Creating your own Plug-in
Audacity is designed to support plug-in modules that extend its functionality.
|Type of Plug-in||Language||To Set This Up for Writing Your Own|
|Nyquist||Based on XLisp||Built in to Audacity. A Separate debugger is also available.|
|Batch Chain||None||Built in to Audacity. The built in GUI allows you to select a sequence of existing commands, set their parameters and select a set of files to apply them to. Simple, but goes a long way.|
|External Script||Perl||(Windows) needs standard install of e.g. ActivePerl (Linux) any perl package. This is based on batch chains. As this is still a work-in-progress you will need C++ to add hooks from existing commands that aren't yet available.|
|LADSPA||C/C++ development||Needs LADSPA SDK (Open Source) to develop.|
|VST||C/C++ development||Compile Audacity with VST enabled. Needs VST SDK (Proprietary) to develop, for which you need a license agreement.|
|Vamp||C/C++ development||Vamp SDK is provided as part of Audacity source code.|
|Hi-Jacker||C/C++ development||Same as for Audacity development.|
|wxWidgets Plug-in||C/C++ development||Same as for Audacity development.|
How to choose which kind? It depends so much on what you want to do and what your programming background is. The big choice is between C/C++ or a scripting language. You can get started much much faster with any of the scripting, i.e. Nyquist, Batch Chains or Perl script, however you lose some flexibility in what you can do. Ladspa, VST and Vamp plug-ins are all usable in other programs besides Audacity, which is a big plus. However you can only use them as effects to alter sound or analyse it, not to add new toolbars to Audacity.
There isn't yet a lot of documentation on developing for Audacity. We're hoping to gradually improve that with a developer guide. See that page for details.
There is a built in XLisp interpreter that is used mainly for creating new sound effects. It can also be used to create labels. It's mature, stable, and has been in Audacity from the start. Nyquist. Only limited documentation is available.
Limited ability to do 'the same thing' to a large number of files. Originally written for cleaning up lots of audio tapes, applying noise removal, removing long silences too and converting to mp3. Stable, but quite limited in what it can do.
Still very very experimental. Under windows you can use ActivePerl to drive Audacity. To use this (August 2007) you should be an experienced C++ developer too, as you will almost certainly need to add code into Audacity to process commands which are not yet handled.
Sound effects. C or C++, Ladspa Plug-in. GUI is built from simple instructions.
VST Plug-in. GUI is built by the plug in directly.
Work in progress. C or C++. GUI is built from simple instructions. Similar in concept to LADSPA except this it is designed particularly for analysis of sound, so for example finding particular words in a spoken text.
Plug-In that takes over the entire GUI of Audacity and uses the underlying services for its own ends. (not to be confused with 'Jack')
Work in progress. A still experimental method for adding any feature to Audacity as a plug in. The plug in can use any feature of wxWidgets, and has an API for interaction with the Audacity program.