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2 /** \mainpage Vamp Plugin SDK
4 \section about About Vamp
6 Vamp is an API for C and C++ plugins that process sampled audio data
7 to produce descriptive output (measurements or semantic observations).
8 Find more information at .
10 Although the official API for Vamp plugins is defined in C for maximum
11 binary compatibility, we strongly recommend using the provided C++
12 classes in the SDK to implement your own plugins and hosts.
14 \section plugins For Plugins
16 Plugins should subclass Vamp::Plugin, and then use a
17 Vamp::PluginAdapter to expose the correct C API for the plugin. Read
18 the documentation for Vamp::PluginBase and Vamp::Plugin before
19 starting.
21 Plugins should be compiled and linked into dynamic libraries using the
22 usual convention for your platform, and should link (preferably
23 statically) with -lvamp-sdk. Any number of plugins can reside in a
24 single dynamic library. See plugins.cpp in the example plugins
25 directory for the sort of code that will need to accompany your plugin
26 class or classes, to make it possible for a host to look up your
27 plugins properly.
29 Please read the relevant README file for your platform found in the
30 Vamp SDK build/ directory, for details about how to ensure the
31 resulting dynamic library exports the correct linker symbols.
33 The following example plugins are provided. You may legally reuse any
34 amount of the code from these examples in any plugins you write,
35 whether proprietary or open-source.
37  - ZeroCrossing calculates the positions and density of zero-crossing
38  points in an audio waveform.
40  - SpectralCentroid calculates the centre of gravity of the frequency
41  domain representation of each block of audio.
43  - PowerSpectrum calculates a power spectrum from the input audio.
44  Actually, it doesn't do any work except calculating power from a
45  cartesian complex FFT output. The work of calculating this frequency
46  domain output is done for it by the host or host SDK; the plugin just
47  needs to declare that it wants frequency domain input. This is the
48  simplest of the example plugins.
50  - AmplitudeFollower is a simple implementation of SuperCollider's
51  amplitude-follower algorithm.
53  - PercussionOnsetDetector estimates the locations of percussive
54  onsets using a simple method described in "Drum Source Separation
55  using Percussive Feature Detection and Spectral Modulation" by Dan
56  Barry, Derry Fitzgerald, Eugene Coyle and Bob Lawlor, ISSC 2005.
58  - FixedTempoEstimator calculates a single beats-per-minute value
59  which is an estimate of the tempo of a piece of music that is assumed
60  to be of fixed tempo, using autocorrelation of a frequency domain
61  energy rise metric. It has several outputs that return intermediate
62  results used in the calculation, and may be a useful example of a
63  plugin having several outputs with varying feature structures.
65 Plugin authors should also read the Programmer's Guide at
66 .
68 \section hosts For Hosts
70 Hosts will normally use a Vamp::PluginHostAdapter to convert each
71 plugin's exposed C API back into a useful Vamp::Plugin C++ object.
73 The Vamp::HostExt namespace contains several additional C++ classes to
74 do this work for them, and make the host's life easier:
76  - Vamp::HostExt::PluginLoader provides a very easy interface for a
77  host to discover, load, and find out category information about the
78  available plugins. Most Vamp hosts will probably want to use this
79  class.
81  - Vamp::HostExt::PluginInputDomainAdapter provides a simple means for
82  hosts to handle plugins that want frequency-domain input, without
83  having to convert the input themselves.
85  - Vamp::HostExt::PluginChannelAdapter provides a simple means for
86  hosts to use plugins that do not necessarily support the same number
87  of audio channels as they have available, without having to apply a
88  channel management / mixdown policy themselves.
90  - Vamp::HostExt::PluginBufferingAdapter provides a means for hosts to
91  avoid having to negotiate the input step and block size, instead
92  permitting the host to use any block size they desire (and a step
93  size equal to it). This is particularly useful for "streaming" hosts
94  that cannot seek backwards in the input audio stream and so would
95  otherwise need to implement an additional buffer to support step
96  sizes smaller than the block size.
98  - Vamp::HostExt::PluginSummarisingAdapter provides summarisation
99  methods such as mean and median averages of output features, for use
100  in any context where an available plugin produces individual values
101  but the result that is actually needed is some sort of aggregate.
103 The PluginLoader class can also use the input domain, channel, and
104 buffering adapters automatically to make these conversions transparent
105 to the host if required.
107 Host authors should also refer to the example host code in the host
108 directory of the SDK.
110 Hosts should link with -lvamp-hostsdk.
112 (The following notes in this section are mostly relevant for
113 developers that are not using the HostExt classes, or that wish to
114 know more about the policy they implement.)
116 The Vamp API does not officially specify how to load plugin libraries
117 or where to find them. However, the SDK does include a function
118 (Vamp::PluginHostAdapter::getPluginPath()) that returns a recommended
119 directory search path that hosts may use for plugin libraries, and a
120 class (Vamp::HostExt::PluginLoader) that implements a sensible
121 cross-platform lookup policy using this path. We recommend using this
122 class in your host unless you have a good reason not to want to. This
123 implementation also permits the user to set the environment variable
124 VAMP_PATH to override the default path if desired.
126 The policy used by Vamp::HostExt::PluginLoader -- and our
127 recommendation for any host -- is to search each directory in this
128 path for .DLL (on Windows), .so (on Linux, Solaris, BSD etc) or .dylib
129 (on OS/X) files, then to load each one and perform a dynamic name
130 lookup on the vampGetPluginDescriptor function to enumerate the
131 plugins in the library. The example host has some code that may help,
132 but this operation will necessarily be system-dependent.
134 Vamp also has an informal convention for sorting plugins into
135 functional categories. In addition to the library file itself, a
136 plugin library may install a category file with the same name as the
137 library but .cat extension. The existence and format of this file are
138 not specified by the Vamp API, but by convention the file may contain
139 lines of the format
141 \code
142 vamp:pluginlibrary:pluginname::General Category > Specific Category
143 \endcode
145 which a host may read and use to assign plugins a location within a
146 category tree for display to the user. The expectation is that
147 advanced users may also choose to set up their own preferred category
148 trees, which is why this information is not queried as part of the
149 Vamp plugin's API itself. The Vamp::HostExt::PluginLoader class also
150 provides support for plugin category lookup using this scheme.
152 \section license License
154 This plugin SDK is freely redistributable under a "new-style BSD"
155 licence. See the file COPYING for more details. In short, you may
156 modify and redistribute the SDK and example plugins within any
157 commercial or non-commercial, proprietary or open-source plugin or
158 application under almost any conditions, with no obligation to provide
159 source code, provided you retain the original copyright note.
162 */