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gstreamer/ext/ladspa/ladspa.h
Thomas Vander Stichele ba95437449 added ladspa, doesn't have checks yet though 
Original commit message from CVS:
added ladspa, doesn't have checks yet though
2001-12-23 15:26:43 +00:00

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/* ladspa.h
Linux Audio Developer's Simple Plugin API Version 1.0[LGPL].
Copyright (C) 2000-2001 Richard W.E. Furse, Paul Barton-Davis,
Stefan Westerfeld.
This library 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 library 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307
USA. */
#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.
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 */
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