VampPluginSDK  2.1
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 
46 ZeroCrossing::ZeroCrossing(float inputSampleRate) :
47  Plugin(inputSampleRate),
48  m_stepSize(0),
49  m_previousSample(0.0f)
50 {
51 }
52 
54 {
55 }
56 
57 string
59 {
60  return "zerocrossing";
61 }
62 
63 string
65 {
66  return "Zero Crossings";
67 }
68 
69 string
71 {
72  return "Detect and count zero crossing points";
73 }
74 
75 string
77 {
78  return "Vamp SDK Example Plugins";
79 }
80 
81 int
83 {
84  return 2;
85 }
86 
87 string
89 {
90  return "Freely redistributable (BSD license)";
91 }
92 
93 bool
94 ZeroCrossing::initialise(size_t channels, size_t stepSize, size_t blockSize)
95 {
96  if (channels < getMinChannelCount() ||
97  channels > getMaxChannelCount()) return false;
98 
99  m_stepSize = std::min(stepSize, blockSize);
100 
101  return true;
102 }
103 
104 void
106 {
107  m_previousSample = 0.0f;
108 }
109 
112 {
113  OutputList list;
114 
115  OutputDescriptor zc;
116  zc.identifier = "counts";
117  zc.name = "Zero Crossing Counts";
118  zc.description = "The number of zero crossing points per processing block";
119  zc.unit = "crossings";
120  zc.hasFixedBinCount = true;
121  zc.binCount = 1;
122  zc.hasKnownExtents = false;
123  zc.isQuantized = true;
124  zc.quantizeStep = 1.0;
126  list.push_back(zc);
127 
128  zc.identifier = "zerocrossings";
129  zc.name = "Zero Crossings";
130  zc.description = "The locations of zero crossing points";
131  zc.unit = "";
132  zc.hasFixedBinCount = true;
133  zc.binCount = 0;
136  list.push_back(zc);
137 
138  return list;
139 }
140 
142 ZeroCrossing::process(const float *const *inputBuffers,
143  Vamp::RealTime timestamp)
144 {
145  if (m_stepSize == 0) {
146  cerr << "ERROR: ZeroCrossing::process: "
147  << "ZeroCrossing has not been initialised"
148  << endl;
149  return FeatureSet();
150  }
151 
152  float prev = m_previousSample;
153  size_t count = 0;
154 
155  FeatureSet returnFeatures;
156 
157  for (size_t i = 0; i < m_stepSize; ++i) {
158 
159  float sample = inputBuffers[0][i];
160  bool crossing = false;
161 
162  if (sample <= 0.0) {
163  if (prev > 0.0) crossing = true;
164  } else if (sample > 0.0) {
165  if (prev <= 0.0) crossing = true;
166  }
167 
168  if (crossing) {
169  ++count;
170  Feature feature;
171  feature.hasTimestamp = true;
172  feature.timestamp = timestamp +
174  returnFeatures[1].push_back(feature);
175  }
176 
177  prev = sample;
178  }
179 
180  m_previousSample = prev;
181 
182  Feature feature;
183  feature.hasTimestamp = false;
184  feature.values.push_back(float(count));
185 
186  returnFeatures[0].push_back(feature);
187  return returnFeatures;
188 }
189 
192 {
193  return FeatureSet();
194 }
195