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Added tag vamp-plugin-sdk-v2.7 for changeset 27319718b1f8
author Chris Cannam
date Fri, 24 Feb 2017 16:45:00 +0000
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Chris@6 66 <a href="doc-overview.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a name="l00001"></a><span class="lineno"> 1</span>&#160;</div><div class="line"><a name="l00002"></a><span class="lineno"> 2</span>&#160;/** \mainpage Vamp Plugin SDK</div><div class="line"><a name="l00003"></a><span class="lineno"> 3</span>&#160;</div><div class="line"><a name="l00004"></a><span class="lineno"> 4</span>&#160;\section about About Vamp</div><div class="line"><a name="l00005"></a><span class="lineno"> 5</span>&#160;</div><div class="line"><a name="l00006"></a><span class="lineno"> 6</span>&#160;Vamp is an API for C and C++ plugins that process sampled audio data</div><div class="line"><a name="l00007"></a><span class="lineno"> 7</span>&#160;to produce descriptive output (measurements or semantic observations).</div><div class="line"><a name="l00008"></a><span class="lineno"> 8</span>&#160;Find more information at http://www.vamp-plugins.org/ .</div><div class="line"><a name="l00009"></a><span class="lineno"> 9</span>&#160;</div><div class="line"><a name="l00010"></a><span class="lineno"> 10</span>&#160;Although the official API for Vamp plugins is defined in C for maximum</div><div class="line"><a name="l00011"></a><span class="lineno"> 11</span>&#160;binary compatibility, we strongly recommend using the provided C++</div><div class="line"><a name="l00012"></a><span class="lineno"> 12</span>&#160;classes in the SDK to implement your own plugins and hosts.</div><div class="line"><a name="l00013"></a><span class="lineno"> 13</span>&#160;</div><div class="line"><a name="l00014"></a><span class="lineno"> 14</span>&#160;\section plugins For Plugins</div><div class="line"><a name="l00015"></a><span class="lineno"> 15</span>&#160;</div><div class="line"><a name="l00016"></a><span class="lineno"> 16</span>&#160;Plugins should subclass Vamp::Plugin, and then use a</div><div class="line"><a name="l00017"></a><span class="lineno"> 17</span>&#160;Vamp::PluginAdapter to expose the correct C API for the plugin. Read</div><div class="line"><a name="l00018"></a><span class="lineno"> 18</span>&#160;the documentation for Vamp::PluginBase and Vamp::Plugin before</div><div class="line"><a name="l00019"></a><span class="lineno"> 19</span>&#160;starting.</div><div class="line"><a name="l00020"></a><span class="lineno"> 20</span>&#160;</div><div class="line"><a name="l00021"></a><span class="lineno"> 21</span>&#160;Plugins should be compiled and linked into dynamic libraries using the</div><div class="line"><a name="l00022"></a><span class="lineno"> 22</span>&#160;usual convention for your platform, and should link (preferably</div><div class="line"><a name="l00023"></a><span class="lineno"> 23</span>&#160;statically) with -lvamp-sdk. Any number of plugins can reside in a</div><div class="line"><a name="l00024"></a><span class="lineno"> 24</span>&#160;single dynamic library. See plugins.cpp in the example plugins</div><div class="line"><a name="l00025"></a><span class="lineno"> 25</span>&#160;directory for the sort of code that will need to accompany your plugin</div><div class="line"><a name="l00026"></a><span class="lineno"> 26</span>&#160;class or classes, to make it possible for a host to look up your</div><div class="line"><a name="l00027"></a><span class="lineno"> 27</span>&#160;plugins properly.</div><div class="line"><a name="l00028"></a><span class="lineno"> 28</span>&#160;</div><div class="line"><a name="l00029"></a><span class="lineno"> 29</span>&#160;Please read the relevant README file for your platform found in the</div><div class="line"><a name="l00030"></a><span class="lineno"> 30</span>&#160;Vamp SDK build/ directory, for details about how to ensure the</div><div class="line"><a name="l00031"></a><span class="lineno"> 31</span>&#160;resulting dynamic library exports the correct linker symbols.</div><div class="line"><a name="l00032"></a><span class="lineno"> 32</span>&#160;</div><div class="line"><a name="l00033"></a><span class="lineno"> 33</span>&#160;The following example plugins are provided. You may legally reuse any</div><div class="line"><a name="l00034"></a><span class="lineno"> 34</span>&#160;amount of the code from these examples in any plugins you write,</div><div class="line"><a name="l00035"></a><span class="lineno"> 35</span>&#160;whether proprietary or open-source.</div><div class="line"><a name="l00036"></a><span class="lineno"> 36</span>&#160;</div><div class="line"><a name="l00037"></a><span class="lineno"> 37</span>&#160; - ZeroCrossing calculates the positions and density of zero-crossing</div><div class="line"><a name="l00038"></a><span class="lineno"> 38</span>&#160; points in an audio waveform.</div><div class="line"><a name="l00039"></a><span class="lineno"> 39</span>&#160;</div><div class="line"><a name="l00040"></a><span class="lineno"> 40</span>&#160; - SpectralCentroid calculates the centre of gravity of the frequency</div><div class="line"><a name="l00041"></a><span class="lineno"> 41</span>&#160; domain representation of each block of audio.</div><div class="line"><a name="l00042"></a><span class="lineno"> 42</span>&#160;</div><div class="line"><a name="l00043"></a><span class="lineno"> 43</span>&#160; - PowerSpectrum calculates a power spectrum from the input audio.</div><div class="line"><a name="l00044"></a><span class="lineno"> 44</span>&#160; Actually, it doesn&#39;t do any work except calculating power from a</div><div class="line"><a name="l00045"></a><span class="lineno"> 45</span>&#160; cartesian complex FFT output. The work of calculating this frequency</div><div class="line"><a name="l00046"></a><span class="lineno"> 46</span>&#160; domain output is done for it by the host or host SDK; the plugin just</div><div class="line"><a name="l00047"></a><span class="lineno"> 47</span>&#160; needs to declare that it wants frequency domain input. This is the</div><div class="line"><a name="l00048"></a><span class="lineno"> 48</span>&#160; simplest of the example plugins.</div><div class="line"><a name="l00049"></a><span class="lineno"> 49</span>&#160;</div><div class="line"><a name="l00050"></a><span class="lineno"> 50</span>&#160; - AmplitudeFollower is a simple implementation of SuperCollider&#39;s</div><div class="line"><a name="l00051"></a><span class="lineno"> 51</span>&#160; amplitude-follower algorithm.</div><div class="line"><a name="l00052"></a><span class="lineno"> 52</span>&#160;</div><div class="line"><a name="l00053"></a><span class="lineno"> 53</span>&#160; - PercussionOnsetDetector estimates the locations of percussive</div><div class="line"><a name="l00054"></a><span class="lineno"> 54</span>&#160; onsets using a simple method described in &quot;Drum Source Separation</div><div class="line"><a name="l00055"></a><span class="lineno"> 55</span>&#160; using Percussive Feature Detection and Spectral Modulation&quot; by Dan</div><div class="line"><a name="l00056"></a><span class="lineno"> 56</span>&#160; Barry, Derry Fitzgerald, Eugene Coyle and Bob Lawlor, ISSC 2005.</div><div class="line"><a name="l00057"></a><span class="lineno"> 57</span>&#160;</div><div class="line"><a name="l00058"></a><span class="lineno"> 58</span>&#160; - FixedTempoEstimator calculates a single beats-per-minute value</div><div class="line"><a name="l00059"></a><span class="lineno"> 59</span>&#160; which is an estimate of the tempo of a piece of music that is assumed</div><div class="line"><a name="l00060"></a><span class="lineno"> 60</span>&#160; to be of fixed tempo, using autocorrelation of a frequency domain</div><div class="line"><a name="l00061"></a><span class="lineno"> 61</span>&#160; energy rise metric. It has several outputs that return intermediate</div><div class="line"><a name="l00062"></a><span class="lineno"> 62</span>&#160; results used in the calculation, and may be a useful example of a</div><div class="line"><a name="l00063"></a><span class="lineno"> 63</span>&#160; plugin having several outputs with varying feature structures.</div><div class="line"><a name="l00064"></a><span class="lineno"> 64</span>&#160;</div><div class="line"><a name="l00065"></a><span class="lineno"> 65</span>&#160;Plugin authors should also read the Programmer&#39;s Guide at</div><div class="line"><a name="l00066"></a><span class="lineno"> 66</span>&#160;http://vamp-plugins.org/guide.pdf .</div><div class="line"><a name="l00067"></a><span class="lineno"> 67</span>&#160;</div><div class="line"><a name="l00068"></a><span class="lineno"> 68</span>&#160;\section hosts For Hosts</div><div class="line"><a name="l00069"></a><span class="lineno"> 69</span>&#160;</div><div class="line"><a name="l00070"></a><span class="lineno"> 70</span>&#160;Hosts will normally use a Vamp::PluginHostAdapter to convert each</div><div class="line"><a name="l00071"></a><span class="lineno"> 71</span>&#160;plugin&#39;s exposed C API back into a useful Vamp::Plugin C++ object.</div><div class="line"><a name="l00072"></a><span class="lineno"> 72</span>&#160;</div><div class="line"><a name="l00073"></a><span class="lineno"> 73</span>&#160;The Vamp::HostExt namespace contains several additional C++ classes to</div><div class="line"><a name="l00074"></a><span class="lineno"> 74</span>&#160;do this work for them, and make the host&#39;s life easier:</div><div class="line"><a name="l00075"></a><span class="lineno"> 75</span>&#160;</div><div class="line"><a name="l00076"></a><span class="lineno"> 76</span>&#160; - Vamp::HostExt::PluginLoader provides a very easy interface for a</div><div class="line"><a name="l00077"></a><span class="lineno"> 77</span>&#160; host to discover, load, and find out category information about the</div><div class="line"><a name="l00078"></a><span class="lineno"> 78</span>&#160; available plugins. Most Vamp hosts will probably want to use this</div><div class="line"><a name="l00079"></a><span class="lineno"> 79</span>&#160; class.</div><div class="line"><a name="l00080"></a><span class="lineno"> 80</span>&#160;</div><div class="line"><a name="l00081"></a><span class="lineno"> 81</span>&#160; - Vamp::HostExt::PluginInputDomainAdapter provides a simple means for</div><div class="line"><a name="l00082"></a><span class="lineno"> 82</span>&#160; hosts to handle plugins that want frequency-domain input, without</div><div class="line"><a name="l00083"></a><span class="lineno"> 83</span>&#160; having to convert the input themselves.</div><div class="line"><a name="l00084"></a><span class="lineno"> 84</span>&#160;</div><div class="line"><a name="l00085"></a><span class="lineno"> 85</span>&#160; - Vamp::HostExt::PluginChannelAdapter provides a simple means for</div><div class="line"><a name="l00086"></a><span class="lineno"> 86</span>&#160; hosts to use plugins that do not necessarily support the same number</div><div class="line"><a name="l00087"></a><span class="lineno"> 87</span>&#160; of audio channels as they have available, without having to apply a</div><div class="line"><a name="l00088"></a><span class="lineno"> 88</span>&#160; channel management / mixdown policy themselves.</div><div class="line"><a name="l00089"></a><span class="lineno"> 89</span>&#160;</div><div class="line"><a name="l00090"></a><span class="lineno"> 90</span>&#160; - Vamp::HostExt::PluginBufferingAdapter provides a means for hosts to</div><div class="line"><a name="l00091"></a><span class="lineno"> 91</span>&#160; avoid having to negotiate the input step and block size, instead</div><div class="line"><a name="l00092"></a><span class="lineno"> 92</span>&#160; permitting the host to use any block size they desire (and a step</div><div class="line"><a name="l00093"></a><span class="lineno"> 93</span>&#160; size equal to it). This is particularly useful for &quot;streaming&quot; hosts</div><div class="line"><a name="l00094"></a><span class="lineno"> 94</span>&#160; that cannot seek backwards in the input audio stream and so would</div><div class="line"><a name="l00095"></a><span class="lineno"> 95</span>&#160; otherwise need to implement an additional buffer to support step</div><div class="line"><a name="l00096"></a><span class="lineno"> 96</span>&#160; sizes smaller than the block size.</div><div class="line"><a name="l00097"></a><span class="lineno"> 97</span>&#160;</div><div class="line"><a name="l00098"></a><span class="lineno"> 98</span>&#160; - Vamp::HostExt::PluginSummarisingAdapter provides summarisation</div><div class="line"><a name="l00099"></a><span class="lineno"> 99</span>&#160; methods such as mean and median averages of output features, for use</div><div class="line"><a name="l00100"></a><span class="lineno"> 100</span>&#160; in any context where an available plugin produces individual values</div><div class="line"><a name="l00101"></a><span class="lineno"> 101</span>&#160; but the result that is actually needed is some sort of aggregate.</div><div class="line"><a name="l00102"></a><span class="lineno"> 102</span>&#160;</div><div class="line"><a name="l00103"></a><span class="lineno"> 103</span>&#160;The PluginLoader class can also use the input domain, channel, and</div><div class="line"><a name="l00104"></a><span class="lineno"> 104</span>&#160;buffering adapters automatically to make these conversions transparent</div><div class="line"><a name="l00105"></a><span class="lineno"> 105</span>&#160;to the host if required.</div><div class="line"><a name="l00106"></a><span class="lineno"> 106</span>&#160;</div><div class="line"><a name="l00107"></a><span class="lineno"> 107</span>&#160;Host authors should also refer to the example host code in the host</div><div class="line"><a name="l00108"></a><span class="lineno"> 108</span>&#160;directory of the SDK.</div><div class="line"><a name="l00109"></a><span class="lineno"> 109</span>&#160;</div><div class="line"><a name="l00110"></a><span class="lineno"> 110</span>&#160;Hosts should link with -lvamp-hostsdk.</div><div class="line"><a name="l00111"></a><span class="lineno"> 111</span>&#160;</div><div class="line"><a name="l00112"></a><span class="lineno"> 112</span>&#160;(The following notes in this section are mostly relevant for</div><div class="line"><a name="l00113"></a><span class="lineno"> 113</span>&#160;developers that are not using the HostExt classes, or that wish to</div><div class="line"><a name="l00114"></a><span class="lineno"> 114</span>&#160;know more about the policy they implement.)</div><div class="line"><a name="l00115"></a><span class="lineno"> 115</span>&#160;</div><div class="line"><a name="l00116"></a><span class="lineno"> 116</span>&#160;The Vamp API does not officially specify how to load plugin libraries</div><div class="line"><a name="l00117"></a><span class="lineno"> 117</span>&#160;or where to find them. However, the SDK does include a function</div><div class="line"><a name="l00118"></a><span class="lineno"> 118</span>&#160;(Vamp::PluginHostAdapter::getPluginPath()) that returns a recommended</div><div class="line"><a name="l00119"></a><span class="lineno"> 119</span>&#160;directory search path that hosts may use for plugin libraries, and a</div><div class="line"><a name="l00120"></a><span class="lineno"> 120</span>&#160;class (Vamp::HostExt::PluginLoader) that implements a sensible</div><div class="line"><a name="l00121"></a><span class="lineno"> 121</span>&#160;cross-platform lookup policy using this path. We recommend using this</div><div class="line"><a name="l00122"></a><span class="lineno"> 122</span>&#160;class in your host unless you have a good reason not to want to. This</div><div class="line"><a name="l00123"></a><span class="lineno"> 123</span>&#160;implementation also permits the user to set the environment variable</div><div class="line"><a name="l00124"></a><span class="lineno"> 124</span>&#160;VAMP_PATH to override the default path if desired.</div><div class="line"><a name="l00125"></a><span class="lineno"> 125</span>&#160;</div><div class="line"><a name="l00126"></a><span class="lineno"> 126</span>&#160;The policy used by Vamp::HostExt::PluginLoader -- and our</div><div class="line"><a name="l00127"></a><span class="lineno"> 127</span>&#160;recommendation for any host -- is to search each directory in this</div><div class="line"><a name="l00128"></a><span class="lineno"> 128</span>&#160;path for .DLL (on Windows), .so (on Linux, Solaris, BSD etc) or .dylib</div><div class="line"><a name="l00129"></a><span class="lineno"> 129</span>&#160;(on OS/X) files, then to load each one and perform a dynamic name</div><div class="line"><a name="l00130"></a><span class="lineno"> 130</span>&#160;lookup on the vampGetPluginDescriptor function to enumerate the</div><div class="line"><a name="l00131"></a><span class="lineno"> 131</span>&#160;plugins in the library. The example host has some code that may help,</div><div class="line"><a name="l00132"></a><span class="lineno"> 132</span>&#160;but this operation will necessarily be system-dependent.</div><div class="line"><a name="l00133"></a><span class="lineno"> 133</span>&#160;</div><div class="line"><a name="l00134"></a><span class="lineno"> 134</span>&#160;Vamp also has an informal convention for sorting plugins into</div><div class="line"><a name="l00135"></a><span class="lineno"> 135</span>&#160;functional categories. In addition to the library file itself, a</div><div class="line"><a name="l00136"></a><span class="lineno"> 136</span>&#160;plugin library may install a category file with the same name as the</div><div class="line"><a name="l00137"></a><span class="lineno"> 137</span>&#160;library but .cat extension. The existence and format of this file are</div><div class="line"><a name="l00138"></a><span class="lineno"> 138</span>&#160;not specified by the Vamp API, but by convention the file may contain</div><div class="line"><a name="l00139"></a><span class="lineno"> 139</span>&#160;lines of the format</div><div class="line"><a name="l00140"></a><span class="lineno"> 140</span>&#160;</div><div class="line"><a name="l00141"></a><span class="lineno"> 141</span>&#160;\code</div><div class="line"><a name="l00142"></a><span class="lineno"> 142</span>&#160;vamp:pluginlibrary:pluginname::General Category &gt; Specific Category</div><div class="line"><a name="l00143"></a><span class="lineno"> 143</span>&#160;\endcode</div><div class="line"><a name="l00144"></a><span class="lineno"> 144</span>&#160;</div><div class="line"><a name="l00145"></a><span class="lineno"> 145</span>&#160;which a host may read and use to assign plugins a location within a</div><div class="line"><a name="l00146"></a><span class="lineno"> 146</span>&#160;category tree for display to the user. The expectation is that</div><div class="line"><a name="l00147"></a><span class="lineno"> 147</span>&#160;advanced users may also choose to set up their own preferred category</div><div class="line"><a name="l00148"></a><span class="lineno"> 148</span>&#160;trees, which is why this information is not queried as part of the</div><div class="line"><a name="l00149"></a><span class="lineno"> 149</span>&#160;Vamp plugin&#39;s API itself. The Vamp::HostExt::PluginLoader class also</div><div class="line"><a name="l00150"></a><span class="lineno"> 150</span>&#160;provides support for plugin category lookup using this scheme.</div><div class="line"><a name="l00151"></a><span class="lineno"> 151</span>&#160;</div><div class="line"><a name="l00152"></a><span class="lineno"> 152</span>&#160;\section license License</div><div class="line"><a name="l00153"></a><span class="lineno"> 153</span>&#160;</div><div class="line"><a name="l00154"></a><span class="lineno"> 154</span>&#160;This plugin SDK is freely redistributable under a &quot;new-style BSD&quot;</div><div class="line"><a name="l00155"></a><span class="lineno"> 155</span>&#160;licence. See the file COPYING for more details. In short, you may</div><div class="line"><a name="l00156"></a><span class="lineno"> 156</span>&#160;modify and redistribute the SDK and example plugins within any</div><div class="line"><a name="l00157"></a><span class="lineno"> 157</span>&#160;commercial or non-commercial, proprietary or open-source plugin or</div><div class="line"><a name="l00158"></a><span class="lineno"> 158</span>&#160;application under almost any conditions, with no obligation to provide</div><div class="line"><a name="l00159"></a><span class="lineno"> 159</span>&#160;source code, provided you retain the original copyright note.</div><div class="line"><a name="l00160"></a><span class="lineno"> 160</span>&#160;</div><div class="line"><a name="l00161"></a><span class="lineno"> 161</span>&#160;</div><div class="line"><a name="l00162"></a><span class="lineno"> 162</span>&#160;*/</div></div><!-- fragment --></div><!-- contents -->
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