1 /* ladspa.h 2 3 Linux Audio Developer's Simple Plugin API Version 1.1[LGPL]. 4 Copyright (C) 2000-2002 Richard W.E. Furse, Paul Barton-Davis, 5 Stefan Westerfeld. 6 7 This library is free software; you can redistribute it and/or 8 modify it under the terms of the GNU Lesser General Public License 9 as published by the Free Software Foundation; either version 2.1 of 10 the License, or (at your option) any later version. 11 12 This library is distributed in the hope that it will be useful, but 13 WITHOUT ANY WARRANTY; without even the implied warranty of 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 15 Lesser General Public License for more details. 16 17 You should have received a copy of the GNU Lesser General Public 18 License along with this library; if not, write to the Free Software 19 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 20 USA. */ 21 22 #ifndef LADSPA_INCLUDED 23 #define LADSPA_INCLUDED 24 25 #define LADSPA_VERSION "1.1" 26 #define LADSPA_VERSION_MAJOR 1 27 #define LADSPA_VERSION_MINOR 1 28 29 #ifdef __cplusplus 30 extern "C" { 31 #endif 32 33 /*****************************************************************************/ 34 35 /* Overview: 36 37 There is a large number of synthesis packages in use or development 38 on the Linux platform at this time. This API (`The Linux Audio 39 Developer's Simple Plugin API') attempts to give programmers the 40 ability to write simple `plugin' audio processors in C/C++ and link 41 them dynamically (`plug') into a range of these packages (`hosts'). 42 It should be possible for any host and any plugin to communicate 43 completely through this interface. 44 45 This API is deliberately short and simple. To achieve compatibility 46 with a range of promising Linux sound synthesis packages it 47 attempts to find the `greatest common divisor' in their logical 48 behaviour. Having said this, certain limiting decisions are 49 implicit, notably the use of a fixed type (LADSPA_Data) for all 50 data transfer and absence of a parameterised `initialisation' 51 phase. See below for the LADSPA_Data typedef. 52 53 Plugins are expected to distinguish between control and audio 54 data. Plugins have `ports' that are inputs or outputs for audio or 55 control data and each plugin is `run' for a `block' corresponding 56 to a short time interval measured in samples. Audio data is 57 communicated using arrays of LADSPA_Data, allowing a block of audio 58 to be processed by the plugin in a single pass. Control data is 59 communicated using single LADSPA_Data values. Control data has a 60 single value at the start of a call to the `run()' or `run_adding()' 61 function, and may be considered to remain this value for its 62 duration. The plugin may assume that all its input and output ports 63 have been connected to the relevant data location (see the 64 `connect_port()' function below) before it is asked to run. 65 66 Plugins will reside in shared object files suitable for dynamic 67 linking by dlopen() and family. The file will provide a number of 68 `plugin types' that can be used to instantiate actual plugins 69 (sometimes known as `plugin instances') that can be connected 70 together to perform tasks. 71 72 This API contains very limited error-handling. */ 73 74 /*****************************************************************************/ 75 76 /* Fundamental data type passed in and out of plugin. This data type 77 is used to communicate audio samples and control values. It is 78 assumed that the plugin will work sensibly given any numeric input 79 value although it may have a preferred range (see hints below). 80 81 For audio it is generally assumed that 1.0f is the `0dB' reference 82 amplitude and is a `normal' signal level. */ 83 84 typedef float LADSPA_Data; 85 86 /*****************************************************************************/ 87 88 /* Special Plugin Properties: 89 90 Optional features of the plugin type are encapsulated in the 91 LADSPA_Properties type. This is assembled by ORing individual 92 properties together. */ 93 94 95 typedef int LADSPA_Properties; 96 97 /* Property LADSPA_PROPERTY_REALTIME indicates that the plugin has a 98 real-time dependency (e.g. listens to a MIDI device) and so its 99 output must not be cached or subject to significant latency. */ 100 #define LADSPA_PROPERTY_REALTIME 0x1 101 102 /* Property LADSPA_PROPERTY_INPLACE_BROKEN indicates that the plugin 103 may cease to work correctly if the host elects to use the same data 104 location for both input and output (see connect_port()). This 105 should be avoided as enabling this flag makes it impossible for 106 hosts to use the plugin to process audio `in-place.' */ 107 #define LADSPA_PROPERTY_INPLACE_BROKEN 0x2 108 109 /* Property LADSPA_PROPERTY_HARD_RT_CAPABLE indicates that the plugin 110 is capable of running not only in a conventional host but also in a 111 `hard real-time' environment. To qualify for this the plugin must 112 satisfy all of the following: 113 114 (1) The plugin must not use malloc(), free() or other heap memory 115 management within its run() or run_adding() functions. All new 116 memory used in run() must be managed via the stack. These 117 restrictions only apply to the run() function. 118 119 (2) The plugin will not attempt to make use of any library 120 functions with the exceptions of functions in the ANSI standard C 121 and C maths libraries, which the host is expected to provide. 122 123 (3) The plugin will not access files, devices, pipes, sockets, IPC 124 or any other mechanism that might result in process or thread 125 blocking. 126 127 (4) The plugin will take an amount of time to execute a run() or 128 run_adding() call approximately of form (A+B*SampleCount) where A 129 and B depend on the machine and host in use. This amount of time 130 may not depend on input signals or plugin state. The host is left 131 the responsibility to perform timings to estimate upper bounds for 132 A and B. */ 133 #define LADSPA_PROPERTY_HARD_RT_CAPABLE 0x4 134 135 #define LADSPA_IS_REALTIME(x) ((x) & LADSPA_PROPERTY_REALTIME) 136 #define LADSPA_IS_INPLACE_BROKEN(x) ((x) & LADSPA_PROPERTY_INPLACE_BROKEN) 137 #define LADSPA_IS_HARD_RT_CAPABLE(x) ((x) & LADSPA_PROPERTY_HARD_RT_CAPABLE) 138 139 /*****************************************************************************/ 140 141 /* Plugin Ports: 142 143 Plugins have `ports' that are inputs or outputs for audio or 144 data. Ports can communicate arrays of LADSPA_Data (for audio 145 inputs/outputs) or single LADSPA_Data values (for control 146 input/outputs). This information is encapsulated in the 147 LADSPA_PortDescriptor type which is assembled by ORing individual 148 properties together. 149 150 Note that a port must be an input or an output port but not both 151 and that a port must be a control or audio port but not both. */ 152 153 154 typedef int LADSPA_PortDescriptor; 155 156 /* Property LADSPA_PORT_INPUT indicates that the port is an input. */ 157 #define LADSPA_PORT_INPUT 0x1 158 159 /* Property LADSPA_PORT_OUTPUT indicates that the port is an output. */ 160 #define LADSPA_PORT_OUTPUT 0x2 161 162 /* Property LADSPA_PORT_CONTROL indicates that the port is a control 163 port. */ 164 #define LADSPA_PORT_CONTROL 0x4 165 166 /* Property LADSPA_PORT_AUDIO indicates that the port is a audio 167 port. */ 168 #define LADSPA_PORT_AUDIO 0x8 169 170 #define LADSPA_IS_PORT_INPUT(x) ((x) & LADSPA_PORT_INPUT) 171 #define LADSPA_IS_PORT_OUTPUT(x) ((x) & LADSPA_PORT_OUTPUT) 172 #define LADSPA_IS_PORT_CONTROL(x) ((x) & LADSPA_PORT_CONTROL) 173 #define LADSPA_IS_PORT_AUDIO(x) ((x) & LADSPA_PORT_AUDIO) 174 175 /*****************************************************************************/ 176 177 /* Plugin Port Range Hints: 178 179 The host may wish to provide a representation of data entering or 180 leaving a plugin (e.g. to generate a GUI automatically). To make 181 this more meaningful, the plugin should provide `hints' to the host 182 describing the usual values taken by the data. 183 184 Note that these are only hints. The host may ignore them and the 185 plugin must not assume that data supplied to it is meaningful. If 186 the plugin receives invalid input data it is expected to continue 187 to run without failure and, where possible, produce a sensible 188 output (e.g. a high-pass filter given a negative cutoff frequency 189 might switch to an all-pass mode). 190 191 Hints are meaningful for all input and output ports but hints for 192 input control ports are expected to be particularly useful. 193 194 More hint information is encapsulated in the 195 LADSPA_PortRangeHintDescriptor type which is assembled by ORing 196 individual hint types together. Hints may require further 197 LowerBound and UpperBound information. 198 199 All the hint information for a particular port is aggregated in the 200 LADSPA_PortRangeHint structure. */ 201 202 203 typedef int LADSPA_PortRangeHintDescriptor; 204 205 /* Hint LADSPA_HINT_BOUNDED_BELOW indicates that the LowerBound field 206 of the LADSPA_PortRangeHint should be considered meaningful. The 207 value in this field should be considered the (inclusive) lower 208 bound of the valid range. If LADSPA_HINT_SAMPLE_RATE is also 209 specified then the value of LowerBound should be multiplied by the 210 sample rate. */ 211 #define LADSPA_HINT_BOUNDED_BELOW 0x1 212 213 /* Hint LADSPA_HINT_BOUNDED_ABOVE indicates that the UpperBound field 214 of the LADSPA_PortRangeHint should be considered meaningful. The 215 value in this field should be considered the (inclusive) upper 216 bound of the valid range. If LADSPA_HINT_SAMPLE_RATE is also 217 specified then the value of UpperBound should be multiplied by the 218 sample rate. */ 219 #define LADSPA_HINT_BOUNDED_ABOVE 0x2 220 221 /* Hint LADSPA_HINT_TOGGLED indicates that the data item should be 222 considered a Boolean toggle. Data less than or equal to zero should 223 be considered `off' or `false,' and data above zero should be 224 considered `on' or `true.' LADSPA_HINT_TOGGLED may not be used in 225 conjunction with any other hint except LADSPA_HINT_DEFAULT_0 or 226 LADSPA_HINT_DEFAULT_1. */ 227 #define LADSPA_HINT_TOGGLED 0x4 228 229 /* Hint LADSPA_HINT_SAMPLE_RATE indicates that any bounds specified 230 should be interpreted as multiples of the sample rate. For 231 instance, a frequency range from 0Hz to the Nyquist frequency (half 232 the sample rate) could be requested by this hint in conjunction 233 with LowerBound = 0 and UpperBound = 0.5. Hosts that support bounds 234 at all must support this hint to retain meaning. */ 235 #define LADSPA_HINT_SAMPLE_RATE 0x8 236 237 /* Hint LADSPA_HINT_LOGARITHMIC indicates that it is likely that the 238 user will find it more intuitive to view values using a logarithmic 239 scale. This is particularly useful for frequencies and gains. */ 240 #define LADSPA_HINT_LOGARITHMIC 0x10 241 242 /* Hint LADSPA_HINT_INTEGER indicates that a user interface would 243 probably wish to provide a stepped control taking only integer 244 values. Any bounds set should be slightly wider than the actual 245 integer range required to avoid floating point rounding errors. For 246 instance, the integer set {0,1,2,3} might be described as [-0.1, 247 3.1]. */ 248 #define LADSPA_HINT_INTEGER 0x20 249 250 /* The various LADSPA_HINT_HAS_DEFAULT_* hints indicate a `normal' 251 value for the port that is sensible as a default. For instance, 252 this value is suitable for use as an initial value in a user 253 interface or as a value the host might assign to a control port 254 when the user has not provided one. Defaults are encoded using a 255 mask so only one default may be specified for a port. Some of the 256 hints make use of lower and upper bounds, in which case the 257 relevant bound or bounds must be available and 258 LADSPA_HINT_SAMPLE_RATE must be applied as usual. The resulting 259 default must be rounded if LADSPA_HINT_INTEGER is present. Default 260 values were introduced in LADSPA v1.1. */ 261 #define LADSPA_HINT_DEFAULT_MASK 0x3C0 262 263 /* This default values indicates that no default is provided. */ 264 #define LADSPA_HINT_DEFAULT_NONE 0x0 265 266 /* This default hint indicates that the suggested lower bound for the 267 port should be used. */ 268 #define LADSPA_HINT_DEFAULT_MINIMUM 0x40 269 270 /* This default hint indicates that a low value between the suggested 271 lower and upper bounds should be chosen. For ports with 272 LADSPA_HINT_LOGARITHMIC, this should be exp(log(lower) * 0.75 + 273 log(upper) * 0.25). Otherwise, this should be (lower * 0.75 + upper 274 * 0.25). */ 275 #define LADSPA_HINT_DEFAULT_LOW 0x80 276 277 /* This default hint indicates that a middle value between the 278 suggested lower and upper bounds should be chosen. For ports with 279 LADSPA_HINT_LOGARITHMIC, this should be exp(log(lower) * 0.5 + 280 log(upper) * 0.5). Otherwise, this should be (lower * 0.5 + upper * 281 0.5). */ 282 #define LADSPA_HINT_DEFAULT_MIDDLE 0xC0 283 284 /* This default hint indicates that a high value between the suggested 285 lower and upper bounds should be chosen. For ports with 286 LADSPA_HINT_LOGARITHMIC, this should be exp(log(lower) * 0.25 + 287 log(upper) * 0.75). Otherwise, this should be (lower * 0.25 + upper 288 * 0.75). */ 289 #define LADSPA_HINT_DEFAULT_HIGH 0x100 290 291 /* This default hint indicates that the suggested upper bound for the 292 port should be used. */ 293 #define LADSPA_HINT_DEFAULT_MAXIMUM 0x140 294 295 /* This default hint indicates that the number 0 should be used. Note 296 that this default may be used in conjunction with 297 LADSPA_HINT_TOGGLED. */ 298 #define LADSPA_HINT_DEFAULT_0 0x200 299 300 /* This default hint indicates that the number 1 should be used. Note 301 that this default may be used in conjunction with 302 LADSPA_HINT_TOGGLED. */ 303 #define LADSPA_HINT_DEFAULT_1 0x240 304 305 /* This default hint indicates that the number 100 should be used. */ 306 #define LADSPA_HINT_DEFAULT_100 0x280 307 308 /* This default hint indicates that the Hz frequency of `concert A' 309 should be used. This will be 440 unless the host uses an unusual 310 tuning convention, in which case it may be within a few Hz. */ 311 #define LADSPA_HINT_DEFAULT_440 0x2C0 312 313 #define LADSPA_IS_HINT_BOUNDED_BELOW(x) ((x) & LADSPA_HINT_BOUNDED_BELOW) 314 #define LADSPA_IS_HINT_BOUNDED_ABOVE(x) ((x) & LADSPA_HINT_BOUNDED_ABOVE) 315 #define LADSPA_IS_HINT_TOGGLED(x) ((x) & LADSPA_HINT_TOGGLED) 316 #define LADSPA_IS_HINT_SAMPLE_RATE(x) ((x) & LADSPA_HINT_SAMPLE_RATE) 317 #define LADSPA_IS_HINT_LOGARITHMIC(x) ((x) & LADSPA_HINT_LOGARITHMIC) 318 #define LADSPA_IS_HINT_INTEGER(x) ((x) & LADSPA_HINT_INTEGER) 319 320 #define LADSPA_IS_HINT_HAS_DEFAULT(x) ((x) & LADSPA_HINT_DEFAULT_MASK) 321 #define LADSPA_IS_HINT_DEFAULT_MINIMUM(x) (((x) & LADSPA_HINT_DEFAULT_MASK) \ 322 == LADSPA_HINT_DEFAULT_MINIMUM) 323 #define LADSPA_IS_HINT_DEFAULT_LOW(x) (((x) & LADSPA_HINT_DEFAULT_MASK) \ 324 == LADSPA_HINT_DEFAULT_LOW) 325 #define LADSPA_IS_HINT_DEFAULT_MIDDLE(x) (((x) & LADSPA_HINT_DEFAULT_MASK) \ 326 == LADSPA_HINT_DEFAULT_MIDDLE) 327 #define LADSPA_IS_HINT_DEFAULT_HIGH(x) (((x) & LADSPA_HINT_DEFAULT_MASK) \ 328 == LADSPA_HINT_DEFAULT_HIGH) 329 #define LADSPA_IS_HINT_DEFAULT_MAXIMUM(x) (((x) & LADSPA_HINT_DEFAULT_MASK) \ 330 == LADSPA_HINT_DEFAULT_MAXIMUM) 331 #define LADSPA_IS_HINT_DEFAULT_0(x) (((x) & LADSPA_HINT_DEFAULT_MASK) \ 332 == LADSPA_HINT_DEFAULT_0) 333 #define LADSPA_IS_HINT_DEFAULT_1(x) (((x) & LADSPA_HINT_DEFAULT_MASK) \ 334 == LADSPA_HINT_DEFAULT_1) 335 #define LADSPA_IS_HINT_DEFAULT_100(x) (((x) & LADSPA_HINT_DEFAULT_MASK) \ 336 == LADSPA_HINT_DEFAULT_100) 337 #define LADSPA_IS_HINT_DEFAULT_440(x) (((x) & LADSPA_HINT_DEFAULT_MASK) \ 338 == LADSPA_HINT_DEFAULT_440) 339 340 typedef struct _LADSPA_PortRangeHint { 341 342 /* Hints about the port. */ 343 LADSPA_PortRangeHintDescriptor HintDescriptor; 344 345 /* Meaningful when hint LADSPA_HINT_BOUNDED_BELOW is active. When 346 LADSPA_HINT_SAMPLE_RATE is also active then this value should be 347 multiplied by the relevant sample rate. */ 348 LADSPA_Data LowerBound; 349 350 /* Meaningful when hint LADSPA_HINT_BOUNDED_ABOVE is active. When 351 LADSPA_HINT_SAMPLE_RATE is also active then this value should be 352 multiplied by the relevant sample rate. */ 353 LADSPA_Data UpperBound; 354 355 } LADSPA_PortRangeHint; 356 357 /*****************************************************************************/ 358 359 /* Plugin Handles: 360 361 This plugin handle indicates a particular instance of the plugin 362 concerned. It is valid to compare this to NULL (0 for C++) but 363 otherwise the host should not attempt to interpret it. The plugin 364 may use it to reference internal instance data. */ 365 366 typedef void * LADSPA_Handle; 367 368 /*****************************************************************************/ 369 370 /* Descriptor for a Type of Plugin: 371 372 This structure is used to describe a plugin type. It provides a 373 number of functions to examine the type, instantiate it, link it to 374 buffers and workspaces and to run it. */ 375 376 typedef struct _LADSPA_Descriptor { 377 378 /* This numeric identifier indicates the plugin type 379 uniquely. Plugin programmers may reserve ranges of IDs from a 380 central body to avoid clashes. Hosts may assume that IDs are 381 below 0x1000000. */ 382 unsigned long UniqueID; 383 384 /* This identifier can be used as a unique, case-sensitive 385 identifier for the plugin type within the plugin file. Plugin 386 types should be identified by file and label rather than by index 387 or plugin name, which may be changed in new plugin 388 versions. Labels must not contain white-space characters. */ 389 const char * Label; 390 391 /* This indicates a number of properties of the plugin. */ 392 LADSPA_Properties Properties; 393 394 /* This member points to the null-terminated name of the plugin 395 (e.g. "Sine Oscillator"). */ 396 const char * Name; 397 398 /* This member points to the null-terminated string indicating the 399 maker of the plugin. This can be an empty string but not NULL. */ 400 const char * Maker; 401 402 /* This member points to the null-terminated string indicating any 403 copyright applying to the plugin. If no Copyright applies the 404 string "None" should be used. */ 405 const char * Copyright; 406 407 /* This indicates the number of ports (input AND output) present on 408 the plugin. */ 409 unsigned long PortCount; 410 411 /* This member indicates an array of port descriptors. Valid indices 412 vary from 0 to PortCount-1. */ 413 const LADSPA_PortDescriptor * PortDescriptors; 414 415 /* This member indicates an array of null-terminated strings 416 describing ports (e.g. "Frequency (Hz)"). Valid indices vary from 417 0 to PortCount-1. */ 418 const char * const * PortNames; 419 420 /* This member indicates an array of range hints for each port (see 421 above). Valid indices vary from 0 to PortCount-1. */ 422 const LADSPA_PortRangeHint * PortRangeHints; 423 424 /* This may be used by the plugin developer to pass any custom 425 implementation data into an instantiate call. It must not be used 426 or interpreted by the host. It is expected that most plugin 427 writers will not use this facility as LADSPA_Handle should be 428 used to hold instance data. */ 429 void * ImplementationData; 430 431 /* This member is a function pointer that instantiates a plugin. A 432 handle is returned indicating the new plugin instance. The 433 instantiation function accepts a sample rate as a parameter. The 434 plugin descriptor from which this instantiate function was found 435 must also be passed. This function must return NULL if 436 instantiation fails. 437 438 Note that instance initialisation should generally occur in 439 activate() rather than here. */ 440 LADSPA_Handle (*instantiate)(const struct _LADSPA_Descriptor * Descriptor, 441 unsigned long SampleRate); 442 443 /* This member is a function pointer that connects a port on an 444 instantiated plugin to a memory location at which a block of data 445 for the port will be read/written. The data location is expected 446 to be an array of LADSPA_Data for audio ports or a single 447 LADSPA_Data value for control ports. Memory issues will be 448 managed by the host. The plugin must read/write the data at these 449 locations every time run() or run_adding() is called and the data 450 present at the time of this connection call should not be 451 considered meaningful. 452 453 connect_port() may be called more than once for a plugin instance 454 to allow the host to change the buffers that the plugin is 455 reading or writing. These calls may be made before or after 456 activate() or deactivate() calls. 457 458 connect_port() must be called at least once for each port before 459 run() or run_adding() is called. When working with blocks of 460 LADSPA_Data the plugin should pay careful attention to the block 461 size passed to the run function as the block allocated may only 462 just be large enough to contain the block of samples. 463 464 Plugin writers should be aware that the host may elect to use the 465 same buffer for more than one port and even use the same buffer 466 for both input and output (see LADSPA_PROPERTY_INPLACE_BROKEN). 467 However, overlapped buffers or use of a single buffer for both 468 audio and control data may result in unexpected behaviour. */ 469 void (*connect_port)(LADSPA_Handle Instance, 470 unsigned long Port, 471 LADSPA_Data * DataLocation); 472 473 /* This member is a function pointer that initialises a plugin 474 instance and activates it for use. This is separated from 475 instantiate() to aid real-time support and so that hosts can 476 reinitialise a plugin instance by calling deactivate() and then 477 activate(). In this case the plugin instance must reset all state 478 information dependent on the history of the plugin instance 479 except for any data locations provided by connect_port() and any 480 gain set by set_run_adding_gain(). If there is nothing for 481 activate() to do then the plugin writer may provide a NULL rather 482 than an empty function. 483 484 When present, hosts must call this function once before run() (or 485 run_adding()) is called for the first time. This call should be 486 made as close to the run() call as possible and indicates to 487 real-time plugins that they are now live. Plugins should not rely 488 on a prompt call to run() after activate(). activate() may not be 489 called again unless deactivate() is called first. Note that 490 connect_port() may be called before or after a call to 491 activate(). */ 492 void (*activate)(LADSPA_Handle Instance); 493 494 /* This method is a function pointer that runs an instance of a 495 plugin for a block. Two parameters are required: the first is a 496 handle to the particular instance to be run and the second 497 indicates the block size (in samples) for which the plugin 498 instance may run. 499 500 Note that if an activate() function exists then it must be called 501 before run() or run_adding(). If deactivate() is called for a 502 plugin instance then the plugin instance may not be reused until 503 activate() has been called again. 504 505 If the plugin has the property LADSPA_PROPERTY_HARD_RT_CAPABLE 506 then there are various things that the plugin should not do 507 within the run() or run_adding() functions (see above). */ 508 void (*run)(LADSPA_Handle Instance, 509 unsigned long SampleCount); 510 511 /* This method is a function pointer that runs an instance of a 512 plugin for a block. This has identical behaviour to run() except 513 in the way data is output from the plugin. When run() is used, 514 values are written directly to the memory areas associated with 515 the output ports. However when run_adding() is called, values 516 must be added to the values already present in the memory 517 areas. Furthermore, output values written must be scaled by the 518 current gain set by set_run_adding_gain() (see below) before 519 addition. 520 521 run_adding() is optional. When it is not provided by a plugin, 522 this function pointer must be set to NULL. When it is provided, 523 the function set_run_adding_gain() must be provided also. */ 524 void (*run_adding)(LADSPA_Handle Instance, 525 unsigned long SampleCount); 526 527 /* This method is a function pointer that sets the output gain for 528 use when run_adding() is called (see above). If this function is 529 never called the gain is assumed to default to 1. Gain 530 information should be retained when activate() or deactivate() 531 are called. 532 533 This function should be provided by the plugin if and only if the 534 run_adding() function is provided. When it is absent this 535 function pointer must be set to NULL. */ 536 void (*set_run_adding_gain)(LADSPA_Handle Instance, 537 LADSPA_Data Gain); 538 539 /* This is the counterpart to activate() (see above). If there is 540 nothing for deactivate() to do then the plugin writer may provide 541 a NULL rather than an empty function. 542 543 Hosts must deactivate all activated units after they have been 544 run() (or run_adding()) for the last time. This call should be 545 made as close to the last run() call as possible and indicates to 546 real-time plugins that they are no longer live. Plugins should 547 not rely on prompt deactivation. Note that connect_port() may be 548 called before or after a call to deactivate(). 549 550 Deactivation is not similar to pausing as the plugin instance 551 will be reinitialised when activate() is called to reuse it. */ 552 void (*deactivate)(LADSPA_Handle Instance); 553 554 /* Once an instance of a plugin has been finished with it can be 555 deleted using the following function. The instance handle passed 556 ceases to be valid after this call. 557 558 If activate() was called for a plugin instance then a 559 corresponding call to deactivate() must be made before cleanup() 560 is called. */ 561 void (*cleanup)(LADSPA_Handle Instance); 562 563 } LADSPA_Descriptor; 564 565 /**********************************************************************/ 566 567 /* Accessing a Plugin: */ 568 569 /* The exact mechanism by which plugins are loaded is host-dependent, 570 however all most hosts will need to know is the name of shared 571 object file containing the plugin types. To allow multiple hosts to 572 share plugin types, hosts may wish to check for environment 573 variable LADSPA_PATH. If present, this should contain a 574 colon-separated path indicating directories that should be searched 575 (in order) when loading plugin types. 576 577 A plugin programmer must include a function called 578 "ladspa_descriptor" with the following function prototype within 579 the shared object file. This function will have C-style linkage (if 580 you are using C++ this is taken care of by the `extern "C"' clause 581 at the top of the file). 582 583 A host will find the plugin shared object file by one means or 584 another, find the ladspa_descriptor() function, call it, and 585 proceed from there. 586 587 Plugin types are accessed by index (not ID) using values from 0 588 upwards. Out of range indexes must result in this function 589 returning NULL, so the plugin count can be determined by checking 590 for the least index that results in NULL being returned. */ 591 592 const LADSPA_Descriptor * ladspa_descriptor(unsigned long Index); 593 594 /* Datatype corresponding to the ladspa_descriptor() function. */ 595 typedef const LADSPA_Descriptor * 596 (*LADSPA_Descriptor_Function)(unsigned long Index); 597 598 /**********************************************************************/ 599 600 #ifdef __cplusplus 601 } 602 #endif 603 604 #endif /* LADSPA_INCLUDED */ 605 606 /* EOF */ 607