compcurve()

static float AudioCompressorSnd::compcurve ( float  x, float  k, float  slope, float  linearthreshold, float  linearthresholdknee, float  threshold, float  knee, float  kneedboffset  )

inlinestaticprivate

Definition at line 135 of file audiocompressorsnd.h.

Referenced by AudioCompressorSnd::CompressorState::sf_advancecomp(), and sf_compressor_process().

                                                                                   {
        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));
    }

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compress()

float AudioCompressorSnd::compress

(

float

sample

)

Definition at line 58 of file audiocompressorsnd.cpp.

References AUDIOCOMPRESSORSND_SF_COMPRESSOR_CHUNKSIZE, m_compressorState, m_processedBuffer, m_sampleIndex, m_storageBuffer, and sf_compressor_process().

Referenced by SSBMod::pullAF().

{
    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;
}

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db2lin()

static float AudioCompressorSnd::db2lin ( float  db )

inlinestaticprivate

Definition at line 117 of file audiocompressorsnd.h.

Referenced by AudioCompressorSnd::CompressorState::sf_advancecomp(), and sf_compressor_process().

                                        { // dB to linear
        return powf(10.0f, 0.05f * db);
    }

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fixf()

static float AudioCompressorSnd::fixf ( float  v, float  def  )

inlinestaticprivate

Definition at line 162 of file audiocompressorsnd.h.

Referenced by sf_compressor_process().

                                                {
        // fix NaN and infinity values that sneak in... not sure why this is needed, but it is
        if (isnan(v) || isinf(v))
            return def;
        return v;
    }

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initDefault()

void AudioCompressorSnd::initDefault ( int  rate )

inline

Definition at line 52 of file audiocompressorsnd.h.

    {
        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();
    }

initSimple()

void AudioCompressorSnd::initSimple ( int  rate, float  pregain, float  threshold, float  knee, float  ratio, float  attack, float  release  )

inline

Definition at line 71 of file audiocompressorsnd.h.

Referenced by SSBMod::SSBMod().

    {
        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();
    }

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initState()

void AudioCompressorSnd::initState

(

)

Definition at line 38 of file audiocompressorsnd.cpp.

References m_attack, m_compressorState, m_knee, m_postgain, m_predelay, m_pregain, m_rate, m_ratio, m_release, m_releasezone1, m_releasezone2, m_releasezone3, m_releasezone4, m_threshold, m_wet, and AudioCompressorSnd::CompressorState::sf_advancecomp().

Referenced by SSBMod::applyAudioSampleRate().

{
    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
    );
}

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kneecurve()

static float AudioCompressorSnd::kneecurve ( float  x, float  k, float  linearthreshold  )

inlinestaticprivate

Definition at line 127 of file audiocompressorsnd.h.

Referenced by AudioCompressorSnd::CompressorState::sf_advancecomp().

                                                                          {
        return linearthreshold + (1.0f - expf(-k * (x - linearthreshold))) / k;
    }

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kneeslope()

static float AudioCompressorSnd::kneeslope ( float  x, float  k, float  linearthreshold  )

inlinestaticprivate

Definition at line 131 of file audiocompressorsnd.h.

Referenced by AudioCompressorSnd::CompressorState::sf_advancecomp().

                                                                          {
        return k * x / ((k * linearthreshold + 1.0f) * expf(k * (x - linearthreshold)) - 1);
    }

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lin2db()

static float AudioCompressorSnd::lin2db ( float  lin )

inlinestaticprivate

Definition at line 121 of file audiocompressorsnd.h.

Referenced by AudioCompressorSnd::CompressorState::sf_advancecomp(), and sf_compressor_process().

                                         { // linear to dB
        return 20.0f * log10f(lin);
    }

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sf_compressor_process()

void AudioCompressorSnd::sf_compressor_process ( AudioCompressorSnd::CompressorState *  state, int  size, float *  input, float *  output  )

staticprivate

Definition at line 188 of file audiocompressorsnd.cpp.

References AudioCompressorSnd::CompressorState::a, absf(), adaptivereleasecurve(), AudioCompressorSnd::CompressorState::attacksamplesinv, AUDIOCOMPRESSORSND_SF_COMPRESSOR_SPACINGDB, AUDIOCOMPRESSORSND_SF_COMPRESSOR_SPU, AudioCompressorSnd::CompressorState::b, AudioCompressorSnd::CompressorState::c, clampf(), compcurve(), AudioCompressorSnd::CompressorState::compgain, AudioCompressorSnd::CompressorState::d, db2lin(), AudioCompressorSnd::CompressorState::delaybuf, AudioCompressorSnd::CompressorState::delaybufsize, AudioCompressorSnd::CompressorState::delayreadpos, AudioCompressorSnd::CompressorState::delaywritepos, AudioCompressorSnd::CompressorState::detectoravg, AudioCompressorSnd::CompressorState::dry, fixf(), AudioCompressorSnd::CompressorState::k, AudioCompressorSnd::CompressorState::knee, AudioCompressorSnd::CompressorState::kneedboffset, lin2db(), AudioCompressorSnd::CompressorState::linearpregain, AudioCompressorSnd::CompressorState::linearthreshold, AudioCompressorSnd::CompressorState::linearthresholdknee, M_PI, AudioCompressorSnd::CompressorState::mastergain, AudioCompressorSnd::CompressorState::maxcompdiffdb, AudioCompressorSnd::CompressorState::metergain, AudioCompressorSnd::CompressorState::meterrelease, AudioCompressorSnd::CompressorState::satreleasesamplesinv, AudioCompressorSnd::CompressorState::slope, AudioCompressorSnd::CompressorState::threshold, and AudioCompressorSnd::CompressorState::wet.

Referenced by compress().

{
    // 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;
}

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Member Data Documentation

m_attack

float AudioCompressorSnd::m_attack

Definition at line 106 of file audiocompressorsnd.h.

Referenced by initState().

m_compressorState

CompressorState AudioCompressorSnd::m_compressorState

private

Definition at line 221 of file audiocompressorsnd.h.

Referenced by compress(), and initState().

m_knee

float AudioCompressorSnd::m_knee

Definition at line 104 of file audiocompressorsnd.h.

Referenced by initState().

m_postgain

float AudioCompressorSnd::m_postgain

Definition at line 113 of file audiocompressorsnd.h.

Referenced by initState().

m_predelay

float AudioCompressorSnd::m_predelay

Definition at line 108 of file audiocompressorsnd.h.

Referenced by initState().

m_pregain

float AudioCompressorSnd::m_pregain

Definition at line 102 of file audiocompressorsnd.h.

Referenced by initState().

m_processedBuffer

float AudioCompressorSnd::m_processedBuffer[AUDIOCOMPRESSORSND_SF_COMPRESSOR_CHUNKSIZE]

private

Definition at line 223 of file audiocompressorsnd.h.

Referenced by AudioCompressorSnd(), and compress().

m_rate

float AudioCompressorSnd::m_rate

Definition at line 101 of file audiocompressorsnd.h.

Referenced by SSBMod::applyAudioSampleRate(), and initState().

m_ratio

float AudioCompressorSnd::m_ratio

Definition at line 105 of file audiocompressorsnd.h.

Referenced by initState().

m_release

float AudioCompressorSnd::m_release

Definition at line 107 of file audiocompressorsnd.h.

Referenced by initState().

m_releasezone1

float AudioCompressorSnd::m_releasezone1

Definition at line 109 of file audiocompressorsnd.h.

Referenced by initState().

m_releasezone2

float AudioCompressorSnd::m_releasezone2

Definition at line 110 of file audiocompressorsnd.h.

Referenced by initState().

m_releasezone3

float AudioCompressorSnd::m_releasezone3

Definition at line 111 of file audiocompressorsnd.h.

Referenced by initState().

m_releasezone4

float AudioCompressorSnd::m_releasezone4

Definition at line 112 of file audiocompressorsnd.h.

Referenced by initState().

m_sampleIndex

int AudioCompressorSnd::m_sampleIndex

private

Definition at line 224 of file audiocompressorsnd.h.

Referenced by AudioCompressorSnd(), and compress().

m_storageBuffer

float AudioCompressorSnd::m_storageBuffer[AUDIOCOMPRESSORSND_SF_COMPRESSOR_CHUNKSIZE]

private

Definition at line 222 of file audiocompressorsnd.h.

Referenced by compress().

m_threshold

float AudioCompressorSnd::m_threshold

Definition at line 103 of file audiocompressorsnd.h.

Referenced by initState().

m_wet

float AudioCompressorSnd::m_wet

Definition at line 114 of file audiocompressorsnd.h.

Referenced by initState().

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The documentation for this class was generated from the following files:

• sdrbase/audio/audiocompressorsnd.h
• sdrbase/audio/audiocompressorsnd.cpp