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 
00045 ZeroCrossing::ZeroCrossing(float inputSampleRate) :
00046     Plugin(inputSampleRate),
00047     m_stepSize(0),
00048     m_previousSample(0.0f)
00049 {
00050 }
00051 
00052 ZeroCrossing::~ZeroCrossing()
00053 {
00054 }
00055 
00056 string
00057 ZeroCrossing::getIdentifier() const
00058 {
00059     return "zerocrossing";
00060 }
00061 
00062 string
00063 ZeroCrossing::getName() const
00064 {
00065     return "Zero Crossings";
00066 }
00067 
00068 string
00069 ZeroCrossing::getDescription() const
00070 {
00071     return "Detect and count zero crossing points";
00072 }
00073 
00074 string
00075 ZeroCrossing::getMaker() const
00076 {
00077     return "Vamp SDK Example Plugins";
00078 }
00079 
00080 int
00081 ZeroCrossing::getPluginVersion() const
00082 {
00083     return 2;
00084 }
00085 
00086 string
00087 ZeroCrossing::getCopyright() const
00088 {
00089     return "Freely redistributable (BSD license)";
00090 }
00091 
00092 bool
00093 ZeroCrossing::initialise(size_t channels, size_t stepSize, size_t blockSize)
00094 {
00095     if (channels < getMinChannelCount() ||
00096         channels > getMaxChannelCount()) return false;
00097 
00098     m_stepSize = std::min(stepSize, blockSize);
00099 
00100     return true;
00101 }
00102 
00103 void
00104 ZeroCrossing::reset()
00105 {
00106     m_previousSample = 0.0f;
00107 }
00108 
00109 ZeroCrossing::OutputList
00110 ZeroCrossing::getOutputDescriptors() const
00111 {
00112     OutputList list;
00113 
00114     OutputDescriptor zc;
00115     zc.identifier = "counts";
00116     zc.name = "Zero Crossing Counts";
00117     zc.description = "The number of zero crossing points per processing block";
00118     zc.unit = "crossings";
00119     zc.hasFixedBinCount = true;
00120     zc.binCount = 1;
00121     zc.hasKnownExtents = false;
00122     zc.isQuantized = true;
00123     zc.quantizeStep = 1.0;
00124     zc.sampleType = OutputDescriptor::OneSamplePerStep;
00125     list.push_back(zc);
00126 
00127     zc.identifier = "zerocrossings";
00128     zc.name = "Zero Crossings";
00129     zc.description = "The locations of zero crossing points";
00130     zc.unit = "";
00131     zc.hasFixedBinCount = true;
00132     zc.binCount = 0;
00133     zc.sampleType = OutputDescriptor::VariableSampleRate;
00134     zc.sampleRate = m_inputSampleRate;
00135     list.push_back(zc);
00136 
00137     return list;
00138 }
00139 
00140 ZeroCrossing::FeatureSet
00141 ZeroCrossing::process(const float *const *inputBuffers,
00142                       Vamp::RealTime timestamp)
00143 {
00144     if (m_stepSize == 0) {
00145         cerr << "ERROR: ZeroCrossing::process: "
00146              << "ZeroCrossing has not been initialised"
00147              << endl;
00148         return FeatureSet();
00149     }
00150 
00151     float prev = m_previousSample;
00152     size_t count = 0;
00153 
00154     FeatureSet returnFeatures;
00155 
00156     for (size_t i = 0; i < m_stepSize; ++i) {
00157 
00158         float sample = inputBuffers[0][i];
00159         bool crossing = false;
00160 
00161         if (sample <= 0.0) {
00162             if (prev > 0.0) crossing = true;
00163         } else if (sample > 0.0) {
00164             if (prev <= 0.0) crossing = true;
00165         }
00166 
00167         if (crossing) {
00168             ++count; 
00169             Feature feature;
00170             feature.hasTimestamp = true;
00171             feature.timestamp = timestamp +
00172                 Vamp::RealTime::frame2RealTime(i, (size_t)m_inputSampleRate);
00173             returnFeatures[1].push_back(feature);
00174         }
00175 
00176         prev = sample;
00177     }
00178 
00179     m_previousSample = prev;
00180 
00181     Feature feature;
00182     feature.hasTimestamp = false;
00183     feature.values.push_back(count);
00184 
00185     returnFeatures[0].push_back(feature);
00186     return returnFeatures;
00187 }
00188 
00189 ZeroCrossing::FeatureSet
00190 ZeroCrossing::getRemainingFeatures()
00191 {
00192     return FeatureSet();
00193 }
00194 

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