ZeroCrossing.cpp
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1 /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- vi:set ts=8 sts=4 sw=4: */
2 
3 /*
4  Vamp
5 
6  An API for audio analysis and feature extraction plugins.
7 
8  Centre for Digital Music, Queen Mary, University of London.
9  Copyright 2006 Chris Cannam.
10 
11  Permission is hereby granted, free of charge, to any person
12  obtaining a copy of this software and associated documentation
13  files (the "Software"), to deal in the Software without
14  restriction, including without limitation the rights to use, copy,
15  modify, merge, publish, distribute, sublicense, and/or sell copies
16  of the Software, and to permit persons to whom the Software is
17  furnished to do so, subject to the following conditions:
18 
19  The above copyright notice and this permission notice shall be
20  included in all copies or substantial portions of the Software.
21 
22  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
23  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
24  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
25  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR
26  ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
27  CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
28  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
29 
30  Except as contained in this notice, the names of the Centre for
31  Digital Music; Queen Mary, University of London; and Chris Cannam
32  shall not be used in advertising or otherwise to promote the sale,
33  use or other dealings in this Software without prior written
34  authorization.
35 */
36 
37 #include "ZeroCrossing.h"
38 
39 using std::string;
40 using std::vector;
41 using std::cerr;
42 using std::endl;
43 
44 #include <cmath>
45 #include <algorithm>
46 
47 ZeroCrossing::ZeroCrossing(float inputSampleRate) :
48  Plugin(inputSampleRate),
49  m_stepSize(0),
50  m_previousSample(0.0f)
51 {
52 }
53 
55 {
56 }
57 
58 string
60 {
61  return "zerocrossing";
62 }
63 
64 string
66 {
67  return "Zero Crossings";
68 }
69 
70 string
72 {
73  return "Detect and count zero crossing points";
74 }
75 
76 string
78 {
79  return "Vamp SDK Example Plugins";
80 }
81 
82 int
84 {
85  return 2;
86 }
87 
88 string
90 {
91  return "Freely redistributable (BSD license)";
92 }
93 
94 bool
95 ZeroCrossing::initialise(size_t channels, size_t stepSize, size_t blockSize)
96 {
97  if (channels < getMinChannelCount() ||
98  channels > getMaxChannelCount()) return false;
99 
100  m_stepSize = std::min(stepSize, blockSize);
101 
102  return true;
103 }
104 
105 void
107 {
108  m_previousSample = 0.0f;
109 }
110 
113 {
114  OutputList list;
115 
116  OutputDescriptor zc;
117  zc.identifier = "counts";
118  zc.name = "Zero Crossing Counts";
119  zc.description = "The number of zero crossing points per processing block";
120  zc.unit = "crossings";
121  zc.hasFixedBinCount = true;
122  zc.binCount = 1;
123  zc.hasKnownExtents = false;
124  zc.isQuantized = true;
125  zc.quantizeStep = 1.0;
127  list.push_back(zc);
128 
129  zc.identifier = "zerocrossings";
130  zc.name = "Zero Crossings";
131  zc.description = "The locations of zero crossing points";
132  zc.unit = "";
133  zc.hasFixedBinCount = true;
134  zc.binCount = 0;
137  list.push_back(zc);
138 
139  return list;
140 }
141 
143 ZeroCrossing::process(const float *const *inputBuffers,
144  Vamp::RealTime timestamp)
145 {
146  if (m_stepSize == 0) {
147  cerr << "ERROR: ZeroCrossing::process: "
148  << "ZeroCrossing has not been initialised"
149  << endl;
150  return FeatureSet();
151  }
152 
153  float prev = m_previousSample;
154  size_t count = 0;
155 
156  FeatureSet returnFeatures;
157 
158  for (size_t i = 0; i < m_stepSize; ++i) {
159 
160  float sample = inputBuffers[0][i];
161  bool crossing = false;
162 
163  if (sample <= 0.0) {
164  if (prev > 0.0) crossing = true;
165  } else if (sample > 0.0) {
166  if (prev <= 0.0) crossing = true;
167  }
168 
169  if (crossing) {
170  ++count;
171  Feature feature;
172  feature.hasTimestamp = true;
173  feature.timestamp = timestamp +
175  returnFeatures[1].push_back(feature);
176  }
177 
178  prev = sample;
179  }
180 
181  m_previousSample = prev;
182 
183  Feature feature;
184  feature.hasTimestamp = false;
185  feature.values.push_back(float(count));
186 
187  returnFeatures[0].push_back(feature);
188  return returnFeatures;
189 }
190 
193 {
194  return FeatureSet();
195 }
196 
std::vector< OutputDescriptor > OutputList
FeatureSet process(const float *const *inputBuffers, Vamp::RealTime timestamp)
Process a single block of input data.
std::string getMaker() const
Get the name of the author or vendor of the plugin in human-readable form.
float sampleRate
Sample rate of the output results, as samples per second.
std::string getName() const
Get a human-readable name or title of the plugin.
bool hasFixedBinCount
True if the output has the same number of values per sample for every output sample.
std::string getIdentifier() const
Get the computer-usable name of the plugin.
std::vector< float > values
Results for a single sample of this feature.
bool initialise(size_t channels, size_t stepSize, size_t blockSize)
Initialise a plugin to prepare it for use with the given number of input channels, step size (window increment, in sample frames) and block size (window size, in sample frames).
std::map< int, FeatureList > FeatureSet
size_t m_stepSize
Definition: ZeroCrossing.h:73
float quantizeStep
Quantization resolution of the output values (e.g.
FeatureSet getRemainingFeatures()
After all blocks have been processed, calculate and return any remaining features derived from the co...
RealTime timestamp
Timestamp of the output feature.
std::string getDescription() const
Get a human-readable description for the plugin, typically a line of text that may optionally be disp...
std::string description
A human-readable short text describing the output.
void reset()
Reset the plugin after use, to prepare it for another clean run.
std::string identifier
The name of the output, in computer-usable form.
float m_inputSampleRate
virtual ~ZeroCrossing()
ZeroCrossing(float inputSampleRate)
OutputList getOutputDescriptors() const
Get the outputs of this plugin.
std::string unit
The unit of the output, in human-readable form.
std::string name
The human-readable name of the output.
RealTime represents time values to nanosecond precision with accurate arithmetic and frame-rate conve...
bool hasTimestamp
True if an output feature has its own timestamp.
int getPluginVersion() const
Get the version number of the plugin.
static RealTime frame2RealTime(long frame, unsigned int sampleRate)
Convert a sample frame at the given sample rate into a RealTime.
Results from each process() align with that call&#39;s block start.
virtual size_t getMaxChannelCount() const
Get the maximum supported number of input channels.
size_t binCount
The number of values per result of the output.
float m_previousSample
Definition: ZeroCrossing.h:74
bool isQuantized
True if the output values are quantized to a particular resolution.
virtual size_t getMinChannelCount() const
Get the minimum supported number of input channels.
std::string getCopyright() const
Get the copyright statement or licensing summary for the plugin.
SampleType sampleType
Positioning in time of the output results.
Results are unevenly spaced and have individual timestamps.
bool hasKnownExtents
True if the results in each output bin fall within a fixed numeric range (minimum and maximum values)...