1 /* 2 Simple DirectMedia Layer 3 Copyright (C) 1997-2025 Sam Lantinga <slouken@libsdl.org> 4 5 This software is provided 'as-is', without any express or implied 6 warranty. In no event will the authors be held liable for any damages 7 arising from the use of this software. 8 9 Permission is granted to anyone to use this software for any purpose, 10 including commercial applications, and to alter it and redistribute it 11 freely, subject to the following restrictions: 12 13 1. The origin of this software must not be misrepresented; you must not 14 claim that you wrote the original software. If you use this software 15 in a product, an acknowledgment in the product documentation would be 16 appreciated but is not required. 17 2. Altered source versions must be plainly marked as such, and must not be 18 misrepresented as being the original software. 19 3. This notice may not be removed or altered from any source distribution. 20 */ 21 22 /* !!! FIXME: several functions in here need Doxygen comments. */ 23 24 /** 25 * # CategoryAudio 26 * 27 * Access to the raw audio mixing buffer for the SDL library. 28 */ 29 30 #ifndef SDL_audio_h_ 31 #define SDL_audio_h_ 32 33 #include "SDL_stdinc.h" 34 #include "SDL_error.h" 35 #include "SDL_endian.h" 36 #include "SDL_mutex.h" 37 #include "SDL_thread.h" 38 #include "SDL_rwops.h" 39 40 #include "begin_code.h" 41 /* Set up for C function definitions, even when using C++ */ 42 #ifdef __cplusplus 43 extern "C" { 44 #endif 45 46 /** 47 * Audio format flags. 48 * 49 * These are what the 16 bits in SDL_AudioFormat currently mean... 50 * (Unspecified bits are always zero). 51 * 52 * ``` 53 * ++-----------------------sample is signed if set 54 * || 55 * || ++-----------sample is bigendian if set 56 * || || 57 * || || ++---sample is float if set 58 * || || || 59 * || || || +---sample bit size---+ 60 * || || || | | 61 * 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00 62 * ``` 63 * 64 * There are macros in SDL 2.0 and later to query these bits. 65 */ 66 typedef Uint16 SDL_AudioFormat; 67 68 /** 69 * \name Audio flags 70 */ 71 /* @{ */ 72 73 #define SDL_AUDIO_MASK_BITSIZE (0xFF) 74 #define SDL_AUDIO_MASK_DATATYPE (1<<8) 75 #define SDL_AUDIO_MASK_ENDIAN (1<<12) 76 #define SDL_AUDIO_MASK_SIGNED (1<<15) 77 #define SDL_AUDIO_BITSIZE(x) (x & SDL_AUDIO_MASK_BITSIZE) 78 #define SDL_AUDIO_ISFLOAT(x) (x & SDL_AUDIO_MASK_DATATYPE) 79 #define SDL_AUDIO_ISBIGENDIAN(x) (x & SDL_AUDIO_MASK_ENDIAN) 80 #define SDL_AUDIO_ISSIGNED(x) (x & SDL_AUDIO_MASK_SIGNED) 81 #define SDL_AUDIO_ISINT(x) (!SDL_AUDIO_ISFLOAT(x)) 82 #define SDL_AUDIO_ISLITTLEENDIAN(x) (!SDL_AUDIO_ISBIGENDIAN(x)) 83 #define SDL_AUDIO_ISUNSIGNED(x) (!SDL_AUDIO_ISSIGNED(x)) 84 85 /** 86 * \name Audio format flags 87 * 88 * Defaults to LSB byte order. 89 */ 90 /* @{ */ 91 #define AUDIO_U8 0x0008 /**< Unsigned 8-bit samples */ 92 #define AUDIO_S8 0x8008 /**< Signed 8-bit samples */ 93 #define AUDIO_U16LSB 0x0010 /**< Unsigned 16-bit samples */ 94 #define AUDIO_S16LSB 0x8010 /**< Signed 16-bit samples */ 95 #define AUDIO_U16MSB 0x1010 /**< As above, but big-endian byte order */ 96 #define AUDIO_S16MSB 0x9010 /**< As above, but big-endian byte order */ 97 #define AUDIO_U16 AUDIO_U16LSB 98 #define AUDIO_S16 AUDIO_S16LSB 99 /* @} */ 100 101 /** 102 * \name int32 support 103 */ 104 /* @{ */ 105 #define AUDIO_S32LSB 0x8020 /**< 32-bit integer samples */ 106 #define AUDIO_S32MSB 0x9020 /**< As above, but big-endian byte order */ 107 #define AUDIO_S32 AUDIO_S32LSB 108 /* @} */ 109 110 /** 111 * \name float32 support 112 */ 113 /* @{ */ 114 #define AUDIO_F32LSB 0x8120 /**< 32-bit floating point samples */ 115 #define AUDIO_F32MSB 0x9120 /**< As above, but big-endian byte order */ 116 #define AUDIO_F32 AUDIO_F32LSB 117 /* @} */ 118 119 /** 120 * \name Native audio byte ordering 121 */ 122 /* @{ */ 123 #if SDL_BYTEORDER == SDL_LIL_ENDIAN 124 #define AUDIO_U16SYS AUDIO_U16LSB 125 #define AUDIO_S16SYS AUDIO_S16LSB 126 #define AUDIO_S32SYS AUDIO_S32LSB 127 #define AUDIO_F32SYS AUDIO_F32LSB 128 #else 129 #define AUDIO_U16SYS AUDIO_U16MSB 130 #define AUDIO_S16SYS AUDIO_S16MSB 131 #define AUDIO_S32SYS AUDIO_S32MSB 132 #define AUDIO_F32SYS AUDIO_F32MSB 133 #endif 134 /* @} */ 135 136 /** 137 * \name Allow change flags 138 * 139 * Which audio format changes are allowed when opening a device. 140 */ 141 /* @{ */ 142 #define SDL_AUDIO_ALLOW_FREQUENCY_CHANGE 0x00000001 143 #define SDL_AUDIO_ALLOW_FORMAT_CHANGE 0x00000002 144 #define SDL_AUDIO_ALLOW_CHANNELS_CHANGE 0x00000004 145 #define SDL_AUDIO_ALLOW_SAMPLES_CHANGE 0x00000008 146 #define SDL_AUDIO_ALLOW_ANY_CHANGE (SDL_AUDIO_ALLOW_FREQUENCY_CHANGE|SDL_AUDIO_ALLOW_FORMAT_CHANGE|SDL_AUDIO_ALLOW_CHANNELS_CHANGE|SDL_AUDIO_ALLOW_SAMPLES_CHANGE) 147 /* @} */ 148 149 /* @} *//* Audio flags */ 150 151 /** 152 * This function is called when the audio device needs more data. 153 * 154 * \param userdata An application-specific parameter saved in the 155 * SDL_AudioSpec structure. 156 * \param stream A pointer to the audio data buffer. 157 * \param len Length of **stream** in bytes. 158 */ 159 typedef void (SDLCALL * SDL_AudioCallback) (void *userdata, Uint8 * stream, 160 int len); 161 162 /** 163 * The calculated values in this structure are calculated by SDL_OpenAudio(). 164 * 165 * For multi-channel audio, the default SDL channel mapping is: 166 * 167 * ``` 168 * 2: FL FR (stereo) 169 * 3: FL FR LFE (2.1 surround) 170 * 4: FL FR BL BR (quad) 171 * 5: FL FR LFE BL BR (4.1 surround) 172 * 6: FL FR FC LFE SL SR (5.1 surround - last two can also be BL BR) 173 * 7: FL FR FC LFE BC SL SR (6.1 surround) 174 * 8: FL FR FC LFE BL BR SL SR (7.1 surround) 175 * ``` 176 */ 177 typedef struct SDL_AudioSpec 178 { 179 int freq; /**< DSP frequency -- samples per second */ 180 SDL_AudioFormat format; /**< Audio data format */ 181 Uint8 channels; /**< Number of channels: 1 mono, 2 stereo */ 182 Uint8 silence; /**< Audio buffer silence value (calculated) */ 183 Uint16 samples; /**< Audio buffer size in sample FRAMES (total samples divided by channel count) */ 184 Uint16 padding; /**< Necessary for some compile environments */ 185 Uint32 size; /**< Audio buffer size in bytes (calculated) */ 186 SDL_AudioCallback callback; /**< Callback that feeds the audio device (NULL to use SDL_QueueAudio()). */ 187 void *userdata; /**< Userdata passed to callback (ignored for NULL callbacks). */ 188 } SDL_AudioSpec; 189 190 191 struct SDL_AudioCVT; 192 typedef void (SDLCALL * SDL_AudioFilter) (struct SDL_AudioCVT * cvt, 193 SDL_AudioFormat format); 194 195 /** 196 * Upper limit of filters in SDL_AudioCVT 197 * 198 * The maximum number of SDL_AudioFilter functions in SDL_AudioCVT is 199 * currently limited to 9. The SDL_AudioCVT.filters array has 10 pointers, one 200 * of which is the terminating NULL pointer. 201 */ 202 #define SDL_AUDIOCVT_MAX_FILTERS 9 203 204 /** 205 * \struct SDL_AudioCVT 206 * \brief A structure to hold a set of audio conversion filters and buffers. 207 * 208 * Note that various parts of the conversion pipeline can take advantage 209 * of SIMD operations (like SSE2, for example). SDL_AudioCVT doesn't require 210 * you to pass it aligned data, but can possibly run much faster if you 211 * set both its (buf) field to a pointer that is aligned to 16 bytes, and its 212 * (len) field to something that's a multiple of 16, if possible. 213 */ 214 #if defined(__GNUC__) && !defined(__CHERI_PURE_CAPABILITY__) 215 /* This structure is 84 bytes on 32-bit architectures, make sure GCC doesn't 216 pad it out to 88 bytes to guarantee ABI compatibility between compilers. 217 This is not a concern on CHERI architectures, where pointers must be stored 218 at aligned locations otherwise they will become invalid, and thus structs 219 containing pointers cannot be packed without giving a warning or error. 220 vvv 221 The next time we rev the ABI, make sure to size the ints and add padding. 222 */ 223 #define SDL_AUDIOCVT_PACKED __attribute__((packed)) 224 #else 225 #define SDL_AUDIOCVT_PACKED 226 #endif 227 /* */ 228 typedef struct SDL_AudioCVT 229 { 230 int needed; /**< Set to 1 if conversion possible */ 231 SDL_AudioFormat src_format; /**< Source audio format */ 232 SDL_AudioFormat dst_format; /**< Target audio format */ 233 double rate_incr; /**< Rate conversion increment */ 234 Uint8 *buf; /**< Buffer to hold entire audio data */ 235 int len; /**< Length of original audio buffer */ 236 int len_cvt; /**< Length of converted audio buffer */ 237 int len_mult; /**< buffer must be len*len_mult big */ 238 double len_ratio; /**< Given len, final size is len*len_ratio */ 239 SDL_AudioFilter filters[SDL_AUDIOCVT_MAX_FILTERS + 1]; /**< NULL-terminated list of filter functions */ 240 int filter_index; /**< Current audio conversion function */ 241 } SDL_AUDIOCVT_PACKED SDL_AudioCVT; 242 243 244 /* Function prototypes */ 245 246 /** 247 * \name Driver discovery functions 248 * 249 * These functions return the list of built in audio drivers, in the 250 * order that they are normally initialized by default. 251 */ 252 /* @{ */ 253 254 /** 255 * Use this function to get the number of built-in audio drivers. 256 * 257 * This function returns a hardcoded number. This never returns a negative 258 * value; if there are no drivers compiled into this build of SDL, this 259 * function returns zero. The presence of a driver in this list does not mean 260 * it will function, it just means SDL is capable of interacting with that 261 * interface. For example, a build of SDL might have esound support, but if 262 * there's no esound server available, SDL's esound driver would fail if used. 263 * 264 * By default, SDL tries all drivers, in its preferred order, until one is 265 * found to be usable. 266 * 267 * \returns the number of built-in audio drivers. 268 * 269 * \since This function is available since SDL 2.0.0. 270 * 271 * \sa SDL_GetAudioDriver 272 */ 273 extern DECLSPEC int SDLCALL SDL_GetNumAudioDrivers(void); 274 275 /** 276 * Use this function to get the name of a built in audio driver. 277 * 278 * The list of audio drivers is given in the order that they are normally 279 * initialized by default; the drivers that seem more reasonable to choose 280 * first (as far as the SDL developers believe) are earlier in the list. 281 * 282 * The names of drivers are all simple, low-ASCII identifiers, like "alsa", 283 * "coreaudio" or "xaudio2". These never have Unicode characters, and are not 284 * meant to be proper names. 285 * 286 * \param index the index of the audio driver; the value ranges from 0 to 287 * SDL_GetNumAudioDrivers() - 1. 288 * \returns the name of the audio driver at the requested index, or NULL if an 289 * invalid index was specified. 290 * 291 * \since This function is available since SDL 2.0.0. 292 * 293 * \sa SDL_GetNumAudioDrivers 294 */ 295 extern DECLSPEC const char *SDLCALL SDL_GetAudioDriver(int index); 296 /* @} */ 297 298 /** 299 * \name Initialization and cleanup 300 * 301 * \internal These functions are used internally, and should not be used unless 302 * you have a specific need to specify the audio driver you want to 303 * use. You should normally use SDL_Init() or SDL_InitSubSystem(). 304 */ 305 /* @{ */ 306 307 /** 308 * Use this function to initialize a particular audio driver. 309 * 310 * This function is used internally, and should not be used unless you have a 311 * specific need to designate the audio driver you want to use. You should 312 * normally use SDL_Init() or SDL_InitSubSystem(). 313 * 314 * \param driver_name the name of the desired audio driver. 315 * \returns 0 on success or a negative error code on failure; call 316 * SDL_GetError() for more information. 317 * 318 * \since This function is available since SDL 2.0.0. 319 * 320 * \sa SDL_AudioQuit 321 */ 322 extern DECLSPEC int SDLCALL SDL_AudioInit(const char *driver_name); 323 324 /** 325 * Use this function to shut down audio if you initialized it with 326 * SDL_AudioInit(). 327 * 328 * This function is used internally, and should not be used unless you have a 329 * specific need to specify the audio driver you want to use. You should 330 * normally use SDL_Quit() or SDL_QuitSubSystem(). 331 * 332 * \since This function is available since SDL 2.0.0. 333 * 334 * \sa SDL_AudioInit 335 */ 336 extern DECLSPEC void SDLCALL SDL_AudioQuit(void); 337 /* @} */ 338 339 /** 340 * Get the name of the current audio driver. 341 * 342 * The returned string points to internal static memory and thus never becomes 343 * invalid, even if you quit the audio subsystem and initialize a new driver 344 * (although such a case would return a different static string from another 345 * call to this function, of course). As such, you should not modify or free 346 * the returned string. 347 * 348 * \returns the name of the current audio driver or NULL if no driver has been 349 * initialized. 350 * 351 * \since This function is available since SDL 2.0.0. 352 * 353 * \sa SDL_AudioInit 354 */ 355 extern DECLSPEC const char *SDLCALL SDL_GetCurrentAudioDriver(void); 356 357 /** 358 * This function is a legacy means of opening the audio device. 359 * 360 * This function remains for compatibility with SDL 1.2, but also because it's 361 * slightly easier to use than the new functions in SDL 2.0. The new, more 362 * powerful, and preferred way to do this is SDL_OpenAudioDevice(). 363 * 364 * This function is roughly equivalent to: 365 * 366 * ```c 367 * SDL_OpenAudioDevice(NULL, 0, desired, obtained, SDL_AUDIO_ALLOW_ANY_CHANGE); 368 * ``` 369 * 370 * With two notable exceptions: 371 * 372 * - If `obtained` is NULL, we use `desired` (and allow no changes), which 373 * means desired will be modified to have the correct values for silence, 374 * etc, and SDL will convert any differences between your app's specific 375 * request and the hardware behind the scenes. 376 * - The return value is always success or failure, and not a device ID, which 377 * means you can only have one device open at a time with this function. 378 * 379 * \param desired an SDL_AudioSpec structure representing the desired output 380 * format. Please refer to the SDL_OpenAudioDevice 381 * documentation for details on how to prepare this structure. 382 * \param obtained an SDL_AudioSpec structure filled in with the actual 383 * parameters, or NULL. 384 * \returns 0 if successful, placing the actual hardware parameters in the 385 * structure pointed to by `obtained`. 386 * 387 * If `obtained` is NULL, the audio data passed to the callback 388 * function will be guaranteed to be in the requested format, and 389 * will be automatically converted to the actual hardware audio 390 * format if necessary. If `obtained` is NULL, `desired` will have 391 * fields modified. 392 * 393 * This function returns a negative error code on failure to open the 394 * audio device or failure to set up the audio thread; call 395 * SDL_GetError() for more information. 396 * 397 * \since This function is available since SDL 2.0.0. 398 * 399 * \sa SDL_CloseAudio 400 * \sa SDL_LockAudio 401 * \sa SDL_PauseAudio 402 * \sa SDL_UnlockAudio 403 */ 404 extern DECLSPEC int SDLCALL SDL_OpenAudio(SDL_AudioSpec * desired, 405 SDL_AudioSpec * obtained); 406 407 /** 408 * SDL Audio Device IDs. 409 * 410 * A successful call to SDL_OpenAudio() is always device id 1, and legacy SDL 411 * audio APIs assume you want this device ID. SDL_OpenAudioDevice() calls 412 * always returns devices >= 2 on success. The legacy calls are good both for 413 * backwards compatibility and when you don't care about multiple, specific, 414 * or capture devices. 415 */ 416 typedef Uint32 SDL_AudioDeviceID; 417 418 /** 419 * Get the number of built-in audio devices. 420 * 421 * This function is only valid after successfully initializing the audio 422 * subsystem. 423 * 424 * Note that audio capture support is not implemented as of SDL 2.0.4, so the 425 * `iscapture` parameter is for future expansion and should always be zero for 426 * now. 427 * 428 * This function will return -1 if an explicit list of devices can't be 429 * determined. Returning -1 is not an error. For example, if SDL is set up to 430 * talk to a remote audio server, it can't list every one available on the 431 * Internet, but it will still allow a specific host to be specified in 432 * SDL_OpenAudioDevice(). 433 * 434 * In many common cases, when this function returns a value <= 0, it can still 435 * successfully open the default device (NULL for first argument of 436 * SDL_OpenAudioDevice()). 437 * 438 * This function may trigger a complete redetect of available hardware. It 439 * should not be called for each iteration of a loop, but rather once at the 440 * start of a loop: 441 * 442 * ```c 443 * // Don't do this: 444 * for (int i = 0; i < SDL_GetNumAudioDevices(0); i++) 445 * 446 * // do this instead: 447 * const int count = SDL_GetNumAudioDevices(0); 448 * for (int i = 0; i < count; ++i) { do_something_here(); } 449 * ``` 450 * 451 * \param iscapture zero to request playback devices, non-zero to request 452 * recording devices. 453 * \returns the number of available devices exposed by the current driver or 454 * -1 if an explicit list of devices can't be determined. A return 455 * value of -1 does not necessarily mean an error condition. 456 * 457 * \since This function is available since SDL 2.0.0. 458 * 459 * \sa SDL_GetAudioDeviceName 460 * \sa SDL_OpenAudioDevice 461 */ 462 extern DECLSPEC int SDLCALL SDL_GetNumAudioDevices(int iscapture); 463 464 /** 465 * Get the human-readable name of a specific audio device. 466 * 467 * This function is only valid after successfully initializing the audio 468 * subsystem. The values returned by this function reflect the latest call to 469 * SDL_GetNumAudioDevices(); re-call that function to redetect available 470 * hardware. 471 * 472 * The string returned by this function is UTF-8 encoded, read-only, and 473 * managed internally. You are not to free it. If you need to keep the string 474 * for any length of time, you should make your own copy of it, as it will be 475 * invalid next time any of several other SDL functions are called. 476 * 477 * \param index the index of the audio device; valid values range from 0 to 478 * SDL_GetNumAudioDevices() - 1. 479 * \param iscapture non-zero to query the list of recording devices, zero to 480 * query the list of output devices. 481 * \returns the name of the audio device at the requested index, or NULL on 482 * error. 483 * 484 * \since This function is available since SDL 2.0.0. 485 * 486 * \sa SDL_GetNumAudioDevices 487 * \sa SDL_GetDefaultAudioInfo 488 */ 489 extern DECLSPEC const char *SDLCALL SDL_GetAudioDeviceName(int index, 490 int iscapture); 491 492 /** 493 * Get the preferred audio format of a specific audio device. 494 * 495 * This function is only valid after a successfully initializing the audio 496 * subsystem. The values returned by this function reflect the latest call to 497 * SDL_GetNumAudioDevices(); re-call that function to redetect available 498 * hardware. 499 * 500 * `spec` will be filled with the sample rate, sample format, and channel 501 * count. 502 * 503 * \param index the index of the audio device; valid values range from 0 to 504 * SDL_GetNumAudioDevices() - 1. 505 * \param iscapture non-zero to query the list of recording devices, zero to 506 * query the list of output devices. 507 * \param spec The SDL_AudioSpec to be initialized by this function. 508 * \returns 0 on success, nonzero on error. 509 * 510 * \since This function is available since SDL 2.0.16. 511 * 512 * \sa SDL_GetNumAudioDevices 513 * \sa SDL_GetDefaultAudioInfo 514 */ 515 extern DECLSPEC int SDLCALL SDL_GetAudioDeviceSpec(int index, 516 int iscapture, 517 SDL_AudioSpec *spec); 518 519 520 /** 521 * Get the name and preferred format of the default audio device. 522 * 523 * Some (but not all!) platforms have an isolated mechanism to get information 524 * about the "default" device. This can actually be a completely different 525 * device that's not in the list you get from SDL_GetAudioDeviceSpec(). It can 526 * even be a network address! (This is discussed in SDL_OpenAudioDevice().) 527 * 528 * As a result, this call is not guaranteed to be performant, as it can query 529 * the sound server directly every time, unlike the other query functions. You 530 * should call this function sparingly! 531 * 532 * `spec` will be filled with the sample rate, sample format, and channel 533 * count, if a default device exists on the system. If `name` is provided, 534 * will be filled with either a dynamically-allocated UTF-8 string or NULL. 535 * 536 * \param name A pointer to be filled with the name of the default device (can 537 * be NULL). Please call SDL_free() when you are done with this 538 * pointer! 539 * \param spec The SDL_AudioSpec to be initialized by this function. 540 * \param iscapture non-zero to query the default recording device, zero to 541 * query the default output device. 542 * \returns 0 on success, nonzero on error. 543 * 544 * \since This function is available since SDL 2.24.0. 545 * 546 * \sa SDL_GetAudioDeviceName 547 * \sa SDL_GetAudioDeviceSpec 548 * \sa SDL_OpenAudioDevice 549 */ 550 extern DECLSPEC int SDLCALL SDL_GetDefaultAudioInfo(char **name, 551 SDL_AudioSpec *spec, 552 int iscapture); 553 554 555 /** 556 * Open a specific audio device. 557 * 558 * SDL_OpenAudio(), unlike this function, always acts on device ID 1. As such, 559 * this function will never return a 1 so as not to conflict with the legacy 560 * function. 561 * 562 * Please note that SDL 2.0 before 2.0.5 did not support recording; as such, 563 * this function would fail if `iscapture` was not zero. Starting with SDL 564 * 2.0.5, recording is implemented and this value can be non-zero. 565 * 566 * Passing in a `device` name of NULL requests the most reasonable default 567 * (and is equivalent to what SDL_OpenAudio() does to choose a device). The 568 * `device` name is a UTF-8 string reported by SDL_GetAudioDeviceName(), but 569 * some drivers allow arbitrary and driver-specific strings, such as a 570 * hostname/IP address for a remote audio server, or a filename in the 571 * diskaudio driver. 572 * 573 * An opened audio device starts out paused, and should be enabled for playing 574 * by calling SDL_PauseAudioDevice(devid, 0) when you are ready for your audio 575 * callback function to be called. Since the audio driver may modify the 576 * requested size of the audio buffer, you should allocate any local mixing 577 * buffers after you open the audio device. 578 * 579 * The audio callback runs in a separate thread in most cases; you can prevent 580 * race conditions between your callback and other threads without fully 581 * pausing playback with SDL_LockAudioDevice(). For more information about the 582 * callback, see SDL_AudioSpec. 583 * 584 * Managing the audio spec via 'desired' and 'obtained': 585 * 586 * When filling in the desired audio spec structure: 587 * 588 * - `desired->freq` should be the frequency in sample-frames-per-second (Hz). 589 * - `desired->format` should be the audio format (`AUDIO_S16SYS`, etc). 590 * - `desired->samples` is the desired size of the audio buffer, in _sample 591 * frames_ (with stereo output, two samples--left and right--would make a 592 * single sample frame). This number should be a power of two, and may be 593 * adjusted by the audio driver to a value more suitable for the hardware. 594 * Good values seem to range between 512 and 4096 inclusive, depending on 595 * the application and CPU speed. Smaller values reduce latency, but can 596 * lead to underflow if the application is doing heavy processing and cannot 597 * fill the audio buffer in time. Note that the number of sample frames is 598 * directly related to time by the following formula: `ms = 599 * (sampleframes*1000)/freq` 600 * - `desired->size` is the size in _bytes_ of the audio buffer, and is 601 * calculated by SDL_OpenAudioDevice(). You don't initialize this. 602 * - `desired->silence` is the value used to set the buffer to silence, and is 603 * calculated by SDL_OpenAudioDevice(). You don't initialize this. 604 * - `desired->callback` should be set to a function that will be called when 605 * the audio device is ready for more data. It is passed a pointer to the 606 * audio buffer, and the length in bytes of the audio buffer. This function 607 * usually runs in a separate thread, and so you should protect data 608 * structures that it accesses by calling SDL_LockAudioDevice() and 609 * SDL_UnlockAudioDevice() in your code. Alternately, you may pass a NULL 610 * pointer here, and call SDL_QueueAudio() with some frequency, to queue 611 * more audio samples to be played (or for capture devices, call 612 * SDL_DequeueAudio() with some frequency, to obtain audio samples). 613 * - `desired->userdata` is passed as the first parameter to your callback 614 * function. If you passed a NULL callback, this value is ignored. 615 * 616 * `allowed_changes` can have the following flags OR'd together: 617 * 618 * - `SDL_AUDIO_ALLOW_FREQUENCY_CHANGE` 619 * - `SDL_AUDIO_ALLOW_FORMAT_CHANGE` 620 * - `SDL_AUDIO_ALLOW_CHANNELS_CHANGE` 621 * - `SDL_AUDIO_ALLOW_SAMPLES_CHANGE` 622 * - `SDL_AUDIO_ALLOW_ANY_CHANGE` 623 * 624 * These flags specify how SDL should behave when a device cannot offer a 625 * specific feature. If the application requests a feature that the hardware 626 * doesn't offer, SDL will always try to get the closest equivalent. 627 * 628 * For example, if you ask for float32 audio format, but the sound card only 629 * supports int16, SDL will set the hardware to int16. If you had set 630 * SDL_AUDIO_ALLOW_FORMAT_CHANGE, SDL will change the format in the `obtained` 631 * structure. If that flag was *not* set, SDL will prepare to convert your 632 * callback's float32 audio to int16 before feeding it to the hardware and 633 * will keep the originally requested format in the `obtained` structure. 634 * 635 * The resulting audio specs, varying depending on hardware and on what 636 * changes were allowed, will then be written back to `obtained`. 637 * 638 * If your application can only handle one specific data format, pass a zero 639 * for `allowed_changes` and let SDL transparently handle any differences. 640 * 641 * \param device a UTF-8 string reported by SDL_GetAudioDeviceName() or a 642 * driver-specific name as appropriate. NULL requests the most 643 * reasonable default device. 644 * \param iscapture non-zero to specify a device should be opened for 645 * recording, not playback. 646 * \param desired an SDL_AudioSpec structure representing the desired output 647 * format; see SDL_OpenAudio() for more information. 648 * \param obtained an SDL_AudioSpec structure filled in with the actual output 649 * format; see SDL_OpenAudio() for more information. 650 * \param allowed_changes 0, or one or more flags OR'd together. 651 * \returns a valid device ID that is > 0 on success or 0 on failure; call 652 * SDL_GetError() for more information. 653 * 654 * For compatibility with SDL 1.2, this will never return 1, since 655 * SDL reserves that ID for the legacy SDL_OpenAudio() function. 656 * 657 * \since This function is available since SDL 2.0.0. 658 * 659 * \sa SDL_CloseAudioDevice 660 * \sa SDL_GetAudioDeviceName 661 * \sa SDL_LockAudioDevice 662 * \sa SDL_OpenAudio 663 * \sa SDL_PauseAudioDevice 664 * \sa SDL_UnlockAudioDevice 665 */ 666 extern DECLSPEC SDL_AudioDeviceID SDLCALL SDL_OpenAudioDevice( 667 const char *device, 668 int iscapture, 669 const SDL_AudioSpec *desired, 670 SDL_AudioSpec *obtained, 671 int allowed_changes); 672 673 674 675 /** 676 * \name Audio state 677 * 678 * Get the current audio state. 679 */ 680 /* @{ */ 681 typedef enum 682 { 683 SDL_AUDIO_STOPPED = 0, 684 SDL_AUDIO_PLAYING, 685 SDL_AUDIO_PAUSED 686 } SDL_AudioStatus; 687 688 /** 689 * This function is a legacy means of querying the audio device. 690 * 691 * New programs might want to use SDL_GetAudioDeviceStatus() instead. This 692 * function is equivalent to calling... 693 * 694 * ```c 695 * SDL_GetAudioDeviceStatus(1); 696 * ``` 697 * 698 * ...and is only useful if you used the legacy SDL_OpenAudio() function. 699 * 700 * \returns the SDL_AudioStatus of the audio device opened by SDL_OpenAudio(). 701 * 702 * \since This function is available since SDL 2.0.0. 703 * 704 * \sa SDL_GetAudioDeviceStatus 705 */ 706 extern DECLSPEC SDL_AudioStatus SDLCALL SDL_GetAudioStatus(void); 707 708 /** 709 * Use this function to get the current audio state of an audio device. 710 * 711 * \param dev the ID of an audio device previously opened with 712 * SDL_OpenAudioDevice(). 713 * \returns the SDL_AudioStatus of the specified audio device. 714 * 715 * \since This function is available since SDL 2.0.0. 716 * 717 * \sa SDL_PauseAudioDevice 718 */ 719 extern DECLSPEC SDL_AudioStatus SDLCALL SDL_GetAudioDeviceStatus(SDL_AudioDeviceID dev); 720 /* @} *//* Audio State */ 721 722 /** 723 * \name Pause audio functions 724 * 725 * These functions pause and unpause the audio callback processing. 726 * They should be called with a parameter of 0 after opening the audio 727 * device to start playing sound. This is so you can safely initialize 728 * data for your callback function after opening the audio device. 729 * Silence will be written to the audio device during the pause. 730 */ 731 /* @{ */ 732 733 /** 734 * This function is a legacy means of pausing the audio device. 735 * 736 * New programs might want to use SDL_PauseAudioDevice() instead. This 737 * function is equivalent to calling... 738 * 739 * ```c 740 * SDL_PauseAudioDevice(1, pause_on); 741 * ``` 742 * 743 * ...and is only useful if you used the legacy SDL_OpenAudio() function. 744 * 745 * \param pause_on non-zero to pause, 0 to unpause. 746 * 747 * \since This function is available since SDL 2.0.0. 748 * 749 * \sa SDL_GetAudioStatus 750 * \sa SDL_PauseAudioDevice 751 */ 752 extern DECLSPEC void SDLCALL SDL_PauseAudio(int pause_on); 753 754 /** 755 * Use this function to pause and unpause audio playback on a specified 756 * device. 757 * 758 * This function pauses and unpauses the audio callback processing for a given 759 * device. Newly-opened audio devices start in the paused state, so you must 760 * call this function with **pause_on**=0 after opening the specified audio 761 * device to start playing sound. This allows you to safely initialize data 762 * for your callback function after opening the audio device. Silence will be 763 * written to the audio device while paused, and the audio callback is 764 * guaranteed to not be called. Pausing one device does not prevent other 765 * unpaused devices from running their callbacks. 766 * 767 * Pausing state does not stack; even if you pause a device several times, a 768 * single unpause will start the device playing again, and vice versa. This is 769 * different from how SDL_LockAudioDevice() works. 770 * 771 * If you just need to protect a few variables from race conditions vs your 772 * callback, you shouldn't pause the audio device, as it will lead to dropouts 773 * in the audio playback. Instead, you should use SDL_LockAudioDevice(). 774 * 775 * \param dev a device opened by SDL_OpenAudioDevice(). 776 * \param pause_on non-zero to pause, 0 to unpause. 777 * 778 * \since This function is available since SDL 2.0.0. 779 * 780 * \sa SDL_LockAudioDevice 781 */ 782 extern DECLSPEC void SDLCALL SDL_PauseAudioDevice(SDL_AudioDeviceID dev, 783 int pause_on); 784 /* @} *//* Pause audio functions */ 785 786 /** 787 * Load the audio data of a WAVE file into memory. 788 * 789 * Loading a WAVE file requires `src`, `spec`, `audio_buf` and `audio_len` to 790 * be valid pointers. The entire data portion of the file is then loaded into 791 * memory and decoded if necessary. 792 * 793 * If `freesrc` is non-zero, the data source gets automatically closed and 794 * freed before the function returns. 795 * 796 * Supported formats are RIFF WAVE files with the formats PCM (8, 16, 24, and 797 * 32 bits), IEEE Float (32 bits), Microsoft ADPCM and IMA ADPCM (4 bits), and 798 * A-law and mu-law (8 bits). Other formats are currently unsupported and 799 * cause an error. 800 * 801 * If this function succeeds, the pointer returned by it is equal to `spec` 802 * and the pointer to the audio data allocated by the function is written to 803 * `audio_buf` and its length in bytes to `audio_len`. The SDL_AudioSpec 804 * members `freq`, `channels`, and `format` are set to the values of the audio 805 * data in the buffer. The `samples` member is set to a sane default and all 806 * others are set to zero. 807 * 808 * It's necessary to use SDL_FreeWAV() to free the audio data returned in 809 * `audio_buf` when it is no longer used. 810 * 811 * Because of the underspecification of the .WAV format, there are many 812 * problematic files in the wild that cause issues with strict decoders. To 813 * provide compatibility with these files, this decoder is lenient in regards 814 * to the truncation of the file, the fact chunk, and the size of the RIFF 815 * chunk. The hints `SDL_HINT_WAVE_RIFF_CHUNK_SIZE`, 816 * `SDL_HINT_WAVE_TRUNCATION`, and `SDL_HINT_WAVE_FACT_CHUNK` can be used to 817 * tune the behavior of the loading process. 818 * 819 * Any file that is invalid (due to truncation, corruption, or wrong values in 820 * the headers), too big, or unsupported causes an error. Additionally, any 821 * critical I/O error from the data source will terminate the loading process 822 * with an error. The function returns NULL on error and in all cases (with 823 * the exception of `src` being NULL), an appropriate error message will be 824 * set. 825 * 826 * It is required that the data source supports seeking. 827 * 828 * Example: 829 * 830 * ```c 831 * SDL_LoadWAV_RW(SDL_RWFromFile("sample.wav", "rb"), 1, &spec, &buf, &len); 832 * ``` 833 * 834 * Note that the SDL_LoadWAV macro does this same thing for you, but in a less 835 * messy way: 836 * 837 * ```c 838 * SDL_LoadWAV("sample.wav", &spec, &buf, &len); 839 * ``` 840 * 841 * \param src The data source for the WAVE data. 842 * \param freesrc If non-zero, SDL will _always_ free the data source. 843 * \param spec An SDL_AudioSpec that will be filled in with the wave file's 844 * format details. 845 * \param audio_buf A pointer filled with the audio data, allocated by the 846 * function. 847 * \param audio_len A pointer filled with the length of the audio data buffer 848 * in bytes. 849 * \returns This function, if successfully called, returns `spec`, which will 850 * be filled with the audio data format of the wave source data. 851 * `audio_buf` will be filled with a pointer to an allocated buffer 852 * containing the audio data, and `audio_len` is filled with the 853 * length of that audio buffer in bytes. 854 * 855 * This function returns NULL if the .WAV file cannot be opened, uses 856 * an unknown data format, or is corrupt; call SDL_GetError() for 857 * more information. 858 * 859 * When the application is done with the data returned in 860 * `audio_buf`, it should call SDL_FreeWAV() to dispose of it. 861 * 862 * \since This function is available since SDL 2.0.0. 863 * 864 * \sa SDL_FreeWAV 865 * \sa SDL_LoadWAV 866 */ 867 extern DECLSPEC SDL_AudioSpec *SDLCALL SDL_LoadWAV_RW(SDL_RWops * src, 868 int freesrc, 869 SDL_AudioSpec * spec, 870 Uint8 ** audio_buf, 871 Uint32 * audio_len); 872 873 /** 874 * Loads a WAV from a file. 875 * 876 * Compatibility convenience function. 877 */ 878 #define SDL_LoadWAV(file, spec, audio_buf, audio_len) \ 879 SDL_LoadWAV_RW(SDL_RWFromFile(file, "rb"),1, spec,audio_buf,audio_len) 880 881 /** 882 * Free data previously allocated with SDL_LoadWAV() or SDL_LoadWAV_RW(). 883 * 884 * After a WAVE file has been opened with SDL_LoadWAV() or SDL_LoadWAV_RW() 885 * its data can eventually be freed with SDL_FreeWAV(). It is safe to call 886 * this function with a NULL pointer. 887 * 888 * \param audio_buf a pointer to the buffer created by SDL_LoadWAV() or 889 * SDL_LoadWAV_RW(). 890 * 891 * \since This function is available since SDL 2.0.0. 892 * 893 * \sa SDL_LoadWAV 894 * \sa SDL_LoadWAV_RW 895 */ 896 extern DECLSPEC void SDLCALL SDL_FreeWAV(Uint8 * audio_buf); 897 898 /** 899 * Initialize an SDL_AudioCVT structure for conversion. 900 * 901 * Before an SDL_AudioCVT structure can be used to convert audio data it must 902 * be initialized with source and destination information. 903 * 904 * This function will zero out every field of the SDL_AudioCVT, so it must be 905 * called before the application fills in the final buffer information. 906 * 907 * Once this function has returned successfully, and reported that a 908 * conversion is necessary, the application fills in the rest of the fields in 909 * SDL_AudioCVT, now that it knows how large a buffer it needs to allocate, 910 * and then can call SDL_ConvertAudio() to complete the conversion. 911 * 912 * \param cvt an SDL_AudioCVT structure filled in with audio conversion 913 * information. 914 * \param src_format the source format of the audio data; for more info see 915 * SDL_AudioFormat. 916 * \param src_channels the number of channels in the source. 917 * \param src_rate the frequency (sample-frames-per-second) of the source. 918 * \param dst_format the destination format of the audio data; for more info 919 * see SDL_AudioFormat. 920 * \param dst_channels the number of channels in the destination. 921 * \param dst_rate the frequency (sample-frames-per-second) of the 922 * destination. 923 * \returns 1 if the audio filter is prepared, 0 if no conversion is needed, 924 * or a negative error code on failure; call SDL_GetError() for more 925 * information. 926 * 927 * \since This function is available since SDL 2.0.0. 928 * 929 * \sa SDL_ConvertAudio 930 */ 931 extern DECLSPEC int SDLCALL SDL_BuildAudioCVT(SDL_AudioCVT * cvt, 932 SDL_AudioFormat src_format, 933 Uint8 src_channels, 934 int src_rate, 935 SDL_AudioFormat dst_format, 936 Uint8 dst_channels, 937 int dst_rate); 938 939 /** 940 * Convert audio data to a desired audio format. 941 * 942 * This function does the actual audio data conversion, after the application 943 * has called SDL_BuildAudioCVT() to prepare the conversion information and 944 * then filled in the buffer details. 945 * 946 * Once the application has initialized the `cvt` structure using 947 * SDL_BuildAudioCVT(), allocated an audio buffer and filled it with audio 948 * data in the source format, this function will convert the buffer, in-place, 949 * to the desired format. 950 * 951 * The data conversion may go through several passes; any given pass may 952 * possibly temporarily increase the size of the data. For example, SDL might 953 * expand 16-bit data to 32 bits before resampling to a lower frequency, 954 * shrinking the data size after having grown it briefly. Since the supplied 955 * buffer will be both the source and destination, converting as necessary 956 * in-place, the application must allocate a buffer that will fully contain 957 * the data during its largest conversion pass. After SDL_BuildAudioCVT() 958 * returns, the application should set the `cvt->len` field to the size, in 959 * bytes, of the source data, and allocate a buffer that is `cvt->len * 960 * cvt->len_mult` bytes long for the `buf` field. 961 * 962 * The source data should be copied into this buffer before the call to 963 * SDL_ConvertAudio(). Upon successful return, this buffer will contain the 964 * converted audio, and `cvt->len_cvt` will be the size of the converted data, 965 * in bytes. Any bytes in the buffer past `cvt->len_cvt` are undefined once 966 * this function returns. 967 * 968 * \param cvt an SDL_AudioCVT structure that was previously set up by 969 * SDL_BuildAudioCVT(). 970 * \returns 0 if the conversion was completed successfully or a negative error 971 * code on failure; call SDL_GetError() for more information. 972 * 973 * \since This function is available since SDL 2.0.0. 974 * 975 * \sa SDL_BuildAudioCVT 976 */ 977 extern DECLSPEC int SDLCALL SDL_ConvertAudio(SDL_AudioCVT * cvt); 978 979 /* SDL_AudioStream is a new audio conversion interface. 980 The benefits vs SDL_AudioCVT: 981 - it can handle resampling data in chunks without generating 982 artifacts, when it doesn't have the complete buffer available. 983 - it can handle incoming data in any variable size. 984 - You push data as you have it, and pull it when you need it 985 */ 986 /* this is opaque to the outside world. */ 987 struct _SDL_AudioStream; 988 typedef struct _SDL_AudioStream SDL_AudioStream; 989 990 /** 991 * Create a new audio stream. 992 * 993 * \param src_format The format of the source audio. 994 * \param src_channels The number of channels of the source audio. 995 * \param src_rate The sampling rate of the source audio. 996 * \param dst_format The format of the desired audio output. 997 * \param dst_channels The number of channels of the desired audio output. 998 * \param dst_rate The sampling rate of the desired audio output. 999 * \returns 0 on success, or -1 on error. 1000 * 1001 * \since This function is available since SDL 2.0.7. 1002 * 1003 * \sa SDL_AudioStreamPut 1004 * \sa SDL_AudioStreamGet 1005 * \sa SDL_AudioStreamAvailable 1006 * \sa SDL_AudioStreamFlush 1007 * \sa SDL_AudioStreamClear 1008 * \sa SDL_FreeAudioStream 1009 */ 1010 extern DECLSPEC SDL_AudioStream * SDLCALL SDL_NewAudioStream(const SDL_AudioFormat src_format, 1011 const Uint8 src_channels, 1012 const int src_rate, 1013 const SDL_AudioFormat dst_format, 1014 const Uint8 dst_channels, 1015 const int dst_rate); 1016 1017 /** 1018 * Add data to be converted/resampled to the stream. 1019 * 1020 * \param stream The stream the audio data is being added to. 1021 * \param buf A pointer to the audio data to add. 1022 * \param len The number of bytes to write to the stream. 1023 * \returns 0 on success, or -1 on error. 1024 * 1025 * \since This function is available since SDL 2.0.7. 1026 * 1027 * \sa SDL_NewAudioStream 1028 * \sa SDL_AudioStreamGet 1029 * \sa SDL_AudioStreamAvailable 1030 * \sa SDL_AudioStreamFlush 1031 * \sa SDL_AudioStreamClear 1032 * \sa SDL_FreeAudioStream 1033 */ 1034 extern DECLSPEC int SDLCALL SDL_AudioStreamPut(SDL_AudioStream *stream, const void *buf, int len); 1035 1036 /** 1037 * Get converted/resampled data from the stream 1038 * 1039 * \param stream The stream the audio is being requested from. 1040 * \param buf A buffer to fill with audio data. 1041 * \param len The maximum number of bytes to fill. 1042 * \returns the number of bytes read from the stream, or -1 on error. 1043 * 1044 * \since This function is available since SDL 2.0.7. 1045 * 1046 * \sa SDL_NewAudioStream 1047 * \sa SDL_AudioStreamPut 1048 * \sa SDL_AudioStreamAvailable 1049 * \sa SDL_AudioStreamFlush 1050 * \sa SDL_AudioStreamClear 1051 * \sa SDL_FreeAudioStream 1052 */ 1053 extern DECLSPEC int SDLCALL SDL_AudioStreamGet(SDL_AudioStream *stream, void *buf, int len); 1054 1055 /** 1056 * Get the number of converted/resampled bytes available. 1057 * 1058 * The stream may be buffering data behind the scenes until it has enough to 1059 * resample correctly, so this number might be lower than what you expect, or 1060 * even be zero. Add more data or flush the stream if you need the data now. 1061 * 1062 * \since This function is available since SDL 2.0.7. 1063 * 1064 * \sa SDL_NewAudioStream 1065 * \sa SDL_AudioStreamPut 1066 * \sa SDL_AudioStreamGet 1067 * \sa SDL_AudioStreamFlush 1068 * \sa SDL_AudioStreamClear 1069 * \sa SDL_FreeAudioStream 1070 */ 1071 extern DECLSPEC int SDLCALL SDL_AudioStreamAvailable(SDL_AudioStream *stream); 1072 1073 /** 1074 * Tell the stream that you're done sending data, and anything being buffered 1075 * should be converted/resampled and made available immediately. 1076 * 1077 * It is legal to add more data to a stream after flushing, but there will be 1078 * audio gaps in the output. Generally this is intended to signal the end of 1079 * input, so the complete output becomes available. 1080 * 1081 * \since This function is available since SDL 2.0.7. 1082 * 1083 * \sa SDL_NewAudioStream 1084 * \sa SDL_AudioStreamPut 1085 * \sa SDL_AudioStreamGet 1086 * \sa SDL_AudioStreamAvailable 1087 * \sa SDL_AudioStreamClear 1088 * \sa SDL_FreeAudioStream 1089 */ 1090 extern DECLSPEC int SDLCALL SDL_AudioStreamFlush(SDL_AudioStream *stream); 1091 1092 /** 1093 * Clear any pending data in the stream without converting it 1094 * 1095 * \since This function is available since SDL 2.0.7. 1096 * 1097 * \sa SDL_NewAudioStream 1098 * \sa SDL_AudioStreamPut 1099 * \sa SDL_AudioStreamGet 1100 * \sa SDL_AudioStreamAvailable 1101 * \sa SDL_AudioStreamFlush 1102 * \sa SDL_FreeAudioStream 1103 */ 1104 extern DECLSPEC void SDLCALL SDL_AudioStreamClear(SDL_AudioStream *stream); 1105 1106 /** 1107 * Free an audio stream 1108 * 1109 * \since This function is available since SDL 2.0.7. 1110 * 1111 * \sa SDL_NewAudioStream 1112 * \sa SDL_AudioStreamPut 1113 * \sa SDL_AudioStreamGet 1114 * \sa SDL_AudioStreamAvailable 1115 * \sa SDL_AudioStreamFlush 1116 * \sa SDL_AudioStreamClear 1117 */ 1118 extern DECLSPEC void SDLCALL SDL_FreeAudioStream(SDL_AudioStream *stream); 1119 1120 /** 1121 * Maximum volume allowed in calls to SDL_MixAudio and SDL_MixAudioFormat. 1122 */ 1123 #define SDL_MIX_MAXVOLUME 128 1124 1125 /** 1126 * This function is a legacy means of mixing audio. 1127 * 1128 * This function is equivalent to calling... 1129 * 1130 * ```c 1131 * SDL_MixAudioFormat(dst, src, format, len, volume); 1132 * ``` 1133 * 1134 * ...where `format` is the obtained format of the audio device from the 1135 * legacy SDL_OpenAudio() function. 1136 * 1137 * \param dst the destination for the mixed audio. 1138 * \param src the source audio buffer to be mixed. 1139 * \param len the length of the audio buffer in bytes. 1140 * \param volume ranges from 0 - 128, and should be set to SDL_MIX_MAXVOLUME 1141 * for full audio volume. 1142 * 1143 * \since This function is available since SDL 2.0.0. 1144 * 1145 * \sa SDL_MixAudioFormat 1146 */ 1147 extern DECLSPEC void SDLCALL SDL_MixAudio(Uint8 * dst, const Uint8 * src, 1148 Uint32 len, int volume); 1149 1150 /** 1151 * Mix audio data in a specified format. 1152 * 1153 * This takes an audio buffer `src` of `len` bytes of `format` data and mixes 1154 * it into `dst`, performing addition, volume adjustment, and overflow 1155 * clipping. The buffer pointed to by `dst` must also be `len` bytes of 1156 * `format` data. 1157 * 1158 * This is provided for convenience -- you can mix your own audio data. 1159 * 1160 * Do not use this function for mixing together more than two streams of 1161 * sample data. The output from repeated application of this function may be 1162 * distorted by clipping, because there is no accumulator with greater range 1163 * than the input (not to mention this being an inefficient way of doing it). 1164 * 1165 * It is a common misconception that this function is required to write audio 1166 * data to an output stream in an audio callback. While you can do that, 1167 * SDL_MixAudioFormat() is really only needed when you're mixing a single 1168 * audio stream with a volume adjustment. 1169 * 1170 * \param dst the destination for the mixed audio. 1171 * \param src the source audio buffer to be mixed. 1172 * \param format the SDL_AudioFormat structure representing the desired audio 1173 * format. 1174 * \param len the length of the audio buffer in bytes. 1175 * \param volume ranges from 0 - 128, and should be set to SDL_MIX_MAXVOLUME 1176 * for full audio volume. 1177 * 1178 * \since This function is available since SDL 2.0.0. 1179 */ 1180 extern DECLSPEC void SDLCALL SDL_MixAudioFormat(Uint8 * dst, 1181 const Uint8 * src, 1182 SDL_AudioFormat format, 1183 Uint32 len, int volume); 1184 1185 /** 1186 * Queue more audio on non-callback devices. 1187 * 1188 * If you are looking to retrieve queued audio from a non-callback capture 1189 * device, you want SDL_DequeueAudio() instead. SDL_QueueAudio() will return 1190 * -1 to signify an error if you use it with capture devices. 1191 * 1192 * SDL offers two ways to feed audio to the device: you can either supply a 1193 * callback that SDL triggers with some frequency to obtain more audio (pull 1194 * method), or you can supply no callback, and then SDL will expect you to 1195 * supply data at regular intervals (push method) with this function. 1196 * 1197 * There are no limits on the amount of data you can queue, short of 1198 * exhaustion of address space. Queued data will drain to the device as 1199 * necessary without further intervention from you. If the device needs audio 1200 * but there is not enough queued, it will play silence to make up the 1201 * difference. This means you will have skips in your audio playback if you 1202 * aren't routinely queueing sufficient data. 1203 * 1204 * This function copies the supplied data, so you are safe to free it when the 1205 * function returns. This function is thread-safe, but queueing to the same 1206 * device from two threads at once does not promise which buffer will be 1207 * queued first. 1208 * 1209 * You may not queue audio on a device that is using an application-supplied 1210 * callback; doing so returns an error. You have to use the audio callback or 1211 * queue audio with this function, but not both. 1212 * 1213 * You should not call SDL_LockAudio() on the device before queueing; SDL 1214 * handles locking internally for this function. 1215 * 1216 * Note that SDL2 does not support planar audio. You will need to resample 1217 * from planar audio formats into a non-planar one (see SDL_AudioFormat) 1218 * before queuing audio. 1219 * 1220 * \param dev the device ID to which we will queue audio. 1221 * \param data the data to queue to the device for later playback. 1222 * \param len the number of bytes (not samples!) to which `data` points. 1223 * \returns 0 on success or a negative error code on failure; call 1224 * SDL_GetError() for more information. 1225 * 1226 * \since This function is available since SDL 2.0.4. 1227 * 1228 * \sa SDL_ClearQueuedAudio 1229 * \sa SDL_GetQueuedAudioSize 1230 */ 1231 extern DECLSPEC int SDLCALL SDL_QueueAudio(SDL_AudioDeviceID dev, const void *data, Uint32 len); 1232 1233 /** 1234 * Dequeue more audio on non-callback devices. 1235 * 1236 * If you are looking to queue audio for output on a non-callback playback 1237 * device, you want SDL_QueueAudio() instead. SDL_DequeueAudio() will always 1238 * return 0 if you use it with playback devices. 1239 * 1240 * SDL offers two ways to retrieve audio from a capture device: you can either 1241 * supply a callback that SDL triggers with some frequency as the device 1242 * records more audio data, (push method), or you can supply no callback, and 1243 * then SDL will expect you to retrieve data at regular intervals (pull 1244 * method) with this function. 1245 * 1246 * There are no limits on the amount of data you can queue, short of 1247 * exhaustion of address space. Data from the device will keep queuing as 1248 * necessary without further intervention from you. This means you will 1249 * eventually run out of memory if you aren't routinely dequeueing data. 1250 * 1251 * Capture devices will not queue data when paused; if you are expecting to 1252 * not need captured audio for some length of time, use SDL_PauseAudioDevice() 1253 * to stop the capture device from queueing more data. This can be useful 1254 * during, say, level loading times. When unpaused, capture devices will start 1255 * queueing data from that point, having flushed any capturable data available 1256 * while paused. 1257 * 1258 * This function is thread-safe, but dequeueing from the same device from two 1259 * threads at once does not promise which thread will dequeue data first. 1260 * 1261 * You may not dequeue audio from a device that is using an 1262 * application-supplied callback; doing so returns an error. You have to use 1263 * the audio callback, or dequeue audio with this function, but not both. 1264 * 1265 * You should not call SDL_LockAudio() on the device before dequeueing; SDL 1266 * handles locking internally for this function. 1267 * 1268 * \param dev the device ID from which we will dequeue audio. 1269 * \param data a pointer into where audio data should be copied. 1270 * \param len the number of bytes (not samples!) to which (data) points. 1271 * \returns the number of bytes dequeued, which could be less than requested; 1272 * call SDL_GetError() for more information. 1273 * 1274 * \since This function is available since SDL 2.0.5. 1275 * 1276 * \sa SDL_ClearQueuedAudio 1277 * \sa SDL_GetQueuedAudioSize 1278 */ 1279 extern DECLSPEC Uint32 SDLCALL SDL_DequeueAudio(SDL_AudioDeviceID dev, void *data, Uint32 len); 1280 1281 /** 1282 * Get the number of bytes of still-queued audio. 1283 * 1284 * For playback devices: this is the number of bytes that have been queued for 1285 * playback with SDL_QueueAudio(), but have not yet been sent to the hardware. 1286 * 1287 * Once we've sent it to the hardware, this function can not decide the exact 1288 * byte boundary of what has been played. It's possible that we just gave the 1289 * hardware several kilobytes right before you called this function, but it 1290 * hasn't played any of it yet, or maybe half of it, etc. 1291 * 1292 * For capture devices, this is the number of bytes that have been captured by 1293 * the device and are waiting for you to dequeue. This number may grow at any 1294 * time, so this only informs of the lower-bound of available data. 1295 * 1296 * You may not queue or dequeue audio on a device that is using an 1297 * application-supplied callback; calling this function on such a device 1298 * always returns 0. You have to use the audio callback or queue audio, but 1299 * not both. 1300 * 1301 * You should not call SDL_LockAudio() on the device before querying; SDL 1302 * handles locking internally for this function. 1303 * 1304 * \param dev the device ID of which we will query queued audio size. 1305 * \returns the number of bytes (not samples!) of queued audio. 1306 * 1307 * \since This function is available since SDL 2.0.4. 1308 * 1309 * \sa SDL_ClearQueuedAudio 1310 * \sa SDL_QueueAudio 1311 * \sa SDL_DequeueAudio 1312 */ 1313 extern DECLSPEC Uint32 SDLCALL SDL_GetQueuedAudioSize(SDL_AudioDeviceID dev); 1314 1315 /** 1316 * Drop any queued audio data waiting to be sent to the hardware. 1317 * 1318 * Immediately after this call, SDL_GetQueuedAudioSize() will return 0. For 1319 * output devices, the hardware will start playing silence if more audio isn't 1320 * queued. For capture devices, the hardware will start filling the empty 1321 * queue with new data if the capture device isn't paused. 1322 * 1323 * This will not prevent playback of queued audio that's already been sent to 1324 * the hardware, as we can not undo that, so expect there to be some fraction 1325 * of a second of audio that might still be heard. This can be useful if you 1326 * want to, say, drop any pending music or any unprocessed microphone input 1327 * during a level change in your game. 1328 * 1329 * You may not queue or dequeue audio on a device that is using an 1330 * application-supplied callback; calling this function on such a device 1331 * always returns 0. You have to use the audio callback or queue audio, but 1332 * not both. 1333 * 1334 * You should not call SDL_LockAudio() on the device before clearing the 1335 * queue; SDL handles locking internally for this function. 1336 * 1337 * This function always succeeds and thus returns void. 1338 * 1339 * \param dev the device ID of which to clear the audio queue. 1340 * 1341 * \since This function is available since SDL 2.0.4. 1342 * 1343 * \sa SDL_GetQueuedAudioSize 1344 * \sa SDL_QueueAudio 1345 * \sa SDL_DequeueAudio 1346 */ 1347 extern DECLSPEC void SDLCALL SDL_ClearQueuedAudio(SDL_AudioDeviceID dev); 1348 1349 1350 /** 1351 * \name Audio lock functions 1352 * 1353 * The lock manipulated by these functions protects the callback function. 1354 * During a SDL_LockAudio()/SDL_UnlockAudio() pair, you can be guaranteed that 1355 * the callback function is not running. Do not call these from the callback 1356 * function or you will cause deadlock. 1357 */ 1358 /* @{ */ 1359 1360 /** 1361 * This function is a legacy means of locking the audio device. 1362 * 1363 * New programs might want to use SDL_LockAudioDevice() instead. This function 1364 * is equivalent to calling... 1365 * 1366 * ```c 1367 * SDL_LockAudioDevice(1); 1368 * ``` 1369 * 1370 * ...and is only useful if you used the legacy SDL_OpenAudio() function. 1371 * 1372 * \since This function is available since SDL 2.0.0. 1373 * 1374 * \sa SDL_LockAudioDevice 1375 * \sa SDL_UnlockAudio 1376 * \sa SDL_UnlockAudioDevice 1377 */ 1378 extern DECLSPEC void SDLCALL SDL_LockAudio(void); 1379 1380 /** 1381 * Use this function to lock out the audio callback function for a specified 1382 * device. 1383 * 1384 * The lock manipulated by these functions protects the audio callback 1385 * function specified in SDL_OpenAudioDevice(). During a 1386 * SDL_LockAudioDevice()/SDL_UnlockAudioDevice() pair, you can be guaranteed 1387 * that the callback function for that device is not running, even if the 1388 * device is not paused. While a device is locked, any other unpaused, 1389 * unlocked devices may still run their callbacks. 1390 * 1391 * Calling this function from inside your audio callback is unnecessary. SDL 1392 * obtains this lock before calling your function, and releases it when the 1393 * function returns. 1394 * 1395 * You should not hold the lock longer than absolutely necessary. If you hold 1396 * it too long, you'll experience dropouts in your audio playback. Ideally, 1397 * your application locks the device, sets a few variables and unlocks again. 1398 * Do not do heavy work while holding the lock for a device. 1399 * 1400 * It is safe to lock the audio device multiple times, as long as you unlock 1401 * it an equivalent number of times. The callback will not run until the 1402 * device has been unlocked completely in this way. If your application fails 1403 * to unlock the device appropriately, your callback will never run, you might 1404 * hear repeating bursts of audio, and SDL_CloseAudioDevice() will probably 1405 * deadlock. 1406 * 1407 * Internally, the audio device lock is a mutex; if you lock from two threads 1408 * at once, not only will you block the audio callback, you'll block the other 1409 * thread. 1410 * 1411 * \param dev the ID of the device to be locked. 1412 * 1413 * \since This function is available since SDL 2.0.0. 1414 * 1415 * \sa SDL_UnlockAudioDevice 1416 */ 1417 extern DECLSPEC void SDLCALL SDL_LockAudioDevice(SDL_AudioDeviceID dev); 1418 1419 /** 1420 * This function is a legacy means of unlocking the audio device. 1421 * 1422 * New programs might want to use SDL_UnlockAudioDevice() instead. This 1423 * function is equivalent to calling... 1424 * 1425 * ```c 1426 * SDL_UnlockAudioDevice(1); 1427 * ``` 1428 * 1429 * ...and is only useful if you used the legacy SDL_OpenAudio() function. 1430 * 1431 * \since This function is available since SDL 2.0.0. 1432 * 1433 * \sa SDL_LockAudio 1434 * \sa SDL_UnlockAudioDevice 1435 */ 1436 extern DECLSPEC void SDLCALL SDL_UnlockAudio(void); 1437 1438 /** 1439 * Use this function to unlock the audio callback function for a specified 1440 * device. 1441 * 1442 * This function should be paired with a previous SDL_LockAudioDevice() call. 1443 * 1444 * \param dev the ID of the device to be unlocked. 1445 * 1446 * \since This function is available since SDL 2.0.0. 1447 * 1448 * \sa SDL_LockAudioDevice 1449 */ 1450 extern DECLSPEC void SDLCALL SDL_UnlockAudioDevice(SDL_AudioDeviceID dev); 1451 /* @} *//* Audio lock functions */ 1452 1453 /** 1454 * This function is a legacy means of closing the audio device. 1455 * 1456 * This function is equivalent to calling... 1457 * 1458 * ```c 1459 * SDL_CloseAudioDevice(1); 1460 * ``` 1461 * 1462 * ...and is only useful if you used the legacy SDL_OpenAudio() function. 1463 * 1464 * \since This function is available since SDL 2.0.0. 1465 * 1466 * \sa SDL_OpenAudio 1467 */ 1468 extern DECLSPEC void SDLCALL SDL_CloseAudio(void); 1469 1470 /** 1471 * Use this function to shut down audio processing and close the audio device. 1472 * 1473 * The application should close open audio devices once they are no longer 1474 * needed. Calling this function will wait until the device's audio callback 1475 * is not running, release the audio hardware and then clean up internal 1476 * state. No further audio will play from this device once this function 1477 * returns. 1478 * 1479 * This function may block briefly while pending audio data is played by the 1480 * hardware, so that applications don't drop the last buffer of data they 1481 * supplied. 1482 * 1483 * The device ID is invalid as soon as the device is closed, and is eligible 1484 * for reuse in a new SDL_OpenAudioDevice() call immediately. 1485 * 1486 * \param dev an audio device previously opened with SDL_OpenAudioDevice(). 1487 * 1488 * \since This function is available since SDL 2.0.0. 1489 * 1490 * \sa SDL_OpenAudioDevice 1491 */ 1492 extern DECLSPEC void SDLCALL SDL_CloseAudioDevice(SDL_AudioDeviceID dev); 1493 1494 /* Ends C function definitions when using C++ */ 1495 #ifdef __cplusplus 1496 } 1497 #endif 1498 #include "close_code.h" 1499 1500 #endif /* SDL_audio_h_ */ 1501 1502 /* vi: set ts=4 sw=4 expandtab: */