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AmplitudeFollower.cpp

/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */

/*
    Vamp

    An API for audio analysis and feature extraction plugins.

    Centre for Digital Music, Queen Mary, University of London.
    This file copyright 2006 Dan Stowell.
  
    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 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 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.

    Except as contained in this notice, the names of the Centre for
    Digital Music; Queen Mary, University of London; and Chris Cannam
    shall not be used in advertising or otherwise to promote the sale,
    use or other dealings in this Software without prior written
    authorization.
*/

#include "AmplitudeFollower.h"

#include <cmath>

#include <string>
#include <vector>
#include <iostream>

using std::string;
using std::vector;
using std::cerr;
using std::endl;

/**
 * An implementation of SuperCollider's amplitude-follower algorithm
 * as a simple Vamp plugin.
 */

00055 AmplitudeFollower::AmplitudeFollower(float inputSampleRate) :
    Plugin(inputSampleRate),
    m_stepSize(0),
    m_previn(0.0f),
    m_clampcoef(0.01f),
    m_relaxcoef(0.01f)
{
}

AmplitudeFollower::~AmplitudeFollower()
{
}

string
00069 AmplitudeFollower::getIdentifier() const
{
    return "amplitudefollower";
}

string
00075 AmplitudeFollower::getName() const
{
    return "Amplitude Follower";
}

string
00081 AmplitudeFollower::getDescription() const
{
    return "Track the amplitude of the audio signal";
}

string
00087 AmplitudeFollower::getMaker() const
{
    return "Vamp SDK Example Plugins";
}

int
00093 AmplitudeFollower::getPluginVersion() const
{
    return 1;
}

string
00099 AmplitudeFollower::getCopyright() const
{
    return "Code copyright 2006 Dan Stowell; method from SuperCollider.  Freely redistributable (BSD license)";
}

bool
00105 AmplitudeFollower::initialise(size_t channels, size_t stepSize, size_t blockSize)
{
    if (channels < getMinChannelCount() ||
      channels > getMaxChannelCount()) return false;

    m_stepSize = std::min(stepSize, blockSize);
      
    // Translate the coefficients 
    // from their "convenient" 60dB convergence-time values
    // to real coefficients
    m_clampcoef = m_clampcoef==0.0 ? 0.0 : exp(log(0.1)/(m_clampcoef * m_inputSampleRate));
    m_relaxcoef = m_relaxcoef==0.0 ? 0.0 : exp(log(0.1)/(m_relaxcoef * m_inputSampleRate));

    return true;
}

void
00122 AmplitudeFollower::reset()
{
    m_previn = 0.0f;
}

AmplitudeFollower::OutputList
00128 AmplitudeFollower::getOutputDescriptors() const
{
    OutputList list;

    OutputDescriptor sca;
    sca.identifier = "amplitude";
    sca.name = "Amplitude";
    sca.description = "";
    sca.unit = "V";
    sca.hasFixedBinCount = true;
    sca.binCount = 1;
    sca.hasKnownExtents = false;
    sca.isQuantized = false;
    sca.sampleType = OutputDescriptor::OneSamplePerStep;
    list.push_back(sca);

    return list;
}

AmplitudeFollower::ParameterList
00148 AmplitudeFollower::getParameterDescriptors() const
{
    ParameterList list;
      
    ParameterDescriptor att;
    att.identifier = "attack";
    att.name = "Attack time";
    att.description = "";
    att.unit = "s";
    att.minValue = 0.0f;
    att.maxValue = 1.f;
    att.defaultValue = 0.01f;
    att.isQuantized = false;
    
    list.push_back(att);
    
    ParameterDescriptor dec;
    dec.identifier = "release";
    dec.name = "Release time";
    dec.description = "";
    dec.unit = "s";
    dec.minValue = 0.0f;
    dec.maxValue = 1.f;
    dec.defaultValue = 0.01f;
    dec.isQuantized = false;
    
    list.push_back(dec);
    
    return list;
}

00179 void AmplitudeFollower::setParameter(std::string paramid, float newval)
{
    if (paramid == "attack") {
        m_clampcoef = newval;
    } else if (paramid == "release") {
        m_relaxcoef = newval;
    }
}

00188 float AmplitudeFollower::getParameter(std::string paramid) const
{
    if (paramid == "attack") {
        return m_clampcoef;
    } else if (paramid == "release") {
        return m_relaxcoef;
    }

    return 0.0f;
}

AmplitudeFollower::FeatureSet
00200 AmplitudeFollower::process(const float *const *inputBuffers,
                           Vamp::RealTime timestamp)
{
    if (m_stepSize == 0) {
      cerr << "ERROR: AmplitudeFollower::process: "
           << "AmplitudeFollower has not been initialised"
           << endl;
      return FeatureSet();
    }

    float previn = m_previn;

    FeatureSet returnFeatures;
      
    float val;
    float peak = 0.0f;

    for (size_t i = 0; i < m_stepSize; ++i) {

        val = fabs(inputBuffers[0][i]);
            
        if (val < previn) {
            val = val + (previn - val) * m_relaxcoef;
        } else {
            val = val + (previn - val) * m_clampcoef;
        }

        if (val > peak) peak = val;
        previn = val;
    }

    m_previn = previn;

    // Now store the "feature" (peak amp) for this sample
    Feature feature;
    feature.hasTimestamp = false;
    feature.values.push_back(peak);
    returnFeatures[0].push_back(feature);

    return returnFeatures;
}

AmplitudeFollower::FeatureSet
00243 AmplitudeFollower::getRemainingFeatures()
{
    return FeatureSet();
}


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