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ZeroCrossing.cpp
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    00001 /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
    00002
    00003 /*
    00004     Vamp
    00005
    00006     An API for audio analysis and feature extraction plugins.
    00007
    00008     Centre for Digital Music, Queen Mary, University of London.
    00009     Copyright 2006 Chris Cannam.
    00010
    00011     Permission is hereby granted, free of charge, to any person
    00012     obtaining a copy of this software and associated documentation
    00013     files (the "Software"), to deal in the Software without
    00014     restriction, including without limitation the rights to use, copy,
    00015     modify, merge, publish, distribute, sublicense, and/or sell copies
    00016     of the Software, and to permit persons to whom the Software is
    00017     furnished to do so, subject to the following conditions:
    00018
    00019     The above copyright notice and this permission notice shall be
    00020     included in all copies or substantial portions of the Software.
    00021
    00022     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
    00023     EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
    00024     MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
    00025     NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR
    00026     ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
    00027     CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
    00028     WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
    00029
    00030     Except as contained in this notice, the names of the Centre for
    00031     Digital Music; Queen Mary, University of London; and Chris Cannam
    00032     shall not be used in advertising or otherwise to promote the sale,
    00033     use or other dealings in this Software without prior written
    00034     authorization.
    00035 */
    00036
    00037 #include "ZeroCrossing.h"
    00038
    00039 using std::string;
    00040 using std::vector;
    00041 using std::cerr;
    00042 using std::endl;
    00043
    00044 #include <cmath>
    00045
    00046 ZeroCrossing::ZeroCrossing(float inputSampleRate) :
    00047     Plugin(inputSampleRate),
    00048     m_stepSize(0),
    00049     m_previousSample(0.0f)
    00050 {
    00051 }
    00052
    00053 ZeroCrossing::~ZeroCrossing()
    00054 {
    00055 }
    00056
    00057 string
    00058 ZeroCrossing::getIdentifier() const
    00059 {
    00060     return "zerocrossing";
    00061 }
    00062
    00063 string
    00064 ZeroCrossing::getName() const
    00065 {
    00066     return "Zero Crossings";
    00067 }
    00068
    00069 string
    00070 ZeroCrossing::getDescription() const
    00071 {
    00072     return "Detect and count zero crossing points";
    00073 }
    00074
    00075 string
    00076 ZeroCrossing::getMaker() const
    00077 {
    00078     return "Vamp SDK Example Plugins";
    00079 }
    00080
    00081 int
    00082 ZeroCrossing::getPluginVersion() const
    00083 {
    00084     return 2;
    00085 }
    00086
    00087 string
    00088 ZeroCrossing::getCopyright() const
    00089 {
    00090     return "Freely redistributable (BSD license)";
    00091 }
    00092
    00093 bool
    00094 ZeroCrossing::initialise(size_t channels, size_t stepSize, size_t blockSize)
    00095 {
    00096     if (channels < getMinChannelCount() ||
    00097         channels > getMaxChannelCount()) return false;
    00098
    00099     m_stepSize = std::min(stepSize, blockSize);
    00100
    00101     return true;
    00102 }
    00103
    00104 void
    00105 ZeroCrossing::reset()
    00106 {
    00107     m_previousSample = 0.0f;
    00108 }
    00109
    00110 ZeroCrossing::OutputList
    00111 ZeroCrossing::getOutputDescriptors() const
    00112 {
    00113     OutputList list;
    00114
    00115     OutputDescriptor zc;
    00116     zc.identifier = "counts";
    00117     zc.name = "Zero Crossing Counts";
    00118     zc.description = "The number of zero crossing points per processing block";
    00119     zc.unit = "crossings";
    00120     zc.hasFixedBinCount = true;
    00121     zc.binCount = 1;
    00122     zc.hasKnownExtents = false;
    00123     zc.isQuantized = true;
    00124     zc.quantizeStep = 1.0;
    00125     zc.sampleType = OutputDescriptor::OneSamplePerStep;
    00126     list.push_back(zc);
    00127
    00128     zc.identifier = "zerocrossings";
    00129     zc.name = "Zero Crossings";
    00130     zc.description = "The locations of zero crossing points";
    00131     zc.unit = "";
    00132     zc.hasFixedBinCount = true;
    00133     zc.binCount = 0;
    00134     zc.sampleType = OutputDescriptor::VariableSampleRate;
    00135     zc.sampleRate = m_inputSampleRate;
    00136     list.push_back(zc);
    00137
    00138     return list;
    00139 }
    00140
    00141 ZeroCrossing::FeatureSet
    00142 ZeroCrossing::process(const float *const *inputBuffers,
    00143                       Vamp::RealTime timestamp)
    00144 {
    00145     if (m_stepSize == 0) {
    00146         cerr << "ERROR: ZeroCrossing::process: "
    00147              << "ZeroCrossing has not been initialised"
    00148              << endl;
    00149         return FeatureSet();
    00150     }
    00151
    00152     float prev = m_previousSample;
    00153     size_t count = 0;
    00154
    00155     FeatureSet returnFeatures;
    00156
    00157     for (size_t i = 0; i < m_stepSize; ++i) {
    00158
    00159         float sample = inputBuffers[0][i];
    00160         bool crossing = false;
    00161
    00162         if (sample <= 0.0) {
    00163             if (prev > 0.0) crossing = true;
    00164         } else if (sample > 0.0) {
    00165             if (prev <= 0.0) crossing = true;
    00166         }
    00167
    00168         if (crossing) {
    00169             ++count;
    00170             Feature feature;
    00171             feature.hasTimestamp = true;
    00172             feature.timestamp = timestamp +
    00173                 Vamp::RealTime::frame2RealTime(i, (size_t)m_inputSampleRate);
    00174             returnFeatures[1].push_back(feature);
    00175         }
    00176
    00177         prev = sample;
    00178     }
    00179
    00180     m_previousSample = prev;
    00181
    00182     Feature feature;
    00183     feature.hasTimestamp = false;
    00184     feature.values.push_back(float(count));
    00185
    00186     returnFeatures[0].push_back(feature);
    00187     return returnFeatures;
    00188 }
    00189
    00190 ZeroCrossing::FeatureSet
    00191 ZeroCrossing::getRemainingFeatures()
    00192 {
    00193     return FeatureSet();
    00194 }
    00195