| Version | 1.18.9 |
|---|
Core LV2 specification.
See http://lv2plug.in/ns/lv2core for details.
Data Structures | |
| struct | LV2_Feature |
| struct | LV2_Descriptor |
| struct | LV2_Lib_Descriptor |
Typedefs | |
| typedef void * | LV2_Handle |
| typedef const LV2_Descriptor *(* | LV2_Descriptor_Function) (uint32_t index) |
| typedef void * | LV2_Lib_Handle |
| typedef const LV2_Lib_Descriptor *(* | LV2_Lib_Descriptor_Function) (const char *bundle_path, const LV2_Feature *const *features) |
Functions | |
| LV2_SYMBOL_EXPORT const LV2_Descriptor * | lv2_descriptor (uint32_t index) |
| LV2_SYMBOL_EXPORT const LV2_Lib_Descriptor * | lv2_lib_descriptor (const char *bundle_path, const LV2_Feature *const *features) |
| struct LV2_Feature |
Feature.
Features allow hosts to make additional functionality available to plugins without requiring modification to the LV2 API. Extensions may define new features and specify the URI and data to be used if necessary. Some features, such as lv2:isLive, do not require the host to pass data.
| struct LV2_Descriptor |
Plugin Descriptor.
This structure provides the core functions necessary to instantiate and use a plugin.
Data Fields | |
| const char * | URI |
| LV2_Handle(* | instantiate )(const struct LV2_Descriptor *descriptor, double sample_rate, const char *bundle_path, const LV2_Feature *const *features) |
| void(* | connect_port )(LV2_Handle instance, uint32_t port, void *data_location) |
| void(* | activate )(LV2_Handle instance) |
| void(* | run )(LV2_Handle instance, uint32_t sample_count) |
| void(* | deactivate )(LV2_Handle instance) |
| void(* | cleanup )(LV2_Handle instance) |
| const void *(* | extension_data )(const char *uri) |
| const char* LV2_Descriptor::URI |
A globally unique, case-sensitive identifier for this plugin.
This MUST be a valid URI string as defined by RFC 3986. All plugins with the same URI MUST be compatible to some degree, see http://lv2plug.in/ns/lv2core for details.
| LV2_Handle(* LV2_Descriptor::instantiate) (const struct LV2_Descriptor *descriptor, double sample_rate, const char *bundle_path, const LV2_Feature *const *features) |
Instantiate the plugin.
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.
| descriptor | Descriptor of the plugin to instantiate. |
| sample_rate | Sample rate, in Hz, for the new plugin instance. |
| bundle_path | Path to the LV2 bundle which contains this plugin binary. It MUST include the trailing directory separator so that simply appending a filename will yield the path to that file in the bundle. |
| features | 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 MUST NOT use this as a discovery mechanism: instead, use the RDF data to determine which features are required and do not attempt to instantiate unsupported plugins at all. This parameter MUST NOT be NULL, i.e. a host that supports no features MUST pass a single element array containing NULL. |
| void(* LV2_Descriptor::connect_port) (LV2_Handle instance, uint32_t port, void *data_location) |
Connect a port on a plugin instance to a memory location.
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).
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 lv2core.ttl for details.
connect_port() MUST be called at least once for each port before run() is called, unless that port is lv2:connectionOptional. The plugin must pay careful attention to the block size passed to run() since the block allocated may only just be large enough to contain the data, and is not guaranteed to remain constant between run() calls.
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.
| instance | Plugin instance containing the port. |
| port | Index of the port to connect. The host MUST NOT try to connect a port index that is not defined in the plugin's RDF data. If it does, the plugin's behaviour is undefined (a crash is likely). |
| data_location | Pointer to data of the type defined by the port type in the plugin's RDF data (for example, an array of float for an lv2:AudioPort). This pointer must be stored by the plugin instance and used to read/write data when run() is called. Data present at the time of the connect_port() call MUST NOT be considered meaningful. |
| void(* LV2_Descriptor::activate) (LV2_Handle instance) |
Initialise a plugin instance and activate 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 this field may be NULL.
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().
The host MUST NOT call activate() again until deactivate() has been called first. 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 activate().
| void(* LV2_Descriptor::run) (LV2_Handle instance, uint32_t sample_count) |
Run a plugin instance for a block.
Note that if an activate() function exists then it must be called before run(). If deactivate() is called for a plugin instance then run() may not be called 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 lv2core.ttl for details).
As a special case, when sample_count is 0, the plugin should update any output ports that represent a single instant in time (for example, control ports, but not audio ports). This is particularly useful for latent plugins, which should update their latency output port so hosts can pre-roll plugins to compute latency. Plugins MUST NOT crash when sample_count is 0.
| instance | Instance to be run. |
| sample_count | The block size (in samples) for which the plugin instance must run. |
| void(* LV2_Descriptor::deactivate) (LV2_Handle instance) |
Deactivate a plugin instance (counterpart to activate()).
Hosts MUST deactivate all activated instances 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. If there is nothing for deactivate() to do then this field may be NULL
Deactivation is not similar to pausing since the plugin instance will be reinitialised by activate(). However, deactivate() itself MUST NOT fully reset plugin state. For example, the host may deactivate a plugin, then store its state (using some extension to do so).
Hosts MUST NOT call deactivate() unless activate() was previously called. Note that connect_port() may be called before or after deactivate().
| void(* LV2_Descriptor::cleanup) (LV2_Handle instance) |
Clean up a plugin instance (counterpart to instantiate()).
Once an instance of a plugin has been finished with it must 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.
| const void *(* LV2_Descriptor::extension_data) (const char *uri) |
Return additional plugin data defined by some extension.
A typical use of this facility is to return a struct containing function pointers to extend the LV2_Descriptor API.
The actual type and meaning of the returned object MUST be specified precisely by the extension. This function MUST return NULL for any unsupported URI. If a plugin does not support any extension data, this field may be NULL.
The host is never responsible for freeing the returned value.
| struct LV2_Lib_Descriptor |
Descriptor for a plugin library.
To access a plugin library, the host creates an LV2_Lib_Descriptor via the lv2_lib_descriptor() function in the shared object.
Data Fields | |
| LV2_Lib_Handle | handle |
| uint32_t | size |
| void(* | cleanup )(LV2_Lib_Handle handle) |
| const LV2_Descriptor *(* | get_plugin )(LV2_Lib_Handle handle, uint32_t index) |
| LV2_Lib_Handle LV2_Lib_Descriptor::handle |
Opaque library data which must be passed as the first parameter to all the methods of this struct.
| uint32_t LV2_Lib_Descriptor::size |
The total size of this struct.
This allows for this struct to be expanded in the future if necessary. This MUST be set by the library to sizeof(LV2_Lib_Descriptor). The host MUST NOT access any fields of this struct beyond get_plugin() unless this field indicates they are present.
| void(* LV2_Lib_Descriptor::cleanup) (LV2_Lib_Handle handle) |
Destroy this library descriptor and free all related resources.
| const LV2_Descriptor *(* LV2_Lib_Descriptor::get_plugin) (LV2_Lib_Handle handle, uint32_t index) |
Plugin accessor.
Plugins are accessed by index using values from 0 upwards. Out of range indices MUST result in this function returning NULL, so the host can enumerate plugins by increasing index until NULL is returned.
| #define LV2_CORE_URI "http://lv2plug.in/ns/lv2core" |
| #define LV2_CORE_PREFIX LV2_CORE_URI "#" |
| #define LV2_CORE__AllpassPlugin LV2_CORE_PREFIX "AllpassPlugin" |
| #define LV2_CORE__AmplifierPlugin LV2_CORE_PREFIX "AmplifierPlugin" |
| #define LV2_CORE__AnalyserPlugin LV2_CORE_PREFIX "AnalyserPlugin" |
| #define LV2_CORE__AudioPort LV2_CORE_PREFIX "AudioPort" |
| #define LV2_CORE__BandpassPlugin LV2_CORE_PREFIX "BandpassPlugin" |
| #define LV2_CORE__CVPort LV2_CORE_PREFIX "CVPort" |
| #define LV2_CORE__ChorusPlugin LV2_CORE_PREFIX "ChorusPlugin" |
| #define LV2_CORE__CombPlugin LV2_CORE_PREFIX "CombPlugin" |
| #define LV2_CORE__CompressorPlugin LV2_CORE_PREFIX "CompressorPlugin" |
| #define LV2_CORE__ConstantPlugin LV2_CORE_PREFIX "ConstantPlugin" |
| #define LV2_CORE__ControlPort LV2_CORE_PREFIX "ControlPort" |
| #define LV2_CORE__ConverterPlugin LV2_CORE_PREFIX "ConverterPlugin" |
| #define LV2_CORE__DelayPlugin LV2_CORE_PREFIX "DelayPlugin" |
| #define LV2_CORE__DistortionPlugin LV2_CORE_PREFIX "DistortionPlugin" |
| #define LV2_CORE__DynamicsPlugin LV2_CORE_PREFIX "DynamicsPlugin" |
| #define LV2_CORE__EQPlugin LV2_CORE_PREFIX "EQPlugin" |
| #define LV2_CORE__EnvelopePlugin LV2_CORE_PREFIX "EnvelopePlugin" |
| #define LV2_CORE__ExpanderPlugin LV2_CORE_PREFIX "ExpanderPlugin" |
| #define LV2_CORE__ExtensionData LV2_CORE_PREFIX "ExtensionData" |
| #define LV2_CORE__Feature LV2_CORE_PREFIX "Feature" |
| #define LV2_CORE__FilterPlugin LV2_CORE_PREFIX "FilterPlugin" |
| #define LV2_CORE__FlangerPlugin LV2_CORE_PREFIX "FlangerPlugin" |
| #define LV2_CORE__FunctionPlugin LV2_CORE_PREFIX "FunctionPlugin" |
| #define LV2_CORE__GatePlugin LV2_CORE_PREFIX "GatePlugin" |
| #define LV2_CORE__GeneratorPlugin LV2_CORE_PREFIX "GeneratorPlugin" |
| #define LV2_CORE__HighpassPlugin LV2_CORE_PREFIX "HighpassPlugin" |
| #define LV2_CORE__InputPort LV2_CORE_PREFIX "InputPort" |
| #define LV2_CORE__InstrumentPlugin LV2_CORE_PREFIX "InstrumentPlugin" |
| #define LV2_CORE__LimiterPlugin LV2_CORE_PREFIX "LimiterPlugin" |
| #define LV2_CORE__LowpassPlugin LV2_CORE_PREFIX "LowpassPlugin" |
| #define LV2_CORE__MixerPlugin LV2_CORE_PREFIX "MixerPlugin" |
| #define LV2_CORE__ModulatorPlugin LV2_CORE_PREFIX "ModulatorPlugin" |
| #define LV2_CORE__MultiEQPlugin LV2_CORE_PREFIX "MultiEQPlugin" |
| #define LV2_CORE__OscillatorPlugin LV2_CORE_PREFIX "OscillatorPlugin" |
| #define LV2_CORE__OutputPort LV2_CORE_PREFIX "OutputPort" |
| #define LV2_CORE__ParaEQPlugin LV2_CORE_PREFIX "ParaEQPlugin" |
| #define LV2_CORE__PhaserPlugin LV2_CORE_PREFIX "PhaserPlugin" |
| #define LV2_CORE__PitchPlugin LV2_CORE_PREFIX "PitchPlugin" |
| #define LV2_CORE__Plugin LV2_CORE_PREFIX "Plugin" |
| #define LV2_CORE__PluginBase LV2_CORE_PREFIX "PluginBase" |
| #define LV2_CORE__Point LV2_CORE_PREFIX "Point" |
| #define LV2_CORE__Port LV2_CORE_PREFIX "Port" |
| #define LV2_CORE__PortProperty LV2_CORE_PREFIX "PortProperty" |
| #define LV2_CORE__Resource LV2_CORE_PREFIX "Resource" |
| #define LV2_CORE__ReverbPlugin LV2_CORE_PREFIX "ReverbPlugin" |
| #define LV2_CORE__ScalePoint LV2_CORE_PREFIX "ScalePoint" |
| #define LV2_CORE__SimulatorPlugin LV2_CORE_PREFIX "SimulatorPlugin" |
| #define LV2_CORE__SpatialPlugin LV2_CORE_PREFIX "SpatialPlugin" |
| #define LV2_CORE__Specification LV2_CORE_PREFIX "Specification" |
| #define LV2_CORE__SpectralPlugin LV2_CORE_PREFIX "SpectralPlugin" |
| #define LV2_CORE__UtilityPlugin LV2_CORE_PREFIX "UtilityPlugin" |
| #define LV2_CORE__WaveshaperPlugin LV2_CORE_PREFIX "WaveshaperPlugin" |
| #define LV2_CORE__appliesTo LV2_CORE_PREFIX "appliesTo" |
| #define LV2_CORE__binary LV2_CORE_PREFIX "binary" |
| #define LV2_CORE__connectionOptional LV2_CORE_PREFIX "connectionOptional" |
| #define LV2_CORE__control LV2_CORE_PREFIX "control" |
| #define LV2_CORE__default LV2_CORE_PREFIX "default" |
| #define LV2_CORE__designation LV2_CORE_PREFIX "designation" |
| #define LV2_CORE__documentation LV2_CORE_PREFIX "documentation" |
| #define LV2_CORE__enabled LV2_CORE_PREFIX "enabled" |
| #define LV2_CORE__enumeration LV2_CORE_PREFIX "enumeration" |
| #define LV2_CORE__extensionData LV2_CORE_PREFIX "extensionData" |
| #define LV2_CORE__freeWheeling LV2_CORE_PREFIX "freeWheeling" |
| #define LV2_CORE__hardRTCapable LV2_CORE_PREFIX "hardRTCapable" |
| #define LV2_CORE__inPlaceBroken LV2_CORE_PREFIX "inPlaceBroken" |
| #define LV2_CORE__index LV2_CORE_PREFIX "index" |
| #define LV2_CORE__integer LV2_CORE_PREFIX "integer" |
| #define LV2_CORE__isLive LV2_CORE_PREFIX "isLive" |
| #define LV2_CORE__latency LV2_CORE_PREFIX "latency" |
| #define LV2_CORE__maximum LV2_CORE_PREFIX "maximum" |
| #define LV2_CORE__microVersion LV2_CORE_PREFIX "microVersion" |
| #define LV2_CORE__minimum LV2_CORE_PREFIX "minimum" |
| #define LV2_CORE__minorVersion LV2_CORE_PREFIX "minorVersion" |
| #define LV2_CORE__name LV2_CORE_PREFIX "name" |
| #define LV2_CORE__optionalFeature LV2_CORE_PREFIX "optionalFeature" |
| #define LV2_CORE__port LV2_CORE_PREFIX "port" |
| #define LV2_CORE__portProperty LV2_CORE_PREFIX "portProperty" |
| #define LV2_CORE__project LV2_CORE_PREFIX "project" |
| #define LV2_CORE__prototype LV2_CORE_PREFIX "prototype" |
| #define LV2_CORE__reportsLatency LV2_CORE_PREFIX "reportsLatency" |
| #define LV2_CORE__requiredFeature LV2_CORE_PREFIX "requiredFeature" |
| #define LV2_CORE__sampleRate LV2_CORE_PREFIX "sampleRate" |
| #define LV2_CORE__scalePoint LV2_CORE_PREFIX "scalePoint" |
| #define LV2_CORE__symbol LV2_CORE_PREFIX "symbol" |
| #define LV2_CORE__toggled LV2_CORE_PREFIX "toggled" |
| #define LV2_SYMBOL_EXTERN |
Helper macro needed for LV2_SYMBOL_EXPORT when using C++.
| #define LV2_SYMBOL_EXPORT LV2_SYMBOL_EXTERN __attribute__((visibility("default"))) |
Put this (LV2_SYMBOL_EXPORT) before any functions that are to be loaded by the host as a symbol from the dynamic library.
| typedef void* LV2_Handle |
Plugin Instance Handle.
This is a handle for one particular instance of a plugin. It is valid to compare to NULL (or 0 for C++) but otherwise the host MUST NOT attempt to interpret it.
| typedef const LV2_Descriptor *(* LV2_Descriptor_Function) (uint32_t index) |
Type of the lv2_descriptor() function in a library (old discovery API).
| typedef void* LV2_Lib_Handle |
Handle for a library descriptor.
| typedef const LV2_Lib_Descriptor *(* LV2_Lib_Descriptor_Function) (const char *bundle_path, const LV2_Feature *const *features) |
Type of the lv2_lib_descriptor() function in an LV2 library.
| LV2_SYMBOL_EXPORT const LV2_Descriptor * lv2_descriptor | ( | uint32_t | index | ) |
Prototype for plugin accessor function.
Plugins are discovered by hosts using RDF data (not by loading libraries). See http://lv2plug.in for details on the discovery process, though most hosts should use an existing library to implement this functionality.
This is the simple plugin discovery API, suitable for most statically defined plugins. Advanced plugins that need access to their bundle during discovery can use lv2_lib_descriptor() instead. Plugin libraries MUST include a function called "lv2_descriptor" or "lv2_lib_descriptor" with C-style linkage, but SHOULD provide "lv2_descriptor" wherever possible.
When it is time to load a plugin (designated by its URI), the host loads the plugin's library, gets the lv2_descriptor() function from it, and uses this function to find the LV2_Descriptor for the desired plugin. Plugins are accessed by index using values from 0 upwards. This function MUST return NULL for out of range indices, so the host can enumerate plugins by increasing index until NULL is returned.
Note that index has no meaning, hosts MUST NOT depend on it remaining consistent between loads of the plugin library.
| LV2_SYMBOL_EXPORT const LV2_Lib_Descriptor * lv2_lib_descriptor | ( | const char * | bundle_path, |
| const LV2_Feature *const * | features | ||
| ) |
Prototype for library accessor function.
This is the more advanced discovery API, which allows plugin libraries to access their bundles during discovery, which makes it possible for plugins to be dynamically defined by files in their bundle. This API also has an explicit cleanup function, removing any need for non-portable shared library destructors. Simple plugins that do not require these features may use lv2_descriptor() instead.
This is the entry point for a plugin library. Hosts load this symbol from the library and call this function to obtain a library descriptor which can be used to access all the contained plugins. The returned object must not be destroyed (using LV2_Lib_Descriptor::cleanup()) until all plugins loaded from that library have been destroyed.