diff options
| -rw-r--r-- | core.lv2/lv2.h | 135 | ||||
| -rw-r--r-- | core.lv2/lv2.ttl | 71 |
2 files changed, 93 insertions, 113 deletions
diff --git a/core.lv2/lv2.h b/core.lv2/lv2.h index ded1512..f1758cf 100644 --- a/core.lv2/lv2.h +++ b/core.lv2/lv2.h @@ -1,9 +1,9 @@ -/* LV2 - LADSPA (Linux Audio Developer's Simple Plugin API) Version 2 - * Revision 1 +/* LV2 - An audio plugin interface specification + * Revision 4 * * Copyright (C) 2000-2002 Richard W.E. Furse, Paul Barton-Davis, * Stefan Westerfeld. - * Copyright (C) 2006-2008 Steve Harris, David Robillard. + * Copyright (C) 2006-2010 Steve Harris, David Robillard. * * This header is free software; you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License as published @@ -21,6 +21,11 @@ * USA. */ +/** @file lv2.h + * C header for the LV2 specification <http://lv2plug.in/ns/lv2core>. + * Revision: 4 + */ + #ifndef LV2_H_INCLUDED #define LV2_H_INCLUDED @@ -30,85 +35,7 @@ extern "C" { #endif - -/* ************************************************************************* */ - - -/** @file lv2.h - * C header for the LV2 specification <http://lv2plug.in/ns/lv2core>. - * Revision: 1 - * - * == Overview == - * - * There are a large number of open source and free software synthesis - * packages in use or development at this time. This API ('LV2') - * attempts to give programmers the ability to write simple 'plugin' - * audio processors in C/C++ and link them dynamically ('plug') into - * a range of these packages ('hosts'). It should be possible for any - * host and any plugin to communicate completely through this interface. - * - * This API is deliberately as short and simple as possible. - * The information required to use a plugin is in a companion data - * (RDF) file. The shared library portion of the API (defined in this - * header) does not contain enough information to make use of the plugin - * possible - the data file is mandatory. - * - * Plugins are expected to distinguish between control rate and audio - * rate data (or other types of data defined by extensions). Plugins have - * 'ports' that are inputs or outputs and each plugin is 'run' for a 'block' - * corresponding to a short time interval measured in samples. Audio rate - * data is communicated using arrays with one element per sample processed, - * allowing a block of audio to be processed by the plugin in a single - * pass. Control rate data is communicated using single values. Control - * rate data has a single value at the start of a call to the 'run()' - * function, and may be considered to remain this value for its duration. - * Thus the 'control rate' is determined by the block size, controlled by - * the host. The plugin may assume that all its input and output ports have - * been connected to the relevant data location (see the 'connect_port()' - * function below) before it is asked to run, unless the port has been set - * 'connection optional' in the plugin's data file. - * - * Plugins will reside in shared object files suitable for dynamic linking - * by dlopen() and family. The file will provide a number of 'plugin - * types' that can be used to instantiate actual plugins (sometimes known - * as 'plugin instances') that can be connected together to perform tasks. - * The host can access these plugin types using the lv2_descriptor() - * function. - * - * This API contains very limited error-handling. - * - * == Threading rules == - * - * Certain hosts may need to call the functions provided by a plugin from - * multiple threads. For this to be safe, the plugin must be written so that - * those functions can be executed simultaneously without problems. - * To facilitate this, the functions provided by a plugin are divided into - * classes: - * - * - Discovery class: lv2_descriptor(), extension_data() - * - Instantiation class: instantiate(), cleanup(), activate(), deactivate() - * - Audio class: run(), connect_port() - * - * Extensions to this specification which add new functions MUST declare in - * which of these classes the functions belong, or define new classes for them. - * The rules that hosts must follow are these: - * - * - When a function from the Discovery class is running, no other - * functions in the same shared object file may run. - * - When a function from the Instantiation class is running for a plugin - * instance, no other functions for that instance may run. - * - When a function is running for a plugin instance, no other - * function in the same class may run for that instance. - * - * Any simultaneous calls that are not explicitly forbidden by these rules - * are allowed. For example, a host may call run() for two different plugin - * instances simultaneously. - */ - - -/* ************************************************************************* */ - - + /** Plugin Handle. * * This plugin handle indicates a particular instance of the plugin @@ -117,10 +44,7 @@ extern "C" { * may use it to reference internal instance data. */ typedef void * LV2_Handle; - -/* ************************************************************************* */ - - + /** Feature data. * * These are passed to a plugin's instantiate method to represent a special @@ -130,6 +54,7 @@ typedef void * LV2_Handle; * LV2 specification does not define any features; hosts are not required * to use this facility. */ typedef struct _LV2_Feature { + /** A globally unique, case-sensitive identifier for this feature. * * This MUST be defined in the specification of any LV2 extension which @@ -145,13 +70,11 @@ typedef struct _LV2_Feature { * this feature. * If no data is required, this may be set to NULL. */ void * data; + } LV2_Feature; -/* ************************************************************************* */ - - -/** Descriptor for a Type of Plugin. +/** Descriptor for a Plugin. * * This structure is used to describe a plugin type. It provides a number * of functions to instantiate it, link it to buffers and run it. */ @@ -335,33 +258,28 @@ typedef struct _LV2_Descriptor { } LV2_Descriptor; -/* ****************************************************************** */ - - -/** Accessing Plugin Types. +/** Accessing Plugins. * - * The exact mechanism by which plugins are loaded is host-dependent, - * however all most hosts will need to know is the URI of the plugin they - * wish to load. The environment variable LV2_PATH, if present, should - * contain a colon-separated path indicating directories (containing - * plugin bundle subdirectories) that should be searched (in order) - * for plugins. It is expected that hosts will use a library to provide - * this functionality. + * The exact mechanism by which plugins are loaded is host and system + * dependent, however all hosts need to know is the URI of the plugin they + * wish to load. Documentation on best practices for plugin discovery can + * be found at <http://lv2plug.in>, however it is expected that hosts use + * a library to provide this functionality. * - * A plugin programmer must include a function called "lv2_descriptor" + * A plugin programmer MUST include a function called "lv2_descriptor" * with the following function prototype within the shared object * file. This function will have C-style linkage (if you are using * C++ this is taken care of by the 'extern "C"' clause at the top of - * the file). + * this file). * * A host will find the plugin shared object file by one means or another, * find the lv2_descriptor() function, call it, and proceed from there. * * Plugin types are accessed by index (not ID) using values from 0 - * upwards. Out of range indexes must result in this function returning + * upwards. Out of range indexes MUST result in this function returning * NULL, so the plugin count can be determined by checking for the least * index that results in NULL being returned. Index has no meaning, - * hosts MUST NOT depend on it remaining constant (ie when serialising) + * hosts MUST NOT depend on it remaining constant (e.g. when serialising) * in any way. */ const LV2_Descriptor * lv2_descriptor(uint32_t index); @@ -371,12 +289,8 @@ typedef const LV2_Descriptor * (*LV2_Descriptor_Function)(uint32_t index); -/* ******************************************************************** */ - - /* Put this (LV2_SYMBOL_EXPORT) before any functions that are to be loaded - * by the host as a symbol from the dynamic library. - */ + * by the host as a symbol from the dynamic library. */ #ifdef WIN32 #define LV2_SYMBOL_EXPORT __declspec(dllexport) #else @@ -389,4 +303,3 @@ typedef const LV2_Descriptor * #endif #endif /* LV2_H_INCLUDED */ - diff --git a/core.lv2/lv2.ttl b/core.lv2/lv2.ttl index 23f014d..c3abdbf 100644 --- a/core.lv2/lv2.ttl +++ b/core.lv2/lv2.ttl @@ -67,7 +67,7 @@ more details. doap:name "LV2" ; doap:homepage <http://lv2plug.in> ; doap:created "2004-04-21" ; - doap:shortdesc "An audio processing plugin specification" ; + doap:shortdesc "An audio plugin interface specification" ; doap:programming-language "C" ; doap:release [ doap:revision "4" ; @@ -83,7 +83,74 @@ more details. foaf:name "David Robillard" ; foaf:homepage <http://drobilla.net/> ; rdfs:seeAlso <http://drobilla.net/drobilla.rdf> - ] . + ] ; rdfs:comment """ +<h4>Overview</h4> +There are a large number of open source and free software synthesis packages in +use or development at this time. This API ("LV2") attempts to give programmers +the ability to write simple "plugin" audio processors in C/C++ and link +them dynamically ("plug" them) into a range of these packages ("hosts"). +It should be possible for any host and any plugin to communicate completely +through this interface. + +This API is deliberately as short and simple as possible. The information +required to use a plugin is in a companion data (RDF) file. The shared +library portion of the API does not contain enough information to make use +of the plugin possible; the data file is mandatory. + +Plugins can operate on any type of data. Plugins have "ports" that are +inputs or outputs and each plugin is "run" for a "block" corresponding to +a short time interval measured in samples. The plugin may assume that all +its input and output ports have been connected to the relevant data location +(using the connect_port() function) before it is asked to run, unless the +port has been set "connection optional" in the plugin's data file. + +This "core" specification defines two types of port data, equivalent to those +in LADSPA: control rate and audio rate. Audio rate data is communicated using +arrays with one <code>float</code> element per sample processed, allowing +a block of audio to be processed by the plugin in a single pass. Control +rate data is communicated using single <code>float</code> values. Control +rate data has a single value at the start of a call to the run() function +which is considered valid for the duration of the call to run(). Thus the +"control rate" is determined by the block size, controlled by the host. + +Plugins reside in shared object files suitable for dynamic linking (e.g. by +dlopen() and family). This file provides one or many plugins via the +lv2_descriptor() function. These plugins can be instantiated to create +"plugin instances", which can be connected together to perform tasks. + +This API contains very limited error-handling. + +<h4>Threading Rules</h4> Certain hosts may need to call the functions +provided by a plugin from multiple threads. For this to be safe, the plugin +must be written so that those functions can be executed simultaneously +without problems. To facilitate this, the functions provided by a plugin +are divided into classes: + +<dl> +<dt>Discovery Class</dt> +<dd>lv2_descriptor(), extension_data()</dd> +<dt>Instantiation Class</dt> +<dd>instantiate(), cleanup(), activate(), deactivate()</dd> +<dt>Audio Class</dt> +<dd>run(), connect_port()</dd> +</dl> + +Extensions to this specification which add new functions MUST declare in +which of these classes the functions belong, or define new classes for them. +The rules that hosts MUST follow are: + +<ul> +<li>When a function is running for a plugin instance, no other + function in the same class may run for that instance.</li> +<li>When a function from the Discovery class is running, no other + functions in the same shared object file may run.</li> +<li>When a function from the Instantiation class is running for a plugin + instance, no other functions for that instance may run.</li> +</ul> +Any simultaneous calls that are not explicitly forbidden by these rules +are allowed. For example, a host may call run() for two different plugin +instances simultaneously. +""" . |