annotate README @ 59:fa79c4ec847d host-factory-stuff

* Put hostext stuff in the HostExt sub-namespace * Tidy up system-specific stuff in PluginLoader * Make PluginLoader return a deletion-notifying wrapper which permits the library to be unloaded when no longer in use * Add PluginChannelAdapter * Make vamp-simple-host use PluginChannelAdapter, and use the PluginLoader for plugin-running task. Also some other enhancements to host
author cannam
date Thu, 24 May 2007 15:17:07 +0000
parents 0284955e31e5
children fe5486ee1c70
rev   line source
cannam@14 1
cannam@14 2 Vamp
cannam@14 3 ====
cannam@14 4
cannam@14 5 An API for audio analysis and feature extraction plugins.
cannam@14 6
cannam@44 7 http://www.vamp-plugins.org/
cannam@44 8
cannam@14 9 Vamp is an API for C and C++ plugins that process sampled audio data
cannam@18 10 to produce descriptive output (measurements or semantic observations).
cannam@14 11
cannam@14 12 The principal differences between Vamp and a real-time audio
cannam@14 13 processing plugin system such as VST are:
cannam@14 14
cannam@14 15 * Vamp plugins may output complex multidimensional data with labels.
cannam@14 16 As a consequence, they are likely to work best when the output
cannam@14 17 data has a much lower sampling rate than the input. (This also
cannam@14 18 means it is usually desirable to implement them in C++ using the
cannam@14 19 high-level base class provided rather than use the raw C API.)
cannam@14 20
cannam@14 21 * While Vamp plugins receive data block-by-block, they are not
cannam@14 22 required to return output immediately on receiving the input.
cannam@14 23 A Vamp plugin may be non-causal, preferring to store up data
cannam@14 24 based on its input until the end of a processing run and then
cannam@14 25 return all results at once.
cannam@14 26
cannam@14 27 * Vamp plugins have more control over their inputs than a typical
cannam@14 28 real-time processing plugin. For example, they can indicate to
cannam@18 29 the host their preferred processing block and step sizes, and these
cannam@18 30 may differ.
cannam@18 31
cannam@18 32 * Vamp plugins may ask to receive data in the frequency domain
cannam@18 33 instead of the time domain. The host takes the responsibility
cannam@18 34 for converting the input data using an FFT of windowed frames.
cannam@18 35 This simplifies plugins that do straightforward frequency-domain
cannam@18 36 processing and permits the host to cache frequency-domain data
cannam@18 37 when possible.
cannam@14 38
cannam@14 39 * A Vamp plugin is configured once before each processing run, and
cannam@14 40 receives no further parameter changes during use -- unlike real
cannam@14 41 time plugin APIs in which the input parameters may change at any
cannam@14 42 time. This also means that fundamental properties such as the
cannam@14 43 number of values per output or the preferred processing block
cannam@18 44 size may depend on the input parameters.
cannam@14 45
cannam@38 46 * Vamp plugins do not have to be able to run in real time.
cannam@38 47
cannam@14 48
cannam@14 49 About this SDK
cannam@14 50 ==============
cannam@14 51
cannam@14 52 This Software Development Kit contains the following:
cannam@14 53
cannam@14 54 * vamp/vamp.h
cannam@14 55
cannam@14 56 The formal C language plugin API for Vamp plugins.
cannam@14 57
cannam@14 58 A Vamp plugin is a dynamic library (.so, .dll or .dylib depending on
cannam@14 59 platform) exposing one C-linkage entry point (vampGetPluginDescriptor)
cannam@14 60 which returns data defined in the rest of this C header.
cannam@14 61
cannam@14 62 Although this is the official API for Vamp, we don't recommend that
cannam@14 63 you program directly to it. The C++ abstraction in the SDK directory
cannam@18 64 (below) is likely to be preferable for most purposes, and is better
cannam@14 65 documented.
cannam@14 66
cannam@14 67 * vamp-sdk
cannam@14 68
cannam@14 69 C++ classes for straightforwardly implementing Vamp plugins and hosts.
cannam@18 70
cannam@18 71 Plugins should subclass Vamp::Plugin and then use a
cannam@18 72 Vamp::PluginAdapter to expose the correct C API for the plugin. Read
cannam@51 73 vamp-sdk/PluginBase.h and Plugin.h for code documentation. Plugins
cannam@51 74 should link with -lvamp-sdk.
cannam@18 75
cannam@14 76 Hosts may use the Vamp::PluginHostAdapter to convert the loaded
cannam@51 77 plugin's C API back into a Vamp::Plugin object. Hosts should link
cannam@51 78 with -lvamp-hostsdk.
cannam@14 79
cannam@14 80 * examples
cannam@14 81
cannam@14 82 Example plugins implemented using the C++ classes. ZeroCrossing
cannam@14 83 calculates the positions and density of zero-crossing points in an
cannam@35 84 audio waveform. SpectralCentroid calculates the centre of gravity of
cannam@14 85 the frequency domain representation of each block of audio.
cannam@35 86 PercussionOnsetDetector estimates the locations of percussive onsets
cannam@35 87 using a simple method described in "Drum Source Separation using
cannam@35 88 Percussive Feature Detection and Spectral Modulation" by Dan Barry,
cannam@35 89 Derry Fitzgerald, Eugene Coyle and Bob Lawlor, ISSC 2005.
cannam@14 90
cannam@14 91 * host
cannam@14 92
cannam@16 93 A simple command-line Vamp host, capable of loading a plugin and using
cannam@16 94 it to process a complete audio file, with its default parameters.
cannam@58 95 Requires libsndfile (http://www.mega-nerd.com/libsndfile/).
cannam@58 96
cannam@58 97 If you don't have libsndfile, you may want to edit the Makefile to
cannam@58 98 change the default build target from "all" to "sdk" so as to compile
cannam@58 99 only the SDK.
cannam@14 100
cannam@40 101
cannam@40 102 Plugin Lookup and Categorisation
cannam@40 103 ================================
cannam@40 104
cannam@40 105 The Vamp API does not officially specify how to load plugin libraries
cannam@40 106 or where to find them. However, the SDK does include a function
cannam@40 107 (Vamp::PluginHostAdapter::getPluginPath()) that returns a recommended
cannam@40 108 directory search path that hosts may use for plugin libraries.
cannam@40 109
cannam@40 110 Our suggestion for a host is to search each directory in this path for
cannam@40 111 .DLL (on Windows), .so (on Linux, Solaris, BSD etc) or .dylib (on
cannam@40 112 OS/X) files, then to load each one and perform a dynamic name lookup
cannam@40 113 on the vampGetPluginDescriptor function to enumerate the plugins in
cannam@40 114 the library. The example host has some code that may help, but this
cannam@40 115 operation will necessarily be system-dependent.
cannam@40 116
cannam@40 117 Vamp also has an informal convention for sorting plugins into
cannam@40 118 functional categories. In addition to the library file itself, a
cannam@40 119 plugin library may install a category file with the same name as the
cannam@40 120 library but .cat extension. The existence and format of this file are
cannam@40 121 not specified by the Vamp API, but by convention the file may contain
cannam@40 122 lines of the format
cannam@40 123
cannam@40 124 vamp:pluginlibrary:pluginname::General Category > Specific Category
cannam@40 125
cannam@40 126 which a host may read and use to assign plugins a location within a
cannam@40 127 category tree for display to the user. The expectation is that
cannam@40 128 advanced users may also choose to set up their own preferred category
cannam@40 129 trees, which is why this information is not queried as part of the
cannam@40 130 Vamp API itself.
cannam@32 131
cannam@14 132
cannam@42 133 Building and Installing the SDK and Examples
cannam@42 134 ============================================
cannam@14 135
cannam@42 136 To build the SDK, the simple host, and the example plugins, edit the
cannam@42 137 Makefile to suit your platform according to the comments in it, then
cannam@42 138 run "make".
cannam@42 139
cannam@42 140 Installing the example plugins so that they can be found by other Vamp
cannam@42 141 hosts depends on your platform:
cannam@42 142
cannam@44 143 * Windows: copy the files
cannam@44 144 examples/vamp-example-plugins.dll
cannam@44 145 examples/vamp-example-plugins.cat
cannam@44 146 to
cannam@44 147 C:\Program Files\Vamp Plugins
cannam@42 148
cannam@44 149 * Linux: copy the files
cannam@44 150 examples/vamp-example-plugins.so
cannam@44 151 examples/vamp-example-plugins.cat
cannam@44 152 to
cannam@44 153 /usr/local/lib/vamp/
cannam@42 154
cannam@44 155 * OS/X: copy the files
cannam@44 156 examples/vamp-example-plugins.dylib
cannam@44 157 examples/vamp-example-plugins.cat
cannam@44 158 to
cannam@44 159 /Library/Audio/Plug-Ins/Vamp
cannam@42 160
cannam@42 161 When building a plugin or host of your own using the SDK, you will
cannam@44 162 need to include the headers from the vamp-sdk directory; then when
cannam@44 163 linking your plugin or host, we suggest statically linking the SDK
cannam@44 164 code (in preference to distributing it alongside your program in DLL
cannam@44 165 form). An easy way to do this, if using a project-based build tool
cannam@42 166 such as Visual Studio or XCode, is simply to add the .cpp files in the
cannam@42 167 vamp-sdk directory to your project.
cannam@14 168
cannam@14 169
cannam@14 170 Licensing
cannam@14 171 =========
cannam@14 172
cannam@18 173 This plugin SDK is freely redistributable under a "new-style BSD"
cannam@42 174 licence. See the file COPYING for more details. In short, you may
cannam@42 175 modify and redistribute the SDK and example plugins within any
cannam@42 176 commercial or non-commercial, proprietary or open-source plugin or
cannam@42 177 application under almost any conditions, with no obligation to provide
cannam@42 178 source code, provided you retain the original copyright note.
cannam@14 179
cannam@14 180
cannam@14 181 See Also
cannam@14 182 ========
cannam@14 183
cannam@14 184 Sonic Visualiser, an interactive open-source graphical audio
cannam@14 185 inspection, analysis and visualisation tool supporting Vamp plugins.
cannam@35 186 http://www.sonicvisualiser.org/
cannam@14 187
cannam@14 188
cannam@44 189 Authors
cannam@44 190 =======
cannam@44 191
cannam@44 192 Vamp and the Vamp SDK were designed and made at the Centre for Digital
cannam@59 193 Music at Queen Mary, University of London.
cannam@44 194
cannam@59 195 The SDK was written by Chris Cannam, copyright (c) 2005-2007
cannam@59 196 Chris Cannam and QMUL.
cannam@59 197
cannam@59 198 Mark Sandler and Christian Landone provided ideas and direction, and
cannam@59 199 Mark Levy, Dan Stowell, Martin Gasser and Craig Sapp provided testing
cannam@59 200 and other input for the 1.0 API and SDK. The API also uses some ideas
cannam@59 201 from prior plugin systems, notably DSSI (http://dssi.sourceforge.net)
cannam@59 202 and FEAPI (http://feapi.sourceforge.net).
cannam@59 203