skuyuy / clap

Audio Plugin API

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CLever Audio Plugin.

• Learn about CLAP
  • Entry point
  • Extensions
  • Fundamental extensions
  • GUI extensions
  • Extra extensions
• Resources
  • Programming Language Bingings
  • Examples
  • Community related projects

Learn about CLAP

To work with clap, include clap/clap.h.

The two most important objects are clap_host and clap_plugin.

Entry point

The entry point is declared in entry.h.

Extensions

Most features comes from extensions, which are in fact C interfaces.

// host extension
const clap_host_log *log = host->extension(host, CLAP_EXT_LOG);
if (log)
   log->log(host, CLAP_LOG_INFO, "Hello World! ;^)");

// plugin extension
const clap_plugin_params *params = plugin->extension(plugin, CLAP_EXT_PARAMS);
if (params)
{
   uint32_t paramsCount = params->count(plugin);
   // ...
}

The extensions are defined in ext folder.

Some extensions are still in the progress of being designed and they are in the draft folder.

An extension comes with:

• an header #include <clap/ext/xxx.h>
• an extension identifier: #define CLAP_EXT_XXX "clap/XXX"
• host interfaces are named like: struct clap_host_xxx
• plugin interfaces are named like: struct clap_plugin_xxx
• each methods must have a clear thread specification

You can create your own extensions and share them, make sure that the extension identifier

• includes versioning in case the ABI breaks
• a unique identifier

All strings are valid UTF-8.

Fundamental extensions

This is a list of the extensions that you most likely want to implement and use to get a basic plugin experience:

• log, lets the host aggregate plugin logs
• thread-check, check which thread you are currently on, useful for correctness validation
• audio-ports, define the audio ports
• note-ports, define the note ports
• params, parameters management
• latency, report the plugin latency
• state, save and load the plugin state

GUI extensions

• gui, generic gui controller
• gui-win32, win32 specific
• gui-cocoa, cocoa specific
• gui-x11, x11 specific
• gui-free-standing, open the gui without embedding it into the host's window
• timer-support, lets the plugin register timer handlers
• posix-fd-support, lets the plugin register I/O handlers

Extra extensions

• render, renders realtime or offline
• note-name, give a name to notes, useful for drum machines
• tuning, host provided microtuning
• track-info
• thread-pool, use the host thread pool
• quick-controls, bank of controls that can be mapped on a controlles with 8 knobs
• file-reference, let the host know about the plugin's file reference, and perform "Collect & Save"
• check-for-update, check if there is a new version of a plugin
• audio-ports-config, simple list of possible configurations
• surround, inspect the surround channel mapping

Resources

Programming Language Bingings

• clap-sys, rust binding
• CLAP-for-Delphi, Delphi binding

Examples

• clap-host, very simple host
• clap-plugins, very simple plugins

Community related projects

• clap-juce-extension, juce add-on
• MIP2, host and plugins
• schwaaa's plugin, basic example for prototyping CLAP audio plugins using Dear ImGui as the user interface