SDL 3.0
SDL_audio.h
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1/*
2 Simple DirectMedia Layer
3 Copyright (C) 1997-2024 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/**
23 * # CategoryAudio
24 *
25 * Audio functionality for the SDL library.
26 *
27 * All audio in SDL3 revolves around SDL_AudioStream. Whether you want to play
28 * or record audio, convert it, stream it, buffer it, or mix it, you're going
29 * to be passing it through an audio stream.
30 *
31 * Audio streams are quite flexible; they can accept any amount of data at a
32 * time, in any supported format, and output it as needed in any other format,
33 * even if the data format changes on either side halfway through.
34 *
35 * An app opens an audio device and binds any number of audio streams to it,
36 * feeding more data to it as available. When the devices needs more data, it
37 * will pull it from all bound streams and mix them together for playback.
38 *
39 * Audio streams can also use an app-provided callback to supply data
40 * on-demand, which maps pretty closely to the SDL2 audio model.
41 *
42 * SDL also provides a simple .WAV loader in SDL_LoadWAV (and SDL_LoadWAV_IO
43 * if you aren't reading from a file) as a basic means to load sound data into
44 * your program.
45 *
46 * ## Channel layouts
47 *
48 * Audio data passing through SDL is uncompressed PCM data, interleaved. One
49 * can provide their own decompression through an MP3, etc, decoder, but SDL
50 * does not provide this directly. Each interleaved channel of data is meant
51 * to be in a specific order.
52 *
53 * Abbreviations:
54 *
55 * - FRONT = single mono speaker
56 * - FL = front left speaker
57 * - FR = front right speaker
58 * - FC = front center speaker
59 * - BL = back left speaker
60 * - BR = back right speaker
61 * - SR = surround right speaker
62 * - SL = surround left speaker
63 * - BC = back center speaker
64 * - LFE = low-frequency speaker
65 *
66 * These are listed in the order they are laid out in memory, so "FL, FR"
67 * means "the front left speaker is laid out in memory first, then the front
68 * right, then it repeats for the next audio frame".
69 *
70 * - 1 channel (mono) layout: FRONT
71 * - 2 channels (stereo) layout: FL, FR
72 * - 3 channels (2.1) layout: FL, FR, LFE
73 * - 4 channels (quad) layout: FL, FR, BL, BR
74 * - 5 channels (4.1) layout: FL, FR, LFE, BL, BR
75 * - 6 channels (5.1) layout: FL, FR, FC, LFE, BL, BR (last two can also be
76 * BL, BR)
77 * - 7 channels (6.1) layout: FL, FR, FC, LFE, BC, SL, SR
78 * - 8 channels (7.1) layout: FL, FR, FC, LFE, BL, BR, SL, SR
79 *
80 * This is the same order as DirectSound expects, but applied to all
81 * platforms; SDL will swizzle the channels as necessary if a platform expects
82 * something different.
83 *
84 * SDL_AudioStream can also be provided channel maps to change this ordering
85 * to whatever is necessary, in other audio processing scenarios.
86 */
87
88#ifndef SDL_audio_h_
89#define SDL_audio_h_
90
91#include <SDL3/SDL_stdinc.h>
92#include <SDL3/SDL_endian.h>
93#include <SDL3/SDL_error.h>
94#include <SDL3/SDL_mutex.h>
95#include <SDL3/SDL_properties.h>
96#include <SDL3/SDL_iostream.h>
97#include <SDL3/SDL_thread.h>
98
99#include <SDL3/SDL_begin_code.h>
100/* Set up for C function definitions, even when using C++ */
101#ifdef __cplusplus
102extern "C" {
103#endif
104
105/* masks for different parts of SDL_AudioFormat. */
106#define SDL_AUDIO_MASK_BITSIZE (0xFFu)
107#define SDL_AUDIO_MASK_FLOAT (1u<<8)
108#define SDL_AUDIO_MASK_BIG_ENDIAN (1u<<12)
109#define SDL_AUDIO_MASK_SIGNED (1u<<15)
110
111#define SDL_DEFINE_AUDIO_FORMAT(signed, bigendian, float, size) \
112 (((Uint16)(signed) << 15) | ((Uint16)(bigendian) << 12) | ((Uint16)(float) << 8) | ((size) & SDL_AUDIO_MASK_BITSIZE))
113
114/**
115 * Audio format.
116 *
117 * \since This enum is available since SDL 3.0.0.
118 *
119 * \sa SDL_AUDIO_BITSIZE
120 * \sa SDL_AUDIO_BYTESIZE
121 * \sa SDL_AUDIO_ISINT
122 * \sa SDL_AUDIO_ISFLOAT
123 * \sa SDL_AUDIO_ISBIGENDIAN
124 * \sa SDL_AUDIO_ISLITTLEENDIAN
125 * \sa SDL_AUDIO_ISSIGNED
126 * \sa SDL_AUDIO_ISUNSIGNED
127 */
128typedef enum SDL_AudioFormat
129{
130 SDL_AUDIO_U8 = 0x0008u, /**< Unsigned 8-bit samples */
131 /* SDL_DEFINE_AUDIO_FORMAT(0, 0, 0, 8), */
132 SDL_AUDIO_S8 = 0x8008u, /**< Signed 8-bit samples */
133 /* SDL_DEFINE_AUDIO_FORMAT(1, 0, 0, 8), */
134 SDL_AUDIO_S16LE = 0x8010u, /**< Signed 16-bit samples */
135 /* SDL_DEFINE_AUDIO_FORMAT(1, 0, 0, 16), */
136 SDL_AUDIO_S16BE = 0x9010u, /**< As above, but big-endian byte order */
137 /* SDL_DEFINE_AUDIO_FORMAT(1, 1, 0, 16), */
138 SDL_AUDIO_S32LE = 0x8020u, /**< 32-bit integer samples */
139 /* SDL_DEFINE_AUDIO_FORMAT(1, 0, 0, 32), */
140 SDL_AUDIO_S32BE = 0x9020u, /**< As above, but big-endian byte order */
141 /* SDL_DEFINE_AUDIO_FORMAT(1, 1, 0, 32), */
142 SDL_AUDIO_F32LE = 0x8120u, /**< 32-bit floating point samples */
143 /* SDL_DEFINE_AUDIO_FORMAT(1, 0, 1, 32), */
144 SDL_AUDIO_F32BE = 0x9120u, /**< As above, but big-endian byte order */
145 /* SDL_DEFINE_AUDIO_FORMAT(1, 1, 1, 32), */
147
148#if SDL_BYTEORDER == SDL_LIL_ENDIAN
149#define SDL_AUDIO_S16 SDL_AUDIO_S16LE
150#define SDL_AUDIO_S32 SDL_AUDIO_S32LE
151#define SDL_AUDIO_F32 SDL_AUDIO_F32LE
152#else
153#define SDL_AUDIO_S16 SDL_AUDIO_S16BE
154#define SDL_AUDIO_S32 SDL_AUDIO_S32BE
155#define SDL_AUDIO_F32 SDL_AUDIO_F32BE
156#endif
157
158
159/**
160 * Retrieve the size, in bits, from an SDL_AudioFormat.
161 *
162 * For example, `SDL_AUDIO_BITSIZE(SDL_AUDIO_S16)` returns 16.
163 *
164 * \param x an SDL_AudioFormat value.
165 * \returns data size in bits.
166 *
167 * \threadsafety It is safe to call this macro from any thread.
168 *
169 * \since This macro is available since SDL 3.0.0.
170 */
171#define SDL_AUDIO_BITSIZE(x) ((x) & SDL_AUDIO_MASK_BITSIZE)
172
173/**
174 * Retrieve the size, in bytes, from an SDL_AudioFormat.
175 *
176 * For example, `SDL_AUDIO_BYTESIZE(SDL_AUDIO_S16)` returns 2.
177 *
178 * \param x an SDL_AudioFormat value.
179 * \returns data size in bytes.
180 *
181 * \threadsafety It is safe to call this macro from any thread.
182 *
183 * \since This macro is available since SDL 3.0.0.
184 */
185#define SDL_AUDIO_BYTESIZE(x) (SDL_AUDIO_BITSIZE(x) / 8)
186
187/**
188 * Determine if an SDL_AudioFormat represents floating point data.
189 *
190 * For example, `SDL_AUDIO_ISFLOAT(SDL_AUDIO_S16)` returns 0.
191 *
192 * \param x an SDL_AudioFormat value.
193 * \returns non-zero if format is floating point, zero otherwise.
194 *
195 * \threadsafety It is safe to call this macro from any thread.
196 *
197 * \since This macro is available since SDL 3.0.0.
198 */
199#define SDL_AUDIO_ISFLOAT(x) ((x) & SDL_AUDIO_MASK_FLOAT)
200
201/**
202 * Determine if an SDL_AudioFormat represents bigendian data.
203 *
204 * For example, `SDL_AUDIO_ISBIGENDIAN(SDL_AUDIO_S16LE)` returns 0.
205 *
206 * \param x an SDL_AudioFormat value.
207 * \returns non-zero if format is bigendian, zero otherwise.
208 *
209 * \threadsafety It is safe to call this macro from any thread.
210 *
211 * \since This macro is available since SDL 3.0.0.
212 */
213#define SDL_AUDIO_ISBIGENDIAN(x) ((x) & SDL_AUDIO_MASK_BIG_ENDIAN)
214
215/**
216 * Determine if an SDL_AudioFormat represents littleendian data.
217 *
218 * For example, `SDL_AUDIO_ISLITTLEENDIAN(SDL_AUDIO_S16BE)` returns 0.
219 *
220 * \param x an SDL_AudioFormat value.
221 * \returns non-zero if format is littleendian, zero otherwise.
222 *
223 * \threadsafety It is safe to call this macro from any thread.
224 *
225 * \since This macro is available since SDL 3.0.0.
226 */
227#define SDL_AUDIO_ISLITTLEENDIAN(x) (!SDL_AUDIO_ISBIGENDIAN(x))
228
229/**
230 * Determine if an SDL_AudioFormat represents signed data.
231 *
232 * For example, `SDL_AUDIO_ISSIGNED(SDL_AUDIO_U8)` returns 0.
233 *
234 * \param x an SDL_AudioFormat value.
235 * \returns non-zero if format is signed, zero otherwise.
236 *
237 * \threadsafety It is safe to call this macro from any thread.
238 *
239 * \since This macro is available since SDL 3.0.0.
240 */
241#define SDL_AUDIO_ISSIGNED(x) ((x) & SDL_AUDIO_MASK_SIGNED)
242
243/**
244 * Determine if an SDL_AudioFormat represents integer data.
245 *
246 * For example, `SDL_AUDIO_ISINT(SDL_AUDIO_F32)` returns 0.
247 *
248 * \param x an SDL_AudioFormat value.
249 * \returns non-zero if format is integer, zero otherwise.
250 *
251 * \threadsafety It is safe to call this macro from any thread.
252 *
253 * \since This macro is available since SDL 3.0.0.
254 */
255#define SDL_AUDIO_ISINT(x) (!SDL_AUDIO_ISFLOAT(x))
256
257/**
258 * Determine if an SDL_AudioFormat represents unsigned data.
259 *
260 * For example, `SDL_AUDIO_ISUNSIGNED(SDL_AUDIO_S16)` returns 0.
261 *
262 * \param x an SDL_AudioFormat value.
263 * \returns non-zero if format is unsigned, zero otherwise.
264 *
265 * \threadsafety It is safe to call this macro from any thread.
266 *
267 * \since This macro is available since SDL 3.0.0.
268 */
269#define SDL_AUDIO_ISUNSIGNED(x) (!SDL_AUDIO_ISSIGNED(x))
270
271
272/**
273 * SDL Audio Device instance IDs.
274 *
275 * Zero is used to signify an invalid/null device.
276 *
277 * \since This datatype is available since SDL 3.0.0.
278 */
280
281/**
282 * A value used to request a default playback audio device.
283 *
284 * Several functions that require an SDL_AudioDeviceID will accept this value
285 * to signify the app just wants the system to choose a default device instead
286 * of the app providing a specific one.
287 *
288 * \since This macro is available since SDL 3.0.0.
289 */
290#define SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK ((SDL_AudioDeviceID) 0xFFFFFFFFu)
291
292/**
293 * A value used to request a default recording audio device.
294 *
295 * Several functions that require an SDL_AudioDeviceID will accept this value
296 * to signify the app just wants the system to choose a default device instead
297 * of the app providing a specific one.
298 *
299 * \since This macro is available since SDL 3.0.0.
300 */
301#define SDL_AUDIO_DEVICE_DEFAULT_RECORDING ((SDL_AudioDeviceID) 0xFFFFFFFEu)
302
303/**
304 * Format specifier for audio data.
305 *
306 * \since This struct is available since SDL 3.0.0.
307 *
308 * \sa SDL_AudioFormat
309 */
310typedef struct SDL_AudioSpec
311{
312 SDL_AudioFormat format; /**< Audio data format */
313 int channels; /**< Number of channels: 1 mono, 2 stereo, etc */
314 int freq; /**< sample rate: sample frames per second */
316
317/**
318 * Calculate the size of each audio frame (in bytes) from an SDL_AudioSpec.
319 *
320 * This reports on the size of an audio sample frame: stereo Sint16 data (2
321 * channels of 2 bytes each) would be 4 bytes per frame, for example.
322 *
323 * \param x an SDL_AudioSpec to query.
324 * \returns the number of bytes used per sample frame.
325 *
326 * \threadsafety It is safe to call this macro from any thread.
327 *
328 * \since This macro is available since SDL 3.0.0.
329 */
330#define SDL_AUDIO_FRAMESIZE(x) (SDL_AUDIO_BYTESIZE((x).format) * (x).channels)
331
332/**
333 * The opaque handle that represents an audio stream.
334 *
335 * SDL_AudioStream is an audio conversion interface.
336 *
337 * - It can handle resampling data in chunks without generating artifacts,
338 * when it doesn't have the complete buffer available.
339 * - It can handle incoming data in any variable size.
340 * - It can handle input/output format changes on the fly.
341 * - It can remap audio channels between inputs and outputs.
342 * - You push data as you have it, and pull it when you need it
343 * - It can also function as a basic audio data queue even if you just have
344 * sound that needs to pass from one place to another.
345 * - You can hook callbacks up to them when more data is added or requested,
346 * to manage data on-the-fly.
347 *
348 * Audio streams are the core of the SDL3 audio interface. You create one or
349 * more of them, bind them to an opened audio device, and feed data to them
350 * (or for recording, consume data from them).
351 *
352 * \since This struct is available since SDL 3.0.0.
353 *
354 * \sa SDL_CreateAudioStream
355 */
357
358
359/* Function prototypes */
360
361/**
362 * \name Driver discovery functions
363 *
364 * These functions return the list of built in audio drivers, in the
365 * order that they are normally initialized by default.
366 */
367/* @{ */
368
369/**
370 * Use this function to get the number of built-in audio drivers.
371 *
372 * This function returns a hardcoded number. This never returns a negative
373 * value; if there are no drivers compiled into this build of SDL, this
374 * function returns zero. The presence of a driver in this list does not mean
375 * it will function, it just means SDL is capable of interacting with that
376 * interface. For example, a build of SDL might have esound support, but if
377 * there's no esound server available, SDL's esound driver would fail if used.
378 *
379 * By default, SDL tries all drivers, in its preferred order, until one is
380 * found to be usable.
381 *
382 * \returns the number of built-in audio drivers.
383 *
384 * \threadsafety It is safe to call this function from any thread.
385 *
386 * \since This function is available since SDL 3.0.0.
387 *
388 * \sa SDL_GetAudioDriver
389 */
390extern SDL_DECLSPEC int SDLCALL SDL_GetNumAudioDrivers(void);
391
392/**
393 * Use this function to get the name of a built in audio driver.
394 *
395 * The list of audio drivers is given in the order that they are normally
396 * initialized by default; the drivers that seem more reasonable to choose
397 * first (as far as the SDL developers believe) are earlier in the list.
398 *
399 * The names of drivers are all simple, low-ASCII identifiers, like "alsa",
400 * "coreaudio" or "wasapi". These never have Unicode characters, and are not
401 * meant to be proper names.
402 *
403 * \param index the index of the audio driver; the value ranges from 0 to
404 * SDL_GetNumAudioDrivers() - 1.
405 * \returns the name of the audio driver at the requested index, or NULL if an
406 * invalid index was specified.
407 *
408 * \threadsafety It is safe to call this function from any thread.
409 *
410 * \since This function is available since SDL 3.0.0.
411 *
412 * \sa SDL_GetNumAudioDrivers
413 */
414extern SDL_DECLSPEC const char * SDLCALL SDL_GetAudioDriver(int index);
415/* @} */
416
417/**
418 * Get the name of the current audio driver.
419 *
420 * The names of drivers are all simple, low-ASCII identifiers, like "alsa",
421 * "coreaudio" or "wasapi". These never have Unicode characters, and are not
422 * meant to be proper names.
423 *
424 * \returns the name of the current audio driver or NULL if no driver has been
425 * initialized.
426 *
427 * \threadsafety It is safe to call this function from any thread.
428 *
429 * \since This function is available since SDL 3.0.0.
430 */
431extern SDL_DECLSPEC const char * SDLCALL SDL_GetCurrentAudioDriver(void);
432
433/**
434 * Get a list of currently-connected audio playback devices.
435 *
436 * This returns of list of available devices that play sound, perhaps to
437 * speakers or headphones ("playback" devices). If you want devices that
438 * record audio, like a microphone ("recording" devices), use
439 * SDL_GetAudioRecordingDevices() instead.
440 *
441 * This only returns a list of physical devices; it will not have any device
442 * IDs returned by SDL_OpenAudioDevice().
443 *
444 * If this function returns NULL, to signify an error, `*count` will be set to
445 * zero.
446 *
447 * \param count a pointer filled in with the number of devices returned, may
448 * be NULL.
449 * \returns a 0 terminated array of device instance IDs or NULL on error; call
450 * SDL_GetError() for more information. This should be freed with
451 * SDL_free() when it is no longer needed.
452 *
453 * \threadsafety It is safe to call this function from any thread.
454 *
455 * \since This function is available since SDL 3.0.0.
456 *
457 * \sa SDL_OpenAudioDevice
458 * \sa SDL_GetAudioRecordingDevices
459 */
460extern SDL_DECLSPEC SDL_AudioDeviceID * SDLCALL SDL_GetAudioPlaybackDevices(int *count);
461
462/**
463 * Get a list of currently-connected audio recording devices.
464 *
465 * This returns of list of available devices that record audio, like a
466 * microphone ("recording" devices). If you want devices that play sound,
467 * perhaps to speakers or headphones ("playback" devices), use
468 * SDL_GetAudioPlaybackDevices() instead.
469 *
470 * This only returns a list of physical devices; it will not have any device
471 * IDs returned by SDL_OpenAudioDevice().
472 *
473 * If this function returns NULL, to signify an error, `*count` will be set to
474 * zero.
475 *
476 * \param count a pointer filled in with the number of devices returned, may
477 * be NULL.
478 * \returns a 0 terminated array of device instance IDs, or NULL on failure;
479 * call SDL_GetError() for more information. This should be freed
480 * with SDL_free() when it is no longer needed.
481 *
482 * \threadsafety It is safe to call this function from any thread.
483 *
484 * \since This function is available since SDL 3.0.0.
485 *
486 * \sa SDL_OpenAudioDevice
487 * \sa SDL_GetAudioPlaybackDevices
488 */
489extern SDL_DECLSPEC SDL_AudioDeviceID * SDLCALL SDL_GetAudioRecordingDevices(int *count);
490
491/**
492 * Get the human-readable name of a specific audio device.
493 *
494 * \param devid the instance ID of the device to query.
495 * \returns the name of the audio device, or NULL on failure; call
496 * SDL_GetError() for more information.
497 *
498 * \threadsafety It is safe to call this function from any thread.
499 *
500 * \since This function is available since SDL 3.0.0.
501 *
502 * \sa SDL_GetAudioPlaybackDevices
503 * \sa SDL_GetAudioRecordingDevices
504 * \sa SDL_GetDefaultAudioInfo
505 */
506extern SDL_DECLSPEC const char * SDLCALL SDL_GetAudioDeviceName(SDL_AudioDeviceID devid);
507
508/**
509 * Get the current audio format of a specific audio device.
510 *
511 * For an opened device, this will report the format the device is currently
512 * using. If the device isn't yet opened, this will report the device's
513 * preferred format (or a reasonable default if this can't be determined).
514 *
515 * You may also specify SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK or
516 * SDL_AUDIO_DEVICE_DEFAULT_RECORDING here, which is useful for getting a
517 * reasonable recommendation before opening the system-recommended default
518 * device.
519 *
520 * You can also use this to request the current device buffer size. This is
521 * specified in sample frames and represents the amount of data SDL will feed
522 * to the physical hardware in each chunk. This can be converted to
523 * milliseconds of audio with the following equation:
524 *
525 * `ms = (int) ((((Sint64) frames) * 1000) / spec.freq);`
526 *
527 * Buffer size is only important if you need low-level control over the audio
528 * playback timing. Most apps do not need this.
529 *
530 * \param devid the instance ID of the device to query.
531 * \param spec on return, will be filled with device details.
532 * \param sample_frames pointer to store device buffer size, in sample frames.
533 * Can be NULL.
534 * \returns 0 on success or a negative error code on failure; call
535 * SDL_GetError() for more information.
536 *
537 * \threadsafety It is safe to call this function from any thread.
538 *
539 * \since This function is available since SDL 3.0.0.
540 */
541extern SDL_DECLSPEC int SDLCALL SDL_GetAudioDeviceFormat(SDL_AudioDeviceID devid, SDL_AudioSpec *spec, int *sample_frames);
542
543/**
544 * Get the current channel map of an audio device.
545 *
546 * Channel maps are optional; most things do not need them, instead passing
547 * data in the [order that SDL expects](CategoryAudio#channel-layouts).
548 *
549 * Audio devices usually have no remapping applied. This is represented by
550 * returning NULL, and does not signify an error.
551 *
552 * \param devid the instance ID of the device to query.
553 * \param count On output, set to number of channels in the map. Can be NULL.
554 * \returns an array of the current channel mapping, with as many elements as
555 * the current output spec's channels, or NULL if default. This
556 * should be freed with SDL_free() when it is no longer needed.
557 *
558 * \threadsafety It is safe to call this function from any thread.
559 *
560 * \since This function is available since SDL 3.0.0.
561 *
562 * \sa SDL_SetAudioStreamInputChannelMap
563 */
564extern SDL_DECLSPEC int * SDLCALL SDL_GetAudioDeviceChannelMap(SDL_AudioDeviceID devid, int *count);
565
566/**
567 * Open a specific audio device.
568 *
569 * You can open both playback and recording devices through this function.
570 * Playback devices will take data from bound audio streams, mix it, and send
571 * it to the hardware. Recording devices will feed any bound audio streams
572 * with a copy of any incoming data.
573 *
574 * An opened audio device starts out with no audio streams bound. To start
575 * audio playing, bind a stream and supply audio data to it. Unlike SDL2,
576 * there is no audio callback; you only bind audio streams and make sure they
577 * have data flowing into them (however, you can simulate SDL2's semantics
578 * fairly closely by using SDL_OpenAudioDeviceStream instead of this
579 * function).
580 *
581 * If you don't care about opening a specific device, pass a `devid` of either
582 * `SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK` or
583 * `SDL_AUDIO_DEVICE_DEFAULT_RECORDING`. In this case, SDL will try to pick
584 * the most reasonable default, and may also switch between physical devices
585 * seamlessly later, if the most reasonable default changes during the
586 * lifetime of this opened device (user changed the default in the OS's system
587 * preferences, the default got unplugged so the system jumped to a new
588 * default, the user plugged in headphones on a mobile device, etc). Unless
589 * you have a good reason to choose a specific device, this is probably what
590 * you want.
591 *
592 * You may request a specific format for the audio device, but there is no
593 * promise the device will honor that request for several reasons. As such,
594 * it's only meant to be a hint as to what data your app will provide. Audio
595 * streams will accept data in whatever format you specify and manage
596 * conversion for you as appropriate. SDL_GetAudioDeviceFormat can tell you
597 * the preferred format for the device before opening and the actual format
598 * the device is using after opening.
599 *
600 * It's legal to open the same device ID more than once; each successful open
601 * will generate a new logical SDL_AudioDeviceID that is managed separately
602 * from others on the same physical device. This allows libraries to open a
603 * device separately from the main app and bind its own streams without
604 * conflicting.
605 *
606 * It is also legal to open a device ID returned by a previous call to this
607 * function; doing so just creates another logical device on the same physical
608 * device. This may be useful for making logical groupings of audio streams.
609 *
610 * This function returns the opened device ID on success. This is a new,
611 * unique SDL_AudioDeviceID that represents a logical device.
612 *
613 * Some backends might offer arbitrary devices (for example, a networked audio
614 * protocol that can connect to an arbitrary server). For these, as a change
615 * from SDL2, you should open a default device ID and use an SDL hint to
616 * specify the target if you care, or otherwise let the backend figure out a
617 * reasonable default. Most backends don't offer anything like this, and often
618 * this would be an end user setting an environment variable for their custom
619 * need, and not something an application should specifically manage.
620 *
621 * When done with an audio device, possibly at the end of the app's life, one
622 * should call SDL_CloseAudioDevice() on the returned device id.
623 *
624 * \param devid the device instance id to open, or
625 * SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK or
626 * SDL_AUDIO_DEVICE_DEFAULT_RECORDING for the most reasonable
627 * default device.
628 * \param spec the requested device configuration. Can be NULL to use
629 * reasonable defaults.
630 * \returns the device ID on success or 0 on failure; call SDL_GetError() for
631 * more information.
632 *
633 * \threadsafety It is safe to call this function from any thread.
634 *
635 * \since This function is available since SDL 3.0.0.
636 *
637 * \sa SDL_CloseAudioDevice
638 * \sa SDL_GetAudioDeviceFormat
639 */
640extern SDL_DECLSPEC SDL_AudioDeviceID SDLCALL SDL_OpenAudioDevice(SDL_AudioDeviceID devid, const SDL_AudioSpec *spec);
641
642/**
643 * Use this function to pause audio playback on a specified device.
644 *
645 * This function pauses audio processing for a given device. Any bound audio
646 * streams will not progress, and no audio will be generated. Pausing one
647 * device does not prevent other unpaused devices from running.
648 *
649 * Unlike in SDL2, audio devices start in an _unpaused_ state, since an app
650 * has to bind a stream before any audio will flow. Pausing a paused device is
651 * a legal no-op.
652 *
653 * Pausing a device can be useful to halt all audio without unbinding all the
654 * audio streams. This might be useful while a game is paused, or a level is
655 * loading, etc.
656 *
657 * Physical devices can not be paused or unpaused, only logical devices
658 * created through SDL_OpenAudioDevice() can be.
659 *
660 * \param dev a device opened by SDL_OpenAudioDevice().
661 * \returns 0 on success or a negative error code on failure; call
662 * SDL_GetError() for more information.
663 *
664 * \threadsafety It is safe to call this function from any thread.
665 *
666 * \since This function is available since SDL 3.0.0.
667 *
668 * \sa SDL_ResumeAudioDevice
669 * \sa SDL_AudioDevicePaused
670 */
671extern SDL_DECLSPEC int SDLCALL SDL_PauseAudioDevice(SDL_AudioDeviceID dev);
672
673/**
674 * Use this function to unpause audio playback on a specified device.
675 *
676 * This function unpauses audio processing for a given device that has
677 * previously been paused with SDL_PauseAudioDevice(). Once unpaused, any
678 * bound audio streams will begin to progress again, and audio can be
679 * generated.
680 *
681 * Unlike in SDL2, audio devices start in an _unpaused_ state, since an app
682 * has to bind a stream before any audio will flow. Unpausing an unpaused
683 * device is a legal no-op.
684 *
685 * Physical devices can not be paused or unpaused, only logical devices
686 * created through SDL_OpenAudioDevice() can be.
687 *
688 * \param dev a device opened by SDL_OpenAudioDevice().
689 * \returns 0 on success or a negative error code on failure; call
690 * SDL_GetError() for more information.
691 *
692 * \threadsafety It is safe to call this function from any thread.
693 *
694 * \since This function is available since SDL 3.0.0.
695 *
696 * \sa SDL_AudioDevicePaused
697 * \sa SDL_PauseAudioDevice
698 */
699extern SDL_DECLSPEC int SDLCALL SDL_ResumeAudioDevice(SDL_AudioDeviceID dev);
700
701/**
702 * Use this function to query if an audio device is paused.
703 *
704 * Unlike in SDL2, audio devices start in an _unpaused_ state, since an app
705 * has to bind a stream before any audio will flow.
706 *
707 * Physical devices can not be paused or unpaused, only logical devices
708 * created through SDL_OpenAudioDevice() can be. Physical and invalid device
709 * IDs will report themselves as unpaused here.
710 *
711 * \param dev a device opened by SDL_OpenAudioDevice().
712 * \returns SDL_TRUE if device is valid and paused, SDL_FALSE otherwise.
713 *
714 * \threadsafety It is safe to call this function from any thread.
715 *
716 * \since This function is available since SDL 3.0.0.
717 *
718 * \sa SDL_PauseAudioDevice
719 * \sa SDL_ResumeAudioDevice
720 */
721extern SDL_DECLSPEC SDL_bool SDLCALL SDL_AudioDevicePaused(SDL_AudioDeviceID dev);
722
723/**
724 * Get the gain of an audio device.
725 *
726 * The gain of a device is its volume; a larger gain means a louder output,
727 * with a gain of zero being silence.
728 *
729 * Audio devices default to a gain of 1.0f (no change in output).
730 *
731 * Physical devices may not have their gain changed, only logical devices, and
732 * this function will always return -1.0f when used on physical devices.
733 *
734 * \param devid the audio device to query.
735 * \returns the gain of the device or -1.0f on failure; call SDL_GetError()
736 * for more information.
737 *
738 * \threadsafety It is safe to call this function from any thread.
739 *
740 * \since This function is available since SDL 3.0.0.
741 *
742 * \sa SDL_SetAudioDeviceGain
743 */
744extern SDL_DECLSPEC float SDLCALL SDL_GetAudioDeviceGain(SDL_AudioDeviceID devid);
745
746/**
747 * Change the gain of an audio device.
748 *
749 * The gain of a device is its volume; a larger gain means a louder output,
750 * with a gain of zero being silence.
751 *
752 * Audio devices default to a gain of 1.0f (no change in output).
753 *
754 * Physical devices may not have their gain changed, only logical devices, and
755 * this function will always return -1 when used on physical devices. While it
756 * might seem attractive to adjust several logical devices at once in this
757 * way, it would allow an app or library to interfere with another portion of
758 * the program's otherwise-isolated devices.
759 *
760 * This is applied, along with any per-audiostream gain, during playback to
761 * the hardware, and can be continuously changed to create various effects. On
762 * recording devices, this will adjust the gain before passing the data into
763 * an audiostream; that recording audiostream can then adjust its gain further
764 * when outputting the data elsewhere, if it likes, but that second gain is
765 * not applied until the data leaves the audiostream again.
766 *
767 * \param devid the audio device on which to change gain.
768 * \param gain the gain. 1.0f is no change, 0.0f is silence.
769 * \returns 0 on success or a negative error code on failure; call
770 * SDL_GetError() for more information.
771 *
772 * \threadsafety It is safe to call this function from any thread, as it holds
773 * a stream-specific mutex while running.
774 *
775 * \since This function is available since SDL 3.0.0.
776 *
777 * \sa SDL_GetAudioDeviceGain
778 */
779extern SDL_DECLSPEC int SDLCALL SDL_SetAudioDeviceGain(SDL_AudioDeviceID devid, float gain);
780
781/**
782 * Close a previously-opened audio device.
783 *
784 * The application should close open audio devices once they are no longer
785 * needed.
786 *
787 * This function may block briefly while pending audio data is played by the
788 * hardware, so that applications don't drop the last buffer of data they
789 * supplied if terminating immediately afterwards.
790 *
791 * \param devid an audio device id previously returned by
792 * SDL_OpenAudioDevice().
793 *
794 * \threadsafety It is safe to call this function from any thread.
795 *
796 * \since This function is available since SDL 3.0.0.
797 *
798 * \sa SDL_OpenAudioDevice
799 */
800extern SDL_DECLSPEC void SDLCALL SDL_CloseAudioDevice(SDL_AudioDeviceID devid);
801
802/**
803 * Bind a list of audio streams to an audio device.
804 *
805 * Audio data will flow through any bound streams. For a playback device, data
806 * for all bound streams will be mixed together and fed to the device. For a
807 * recording device, a copy of recorded data will be provided to each bound
808 * stream.
809 *
810 * Audio streams can only be bound to an open device. This operation is
811 * atomic--all streams bound in the same call will start processing at the
812 * same time, so they can stay in sync. Also: either all streams will be bound
813 * or none of them will be.
814 *
815 * It is an error to bind an already-bound stream; it must be explicitly
816 * unbound first.
817 *
818 * Binding a stream to a device will set its output format for playback
819 * devices, and its input format for recording devices, so they match the
820 * device's settings. The caller is welcome to change the other end of the
821 * stream's format at any time.
822 *
823 * \param devid an audio device to bind a stream to.
824 * \param streams an array of audio streams to unbind.
825 * \param num_streams number streams listed in the `streams` array.
826 * \returns 0 on success or a negative error code on failure; call
827 * SDL_GetError() for more information.
828 *
829 * \threadsafety It is safe to call this function from any thread.
830 *
831 * \since This function is available since SDL 3.0.0.
832 *
833 * \sa SDL_BindAudioStreams
834 * \sa SDL_UnbindAudioStream
835 * \sa SDL_GetAudioStreamDevice
836 */
837extern SDL_DECLSPEC int SDLCALL SDL_BindAudioStreams(SDL_AudioDeviceID devid, SDL_AudioStream **streams, int num_streams);
838
839/**
840 * Bind a single audio stream to an audio device.
841 *
842 * This is a convenience function, equivalent to calling
843 * `SDL_BindAudioStreams(devid, &stream, 1)`.
844 *
845 * \param devid an audio device to bind a stream to.
846 * \param stream an audio stream to bind to a device.
847 * \returns 0 on success or a negative error code on failure; call
848 * SDL_GetError() for more information.
849 *
850 * \threadsafety It is safe to call this function from any thread.
851 *
852 * \since This function is available since SDL 3.0.0.
853 *
854 * \sa SDL_BindAudioStreams
855 * \sa SDL_UnbindAudioStream
856 * \sa SDL_GetAudioStreamDevice
857 */
858extern SDL_DECLSPEC int SDLCALL SDL_BindAudioStream(SDL_AudioDeviceID devid, SDL_AudioStream *stream);
859
860/**
861 * Unbind a list of audio streams from their audio devices.
862 *
863 * The streams being unbound do not all have to be on the same device. All
864 * streams on the same device will be unbound atomically (data will stop
865 * flowing through all unbound streams on the same device at the same time).
866 *
867 * Unbinding a stream that isn't bound to a device is a legal no-op.
868 *
869 * \param streams an array of audio streams to unbind.
870 * \param num_streams number streams listed in the `streams` array.
871 *
872 * \threadsafety It is safe to call this function from any thread.
873 *
874 * \since This function is available since SDL 3.0.0.
875 *
876 * \sa SDL_BindAudioStreams
877 */
878extern SDL_DECLSPEC void SDLCALL SDL_UnbindAudioStreams(SDL_AudioStream **streams, int num_streams);
879
880/**
881 * Unbind a single audio stream from its audio device.
882 *
883 * This is a convenience function, equivalent to calling
884 * `SDL_UnbindAudioStreams(&stream, 1)`.
885 *
886 * \param stream an audio stream to unbind from a device.
887 *
888 * \threadsafety It is safe to call this function from any thread.
889 *
890 * \since This function is available since SDL 3.0.0.
891 *
892 * \sa SDL_BindAudioStream
893 */
894extern SDL_DECLSPEC void SDLCALL SDL_UnbindAudioStream(SDL_AudioStream *stream);
895
896/**
897 * Query an audio stream for its currently-bound device.
898 *
899 * This reports the audio device that an audio stream is currently bound to.
900 *
901 * If not bound, or invalid, this returns zero, which is not a valid device
902 * ID.
903 *
904 * \param stream the audio stream to query.
905 * \returns the bound audio device, or 0 if not bound or invalid.
906 *
907 * \threadsafety It is safe to call this function from any thread.
908 *
909 * \since This function is available since SDL 3.0.0.
910 *
911 * \sa SDL_BindAudioStream
912 * \sa SDL_BindAudioStreams
913 */
914extern SDL_DECLSPEC SDL_AudioDeviceID SDLCALL SDL_GetAudioStreamDevice(SDL_AudioStream *stream);
915
916/**
917 * Create a new audio stream.
918 *
919 * \param src_spec the format details of the input audio.
920 * \param dst_spec the format details of the output audio.
921 * \returns a new audio stream on success or NULL on failure; call
922 * SDL_GetError() for more information.
923 *
924 * \threadsafety It is safe to call this function from any thread.
925 *
926 * \since This function is available since SDL 3.0.0.
927 *
928 * \sa SDL_PutAudioStreamData
929 * \sa SDL_GetAudioStreamData
930 * \sa SDL_GetAudioStreamAvailable
931 * \sa SDL_FlushAudioStream
932 * \sa SDL_ClearAudioStream
933 * \sa SDL_SetAudioStreamFormat
934 * \sa SDL_DestroyAudioStream
935 */
936extern SDL_DECLSPEC SDL_AudioStream * SDLCALL SDL_CreateAudioStream(const SDL_AudioSpec *src_spec, const SDL_AudioSpec *dst_spec);
937
938/**
939 * Get the properties associated with an audio stream.
940 *
941 * \param stream the SDL_AudioStream to query.
942 * \returns a valid property ID on success or 0 on failure; call
943 * SDL_GetError() for more information.
944 *
945 * \since This function is available since SDL 3.0.0.
946 */
948
949/**
950 * Query the current format of an audio stream.
951 *
952 * \param stream the SDL_AudioStream to query.
953 * \param src_spec where to store the input audio format; ignored if NULL.
954 * \param dst_spec where to store the output audio format; ignored if NULL.
955 * \returns 0 on success or a negative error code on failure; call
956 * SDL_GetError() for more information.
957 *
958 * \threadsafety It is safe to call this function from any thread, as it holds
959 * a stream-specific mutex while running.
960 *
961 * \since This function is available since SDL 3.0.0.
962 *
963 * \sa SDL_SetAudioStreamFormat
964 */
965extern SDL_DECLSPEC int SDLCALL SDL_GetAudioStreamFormat(SDL_AudioStream *stream,
966 SDL_AudioSpec *src_spec,
967 SDL_AudioSpec *dst_spec);
968
969/**
970 * Change the input and output formats of an audio stream.
971 *
972 * Future calls to and SDL_GetAudioStreamAvailable and SDL_GetAudioStreamData
973 * will reflect the new format, and future calls to SDL_PutAudioStreamData
974 * must provide data in the new input formats.
975 *
976 * Data that was previously queued in the stream will still be operated on in
977 * the format that was current when it was added, which is to say you can put
978 * the end of a sound file in one format to a stream, change formats for the
979 * next sound file, and start putting that new data while the previous sound
980 * file is still queued, and everything will still play back correctly.
981 *
982 * \param stream the stream the format is being changed.
983 * \param src_spec the new format of the audio input; if NULL, it is not
984 * changed.
985 * \param dst_spec the new format of the audio output; if NULL, it is not
986 * changed.
987 * \returns 0 on success or a negative error code on failure; call
988 * SDL_GetError() for more information.
989 *
990 * \threadsafety It is safe to call this function from any thread, as it holds
991 * a stream-specific mutex while running.
992 *
993 * \since This function is available since SDL 3.0.0.
994 *
995 * \sa SDL_GetAudioStreamFormat
996 * \sa SDL_SetAudioStreamFrequencyRatio
997 */
998extern SDL_DECLSPEC int SDLCALL SDL_SetAudioStreamFormat(SDL_AudioStream *stream,
999 const SDL_AudioSpec *src_spec,
1000 const SDL_AudioSpec *dst_spec);
1001
1002/**
1003 * Get the frequency ratio of an audio stream.
1004 *
1005 * \param stream the SDL_AudioStream to query.
1006 * \returns the frequency ratio of the stream or 0.0 on failure; call
1007 * SDL_GetError() for more information.
1008 *
1009 * \threadsafety It is safe to call this function from any thread, as it holds
1010 * a stream-specific mutex while running.
1011 *
1012 * \since This function is available since SDL 3.0.0.
1013 *
1014 * \sa SDL_SetAudioStreamFrequencyRatio
1015 */
1016extern SDL_DECLSPEC float SDLCALL SDL_GetAudioStreamFrequencyRatio(SDL_AudioStream *stream);
1017
1018/**
1019 * Change the frequency ratio of an audio stream.
1020 *
1021 * The frequency ratio is used to adjust the rate at which input data is
1022 * consumed. Changing this effectively modifies the speed and pitch of the
1023 * audio. A value greater than 1.0 will play the audio faster, and at a higher
1024 * pitch. A value less than 1.0 will play the audio slower, and at a lower
1025 * pitch.
1026 *
1027 * This is applied during SDL_GetAudioStreamData, and can be continuously
1028 * changed to create various effects.
1029 *
1030 * \param stream the stream the frequency ratio is being changed.
1031 * \param ratio the frequency ratio. 1.0 is normal speed. Must be between 0.01
1032 * and 100.
1033 * \returns 0 on success or a negative error code on failure; call
1034 * SDL_GetError() for more information.
1035 *
1036 * \threadsafety It is safe to call this function from any thread, as it holds
1037 * a stream-specific mutex while running.
1038 *
1039 * \since This function is available since SDL 3.0.0.
1040 *
1041 * \sa SDL_GetAudioStreamFrequencyRatio
1042 * \sa SDL_SetAudioStreamFormat
1043 */
1044extern SDL_DECLSPEC int SDLCALL SDL_SetAudioStreamFrequencyRatio(SDL_AudioStream *stream, float ratio);
1045
1046/**
1047 * Get the gain of an audio stream.
1048 *
1049 * The gain of a stream is its volume; a larger gain means a louder output,
1050 * with a gain of zero being silence.
1051 *
1052 * Audio streams default to a gain of 1.0f (no change in output).
1053 *
1054 * \param stream the SDL_AudioStream to query.
1055 * \returns the gain of the stream or -1.0f on failure; call SDL_GetError()
1056 * for more information.
1057 *
1058 * \threadsafety It is safe to call this function from any thread, as it holds
1059 * a stream-specific mutex while running.
1060 *
1061 * \since This function is available since SDL 3.0.0.
1062 *
1063 * \sa SDL_SetAudioStreamGain
1064 */
1065extern SDL_DECLSPEC float SDLCALL SDL_GetAudioStreamGain(SDL_AudioStream *stream);
1066
1067/**
1068 * Change the gain of an audio stream.
1069 *
1070 * The gain of a stream is its volume; a larger gain means a louder output,
1071 * with a gain of zero being silence.
1072 *
1073 * Audio streams default to a gain of 1.0f (no change in output).
1074 *
1075 * This is applied during SDL_GetAudioStreamData, and can be continuously
1076 * changed to create various effects.
1077 *
1078 * \param stream the stream on which the gain is being changed.
1079 * \param gain the gain. 1.0f is no change, 0.0f is silence.
1080 * \returns 0 on successor a negative error code on failure; call
1081 * SDL_GetError() for more information.
1082 *
1083 * \threadsafety It is safe to call this function from any thread, as it holds
1084 * a stream-specific mutex while running.
1085 *
1086 * \since This function is available since SDL 3.0.0.
1087 *
1088 * \sa SDL_GetAudioStreamGain
1089 */
1090extern SDL_DECLSPEC int SDLCALL SDL_SetAudioStreamGain(SDL_AudioStream *stream, float gain);
1091
1092/**
1093 * Get the current input channel map of an audio stream.
1094 *
1095 * Channel maps are optional; most things do not need them, instead passing
1096 * data in the [order that SDL expects](CategoryAudio#channel-layouts).
1097 *
1098 * Audio streams default to no remapping applied. This is represented by
1099 * returning NULL, and does not signify an error.
1100 *
1101 * \param stream the SDL_AudioStream to query.
1102 * \param count On output, set to number of channels in the map. Can be NULL.
1103 * \returns an array of the current channel mapping, with as many elements as
1104 * the current output spec's channels, or NULL if default. This
1105 * should be freed with SDL_free() when it is no longer needed.
1106 *
1107 * \threadsafety It is safe to call this function from any thread, as it holds
1108 * a stream-specific mutex while running.
1109 *
1110 * \since This function is available since SDL 3.0.0.
1111 *
1112 * \sa SDL_SetAudioStreamInputChannelMap
1113 */
1114extern SDL_DECLSPEC int * SDLCALL SDL_GetAudioStreamInputChannelMap(SDL_AudioStream *stream, int *count);
1115
1116/**
1117 * Get the current output channel map of an audio stream.
1118 *
1119 * Channel maps are optional; most things do not need them, instead passing
1120 * data in the [order that SDL expects](CategoryAudio#channel-layouts).
1121 *
1122 * Audio streams default to no remapping applied. This is represented by
1123 * returning NULL, and does not signify an error.
1124 *
1125 * \param stream the SDL_AudioStream to query.
1126 * \param count On output, set to number of channels in the map. Can be NULL.
1127 * \returns an array of the current channel mapping, with as many elements as
1128 * the current output spec's channels, or NULL if default. This
1129 * should be freed with SDL_free() when it is no longer needed.
1130 *
1131 * \threadsafety It is safe to call this function from any thread, as it holds
1132 * a stream-specific mutex while running.
1133 *
1134 * \since This function is available since SDL 3.0.0.
1135 *
1136 * \sa SDL_SetAudioStreamInputChannelMap
1137 */
1138extern SDL_DECLSPEC int * SDLCALL SDL_GetAudioStreamOutputChannelMap(SDL_AudioStream *stream, int *count);
1139
1140/**
1141 * Set the current input channel map of an audio stream.
1142 *
1143 * Channel maps are optional; most things do not need them, instead passing
1144 * data in the [order that SDL expects](CategoryAudio#channel-layouts).
1145 *
1146 * The input channel map reorders data that is added to a stream via
1147 * SDL_PutAudioStreamData. Future calls to SDL_PutAudioStreamData must provide
1148 * data in the new channel order.
1149 *
1150 * Each item in the array represents an input channel, and its value is the
1151 * channel that it should be remapped to. To reverse a stereo signal's left
1152 * and right values, you'd have an array of `{ 1, 0 }`. It is legal to remap
1153 * multiple channels to the same thing, so `{ 1, 1 }` would duplicate the
1154 * right channel to both channels of a stereo signal. You cannot change the
1155 * number of channels through a channel map, just reorder them.
1156 *
1157 * Data that was previously queued in the stream will still be operated on in
1158 * the order that was current when it was added, which is to say you can put
1159 * the end of a sound file in one order to a stream, change orders for the
1160 * next sound file, and start putting that new data while the previous sound
1161 * file is still queued, and everything will still play back correctly.
1162 *
1163 * Audio streams default to no remapping applied. Passing a NULL channel map
1164 * is legal, and turns off remapping.
1165 *
1166 * SDL will copy the channel map; the caller does not have to save this array
1167 * after this call.
1168 *
1169 * If `count` is not equal to the current number of channels in the audio
1170 * stream's format, this will fail. This is a safety measure to make sure a a
1171 * race condition hasn't changed the format while you this call is setting the
1172 * channel map.
1173 *
1174 * \param stream the SDL_AudioStream to change.
1175 * \param chmap the new channel map, NULL to reset to default.
1176 * \param count The number of channels in the map.
1177 * \returns 0 on success or a negative error code on failure; call
1178 * SDL_GetError() for more information.
1179 *
1180 * \threadsafety It is safe to call this function from any thread, as it holds
1181 * a stream-specific mutex while running. Don't change the
1182 * stream's format to have a different number of channels from a
1183 * a different thread at the same time, though!
1184 *
1185 * \since This function is available since SDL 3.0.0.
1186 *
1187 * \sa SDL_SetAudioStreamInputChannelMap
1188 */
1189extern SDL_DECLSPEC int SDLCALL SDL_SetAudioStreamInputChannelMap(SDL_AudioStream *stream, const int *chmap, int count);
1190
1191/**
1192 * Set the current output channel map of an audio stream.
1193 *
1194 * Channel maps are optional; most things do not need them, instead passing
1195 * data in the [order that SDL expects](CategoryAudio#channel-layouts).
1196 *
1197 * The output channel map reorders data that leaving a stream via
1198 * SDL_GetAudioStreamData.
1199 *
1200 * Each item in the array represents an output channel, and its value is the
1201 * channel that it should be remapped to. To reverse a stereo signal's left
1202 * and right values, you'd have an array of `{ 1, 0 }`. It is legal to remap
1203 * multiple channels to the same thing, so `{ 1, 1 }` would duplicate the
1204 * right channel to both channels of a stereo signal. You cannot change the
1205 * number of channels through a channel map, just reorder them.
1206 *
1207 * The output channel map can be changed at any time, as output remapping is
1208 * applied during SDL_GetAudioStreamData.
1209 *
1210 * Audio streams default to no remapping applied. Passing a NULL channel map
1211 * is legal, and turns off remapping.
1212 *
1213 * SDL will copy the channel map; the caller does not have to save this array
1214 * after this call.
1215 *
1216 * If `count` is not equal to the current number of channels in the audio
1217 * stream's format, this will fail. This is a safety measure to make sure a a
1218 * race condition hasn't changed the format while you this call is setting the
1219 * channel map.
1220 *
1221 * \param stream the SDL_AudioStream to change.
1222 * \param chmap the new channel map, NULL to reset to default.
1223 * \param count The number of channels in the map.
1224 * \returns 0 on success or a negative error code on failure; call
1225 * SDL_GetError() for more information.
1226 *
1227 * \threadsafety It is safe to call this function from any thread, as it holds
1228 * a stream-specific mutex while running. Don't change the
1229 * stream's format to have a different number of channels from a
1230 * a different thread at the same time, though!
1231 *
1232 * \since This function is available since SDL 3.0.0.
1233 *
1234 * \sa SDL_SetAudioStreamInputChannelMap
1235 */
1236extern SDL_DECLSPEC int SDLCALL SDL_SetAudioStreamOutputChannelMap(SDL_AudioStream *stream, const int *chmap, int count);
1237
1238/**
1239 * Add data to the stream.
1240 *
1241 * This data must match the format/channels/samplerate specified in the latest
1242 * call to SDL_SetAudioStreamFormat, or the format specified when creating the
1243 * stream if it hasn't been changed.
1244 *
1245 * Note that this call simply copies the unconverted data for later. This is
1246 * different than SDL2, where data was converted during the Put call and the
1247 * Get call would just dequeue the previously-converted data.
1248 *
1249 * \param stream the stream the audio data is being added to.
1250 * \param buf a pointer to the audio data to add.
1251 * \param len the number of bytes to write to the stream.
1252 * \returns 0 on success or a negative error code on failure; call
1253 * SDL_GetError() for more information.
1254 *
1255 * \threadsafety It is safe to call this function from any thread, but if the
1256 * stream has a callback set, the caller might need to manage
1257 * extra locking.
1258 *
1259 * \since This function is available since SDL 3.0.0.
1260 *
1261 * \sa SDL_ClearAudioStream
1262 * \sa SDL_FlushAudioStream
1263 * \sa SDL_GetAudioStreamData
1264 * \sa SDL_GetAudioStreamQueued
1265 */
1266extern SDL_DECLSPEC int SDLCALL SDL_PutAudioStreamData(SDL_AudioStream *stream, const void *buf, int len);
1267
1268/**
1269 * Get converted/resampled data from the stream.
1270 *
1271 * The input/output data format/channels/samplerate is specified when creating
1272 * the stream, and can be changed after creation by calling
1273 * SDL_SetAudioStreamFormat.
1274 *
1275 * Note that any conversion and resampling necessary is done during this call,
1276 * and SDL_PutAudioStreamData simply queues unconverted data for later. This
1277 * is different than SDL2, where that work was done while inputting new data
1278 * to the stream and requesting the output just copied the converted data.
1279 *
1280 * \param stream the stream the audio is being requested from.
1281 * \param buf a buffer to fill with audio data.
1282 * \param len the maximum number of bytes to fill.
1283 * \returns the number of bytes read from the stream or a negative error code
1284 * on failure; call SDL_GetError() for more information.
1285 *
1286 * \threadsafety It is safe to call this function from any thread, but if the
1287 * stream has a callback set, the caller might need to manage
1288 * extra locking.
1289 *
1290 * \since This function is available since SDL 3.0.0.
1291 *
1292 * \sa SDL_ClearAudioStream
1293 * \sa SDL_GetAudioStreamAvailable
1294 * \sa SDL_PutAudioStreamData
1295 */
1296extern SDL_DECLSPEC int SDLCALL SDL_GetAudioStreamData(SDL_AudioStream *stream, void *buf, int len);
1297
1298/**
1299 * Get the number of converted/resampled bytes available.
1300 *
1301 * The stream may be buffering data behind the scenes until it has enough to
1302 * resample correctly, so this number might be lower than what you expect, or
1303 * even be zero. Add more data or flush the stream if you need the data now.
1304 *
1305 * If the stream has so much data that it would overflow an int, the return
1306 * value is clamped to a maximum value, but no queued data is lost; if there
1307 * are gigabytes of data queued, the app might need to read some of it with
1308 * SDL_GetAudioStreamData before this function's return value is no longer
1309 * clamped.
1310 *
1311 * \param stream the audio stream to query.
1312 * \returns the number of converted/resampled bytes available.
1313 *
1314 * \threadsafety It is safe to call this function from any thread.
1315 *
1316 * \since This function is available since SDL 3.0.0.
1317 *
1318 * \sa SDL_GetAudioStreamData
1319 * \sa SDL_PutAudioStreamData
1320 */
1321extern SDL_DECLSPEC int SDLCALL SDL_GetAudioStreamAvailable(SDL_AudioStream *stream);
1322
1323
1324/**
1325 * Get the number of bytes currently queued.
1326 *
1327 * Note that audio streams can change their input format at any time, even if
1328 * there is still data queued in a different format, so the returned byte
1329 * count will not necessarily match the number of _sample frames_ available.
1330 * Users of this API should be aware of format changes they make when feeding
1331 * a stream and plan accordingly.
1332 *
1333 * Queued data is not converted until it is consumed by
1334 * SDL_GetAudioStreamData, so this value should be representative of the exact
1335 * data that was put into the stream.
1336 *
1337 * If the stream has so much data that it would overflow an int, the return
1338 * value is clamped to a maximum value, but no queued data is lost; if there
1339 * are gigabytes of data queued, the app might need to read some of it with
1340 * SDL_GetAudioStreamData before this function's return value is no longer
1341 * clamped.
1342 *
1343 * \param stream the audio stream to query.
1344 * \returns the number of bytes queued.
1345 *
1346 * \threadsafety It is safe to call this function from any thread.
1347 *
1348 * \since This function is available since SDL 3.0.0.
1349 *
1350 * \sa SDL_PutAudioStreamData
1351 * \sa SDL_ClearAudioStream
1352 */
1353extern SDL_DECLSPEC int SDLCALL SDL_GetAudioStreamQueued(SDL_AudioStream *stream);
1354
1355
1356/**
1357 * Tell the stream that you're done sending data, and anything being buffered
1358 * should be converted/resampled and made available immediately.
1359 *
1360 * It is legal to add more data to a stream after flushing, but there may be
1361 * audio gaps in the output. Generally this is intended to signal the end of
1362 * input, so the complete output becomes available.
1363 *
1364 * \param stream the audio stream to flush.
1365 * \returns 0 on success or a negative error code on failure; call
1366 * SDL_GetError() for more information.
1367 *
1368 * \threadsafety It is safe to call this function from any thread.
1369 *
1370 * \since This function is available since SDL 3.0.0.
1371 *
1372 * \sa SDL_PutAudioStreamData
1373 */
1374extern SDL_DECLSPEC int SDLCALL SDL_FlushAudioStream(SDL_AudioStream *stream);
1375
1376/**
1377 * Clear any pending data in the stream.
1378 *
1379 * This drops any queued data, so there will be nothing to read from the
1380 * stream until more is added.
1381 *
1382 * \param stream the audio stream to clear.
1383 * \returns 0 on success or a negative error code on failure; call
1384 * SDL_GetError() for more information.
1385 *
1386 * \threadsafety It is safe to call this function from any thread.
1387 *
1388 * \since This function is available since SDL 3.0.0.
1389 *
1390 * \sa SDL_GetAudioStreamAvailable
1391 * \sa SDL_GetAudioStreamData
1392 * \sa SDL_GetAudioStreamQueued
1393 * \sa SDL_PutAudioStreamData
1394 */
1395extern SDL_DECLSPEC int SDLCALL SDL_ClearAudioStream(SDL_AudioStream *stream);
1396
1397/**
1398 * Use this function to pause audio playback on the audio device associated
1399 * with an audio stream.
1400 *
1401 * This function pauses audio processing for a given device. Any bound audio
1402 * streams will not progress, and no audio will be generated. Pausing one
1403 * device does not prevent other unpaused devices from running.
1404 *
1405 * Pausing a device can be useful to halt all audio without unbinding all the
1406 * audio streams. This might be useful while a game is paused, or a level is
1407 * loading, etc.
1408 *
1409 * \param stream the audio stream associated with the audio device to pause.
1410 * \returns 0 on success or a negative error code on failure; call
1411 * SDL_GetError() for more information.
1412 *
1413 * \threadsafety It is safe to call this function from any thread.
1414 *
1415 * \since This function is available since SDL 3.0.0.
1416 *
1417 * \sa SDL_ResumeAudioStreamDevice
1418 */
1419extern SDL_DECLSPEC int SDLCALL SDL_PauseAudioStreamDevice(SDL_AudioStream *stream);
1420
1421/**
1422 * Use this function to unpause audio playback on the audio device associated
1423 * with an audio stream.
1424 *
1425 * This function unpauses audio processing for a given device that has
1426 * previously been paused. Once unpaused, any bound audio streams will begin
1427 * to progress again, and audio can be generated.
1428 *
1429 * \param stream the audio stream associated with the audio device to resume.
1430 * \returns 0 on success or a negative error code on failure; call
1431 * SDL_GetError() for more information.
1432 *
1433 * \threadsafety It is safe to call this function from any thread.
1434 *
1435 * \since This function is available since SDL 3.0.0.
1436 *
1437 * \sa SDL_PauseAudioStreamDevice
1438 */
1439extern SDL_DECLSPEC int SDLCALL SDL_ResumeAudioStreamDevice(SDL_AudioStream *stream);
1440
1441/**
1442 * Lock an audio stream for serialized access.
1443 *
1444 * Each SDL_AudioStream has an internal mutex it uses to protect its data
1445 * structures from threading conflicts. This function allows an app to lock
1446 * that mutex, which could be useful if registering callbacks on this stream.
1447 *
1448 * One does not need to lock a stream to use in it most cases, as the stream
1449 * manages this lock internally. However, this lock is held during callbacks,
1450 * which may run from arbitrary threads at any time, so if an app needs to
1451 * protect shared data during those callbacks, locking the stream guarantees
1452 * that the callback is not running while the lock is held.
1453 *
1454 * As this is just a wrapper over SDL_LockMutex for an internal lock; it has
1455 * all the same attributes (recursive locks are allowed, etc).
1456 *
1457 * \param stream the audio stream to lock.
1458 * \returns 0 on success or a negative error code on failure; call
1459 * SDL_GetError() for more information.
1460 *
1461 * \threadsafety It is safe to call this function from any thread.
1462 *
1463 * \since This function is available since SDL 3.0.0.
1464 *
1465 * \sa SDL_UnlockAudioStream
1466 */
1467extern SDL_DECLSPEC int SDLCALL SDL_LockAudioStream(SDL_AudioStream *stream);
1468
1469
1470/**
1471 * Unlock an audio stream for serialized access.
1472 *
1473 * This unlocks an audio stream after a call to SDL_LockAudioStream.
1474 *
1475 * \param stream the audio stream to unlock.
1476 * \returns 0 on success or a negative error code on failure; call
1477 * SDL_GetError() for more information.
1478 *
1479 * \threadsafety You should only call this from the same thread that
1480 * previously called SDL_LockAudioStream.
1481 *
1482 * \since This function is available since SDL 3.0.0.
1483 *
1484 * \sa SDL_LockAudioStream
1485 */
1486extern SDL_DECLSPEC int SDLCALL SDL_UnlockAudioStream(SDL_AudioStream *stream);
1487
1488/**
1489 * A callback that fires when data passes through an SDL_AudioStream.
1490 *
1491 * Apps can (optionally) register a callback with an audio stream that is
1492 * called when data is added with SDL_PutAudioStreamData, or requested with
1493 * SDL_GetAudioStreamData.
1494 *
1495 * Two values are offered here: one is the amount of additional data needed to
1496 * satisfy the immediate request (which might be zero if the stream already
1497 * has enough data queued) and the other is the total amount being requested.
1498 * In a Get call triggering a Put callback, these values can be different. In
1499 * a Put call triggering a Get callback, these values are always the same.
1500 *
1501 * Byte counts might be slightly overestimated due to buffering or resampling,
1502 * and may change from call to call.
1503 *
1504 * This callback is not required to do anything. Generally this is useful for
1505 * adding/reading data on demand, and the app will often put/get data as
1506 * appropriate, but the system goes on with the data currently available to it
1507 * if this callback does nothing.
1508 *
1509 * \param stream the SDL audio stream associated with this callback.
1510 * \param additional_amount the amount of data, in bytes, that is needed right
1511 * now.
1512 * \param total_amount the total amount of data requested, in bytes, that is
1513 * requested or available.
1514 * \param userdata an opaque pointer provided by the app for their personal
1515 * use.
1516 *
1517 * \threadsafety This callbacks may run from any thread, so if you need to
1518 * protect shared data, you should use SDL_LockAudioStream to
1519 * serialize access; this lock will be held before your callback
1520 * is called, so your callback does not need to manage the lock
1521 * explicitly.
1522 *
1523 * \since This datatype is available since SDL 3.0.0.
1524 *
1525 * \sa SDL_SetAudioStreamGetCallback
1526 * \sa SDL_SetAudioStreamPutCallback
1527 */
1528typedef void (SDLCALL *SDL_AudioStreamCallback)(void *userdata, SDL_AudioStream *stream, int additional_amount, int total_amount);
1529
1530/**
1531 * Set a callback that runs when data is requested from an audio stream.
1532 *
1533 * This callback is called _before_ data is obtained from the stream, giving
1534 * the callback the chance to add more on-demand.
1535 *
1536 * The callback can (optionally) call SDL_PutAudioStreamData() to add more
1537 * audio to the stream during this call; if needed, the request that triggered
1538 * this callback will obtain the new data immediately.
1539 *
1540 * The callback's `approx_request` argument is roughly how many bytes of
1541 * _unconverted_ data (in the stream's input format) is needed by the caller,
1542 * although this may overestimate a little for safety. This takes into account
1543 * how much is already in the stream and only asks for any extra necessary to
1544 * resolve the request, which means the callback may be asked for zero bytes,
1545 * and a different amount on each call.
1546 *
1547 * The callback is not required to supply exact amounts; it is allowed to
1548 * supply too much or too little or none at all. The caller will get what's
1549 * available, up to the amount they requested, regardless of this callback's
1550 * outcome.
1551 *
1552 * Clearing or flushing an audio stream does not call this callback.
1553 *
1554 * This function obtains the stream's lock, which means any existing callback
1555 * (get or put) in progress will finish running before setting the new
1556 * callback.
1557 *
1558 * Setting a NULL function turns off the callback.
1559 *
1560 * \param stream the audio stream to set the new callback on.
1561 * \param callback the new callback function to call when data is added to the
1562 * stream.
1563 * \param userdata an opaque pointer provided to the callback for its own
1564 * personal use.
1565 * \returns 0 on success or a negative error code on failure; call
1566 * SDL_GetError() for more information. This only fails if `stream`
1567 * is NULL.
1568 *
1569 * \threadsafety It is safe to call this function from any thread.
1570 *
1571 * \since This function is available since SDL 3.0.0.
1572 *
1573 * \sa SDL_SetAudioStreamPutCallback
1574 */
1575extern SDL_DECLSPEC int SDLCALL SDL_SetAudioStreamGetCallback(SDL_AudioStream *stream, SDL_AudioStreamCallback callback, void *userdata);
1576
1577/**
1578 * Set a callback that runs when data is added to an audio stream.
1579 *
1580 * This callback is called _after_ the data is added to the stream, giving the
1581 * callback the chance to obtain it immediately.
1582 *
1583 * The callback can (optionally) call SDL_GetAudioStreamData() to obtain audio
1584 * from the stream during this call.
1585 *
1586 * The callback's `approx_request` argument is how many bytes of _converted_
1587 * data (in the stream's output format) was provided by the caller, although
1588 * this may underestimate a little for safety. This value might be less than
1589 * what is currently available in the stream, if data was already there, and
1590 * might be less than the caller provided if the stream needs to keep a buffer
1591 * to aid in resampling. Which means the callback may be provided with zero
1592 * bytes, and a different amount on each call.
1593 *
1594 * The callback may call SDL_GetAudioStreamAvailable to see the total amount
1595 * currently available to read from the stream, instead of the total provided
1596 * by the current call.
1597 *
1598 * The callback is not required to obtain all data. It is allowed to read less
1599 * or none at all. Anything not read now simply remains in the stream for
1600 * later access.
1601 *
1602 * Clearing or flushing an audio stream does not call this callback.
1603 *
1604 * This function obtains the stream's lock, which means any existing callback
1605 * (get or put) in progress will finish running before setting the new
1606 * callback.
1607 *
1608 * Setting a NULL function turns off the callback.
1609 *
1610 * \param stream the audio stream to set the new callback on.
1611 * \param callback the new callback function to call when data is added to the
1612 * stream.
1613 * \param userdata an opaque pointer provided to the callback for its own
1614 * personal use.
1615 * \returns 0 on success or a negative error code on failure; call
1616 * SDL_GetError() for more information. This only fails if `stream`
1617 * is NULL.
1618 *
1619 * \threadsafety It is safe to call this function from any thread.
1620 *
1621 * \since This function is available since SDL 3.0.0.
1622 *
1623 * \sa SDL_SetAudioStreamGetCallback
1624 */
1625extern SDL_DECLSPEC int SDLCALL SDL_SetAudioStreamPutCallback(SDL_AudioStream *stream, SDL_AudioStreamCallback callback, void *userdata);
1626
1627
1628/**
1629 * Free an audio stream.
1630 *
1631 * This will release all allocated data, including any audio that is still
1632 * queued. You do not need to manually clear the stream first.
1633 *
1634 * If this stream was bound to an audio device, it is unbound during this
1635 * call. If this stream was created with SDL_OpenAudioDeviceStream, the audio
1636 * device that was opened alongside this stream's creation will be closed,
1637 * too.
1638 *
1639 * \param stream the audio stream to destroy.
1640 *
1641 * \threadsafety It is safe to call this function from any thread.
1642 *
1643 * \since This function is available since SDL 3.0.0.
1644 *
1645 * \sa SDL_CreateAudioStream
1646 */
1647extern SDL_DECLSPEC void SDLCALL SDL_DestroyAudioStream(SDL_AudioStream *stream);
1648
1649
1650/**
1651 * Convenience function for straightforward audio init for the common case.
1652 *
1653 * If all your app intends to do is provide a single source of PCM audio, this
1654 * function allows you to do all your audio setup in a single call.
1655 *
1656 * This is also intended to be a clean means to migrate apps from SDL2.
1657 *
1658 * This function will open an audio device, create a stream and bind it.
1659 * Unlike other methods of setup, the audio device will be closed when this
1660 * stream is destroyed, so the app can treat the returned SDL_AudioStream as
1661 * the only object needed to manage audio playback.
1662 *
1663 * Also unlike other functions, the audio device begins paused. This is to map
1664 * more closely to SDL2-style behavior, since there is no extra step here to
1665 * bind a stream to begin audio flowing. The audio device should be resumed
1666 * with `SDL_ResumeAudioStreamDevice(stream);`
1667 *
1668 * This function works with both playback and recording devices.
1669 *
1670 * The `spec` parameter represents the app's side of the audio stream. That
1671 * is, for recording audio, this will be the output format, and for playing
1672 * audio, this will be the input format. If spec is NULL, the system will
1673 * choose the format, and the app can use SDL_GetAudioStreamFormat() to obtain
1674 * this information later.
1675 *
1676 * If you don't care about opening a specific audio device, you can (and
1677 * probably _should_), use SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK for playback and
1678 * SDL_AUDIO_DEVICE_DEFAULT_RECORDING for recording.
1679 *
1680 * One can optionally provide a callback function; if NULL, the app is
1681 * expected to queue audio data for playback (or unqueue audio data if
1682 * capturing). Otherwise, the callback will begin to fire once the device is
1683 * unpaused.
1684 *
1685 * Destroying the returned stream with SDL_DestroyAudioStream will also close
1686 * the audio device associated with this stream.
1687 *
1688 * \param devid an audio device to open, or SDL_AUDIO_DEVICE_DEFAULT_PLAYBACK
1689 * or SDL_AUDIO_DEVICE_DEFAULT_RECORDING.
1690 * \param spec the audio stream's data format. Can be NULL.
1691 * \param callback a callback where the app will provide new data for
1692 * playback, or receive new data for recording. Can be NULL,
1693 * in which case the app will need to call
1694 * SDL_PutAudioStreamData or SDL_GetAudioStreamData as
1695 * necessary.
1696 * \param userdata app-controlled pointer passed to callback. Can be NULL.
1697 * Ignored if callback is NULL.
1698 * \returns an audio stream on success, ready to use, or NULL on failure; call
1699 * SDL_GetError() for more information. When done with this stream,
1700 * call SDL_DestroyAudioStream to free resources and close the
1701 * device.
1702 *
1703 * \threadsafety It is safe to call this function from any thread.
1704 *
1705 * \since This function is available since SDL 3.0.0.
1706 *
1707 * \sa SDL_GetAudioStreamDevice
1708 * \sa SDL_ResumeAudioStreamDevice
1709 */
1710extern SDL_DECLSPEC SDL_AudioStream * SDLCALL SDL_OpenAudioDeviceStream(SDL_AudioDeviceID devid, const SDL_AudioSpec *spec, SDL_AudioStreamCallback callback, void *userdata);
1711
1712/**
1713 * A callback that fires when data is about to be fed to an audio device.
1714 *
1715 * This is useful for accessing the final mix, perhaps for writing a
1716 * visualizer or applying a final effect to the audio data before playback.
1717 *
1718 * This callback should run as quickly as possible and not block for any
1719 * significant time, as this callback delays submission of data to the audio
1720 * device, which can cause audio playback problems.
1721 *
1722 * The postmix callback _must_ be able to handle any audio data format
1723 * specified in `spec`, which can change between callbacks if the audio device
1724 * changed. However, this only covers frequency and channel count; data is
1725 * always provided here in SDL_AUDIO_F32 format.
1726 *
1727 * The postmix callback runs _after_ logical device gain and audiostream gain
1728 * have been applied, which is to say you can make the output data louder at
1729 * this point than the gain settings would suggest.
1730 *
1731 * \param userdata a pointer provided by the app through
1732 * SDL_SetAudioPostmixCallback, for its own use.
1733 * \param spec the current format of audio that is to be submitted to the
1734 * audio device.
1735 * \param buffer the buffer of audio samples to be submitted. The callback can
1736 * inspect and/or modify this data.
1737 * \param buflen the size of `buffer` in bytes.
1738 *
1739 * \threadsafety This will run from a background thread owned by SDL. The
1740 * application is responsible for locking resources the callback
1741 * touches that need to be protected.
1742 *
1743 * \since This datatype is available since SDL 3.0.0.
1744 *
1745 * \sa SDL_SetAudioPostmixCallback
1746 */
1747typedef void (SDLCALL *SDL_AudioPostmixCallback)(void *userdata, const SDL_AudioSpec *spec, float *buffer, int buflen);
1748
1749/**
1750 * Set a callback that fires when data is about to be fed to an audio device.
1751 *
1752 * This is useful for accessing the final mix, perhaps for writing a
1753 * visualizer or applying a final effect to the audio data before playback.
1754 *
1755 * The buffer is the final mix of all bound audio streams on an opened device;
1756 * this callback will fire regularly for any device that is both opened and
1757 * unpaused. If there is no new data to mix, either because no streams are
1758 * bound to the device or all the streams are empty, this callback will still
1759 * fire with the entire buffer set to silence.
1760 *
1761 * This callback is allowed to make changes to the data; the contents of the
1762 * buffer after this call is what is ultimately passed along to the hardware.
1763 *
1764 * The callback is always provided the data in float format (values from -1.0f
1765 * to 1.0f), but the number of channels or sample rate may be different than
1766 * the format the app requested when opening the device; SDL might have had to
1767 * manage a conversion behind the scenes, or the playback might have jumped to
1768 * new physical hardware when a system default changed, etc. These details may
1769 * change between calls. Accordingly, the size of the buffer might change
1770 * between calls as well.
1771 *
1772 * This callback can run at any time, and from any thread; if you need to
1773 * serialize access to your app's data, you should provide and use a mutex or
1774 * other synchronization device.
1775 *
1776 * All of this to say: there are specific needs this callback can fulfill, but
1777 * it is not the simplest interface. Apps should generally provide audio in
1778 * their preferred format through an SDL_AudioStream and let SDL handle the
1779 * difference.
1780 *
1781 * This function is extremely time-sensitive; the callback should do the least
1782 * amount of work possible and return as quickly as it can. The longer the
1783 * callback runs, the higher the risk of audio dropouts or other problems.
1784 *
1785 * This function will block until the audio device is in between iterations,
1786 * so any existing callback that might be running will finish before this
1787 * function sets the new callback and returns.
1788 *
1789 * Setting a NULL callback function disables any previously-set callback.
1790 *
1791 * \param devid the ID of an opened audio device.
1792 * \param callback a callback function to be called. Can be NULL.
1793 * \param userdata app-controlled pointer passed to callback. Can be NULL.
1794 * \returns 0 on success or a negative error code on failure; call
1795 * SDL_GetError() for more information.
1796 *
1797 * \threadsafety It is safe to call this function from any thread.
1798 *
1799 * \since This function is available since SDL 3.0.0.
1800 */
1801extern SDL_DECLSPEC int SDLCALL SDL_SetAudioPostmixCallback(SDL_AudioDeviceID devid, SDL_AudioPostmixCallback callback, void *userdata);
1802
1803
1804/**
1805 * Load the audio data of a WAVE file into memory.
1806 *
1807 * Loading a WAVE file requires `src`, `spec`, `audio_buf` and `audio_len` to
1808 * be valid pointers. The entire data portion of the file is then loaded into
1809 * memory and decoded if necessary.
1810 *
1811 * Supported formats are RIFF WAVE files with the formats PCM (8, 16, 24, and
1812 * 32 bits), IEEE Float (32 bits), Microsoft ADPCM and IMA ADPCM (4 bits), and
1813 * A-law and mu-law (8 bits). Other formats are currently unsupported and
1814 * cause an error.
1815 *
1816 * If this function succeeds, the return value is zero and the pointer to the
1817 * audio data allocated by the function is written to `audio_buf` and its
1818 * length in bytes to `audio_len`. The SDL_AudioSpec members `freq`,
1819 * `channels`, and `format` are set to the values of the audio data in the
1820 * buffer.
1821 *
1822 * It's necessary to use SDL_free() to free the audio data returned in
1823 * `audio_buf` when it is no longer used.
1824 *
1825 * Because of the underspecification of the .WAV format, there are many
1826 * problematic files in the wild that cause issues with strict decoders. To
1827 * provide compatibility with these files, this decoder is lenient in regards
1828 * to the truncation of the file, the fact chunk, and the size of the RIFF
1829 * chunk. The hints `SDL_HINT_WAVE_RIFF_CHUNK_SIZE`,
1830 * `SDL_HINT_WAVE_TRUNCATION`, and `SDL_HINT_WAVE_FACT_CHUNK` can be used to
1831 * tune the behavior of the loading process.
1832 *
1833 * Any file that is invalid (due to truncation, corruption, or wrong values in
1834 * the headers), too big, or unsupported causes an error. Additionally, any
1835 * critical I/O error from the data source will terminate the loading process
1836 * with an error. The function returns NULL on error and in all cases (with
1837 * the exception of `src` being NULL), an appropriate error message will be
1838 * set.
1839 *
1840 * It is required that the data source supports seeking.
1841 *
1842 * Example:
1843 *
1844 * ```c
1845 * SDL_LoadWAV_IO(SDL_IOFromFile("sample.wav", "rb"), 1, &spec, &buf, &len);
1846 * ```
1847 *
1848 * Note that the SDL_LoadWAV function does this same thing for you, but in a
1849 * less messy way:
1850 *
1851 * ```c
1852 * SDL_LoadWAV("sample.wav", &spec, &buf, &len);
1853 * ```
1854 *
1855 * \param src the data source for the WAVE data.
1856 * \param closeio if SDL_TRUE, calls SDL_CloseIO() on `src` before returning,
1857 * even in the case of an error.
1858 * \param spec a pointer to an SDL_AudioSpec that will be set to the WAVE
1859 * data's format details on successful return.
1860 * \param audio_buf a pointer filled with the audio data, allocated by the
1861 * function.
1862 * \param audio_len a pointer filled with the length of the audio data buffer
1863 * in bytes.
1864 * \returns 0 on success. `audio_buf` will be filled with a pointer to an
1865 * allocated buffer containing the audio data, and `audio_len` is
1866 * filled with the length of that audio buffer in bytes.
1867 *
1868 * This function returns -1 if the .WAV file cannot be opened, uses
1869 * an unknown data format, or is corrupt; call SDL_GetError() for
1870 * more information.
1871 *
1872 * When the application is done with the data returned in
1873 * `audio_buf`, it should call SDL_free() to dispose of it.
1874 *
1875 * \threadsafety It is safe to call this function from any thread.
1876 *
1877 * \since This function is available since SDL 3.0.0.
1878 *
1879 * \sa SDL_free
1880 * \sa SDL_LoadWAV
1881 */
1882extern SDL_DECLSPEC int SDLCALL SDL_LoadWAV_IO(SDL_IOStream * src, SDL_bool closeio,
1883 SDL_AudioSpec * spec, Uint8 ** audio_buf,
1884 Uint32 * audio_len);
1885
1886/**
1887 * Loads a WAV from a file path.
1888 *
1889 * This is a convenience function that is effectively the same as:
1890 *
1891 * ```c
1892 * SDL_LoadWAV_IO(SDL_IOFromFile(path, "rb"), 1, spec, audio_buf, audio_len);
1893 * ```
1894 *
1895 * \param path the file path of the WAV file to open.
1896 * \param spec a pointer to an SDL_AudioSpec that will be set to the WAVE
1897 * data's format details on successful return.
1898 * \param audio_buf a pointer filled with the audio data, allocated by the
1899 * function.
1900 * \param audio_len a pointer filled with the length of the audio data buffer
1901 * in bytes.
1902 * \returns 0 on success. `audio_buf` will be filled with a pointer to an
1903 * allocated buffer containing the audio data, and `audio_len` is
1904 * filled with the length of that audio buffer in bytes.
1905 *
1906 * This function returns -1 if the .WAV file cannot be opened, uses
1907 * an unknown data format, or is corrupt; call SDL_GetError() for
1908 * more information.
1909 *
1910 * When the application is done with the data returned in
1911 * `audio_buf`, it should call SDL_free() to dispose of it.
1912 *
1913 * \threadsafety It is safe to call this function from any thread.
1914 *
1915 * \since This function is available since SDL 3.0.0.
1916 *
1917 * \sa SDL_free
1918 * \sa SDL_LoadWAV_IO
1919 */
1920extern SDL_DECLSPEC int SDLCALL SDL_LoadWAV(const char *path, SDL_AudioSpec * spec,
1921 Uint8 ** audio_buf, Uint32 * audio_len);
1922
1923/**
1924 * Mix audio data in a specified format.
1925 *
1926 * This takes an audio buffer `src` of `len` bytes of `format` data and mixes
1927 * it into `dst`, performing addition, volume adjustment, and overflow
1928 * clipping. The buffer pointed to by `dst` must also be `len` bytes of
1929 * `format` data.
1930 *
1931 * This is provided for convenience -- you can mix your own audio data.
1932 *
1933 * Do not use this function for mixing together more than two streams of
1934 * sample data. The output from repeated application of this function may be
1935 * distorted by clipping, because there is no accumulator with greater range
1936 * than the input (not to mention this being an inefficient way of doing it).
1937 *
1938 * It is a common misconception that this function is required to write audio
1939 * data to an output stream in an audio callback. While you can do that,
1940 * SDL_MixAudio() is really only needed when you're mixing a single audio
1941 * stream with a volume adjustment.
1942 *
1943 * \param dst the destination for the mixed audio.
1944 * \param src the source audio buffer to be mixed.
1945 * \param format the SDL_AudioFormat structure representing the desired audio
1946 * format.
1947 * \param len the length of the audio buffer in bytes.
1948 * \param volume ranges from 0.0 - 1.0, and should be set to 1.0 for full
1949 * audio volume.
1950 * \returns 0 on success or a negative error code on failure; call
1951 * SDL_GetError() for more information.
1952 *
1953 * \threadsafety It is safe to call this function from any thread.
1954 *
1955 * \since This function is available since SDL 3.0.0.
1956 */
1957extern SDL_DECLSPEC int SDLCALL SDL_MixAudio(Uint8 * dst,
1958 const Uint8 * src,
1959 SDL_AudioFormat format,
1960 Uint32 len, float volume);
1961
1962/**
1963 * Convert some audio data of one format to another format.
1964 *
1965 * Please note that this function is for convenience, but should not be used
1966 * to resample audio in blocks, as it will introduce audio artifacts on the
1967 * boundaries. You should only use this function if you are converting audio
1968 * data in its entirety in one call. If you want to convert audio in smaller
1969 * chunks, use an SDL_AudioStream, which is designed for this situation.
1970 *
1971 * Internally, this function creates and destroys an SDL_AudioStream on each
1972 * use, so it's also less efficient than using one directly, if you need to
1973 * convert multiple times.
1974 *
1975 * \param src_spec the format details of the input audio.
1976 * \param src_data the audio data to be converted.
1977 * \param src_len the len of src_data.
1978 * \param dst_spec the format details of the output audio.
1979 * \param dst_data will be filled with a pointer to converted audio data,
1980 * which should be freed with SDL_free(). On error, it will be
1981 * NULL.
1982 * \param dst_len will be filled with the len of dst_data.
1983 * \returns 0 on success or a negative error code on failure; call
1984 * SDL_GetError() for more information.
1985 *
1986 * \threadsafety It is safe to call this function from any thread.
1987 *
1988 * \since This function is available since SDL 3.0.0.
1989 */
1990extern SDL_DECLSPEC int SDLCALL SDL_ConvertAudioSamples(const SDL_AudioSpec *src_spec,
1991 const Uint8 *src_data,
1992 int src_len,
1993 const SDL_AudioSpec *dst_spec,
1994 Uint8 **dst_data,
1995 int *dst_len);
1996
1997
1998/**
1999 * Get the appropriate memset value for silencing an audio format.
2000 *
2001 * The value returned by this function can be used as the second argument to
2002 * memset (or SDL_memset) to set an audio buffer in a specific format to
2003 * silence.
2004 *
2005 * \param format the audio data format to query.
2006 * \returns a byte value that can be passed to memset.
2007 *
2008 * \threadsafety It is safe to call this function from any thread.
2009 *
2010 * \since This function is available since SDL 3.0.0.
2011 */
2012extern SDL_DECLSPEC int SDLCALL SDL_GetSilenceValueForFormat(SDL_AudioFormat format);
2013
2014
2015/* Ends C function definitions when using C++ */
2016#ifdef __cplusplus
2017}
2018#endif
2019#include <SDL3/SDL_close_code.h>
2020
2021#endif /* SDL_audio_h_ */
int SDL_PauseAudioStreamDevice(SDL_AudioStream *stream)
int SDL_ResumeAudioStreamDevice(SDL_AudioStream *stream)
const char * SDL_GetAudioDeviceName(SDL_AudioDeviceID devid)
SDL_AudioDeviceID * SDL_GetAudioRecordingDevices(int *count)
int * SDL_GetAudioStreamInputChannelMap(SDL_AudioStream *stream, int *count)
int SDL_UnlockAudioStream(SDL_AudioStream *stream)
const char * SDL_GetAudioDriver(int index)
SDL_AudioStream * SDL_CreateAudioStream(const SDL_AudioSpec *src_spec, const SDL_AudioSpec *dst_spec)
void SDL_UnbindAudioStream(SDL_AudioStream *stream)
int SDL_SetAudioPostmixCallback(SDL_AudioDeviceID devid, SDL_AudioPostmixCallback callback, void *userdata)
float SDL_GetAudioDeviceGain(SDL_AudioDeviceID devid)
int SDL_SetAudioStreamPutCallback(SDL_AudioStream *stream, SDL_AudioStreamCallback callback, void *userdata)
struct SDL_AudioStream SDL_AudioStream
Definition SDL_audio.h:356
int SDL_SetAudioStreamGetCallback(SDL_AudioStream *stream, SDL_AudioStreamCallback callback, void *userdata)
int SDL_SetAudioDeviceGain(SDL_AudioDeviceID devid, float gain)
SDL_AudioDeviceID * SDL_GetAudioPlaybackDevices(int *count)
void(* SDL_AudioStreamCallback)(void *userdata, SDL_AudioStream *stream, int additional_amount, int total_amount)
Definition SDL_audio.h:1528
int SDL_SetAudioStreamOutputChannelMap(SDL_AudioStream *stream, const int *chmap, int count)
int SDL_FlushAudioStream(SDL_AudioStream *stream)
int SDL_GetNumAudioDrivers(void)
int SDL_SetAudioStreamFrequencyRatio(SDL_AudioStream *stream, float ratio)
float SDL_GetAudioStreamGain(SDL_AudioStream *stream)
Uint32 SDL_AudioDeviceID
Definition SDL_audio.h:279
int SDL_GetAudioStreamQueued(SDL_AudioStream *stream)
int SDL_ConvertAudioSamples(const SDL_AudioSpec *src_spec, const Uint8 *src_data, int src_len, const SDL_AudioSpec *dst_spec, Uint8 **dst_data, int *dst_len)
int SDL_GetSilenceValueForFormat(SDL_AudioFormat format)
const char * SDL_GetCurrentAudioDriver(void)
SDL_PropertiesID SDL_GetAudioStreamProperties(SDL_AudioStream *stream)
int SDL_BindAudioStream(SDL_AudioDeviceID devid, SDL_AudioStream *stream)
SDL_AudioStream * SDL_OpenAudioDeviceStream(SDL_AudioDeviceID devid, const SDL_AudioSpec *spec, SDL_AudioStreamCallback callback, void *userdata)
void(* SDL_AudioPostmixCallback)(void *userdata, const SDL_AudioSpec *spec, float *buffer, int buflen)
Definition SDL_audio.h:1747
int SDL_PauseAudioDevice(SDL_AudioDeviceID dev)
int SDL_SetAudioStreamGain(SDL_AudioStream *stream, float gain)
float SDL_GetAudioStreamFrequencyRatio(SDL_AudioStream *stream)
int SDL_GetAudioStreamAvailable(SDL_AudioStream *stream)
SDL_AudioFormat
Definition SDL_audio.h:129
@ SDL_AUDIO_S32LE
Definition SDL_audio.h:138
@ SDL_AUDIO_S16LE
Definition SDL_audio.h:134
@ SDL_AUDIO_U8
Definition SDL_audio.h:130
@ SDL_AUDIO_S8
Definition SDL_audio.h:132
@ SDL_AUDIO_F32LE
Definition SDL_audio.h:142
@ SDL_AUDIO_S32BE
Definition SDL_audio.h:140
@ SDL_AUDIO_S16BE
Definition SDL_audio.h:136
@ SDL_AUDIO_F32BE
Definition SDL_audio.h:144
int SDL_GetAudioDeviceFormat(SDL_AudioDeviceID devid, SDL_AudioSpec *spec, int *sample_frames)
int SDL_LoadWAV(const char *path, SDL_AudioSpec *spec, Uint8 **audio_buf, Uint32 *audio_len)
int SDL_PutAudioStreamData(SDL_AudioStream *stream, const void *buf, int len)
int SDL_BindAudioStreams(SDL_AudioDeviceID devid, SDL_AudioStream **streams, int num_streams)
SDL_bool SDL_AudioDevicePaused(SDL_AudioDeviceID dev)
void SDL_UnbindAudioStreams(SDL_AudioStream **streams, int num_streams)
int * SDL_GetAudioStreamOutputChannelMap(SDL_AudioStream *stream, int *count)
void SDL_DestroyAudioStream(SDL_AudioStream *stream)
int SDL_SetAudioStreamInputChannelMap(SDL_AudioStream *stream, const int *chmap, int count)
int SDL_LockAudioStream(SDL_AudioStream *stream)
int SDL_LoadWAV_IO(SDL_IOStream *src, SDL_bool closeio, SDL_AudioSpec *spec, Uint8 **audio_buf, Uint32 *audio_len)
void SDL_CloseAudioDevice(SDL_AudioDeviceID devid)
int SDL_GetAudioStreamData(SDL_AudioStream *stream, void *buf, int len)
int SDL_ResumeAudioDevice(SDL_AudioDeviceID dev)
int SDL_ClearAudioStream(SDL_AudioStream *stream)
SDL_AudioDeviceID SDL_OpenAudioDevice(SDL_AudioDeviceID devid, const SDL_AudioSpec *spec)
int SDL_SetAudioStreamFormat(SDL_AudioStream *stream, const SDL_AudioSpec *src_spec, const SDL_AudioSpec *dst_spec)
int SDL_GetAudioStreamFormat(SDL_AudioStream *stream, SDL_AudioSpec *src_spec, SDL_AudioSpec *dst_spec)
int SDL_MixAudio(Uint8 *dst, const Uint8 *src, SDL_AudioFormat format, Uint32 len, float volume)
int * SDL_GetAudioDeviceChannelMap(SDL_AudioDeviceID devid, int *count)
SDL_AudioDeviceID SDL_GetAudioStreamDevice(SDL_AudioStream *stream)
struct SDL_IOStream SDL_IOStream
Uint32 SDL_PropertiesID
uint8_t Uint8
Definition SDL_stdinc.h:229
int SDL_bool
Definition SDL_stdinc.h:213
uint32_t Uint32
Definition SDL_stdinc.h:265
SDL_AudioFormat format
Definition SDL_audio.h:312