diff examples/AmplitudeFollower.cpp @ 41:31cd55174467

* Add Dan Stowell's simple implementation of the SuperCollider amplitude
  follower method

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/examples/AmplitudeFollower.cpp	Wed Oct 11 11:39:02 2006 +0000
@@ -0,0 +1,237 @@
+/* -*- 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.
+ */
+
+AmplitudeFollower::AmplitudeFollower(float inputSampleRate) :
+    Plugin(inputSampleRate),
+    m_stepSize(0),
+    m_previn(0.0f),
+    m_clampcoef(0.01f),
+    m_relaxcoef(0.01f)
+{
+}
+
+AmplitudeFollower::~AmplitudeFollower()
+{
+}
+
+string
+AmplitudeFollower::getName() const
+{
+    return "amplitudefollower";
+}
+
+string
+AmplitudeFollower::getDescription() const
+{
+    return "Amplitude Follower";
+}
+
+string
+AmplitudeFollower::getMaker() const
+{
+    return "Queen Mary, University of London";
+}
+
+int
+AmplitudeFollower::getPluginVersion() const
+{
+    return 1;
+}
+
+string
+AmplitudeFollower::getCopyright() const
+{
+    return "Code copyright 2006 Dan Stowell; method from SuperCollider.  Freely redistributable (BSD license)";
+}
+
+bool
+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
+AmplitudeFollower::reset()
+{
+    m_previn = 0.0f;
+}
+
+AmplitudeFollower::OutputList
+AmplitudeFollower::getOutputDescriptors() const
+{
+    OutputList list;
+
+    OutputDescriptor sca;
+    sca.name = "amplitude";
+    sca.unit = "V";
+    sca.description = "Amplitude";
+    sca.hasFixedBinCount = true;
+    sca.binCount = 1;
+    sca.hasKnownExtents = false;
+    sca.isQuantized = false;
+    sca.sampleType = OutputDescriptor::OneSamplePerStep;
+    list.push_back(sca);
+
+    return list;
+}
+
+AmplitudeFollower::ParameterList
+AmplitudeFollower::getParameterDescriptors() const
+{
+    ParameterList list;
+	
+    ParameterDescriptor att;
+    att.name = "attack";
+    att.description = "Attack time";
+    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.name = "release";
+    dec.description = "Release time";
+    dec.unit = "s";
+    dec.minValue = 0.0f;
+    dec.maxValue = 1.f;
+    dec.defaultValue = 0.01f;
+    dec.isQuantized = false;
+    
+    list.push_back(dec);
+    
+    return list;
+}
+
+void AmplitudeFollower::setParameter(std::string paramname, float newval)
+{
+    if (paramname == "attack") {
+        m_clampcoef = newval;
+    } else if (paramname == "release") {
+        m_relaxcoef = newval;
+    }
+}
+
+float AmplitudeFollower::getParameter(std::string paramname) const
+{
+    if (paramname == "attack") {
+        return m_clampcoef;
+    } else if (paramname == "release") {
+        return m_relaxcoef;
+    }
+
+    return 0.0f;
+}
+
+AmplitudeFollower::FeatureSet
+AmplitudeFollower::process(float **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
+AmplitudeFollower::getRemainingFeatures()
+{
+    return FeatureSet();
+}
+