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+/* ladspa.h
+
+ Version 1. Copyright 2000 Richard W.E. Furse, Paul Barton-Davis,
+ Stefan Westerfeld. */
+
+#ifndef LADSPA_INCLUDED
+#define LADSPA_INCLUDED
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*****************************************************************************/
+
+/* Overview:
+
+ There is a large number of synthesis packages in use or development
+ on the Linux platform at this time. This API (`The Linux Audio
+ Developer's Simple Plugin API') 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. The LADSPA plugin API is free to
+ use.
+
+ This API is deliberately short and simple. To achieve compatibility
+ with a range of promising Linux sound synthesis packages it
+ attempts to find the `greatest common divisor' in their logical
+ behaviour. Having said this, certain limiting decisions are
+ implicit, notably the use of a fixed type (LADSPA_Data) for all
+ data transfer and absence of a parameterised `initialisation'
+ phase. See below for the LADSPA_Data typedef.
+
+ Plugins are expected to distinguish between control and audio
+ data. Plugins have `ports' that are inputs or outputs for audio or
+ control data and each plugin is `run' for a `block' corresponding
+ to a short time interval measured in samples. Audio data is
+ communicated using arrays of LADSPA_Data, allowing a block of audio
+ to be processed by the plugin in a single pass. Control data is
+ communicated using single LADSPA_Data values. Control data has a
+ single value at the start of a call to the `run()' or `run_adding()'
+ function, and may be considered to remain this value for its
+ duration. 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.
+
+ 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.
+
+ This API contains very limited error-handling. */
+
+/*****************************************************************************/
+
+/* Fundamental data type passed in and out of plugin. This data type
+ is used to communicate audio samples and control values. It is
+ assumed that the plugin will work sensibly given any numeric input
+ value although it may have a preferred range (see hints below). */
+
+typedef float LADSPA_Data;
+
+/*****************************************************************************/
+
+/* Special Plugin Properties:
+
+ Optional features of the plugin type are encapsulated in the
+ LADSPA_Properties type. This is assembled by ORing individual
+ properties together. */
+
+typedef int LADSPA_Properties;
+
+/* Property LADSPA_PROPERTY_REALTIME indicates that the plugin has a
+ real-time dependency (e.g. listens to a MIDI device) and so its
+ output must not be cached or subject to significant latency. */
+#define LADSPA_PROPERTY_REALTIME 0x1
+
+/* Property LADSPA_PROPERTY_INPLACE_BROKEN indicates that the plugin
+ may cease to work correctly if the host elects to use the same data
+ location for both input and output (see connect_port()). This
+ should be avoided as enabling this flag makes it impossible for
+ hosts to use the plugin to process audio `in-place.' */
+#define LADSPA_PROPERTY_INPLACE_BROKEN 0x2
+
+/* Property LADSPA_PROPERTY_HARD_RT_CAPABLE indicates that the plugin
+ is capable of running not only in a conventional host but also in a
+ `hard real-time' environment. To qualify for this the plugin must
+ satisfy all of the following:
+
+ (1) The plugin must not use malloc(), free() or other heap memory
+ management within its run() or run_adding() functions. All new
+ memory used in run() must be managed via the stack. These
+ restrictions only apply to the run() function.
+
+ (2) The plugin will not attempt to make use of any library
+ functions with the exceptions of functions in the ANSI standard C
+ and C maths libraries, which the host is expected to provide.
+
+ (3) The plugin will not access files, devices, pipes, sockets, IPC
+ or any other mechanism that might result in process or thread
+ blocking.
+
+ (4) The plugin will take an amount of time to execute a run() or
+ run_adding() call approximately of form (A+B*SampleCount) where A
+ and B depend on the machine and host in use. This amount of time
+ may not depend on input signals or plugin state. The host is left
+ the responsibility to perform timings to estimate upper bounds for
+ A and B. */
+#define LADSPA_PROPERTY_HARD_RT_CAPABLE 0x4
+
+#define LADSPA_IS_REALTIME(x) ((x) & LADSPA_PROPERTY_REALTIME)
+#define LADSPA_IS_INPLACE_BROKEN(x) ((x) & LADSPA_PROPERTY_INPLACE_BROKEN)
+#define LADSPA_IS_HARD_RT_CAPABLE(x) ((x) & LADSPA_PROPERTY_HARD_RT_CAPABLE)
+
+/*****************************************************************************/
+
+/* Plugin Ports:
+
+ Plugins have `ports' that are inputs or outputs for audio or
+ data. Ports can communicate arrays of LADSPA_Data (for audio
+ inputs/outputs) or single LADSPA_Data values (for control
+ input/outputs). This information is encapsulated in the
+ LADSPA_PortDescriptor type which is assembled by ORing individual
+ properties together.
+
+ Note that a port must be an input or an output port but not both
+ and that a port must be a control or audio port but not both. */
+
+typedef int LADSPA_PortDescriptor;
+
+/* Property LADSPA_PORT_INPUT indicates that the port is an input. */
+#define LADSPA_PORT_INPUT 0x1
+
+/* Property LADSPA_PORT_OUTPUT indicates that the port is an output. */
+#define LADSPA_PORT_OUTPUT 0x2
+
+/* Property LADSPA_PORT_CONTROL indicates that the port is a control
+ port. */
+#define LADSPA_PORT_CONTROL 0x4
+
+/* Property LADSPA_PORT_AUDIO indicates that the port is a audio
+ port. */
+#define LADSPA_PORT_AUDIO 0x8
+
+#define LADSPA_IS_PORT_INPUT(x) ((x) & LADSPA_PORT_INPUT)
+#define LADSPA_IS_PORT_OUTPUT(x) ((x) & LADSPA_PORT_OUTPUT)
+#define LADSPA_IS_PORT_CONTROL(x) ((x) & LADSPA_PORT_CONTROL)
+#define LADSPA_IS_PORT_AUDIO(x) ((x) & LADSPA_PORT_AUDIO)
+
+/*****************************************************************************/
+
+/* Plugin Port Range Hints:
+
+ The host may wish to provide a representation of data entering or
+ leaving a plugin (e.g. to generate a GUI automatically). To make
+ this more meaningful, the plugin should provide `hints' to the host
+ describing the usual values taken by the data.
+
+ Note that these are only hints. The host may ignore them and the
+ plugin must not assume that data supplied to it is meaningful. If
+ the plugin receives invalid input data it is expected to continue
+ to run without failure and, where possible, produce a sensible
+ output (e.g. a high-pass filter given a negative cutoff frequency
+ might switch to an all-pass mode).
+
+ Hints are meaningful for all input and output ports but hints for
+ input control ports are expected to be particularly useful.
+
+ More hint information is encapsulated in the
+ LADSPA_PortRangeHintDescriptor type which is assembled by ORing
+ individual hint types together. Hints may require further
+ LowerBound and UpperBound information.
+
+ All the hint information for a particular port is aggregated in the
+ LADSPA_PortRangeHint structure. */
+
+typedef int LADSPA_PortRangeHintDescriptor;
+
+/* Hint LADSPA_HINT_BOUNDED_BELOW indicates that the LowerBound field
+ of the LADSPA_PortRangeHint should be considered meaningful. The
+ value in this field should be considered the (inclusive) lower
+ bound of the valid range. If LADSPA_HINT_SAMPLE_RATE is also
+ specified then the value of LowerBound should be multiplied by the
+ sample rate. */
+#define LADSPA_HINT_BOUNDED_BELOW 0x1
+
+/* Hint LADSPA_HINT_BOUNDED_ABOVE indicates that the UpperBound field
+ of the LADSPA_PortRangeHint should be considered meaningful. The
+ value in this field should be considered the (inclusive) upper
+ bound of the valid range. If LADSPA_HINT_SAMPLE_RATE is also
+ specified then the value of UpperBound should be multiplied by the
+ sample rate. */
+#define LADSPA_HINT_BOUNDED_ABOVE 0x2
+
+/* Hint LADSPA_HINT_TOGGLED indicates that the data item should be
+ considered a Boolean toggle. Data less than or equal to zero should
+ be considered `off' or `false,' and data above zero should be
+ considered `on' or `true.' LADSPA_HINT_TOGGLED may not be used in
+ conjunction with any other hint. */
+#define LADSPA_HINT_TOGGLED 0x4
+
+/* Hint LADSPA_HINT_SAMPLE_RATE indicates that any bounds specified
+ should be interpreted as multiples of the sample rate. For
+ instance, a frequency range from 0Hz to the Nyquist frequency (half
+ the sample rate) could be requested by this hint in conjunction
+ with LowerBound = 0 and UpperBound = 0.5. Hosts that support bounds
+ at all must support this hint to retain meaning. */
+#define LADSPA_HINT_SAMPLE_RATE 0x8
+
+/* Hint LADSPA_HINT_LOGARITHMIC indicates that it is likely that the
+ user will find it more intuitive to view values using a logarithmic
+ scale. This is particularly useful for frequencies and gains. */
+#define LADSPA_HINT_LOGARITHMIC 0x10
+
+/* Hint LADSPA_HINT_INTEGER indicates that a user interface would
+ probably wish to provide a stepped control taking only integer
+ values. Any bounds set should be slightly wider than the actual
+ integer range required to avoid floating point rounding errors. For
+ instance, the integer set {0,1,2,3} might be described as [-0.1,
+ 3.1]. */
+#define LADSPA_HINT_INTEGER 0x20
+
+#define LADSPA_IS_HINT_BOUNDED_BELOW(x) ((x) & LADSPA_HINT_BOUNDED_BELOW)
+#define LADSPA_IS_HINT_BOUNDED_ABOVE(x) ((x) & LADSPA_HINT_BOUNDED_ABOVE)
+#define LADSPA_IS_HINT_TOGGLED(x) ((x) & LADSPA_HINT_TOGGLED)
+#define LADSPA_IS_HINT_SAMPLE_RATE(x) ((x) & LADSPA_HINT_SAMPLE_RATE)
+#define LADSPA_IS_HINT_LOGARITHMIC(x) ((x) & LADSPA_HINT_LOGARITHMIC)
+#define LADSPA_IS_HINT_INTEGER(x) ((x) & LADSPA_HINT_INTEGER)
+
+typedef struct _LADSPA_PortRangeHint {
+
+ /* Hints about the port. */
+ LADSPA_PortRangeHintDescriptor HintDescriptor;
+
+ /* Meaningful when hint LADSPA_HINT_BOUNDED_BELOW is active. When
+ LADSPA_HINT_SAMPLE_RATE is also active then this value should be
+ multiplied by the relevant sample rate. */
+ LADSPA_Data LowerBound;
+
+ /* Meaningful when hint LADSPA_HINT_BOUNDED_ABOVE is active. When
+ LADSPA_HINT_SAMPLE_RATE is also active then this value should be
+ multiplied by the relevant sample rate. */
+ LADSPA_Data UpperBound;
+
+} LADSPA_PortRangeHint;
+
+/*****************************************************************************/
+
+/* Plugin Handles:
+
+ 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 should not attempt to interpret it. The plugin
+ may use it to reference internal instance data. */
+
+typedef void * LADSPA_Handle;
+
+/*****************************************************************************/
+
+/* Descriptor for a Type of Plugin:
+
+ This structure is used to describe a plugin type. It provides a
+ number of functions to examine the type, instantiate it, link it to
+ buffers and workspaces and to run it. */
+
+typedef struct _LADSPA_Descriptor {
+
+ /* This numeric identifier indicates the plugin type
+ uniquely. Plugin programmers may reserve ranges of IDs from a
+ central body to avoid clashes. Hosts may assume that IDs are
+ below 0x1000000. */
+ unsigned long UniqueID;
+
+ /* This identifier can be used as a unique, case-sensitive
+ identifier for the plugin type within the plugin file. Plugin
+ types should be identified by file and label rather than by index
+ or plugin name, which may be changed in new plugin
+ versions. Labels must not contain white-space characters. */
+ const char * Label;
+
+ /* This indicates a number of properties of the plugin. */
+ LADSPA_Properties Properties;
+
+ /* This member points to the null-terminated name of the plugin
+ (e.g. "Sine Oscillator"). */
+ const char * Name;
+
+ /* This member points to the null-terminated string indicating the
+ maker of the plugin. This can be an empty string but not NULL. */
+ const char * Maker;
+
+ /* This member points to the null-terminated string indicating any
+ copyright applying to the plugin. If no Copyright applies the
+ string "None" should be used. */
+ const char * Copyright;
+
+ /* This indicates the number of ports (input AND output) present on
+ the plugin. */
+ unsigned long PortCount;
+
+ /* This member indicates an array of port descriptors. Valid indices
+ vary from 0 to PortCount-1. */
+ const LADSPA_PortDescriptor * PortDescriptors;
+
+ /* This member indicates an array of null-terminated strings
+ describing ports (e.g. "Frequency (Hz)"). Valid indices vary from
+ 0 to PortCount-1. */
+ const char * const * PortNames;
+
+ /* This member indicates an array of range hints for each port (see
+ above). Valid indices vary from 0 to PortCount-1. */
+ const LADSPA_PortRangeHint * PortRangeHints;
+
+ /* This may be used by the plugin developer to pass any custom
+ implementation data into an instantiate call. It must not be used
+ or interpreted by the host. It is expected that most plugin
+ writers will not use this facility as LADSPA_Handle should be
+ used to hold instance data. */
+ void * ImplementationData;
+
+ /* This member is a 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. The
+ plugin descriptor from which this instantiate function was found
+ must also be passed. This function must return NULL if
+ instantiation fails.
+
+ Note that instance initialisation should generally occur in
+ activate() rather than here. */
+ LADSPA_Handle (*instantiate)(const struct _LADSPA_Descriptor * Descriptor,
+ unsigned long SampleRate);
+
+ /* This member is a function pointer that connects a port on an
+ instantiated plugin to a memory location at which a block of data
+ for the port will be read/written. The data location is expected
+ to be an array of LADSPA_Data for audio ports or a single
+ LADSPA_Data value for control ports. Memory issues will be
+ managed by the host. The plugin must read/write the data at these
+ locations every time run() or run_adding() is called and the data
+ present at the time of this connection call should not be
+ considered meaningful.
+
+ 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.
+
+ connect_port() must be called at least once for each port before
+ run() or run_adding() is called. When working with blocks of
+ LADSPA_Data the plugin should 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 samples.
+
+ 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 LADSPA_PROPERTY_INPLACE_BROKEN).
+ However, overlapped buffers or use of a single buffer for both
+ audio and control data may result in unexpected behaviour. */
+ void (*connect_port)(LADSPA_Handle Instance,
+ unsigned long Port,
+ LADSPA_Data * DataLocation);
+
+ /* This member is a 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() and any
+ gain set by set_run_adding_gain(). 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() (or
+ run_adding()) 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. Plugins should not rely
+ on a prompt call to run() after activate(). activate() may not be
+ called again unless deactivate() is called first. Note that
+ connect_port() may be called before or after a call to
+ activate(). */
+ void (*activate)(LADSPA_Handle Instance);
+
+ /* This method is a function pointer that runs an instance of a
+ plugin 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() or run_adding(). 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 property LADSPA_PROPERTY_HARD_RT_CAPABLE
+ then there are various things that the plugin should not do
+ within the run() or run_adding() functions (see above). */
+ void (*run)(LADSPA_Handle Instance,
+ unsigned long SampleCount);
+
+ /* This method is a function pointer that runs an instance of a
+ plugin for a block. This has identical behaviour to run() except
+ in the way data is output from the plugin. When run() is used,
+ values are written directly to the memory areas associated with
+ the output ports. However when run_adding() is called, values
+ must be added to the values already present in the memory
+ areas. Furthermore, output values written must be scaled by the
+ current gain set by set_run_adding_gain() (see below) before
+ addition.
+
+ run_adding() is optional. When it is not provided by a plugin,
+ this function pointer must be set to NULL. When it is provided,
+ the function set_run_adding_gain() must be provided also. */
+ void (*run_adding)(LADSPA_Handle Instance,
+ unsigned long SampleCount);
+
+ /* This method is a function pointer that sets the output gain for
+ use when run_adding() is called (see above). If this function is
+ never called the gain is assumed to default to 1. Gain
+ information should be retained when activate() or deactivate()
+ are called.
+
+ This function should be provided by the plugin if and only if the
+ run_adding() function is provided. When it is absent this
+ function pointer must be set to NULL. */
+ void (*set_run_adding_gain)(LADSPA_Handle Instance,
+ LADSPA_Data Gain);
+
+ /* 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() (or run_adding()) 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. Plugins should
+ not rely on prompt deactivation. Note that connect_port() may be
+ called before or after a call to deactivate().
+
+ Deactivation is not similar to pausing as the plugin instance
+ will be reinitialised when activate() is called to reuse it. */
+ void (*deactivate)(LADSPA_Handle Instance);
+
+ /* Once an instance of a plugin has been finished with it can be
+ deleted using the following 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. */
+ void (*cleanup)(LADSPA_Handle Instance);
+
+} LADSPA_Descriptor;
+
+/**********************************************************************/
+
+/* Accessing a Plugin: */
+
+/* The exact mechanism by which plugins are loaded is host-dependent,
+ however all most hosts will need to know is the name of shared
+ object file containing the plugin types. To allow multiple hosts to
+ share plugin types, hosts may wish to check for environment
+ variable LADSPA_PATH. If present, this should contain a
+ colon-separated path indicating directories that should be searched
+ (in order) when loading plugin types.
+
+ A plugin programmer must include a function called
+ "ladspa_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).
+
+ A host will find the plugin shared object file by one means or
+ another, find the ladspa_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. */
+
+const LADSPA_Descriptor * ladspa_descriptor(unsigned long Index);
+
+/* Datatype corresponding to the ladspa_descriptor() function. */
+typedef const LADSPA_Descriptor *
+(*LADSPA_Descriptor_Function)(unsigned long Index);
+
+/**********************************************************************/
+
+#ifdef __cplusplus
+};
+#endif
+
+#endif /* LADSPA_INCLUDED */
+
+/* EOF */