/* LV2 - An audio plugin interface specification * Revision 4 * * Copyright (C) 2000-2002 Richard W.E. Furse, Paul Barton-Davis, * Stefan Westerfeld. * 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 * by the Free Software Foundation; either version 2.1 of the License, * or (at your option) any later version. * * This header is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 * USA. */ /** @file lv2.h * C header for the LV2 specification . * Revision: 4 */ #ifndef LV2_H_INCLUDED #define LV2_H_INCLUDED #include #ifdef __cplusplus extern "C" { #endif /** Plugin Handle. * * This plugin handle indicates a particular instance of the plugin * concerned. It is valid to compare this to NULL (0 for C++) but * otherwise the host MUST NOT attempt to interpret it. The plugin * 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 * feature the host has which the plugin may depend on. This is to allow * extensions to the LV2 specification without causing any breakage. * Extensions may specify what data needs to be passed here. The base * 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 * defines a host feature. */ const char * URI; /** Pointer to arbitrary data. * * This is to allow hosts to pass data to a plugin (simple values, data * structures, function pointers, etc) as part of a 'feature'. The LV2 * specification makes no restrictions on the contents of this data. * The data here MUST be cleary defined by the LV2 extension which defines * this feature. * If no data is required, this may be set to NULL. */ void * data; } LV2_Feature; /** 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. */ typedef struct _LV2_Descriptor { /** A globally unique, case-sensitive identifier for this plugin type. * * All plugins with the same URI MUST be compatible in terms of 'port * signature', meaning they have the same number of ports, same port * shortnames, and roughly the same functionality. URIs should * probably contain a version number (or similar) for this reason. * * Rationale: When serializing session/patch/etc files, hosts MUST * refer to a loaded plugin by the plugin URI only. In the future * loading a plugin with this URI MUST yield a plugin with the * same ports (etc) which is 100% compatible. */ const char * URI; /** Function pointer that instantiates a plugin. * * A handle is returned indicating the new plugin instance. The * instantiation function accepts a sample rate as a parameter as well * as the plugin descriptor from which this instantiate function was * found. This function must return NULL if instantiation fails. * * bundle_path is a string of the path to the LV2 bundle which contains * this plugin binary. It MUST include the trailing directory separator * (e.g. '/') so that BundlePath + filename gives the path to a file * in the bundle. * * features is a NULL terminated array of LV2_Feature structs which * represent the features the host supports. Plugins may refuse to * instantiate if required features are not found here (however hosts * SHOULD NOT use this as a discovery mechanism, instead reading the * data file before attempting to instantiate the plugin). This array * must always exist; if a host has no features, it MUST pass a single * element array containing NULL (to simplify plugins). * * Note that instance initialisation should generally occur in * activate() rather than here. If a host calls instantiate, it MUST * call cleanup() at some point in the future. */ LV2_Handle (*instantiate)(const struct _LV2_Descriptor * descriptor, double sample_rate, const char * bundle_path, const LV2_Feature *const * features); /** Function pointer that connects a port on a plugin instance to a memory * location where the block of data for the port will be read/written. * * The data location is expected to be of the type defined in the * plugin's data file (e.g. an array of float for an lv2:AudioPort). * Memory issues are managed by the host. The plugin must read/write * the data at these locations every time run() is called, data * present at the time of this connection call MUST NOT be * considered meaningful. * * The host MUST NOT try to connect a data buffer to a port index * that is not defined in the RDF data for the plugin. If it does, * the plugin's behaviour is undefined. * * connect_port() may be called more than once for a plugin instance * to allow the host to change the buffers that the plugin is reading * or writing. These calls may be made before or after activate() * or deactivate() calls. Note that there may be realtime constraints * on connect_port (see lv2:hardRTCapable in lv2.ttl). * * connect_port() MUST be called at least once for each port before * run() is called. The plugin must pay careful attention to the block * size passed to the run function as the block allocated may only just * be large enough to contain the block of data (typically samples), and * is not guaranteed to be constant. * * Plugin writers should be aware that the host may elect to use the * same buffer for more than one port and even use the same buffer for * both input and output (see lv2:inPlaceBroken in lv2.ttl). * However, overlapped buffers or use of a single buffer for both * audio and control data may result in unexpected behaviour. * * If the plugin has the feature lv2:hardRTCapable then there are * various things that the plugin MUST NOT do within the connect_port() * function (see lv2.ttl). */ void (*connect_port)(LV2_Handle instance, uint32_t port, void * data_location); /** Function pointer that initialises a plugin instance and activates * it for use. * * This is separated from instantiate() to aid real-time support and so * that hosts can reinitialise a plugin instance by calling deactivate() * and then activate(). In this case the plugin instance must reset all * state information dependent on the history of the plugin instance * except for any data locations provided by connect_port(). If there * is nothing for activate() to do then the plugin writer may provide * a NULL rather than an empty function. * * When present, hosts MUST call this function once before run() * is called for the first time. This call SHOULD be made as close * to the run() call as possible and indicates to real-time plugins * that they are now live, however plugins MUST NOT rely on a prompt * call to run() after activate(). activate() may not be called again * unless deactivate() is called first (after which activate() may be * called again, followed by deactivate, etc. etc.). If a host calls * activate, it MUST call deactivate at some point in the future. * * Note that connect_port() may be called before or after a call to * activate(). */ void (*activate)(LV2_Handle instance); /** Function pointer that runs a plugin instance for a block. * * Two parameters are required: the first is a handle to the particular * instance to be run and the second indicates the block size (in * samples) for which the plugin instance may run. * * Note that if an activate() function exists then it must be called * before run(). If deactivate() is called for a plugin instance then * the plugin instance may not be reused until activate() has been * called again. * * If the plugin has the feature lv2:hardRTCapable then there are * various things that the plugin MUST NOT do within the run() * function (see lv2.ttl). */ void (*run)(LV2_Handle instance, uint32_t sample_count); /** This is the counterpart to activate() (see above). If there is * nothing for deactivate() to do then the plugin writer may provide * a NULL rather than an empty function. * * Hosts must deactivate all activated units after they have been run() * for the last time. This call SHOULD be made as close to the last * run() call as possible and indicates to real-time plugins that * they are no longer live, however plugins MUST NOT rely on prompt * deactivation. Note that connect_port() may be called before or * after a call to deactivate(). * * Note that deactivation is not similar to pausing as the plugin * instance will be reinitialised when activate() is called to reuse it. * Hosts MUST NOT call deactivate() unless activate() was previously * called. */ void (*deactivate)(LV2_Handle instance); /** This is the counterpart to instantiate() (see above). Once an instance * of a plugin has been finished with it can be deleted using this * function. The instance handle passed ceases to be valid after * this call. * * If activate() was called for a plugin instance then a corresponding * call to deactivate() MUST be made before cleanup() is called. * Hosts MUST NOT call cleanup() unless instantiate() was previously * called. */ void (*cleanup)(LV2_Handle instance); /** Function pointer that can be used to return additional instance data for * a plugin defined by some extenion (e.g. a struct containing additional * function pointers). * * The actual type and meaning of the returned object MUST be specified * precisely by the extension if it defines any extra data. If a particular * extension does not define extra instance data, this function MUST return * NULL for that extension's URI. If a plugin does not support any * extensions that define extra instance data, this function pointer may be * set to NULL rather than providing an empty function. * * The only parameter is the URI of the extension. The plugin MUST return * NULL if it does not support the extension, but hosts SHOULD NOT use this * as a discovery method (e.g. hosts should only call this function for * extensions known to be supported by the plugin from the data file). * * The host is never responsible for freeing the returned value. * * NOTE: This function should return a struct (likely containing function * pointers) and NOT a direct function pointer. Standard C and C++ do not * allow type casts from void* to a function pointer type. To provide * additional functions a struct should be returned containing the extra * function pointers (which is valid standard code, and a much better idea * for extensibility anyway). */ const void* (*extension_data)(const char * uri); } LV2_Descriptor; /** Accessing Plugins. * * 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 , however it is expected that hosts use * a library to provide this functionality. * * 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 * 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 * 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 (e.g. when serialising) * in any way. */ const LV2_Descriptor * lv2_descriptor(uint32_t index); /** Datatype corresponding to the lv2_descriptor() function. */ 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. */ #ifdef WIN32 #define LV2_SYMBOL_EXPORT __declspec(dllexport) #else #define LV2_SYMBOL_EXPORT #endif #ifdef __cplusplus } #endif #endif /* LV2_H_INCLUDED */ '>307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 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