SDL  2.0
SDL_audio.h
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1 /*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2017 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  * \file SDL_audio.h
24  *
25  * Access to the raw audio mixing buffer for the SDL library.
26  */
27 
28 #ifndef SDL_audio_h_
29 #define SDL_audio_h_
30 
31 #include "SDL_stdinc.h"
32 #include "SDL_error.h"
33 #include "SDL_endian.h"
34 #include "SDL_mutex.h"
35 #include "SDL_thread.h"
36 #include "SDL_rwops.h"
37 
38 #include "begin_code.h"
39 /* Set up for C function definitions, even when using C++ */
40 #ifdef __cplusplus
41 extern "C" {
42 #endif
43 
44 /**
45  * \brief Audio format flags.
46  *
47  * These are what the 16 bits in SDL_AudioFormat currently mean...
48  * (Unspecified bits are always zero).
49  *
50  * \verbatim
51  ++-----------------------sample is signed if set
52  ||
53  || ++-----------sample is bigendian if set
54  || ||
55  || || ++---sample is float if set
56  || || ||
57  || || || +---sample bit size---+
58  || || || | |
59  15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
60  \endverbatim
61  *
62  * There are macros in SDL 2.0 and later to query these bits.
63  */
65 
66 /**
67  * \name Audio flags
68  */
69 /* @{ */
70 
71 #define SDL_AUDIO_MASK_BITSIZE (0xFF)
72 #define SDL_AUDIO_MASK_DATATYPE (1<<8)
73 #define SDL_AUDIO_MASK_ENDIAN (1<<12)
74 #define SDL_AUDIO_MASK_SIGNED (1<<15)
75 #define SDL_AUDIO_BITSIZE(x) (x & SDL_AUDIO_MASK_BITSIZE)
76 #define SDL_AUDIO_ISFLOAT(x) (x & SDL_AUDIO_MASK_DATATYPE)
77 #define SDL_AUDIO_ISBIGENDIAN(x) (x & SDL_AUDIO_MASK_ENDIAN)
78 #define SDL_AUDIO_ISSIGNED(x) (x & SDL_AUDIO_MASK_SIGNED)
79 #define SDL_AUDIO_ISINT(x) (!SDL_AUDIO_ISFLOAT(x))
80 #define SDL_AUDIO_ISLITTLEENDIAN(x) (!SDL_AUDIO_ISBIGENDIAN(x))
81 #define SDL_AUDIO_ISUNSIGNED(x) (!SDL_AUDIO_ISSIGNED(x))
82 
83 /**
84  * \name Audio format flags
85  *
86  * Defaults to LSB byte order.
87  */
88 /* @{ */
89 #define AUDIO_U8 0x0008 /**< Unsigned 8-bit samples */
90 #define AUDIO_S8 0x8008 /**< Signed 8-bit samples */
91 #define AUDIO_U16LSB 0x0010 /**< Unsigned 16-bit samples */
92 #define AUDIO_S16LSB 0x8010 /**< Signed 16-bit samples */
93 #define AUDIO_U16MSB 0x1010 /**< As above, but big-endian byte order */
94 #define AUDIO_S16MSB 0x9010 /**< As above, but big-endian byte order */
95 #define AUDIO_U16 AUDIO_U16LSB
96 #define AUDIO_S16 AUDIO_S16LSB
97 /* @} */
98 
99 /**
100  * \name int32 support
101  */
102 /* @{ */
103 #define AUDIO_S32LSB 0x8020 /**< 32-bit integer samples */
104 #define AUDIO_S32MSB 0x9020 /**< As above, but big-endian byte order */
105 #define AUDIO_S32 AUDIO_S32LSB
106 /* @} */
107 
108 /**
109  * \name float32 support
110  */
111 /* @{ */
112 #define AUDIO_F32LSB 0x8120 /**< 32-bit floating point samples */
113 #define AUDIO_F32MSB 0x9120 /**< As above, but big-endian byte order */
114 #define AUDIO_F32 AUDIO_F32LSB
115 /* @} */
116 
117 /**
118  * \name Native audio byte ordering
119  */
120 /* @{ */
121 #if SDL_BYTEORDER == SDL_LIL_ENDIAN
122 #define AUDIO_U16SYS AUDIO_U16LSB
123 #define AUDIO_S16SYS AUDIO_S16LSB
124 #define AUDIO_S32SYS AUDIO_S32LSB
125 #define AUDIO_F32SYS AUDIO_F32LSB
126 #else
127 #define AUDIO_U16SYS AUDIO_U16MSB
128 #define AUDIO_S16SYS AUDIO_S16MSB
129 #define AUDIO_S32SYS AUDIO_S32MSB
130 #define AUDIO_F32SYS AUDIO_F32MSB
131 #endif
132 /* @} */
133 
134 /**
135  * \name Allow change flags
136  *
137  * Which audio format changes are allowed when opening a device.
138  */
139 /* @{ */
140 #define SDL_AUDIO_ALLOW_FREQUENCY_CHANGE 0x00000001
141 #define SDL_AUDIO_ALLOW_FORMAT_CHANGE 0x00000002
142 #define SDL_AUDIO_ALLOW_CHANNELS_CHANGE 0x00000004
143 #define SDL_AUDIO_ALLOW_ANY_CHANGE (SDL_AUDIO_ALLOW_FREQUENCY_CHANGE|SDL_AUDIO_ALLOW_FORMAT_CHANGE|SDL_AUDIO_ALLOW_CHANNELS_CHANGE)
144 /* @} */
145 
146 /* @} *//* Audio flags */
147 
148 /**
149  * This function is called when the audio device needs more data.
150  *
151  * \param userdata An application-specific parameter saved in
152  * the SDL_AudioSpec structure
153  * \param stream A pointer to the audio data buffer.
154  * \param len The length of that buffer in bytes.
155  *
156  * Once the callback returns, the buffer will no longer be valid.
157  * Stereo samples are stored in a LRLRLR ordering.
158  *
159  * You can choose to avoid callbacks and use SDL_QueueAudio() instead, if
160  * you like. Just open your audio device with a NULL callback.
161  */
162 typedef void (SDLCALL * SDL_AudioCallback) (void *userdata, Uint8 * stream,
163  int len);
164 
165 /**
166  * The calculated values in this structure are calculated by SDL_OpenAudio().
167  */
168 typedef struct SDL_AudioSpec
169 {
170  int freq; /**< DSP frequency -- samples per second */
171  SDL_AudioFormat format; /**< Audio data format */
172  Uint8 channels; /**< Number of channels: 1 mono, 2 stereo */
173  Uint8 silence; /**< Audio buffer silence value (calculated) */
174  Uint16 samples; /**< Audio buffer size in sample FRAMES (total samples divided by channel count) */
175  Uint16 padding; /**< Necessary for some compile environments */
176  Uint32 size; /**< Audio buffer size in bytes (calculated) */
177  SDL_AudioCallback callback; /**< Callback that feeds the audio device (NULL to use SDL_QueueAudio()). */
178  void *userdata; /**< Userdata passed to callback (ignored for NULL callbacks). */
179 } SDL_AudioSpec;
180 
181 
182 struct SDL_AudioCVT;
183 typedef void (SDLCALL * SDL_AudioFilter) (struct SDL_AudioCVT * cvt,
184  SDL_AudioFormat format);
185 
186 /**
187  * \brief Upper limit of filters in SDL_AudioCVT
188  *
189  * The maximum number of SDL_AudioFilter functions in SDL_AudioCVT is
190  * currently limited to 9. The SDL_AudioCVT.filters array has 10 pointers,
191  * one of which is the terminating NULL pointer.
192  */
193 #define SDL_AUDIOCVT_MAX_FILTERS 9
194 
195 /**
196  * \struct SDL_AudioCVT
197  * \brief A structure to hold a set of audio conversion filters and buffers.
198  *
199  * Note that various parts of the conversion pipeline can take advantage
200  * of SIMD operations (like SSE2, for example). SDL_AudioCVT doesn't require
201  * you to pass it aligned data, but can possibly run much faster if you
202  * set both its (buf) field to a pointer that is aligned to 16 bytes, and its
203  * (len) field to something that's a multiple of 16, if possible.
204  */
205 #ifdef __GNUC__
206 /* This structure is 84 bytes on 32-bit architectures, make sure GCC doesn't
207  pad it out to 88 bytes to guarantee ABI compatibility between compilers.
208  vvv
209  The next time we rev the ABI, make sure to size the ints and add padding.
210 */
211 #define SDL_AUDIOCVT_PACKED __attribute__((packed))
212 #else
213 #define SDL_AUDIOCVT_PACKED
214 #endif
215 /* */
216 typedef struct SDL_AudioCVT
217 {
218  int needed; /**< Set to 1 if conversion possible */
219  SDL_AudioFormat src_format; /**< Source audio format */
220  SDL_AudioFormat dst_format; /**< Target audio format */
221  double rate_incr; /**< Rate conversion increment */
222  Uint8 *buf; /**< Buffer to hold entire audio data */
223  int len; /**< Length of original audio buffer */
224  int len_cvt; /**< Length of converted audio buffer */
225  int len_mult; /**< buffer must be len*len_mult big */
226  double len_ratio; /**< Given len, final size is len*len_ratio */
227  SDL_AudioFilter filters[SDL_AUDIOCVT_MAX_FILTERS + 1]; /**< NULL-terminated list of filter functions */
228  int filter_index; /**< Current audio conversion function */
230 
231 
232 /* Function prototypes */
233 
234 /**
235  * \name Driver discovery functions
236  *
237  * These functions return the list of built in audio drivers, in the
238  * order that they are normally initialized by default.
239  */
240 /* @{ */
241 extern DECLSPEC int SDLCALL SDL_GetNumAudioDrivers(void);
242 extern DECLSPEC const char *SDLCALL SDL_GetAudioDriver(int index);
243 /* @} */
244 
245 /**
246  * \name Initialization and cleanup
247  *
248  * \internal These functions are used internally, and should not be used unless
249  * you have a specific need to specify the audio driver you want to
250  * use. You should normally use SDL_Init() or SDL_InitSubSystem().
251  */
252 /* @{ */
253 extern DECLSPEC int SDLCALL SDL_AudioInit(const char *driver_name);
254 extern DECLSPEC void SDLCALL SDL_AudioQuit(void);
255 /* @} */
256 
257 /**
258  * This function returns the name of the current audio driver, or NULL
259  * if no driver has been initialized.
260  */
261 extern DECLSPEC const char *SDLCALL SDL_GetCurrentAudioDriver(void);
262 
263 /**
264  * This function opens the audio device with the desired parameters, and
265  * returns 0 if successful, placing the actual hardware parameters in the
266  * structure pointed to by \c obtained. If \c obtained is NULL, the audio
267  * data passed to the callback function will be guaranteed to be in the
268  * requested format, and will be automatically converted to the hardware
269  * audio format if necessary. This function returns -1 if it failed
270  * to open the audio device, or couldn't set up the audio thread.
271  *
272  * When filling in the desired audio spec structure,
273  * - \c desired->freq should be the desired audio frequency in samples-per-
274  * second.
275  * - \c desired->format should be the desired audio format.
276  * - \c desired->samples is the desired size of the audio buffer, in
277  * samples. This number should be a power of two, and may be adjusted by
278  * the audio driver to a value more suitable for the hardware. Good values
279  * seem to range between 512 and 8096 inclusive, depending on the
280  * application and CPU speed. Smaller values yield faster response time,
281  * but can lead to underflow if the application is doing heavy processing
282  * and cannot fill the audio buffer in time. A stereo sample consists of
283  * both right and left channels in LR ordering.
284  * Note that the number of samples is directly related to time by the
285  * following formula: \code ms = (samples*1000)/freq \endcode
286  * - \c desired->size is the size in bytes of the audio buffer, and is
287  * calculated by SDL_OpenAudio().
288  * - \c desired->silence is the value used to set the buffer to silence,
289  * and is calculated by SDL_OpenAudio().
290  * - \c desired->callback should be set to a function that will be called
291  * when the audio device is ready for more data. It is passed a pointer
292  * to the audio buffer, and the length in bytes of the audio buffer.
293  * This function usually runs in a separate thread, and so you should
294  * protect data structures that it accesses by calling SDL_LockAudio()
295  * and SDL_UnlockAudio() in your code. Alternately, you may pass a NULL
296  * pointer here, and call SDL_QueueAudio() with some frequency, to queue
297  * more audio samples to be played (or for capture devices, call
298  * SDL_DequeueAudio() with some frequency, to obtain audio samples).
299  * - \c desired->userdata is passed as the first parameter to your callback
300  * function. If you passed a NULL callback, this value is ignored.
301  *
302  * The audio device starts out playing silence when it's opened, and should
303  * be enabled for playing by calling \c SDL_PauseAudio(0) when you are ready
304  * for your audio callback function to be called. Since the audio driver
305  * may modify the requested size of the audio buffer, you should allocate
306  * any local mixing buffers after you open the audio device.
307  */
308 extern DECLSPEC int SDLCALL SDL_OpenAudio(SDL_AudioSpec * desired,
309  SDL_AudioSpec * obtained);
310 
311 /**
312  * SDL Audio Device IDs.
313  *
314  * A successful call to SDL_OpenAudio() is always device id 1, and legacy
315  * SDL audio APIs assume you want this device ID. SDL_OpenAudioDevice() calls
316  * always returns devices >= 2 on success. The legacy calls are good both
317  * for backwards compatibility and when you don't care about multiple,
318  * specific, or capture devices.
319  */
321 
322 /**
323  * Get the number of available devices exposed by the current driver.
324  * Only valid after a successfully initializing the audio subsystem.
325  * Returns -1 if an explicit list of devices can't be determined; this is
326  * not an error. For example, if SDL is set up to talk to a remote audio
327  * server, it can't list every one available on the Internet, but it will
328  * still allow a specific host to be specified to SDL_OpenAudioDevice().
329  *
330  * In many common cases, when this function returns a value <= 0, it can still
331  * successfully open the default device (NULL for first argument of
332  * SDL_OpenAudioDevice()).
333  */
334 extern DECLSPEC int SDLCALL SDL_GetNumAudioDevices(int iscapture);
335 
336 /**
337  * Get the human-readable name of a specific audio device.
338  * Must be a value between 0 and (number of audio devices-1).
339  * Only valid after a successfully initializing the audio subsystem.
340  * The values returned by this function reflect the latest call to
341  * SDL_GetNumAudioDevices(); recall that function to redetect available
342  * hardware.
343  *
344  * The string returned by this function is UTF-8 encoded, read-only, and
345  * managed internally. You are not to free it. If you need to keep the
346  * string for any length of time, you should make your own copy of it, as it
347  * will be invalid next time any of several other SDL functions is called.
348  */
349 extern DECLSPEC const char *SDLCALL SDL_GetAudioDeviceName(int index,
350  int iscapture);
351 
352 
353 /**
354  * Open a specific audio device. Passing in a device name of NULL requests
355  * the most reasonable default (and is equivalent to calling SDL_OpenAudio()).
356  *
357  * The device name is a UTF-8 string reported by SDL_GetAudioDeviceName(), but
358  * some drivers allow arbitrary and driver-specific strings, such as a
359  * hostname/IP address for a remote audio server, or a filename in the
360  * diskaudio driver.
361  *
362  * \return 0 on error, a valid device ID that is >= 2 on success.
363  *
364  * SDL_OpenAudio(), unlike this function, always acts on device ID 1.
365  */
366 extern DECLSPEC SDL_AudioDeviceID SDLCALL SDL_OpenAudioDevice(const char
367  *device,
368  int iscapture,
369  const
370  SDL_AudioSpec *
371  desired,
372  SDL_AudioSpec *
373  obtained,
374  int
375  allowed_changes);
376 
377 
378 
379 /**
380  * \name Audio state
381  *
382  * Get the current audio state.
383  */
384 /* @{ */
385 typedef enum
386 {
392 
394 SDL_GetAudioDeviceStatus(SDL_AudioDeviceID dev);
395 /* @} *//* Audio State */
396 
397 /**
398  * \name Pause audio functions
399  *
400  * These functions pause and unpause the audio callback processing.
401  * They should be called with a parameter of 0 after opening the audio
402  * device to start playing sound. This is so you can safely initialize
403  * data for your callback function after opening the audio device.
404  * Silence will be written to the audio device during the pause.
405  */
406 /* @{ */
407 extern DECLSPEC void SDLCALL SDL_PauseAudio(int pause_on);
408 extern DECLSPEC void SDLCALL SDL_PauseAudioDevice(SDL_AudioDeviceID dev,
409  int pause_on);
410 /* @} *//* Pause audio functions */
411 
412 /**
413  * This function loads a WAVE from the data source, automatically freeing
414  * that source if \c freesrc is non-zero. For example, to load a WAVE file,
415  * you could do:
416  * \code
417  * SDL_LoadWAV_RW(SDL_RWFromFile("sample.wav", "rb"), 1, ...);
418  * \endcode
419  *
420  * If this function succeeds, it returns the given SDL_AudioSpec,
421  * filled with the audio data format of the wave data, and sets
422  * \c *audio_buf to a malloc()'d buffer containing the audio data,
423  * and sets \c *audio_len to the length of that audio buffer, in bytes.
424  * You need to free the audio buffer with SDL_FreeWAV() when you are
425  * done with it.
426  *
427  * This function returns NULL and sets the SDL error message if the
428  * wave file cannot be opened, uses an unknown data format, or is
429  * corrupt. Currently raw and MS-ADPCM WAVE files are supported.
430  */
432  int freesrc,
434  Uint8 ** audio_buf,
435  Uint32 * audio_len);
436 
437 /**
438  * Loads a WAV from a file.
439  * Compatibility convenience function.
440  */
441 #define SDL_LoadWAV(file, spec, audio_buf, audio_len) \
442  SDL_LoadWAV_RW(SDL_RWFromFile(file, "rb"),1, spec,audio_buf,audio_len)
443 
444 /**
445  * This function frees data previously allocated with SDL_LoadWAV_RW()
446  */
447 extern DECLSPEC void SDLCALL SDL_FreeWAV(Uint8 * audio_buf);
448 
449 /**
450  * This function takes a source format and rate and a destination format
451  * and rate, and initializes the \c cvt structure with information needed
452  * by SDL_ConvertAudio() to convert a buffer of audio data from one format
453  * to the other. An unsupported format causes an error and -1 will be returned.
454  *
455  * \return 0 if no conversion is needed, 1 if the audio filter is set up,
456  * or -1 on error.
457  */
458 extern DECLSPEC int SDLCALL SDL_BuildAudioCVT(SDL_AudioCVT * cvt,
459  SDL_AudioFormat src_format,
460  Uint8 src_channels,
461  int src_rate,
462  SDL_AudioFormat dst_format,
463  Uint8 dst_channels,
464  int dst_rate);
465 
466 /**
467  * Once you have initialized the \c cvt structure using SDL_BuildAudioCVT(),
468  * created an audio buffer \c cvt->buf, and filled it with \c cvt->len bytes of
469  * audio data in the source format, this function will convert it in-place
470  * to the desired format.
471  *
472  * The data conversion may expand the size of the audio data, so the buffer
473  * \c cvt->buf should be allocated after the \c cvt structure is initialized by
474  * SDL_BuildAudioCVT(), and should be \c cvt->len*cvt->len_mult bytes long.
475  *
476  * \return 0 on success or -1 if \c cvt->buf is NULL.
477  */
478 extern DECLSPEC int SDLCALL SDL_ConvertAudio(SDL_AudioCVT * cvt);
479 
480 #define SDL_MIX_MAXVOLUME 128
481 /**
482  * This takes two audio buffers of the playing audio format and mixes
483  * them, performing addition, volume adjustment, and overflow clipping.
484  * The volume ranges from 0 - 128, and should be set to ::SDL_MIX_MAXVOLUME
485  * for full audio volume. Note this does not change hardware volume.
486  * This is provided for convenience -- you can mix your own audio data.
487  */
488 extern DECLSPEC void SDLCALL SDL_MixAudio(Uint8 * dst, const Uint8 * src,
489  Uint32 len, int volume);
490 
491 /**
492  * This works like SDL_MixAudio(), but you specify the audio format instead of
493  * using the format of audio device 1. Thus it can be used when no audio
494  * device is open at all.
495  */
497  const Uint8 * src,
498  SDL_AudioFormat format,
499  Uint32 len, int volume);
500 
501 /**
502  * Queue more audio on non-callback devices.
503  *
504  * (If you are looking to retrieve queued audio from a non-callback capture
505  * device, you want SDL_DequeueAudio() instead. This will return -1 to
506  * signify an error if you use it with capture devices.)
507  *
508  * SDL offers two ways to feed audio to the device: you can either supply a
509  * callback that SDL triggers with some frequency to obtain more audio
510  * (pull method), or you can supply no callback, and then SDL will expect
511  * you to supply data at regular intervals (push method) with this function.
512  *
513  * There are no limits on the amount of data you can queue, short of
514  * exhaustion of address space. Queued data will drain to the device as
515  * necessary without further intervention from you. If the device needs
516  * audio but there is not enough queued, it will play silence to make up
517  * the difference. This means you will have skips in your audio playback
518  * if you aren't routinely queueing sufficient data.
519  *
520  * This function copies the supplied data, so you are safe to free it when
521  * the function returns. This function is thread-safe, but queueing to the
522  * same device from two threads at once does not promise which buffer will
523  * be queued first.
524  *
525  * You may not queue audio on a device that is using an application-supplied
526  * callback; doing so returns an error. You have to use the audio callback
527  * or queue audio with this function, but not both.
528  *
529  * You should not call SDL_LockAudio() on the device before queueing; SDL
530  * handles locking internally for this function.
531  *
532  * \param dev The device ID to which we will queue audio.
533  * \param data The data to queue to the device for later playback.
534  * \param len The number of bytes (not samples!) to which (data) points.
535  * \return zero on success, -1 on error.
536  *
537  * \sa SDL_GetQueuedAudioSize
538  * \sa SDL_ClearQueuedAudio
539  */
540 extern DECLSPEC int SDLCALL SDL_QueueAudio(SDL_AudioDeviceID dev, const void *data, Uint32 len);
541 
542 /**
543  * Dequeue more audio on non-callback devices.
544  *
545  * (If you are looking to queue audio for output on a non-callback playback
546  * device, you want SDL_QueueAudio() instead. This will always return 0
547  * if you use it with playback devices.)
548  *
549  * SDL offers two ways to retrieve audio from a capture device: you can
550  * either supply a callback that SDL triggers with some frequency as the
551  * device records more audio data, (push method), or you can supply no
552  * callback, and then SDL will expect you to retrieve data at regular
553  * intervals (pull method) with this function.
554  *
555  * There are no limits on the amount of data you can queue, short of
556  * exhaustion of address space. Data from the device will keep queuing as
557  * necessary without further intervention from you. This means you will
558  * eventually run out of memory if you aren't routinely dequeueing data.
559  *
560  * Capture devices will not queue data when paused; if you are expecting
561  * to not need captured audio for some length of time, use
562  * SDL_PauseAudioDevice() to stop the capture device from queueing more
563  * data. This can be useful during, say, level loading times. When
564  * unpaused, capture devices will start queueing data from that point,
565  * having flushed any capturable data available while paused.
566  *
567  * This function is thread-safe, but dequeueing from the same device from
568  * two threads at once does not promise which thread will dequeued data
569  * first.
570  *
571  * You may not dequeue audio from a device that is using an
572  * application-supplied callback; doing so returns an error. You have to use
573  * the audio callback, or dequeue audio with this function, but not both.
574  *
575  * You should not call SDL_LockAudio() on the device before queueing; SDL
576  * handles locking internally for this function.
577  *
578  * \param dev The device ID from which we will dequeue audio.
579  * \param data A pointer into where audio data should be copied.
580  * \param len The number of bytes (not samples!) to which (data) points.
581  * \return number of bytes dequeued, which could be less than requested.
582  *
583  * \sa SDL_GetQueuedAudioSize
584  * \sa SDL_ClearQueuedAudio
585  */
586 extern DECLSPEC Uint32 SDLCALL SDL_DequeueAudio(SDL_AudioDeviceID dev, void *data, Uint32 len);
587 
588 /**
589  * Get the number of bytes of still-queued audio.
590  *
591  * For playback device:
592  *
593  * This is the number of bytes that have been queued for playback with
594  * SDL_QueueAudio(), but have not yet been sent to the hardware. This
595  * number may shrink at any time, so this only informs of pending data.
596  *
597  * Once we've sent it to the hardware, this function can not decide the
598  * exact byte boundary of what has been played. It's possible that we just
599  * gave the hardware several kilobytes right before you called this
600  * function, but it hasn't played any of it yet, or maybe half of it, etc.
601  *
602  * For capture devices:
603  *
604  * This is the number of bytes that have been captured by the device and
605  * are waiting for you to dequeue. This number may grow at any time, so
606  * this only informs of the lower-bound of available data.
607  *
608  * You may not queue audio on a device that is using an application-supplied
609  * callback; calling this function on such a device always returns 0.
610  * You have to queue audio with SDL_QueueAudio()/SDL_DequeueAudio(), or use
611  * the audio callback, but not both.
612  *
613  * You should not call SDL_LockAudio() on the device before querying; SDL
614  * handles locking internally for this function.
615  *
616  * \param dev The device ID of which we will query queued audio size.
617  * \return Number of bytes (not samples!) of queued audio.
618  *
619  * \sa SDL_QueueAudio
620  * \sa SDL_ClearQueuedAudio
621  */
622 extern DECLSPEC Uint32 SDLCALL SDL_GetQueuedAudioSize(SDL_AudioDeviceID dev);
623 
624 /**
625  * Drop any queued audio data. For playback devices, this is any queued data
626  * still waiting to be submitted to the hardware. For capture devices, this
627  * is any data that was queued by the device that hasn't yet been dequeued by
628  * the application.
629  *
630  * Immediately after this call, SDL_GetQueuedAudioSize() will return 0. For
631  * playback devices, the hardware will start playing silence if more audio
632  * isn't queued. Unpaused capture devices will start filling the queue again
633  * as soon as they have more data available (which, depending on the state
634  * of the hardware and the thread, could be before this function call
635  * returns!).
636  *
637  * This will not prevent playback of queued audio that's already been sent
638  * to the hardware, as we can not undo that, so expect there to be some
639  * fraction of a second of audio that might still be heard. This can be
640  * useful if you want to, say, drop any pending music during a level change
641  * in your game.
642  *
643  * You may not queue audio on a device that is using an application-supplied
644  * callback; calling this function on such a device is always a no-op.
645  * You have to queue audio with SDL_QueueAudio()/SDL_DequeueAudio(), or use
646  * the audio callback, but not both.
647  *
648  * You should not call SDL_LockAudio() on the device before clearing the
649  * queue; SDL handles locking internally for this function.
650  *
651  * This function always succeeds and thus returns void.
652  *
653  * \param dev The device ID of which to clear the audio queue.
654  *
655  * \sa SDL_QueueAudio
656  * \sa SDL_GetQueuedAudioSize
657  */
658 extern DECLSPEC void SDLCALL SDL_ClearQueuedAudio(SDL_AudioDeviceID dev);
659 
660 
661 /**
662  * \name Audio lock functions
663  *
664  * The lock manipulated by these functions protects the callback function.
665  * During a SDL_LockAudio()/SDL_UnlockAudio() pair, you can be guaranteed that
666  * the callback function is not running. Do not call these from the callback
667  * function or you will cause deadlock.
668  */
669 /* @{ */
670 extern DECLSPEC void SDLCALL SDL_LockAudio(void);
671 extern DECLSPEC void SDLCALL SDL_LockAudioDevice(SDL_AudioDeviceID dev);
672 extern DECLSPEC void SDLCALL SDL_UnlockAudio(void);
673 extern DECLSPEC void SDLCALL SDL_UnlockAudioDevice(SDL_AudioDeviceID dev);
674 /* @} *//* Audio lock functions */
675 
676 /**
677  * This function shuts down audio processing and closes the audio device.
678  */
679 extern DECLSPEC void SDLCALL SDL_CloseAudio(void);
680 extern DECLSPEC void SDLCALL SDL_CloseAudioDevice(SDL_AudioDeviceID dev);
681 
682 /* Ends C function definitions when using C++ */
683 #ifdef __cplusplus
684 }
685 #endif
686 #include "close_code.h"
687 
688 #endif /* SDL_audio_h_ */
689 
690 /* vi: set ts=4 sw=4 expandtab: */
Uint32 SDL_DequeueAudio(SDL_AudioDeviceID dev, void *data, Uint32 len)
Definition: SDL_audio.c:577
#define SDL_AUDIOCVT_PACKED
Definition: SDL_audio.h:213
void SDL_MixAudio(Uint8 *dst, const Uint8 *src, Uint32 len, int volume)
Definition: SDL_audio.c:1619
#define SDL_AUDIOCVT_MAX_FILTERS
Upper limit of filters in SDL_AudioCVT.
Definition: SDL_audio.h:193
int SDL_BuildAudioCVT(SDL_AudioCVT *cvt, SDL_AudioFormat src_format, Uint8 src_channels, int src_rate, SDL_AudioFormat dst_format, Uint8 dst_channels, int dst_rate)
Definition: SDL_audiocvt.c:863
Uint8 silence
Definition: SDL_audio.h:173
GLenum GLenum dst
Uint8 * buf
Definition: SDL_audio.h:222
void SDL_PauseAudioDevice(SDL_AudioDeviceID dev, int pause_on)
Definition: SDL_audio.c:1458
int filter_index
Definition: SDL_audio.h:228
const char * SDL_GetAudioDriver(int index)
Definition: SDL_audio.c:869
double len_ratio
Definition: SDL_audio.h:226
SDL_AudioStatus
Definition: SDL_audio.h:385
SDL_AudioSpec * SDL_LoadWAV_RW(SDL_RWops *src, int freesrc, SDL_AudioSpec *spec, Uint8 **audio_buf, Uint32 *audio_len)
Definition: SDL_wave.c:448
Uint16 samples
Definition: SDL_audio.h:174
GLint GLenum GLsizei GLsizei GLsizei GLint GLsizei const GLvoid * data
Definition: SDL_opengl.h:1974
Uint16 SDL_AudioFormat
Audio format flags.
Definition: SDL_audio.h:64
uint32_t Uint32
Definition: SDL_stdinc.h:181
GLenum src
int SDL_GetNumAudioDrivers(void)
Definition: SDL_audio.c:863
GLenum GLsizei len
void SDL_MixAudioFormat(Uint8 *dst, const Uint8 *src, SDL_AudioFormat format, Uint32 len, int volume)
Definition: SDL_mixer.c:90
void(* SDL_AudioCallback)(void *userdata, Uint8 *stream, int len)
Definition: SDL_audio.h:162
A structure to hold a set of audio conversion filters and buffers.
Definition: SDL_audio.h:216
void SDL_FreeWAV(Uint8 *audio_buf)
Definition: SDL_wave.c:672
void SDL_PauseAudio(int pause_on)
Definition: SDL_audio.c:1469
GLint GLint GLsizei GLsizei GLsizei GLint GLenum format
Definition: SDL_opengl.h:1572
SDL_AudioSpec spec
Definition: loopwave.c:31
static SDL_AudioDeviceID device
Definition: loopwave.c:37
#define DECLSPEC
Definition: SDL_internal.h:44
SDL_AudioDeviceID SDL_OpenAudioDevice(const char *device, int iscapture, const SDL_AudioSpec *desired, SDL_AudioSpec *obtained, int allowed_changes)
Definition: SDL_audio.c:1427
SDL_AudioFilter filters[SDL_AUDIOCVT_MAX_FILTERS+1]
Definition: SDL_audio.h:227
int SDL_QueueAudio(SDL_AudioDeviceID dev, const void *data, Uint32 len)
Definition: SDL_audio.c:554
void SDL_LockAudio(void)
Definition: SDL_audio.c:1486
GLuint GLuint stream
void SDL_AudioQuit(void)
Definition: SDL_audio.c:1520
Uint8 channels
Definition: SDL_audio.h:172
Uint32 SDL_GetQueuedAudioSize(SDL_AudioDeviceID dev)
Definition: SDL_audio.c:596
uint8_t Uint8
Definition: SDL_stdinc.h:157
const char * SDL_GetCurrentAudioDriver(void)
Definition: SDL_audio.c:943
void SDL_UnlockAudioDevice(SDL_AudioDeviceID dev)
Definition: SDL_audio.c:1492
SDL_AudioStatus SDL_GetAudioDeviceStatus(SDL_AudioDeviceID dev)
Definition: SDL_audio.c:1436
SDL_AudioStatus SDL_GetAudioStatus(void)
Definition: SDL_audio.c:1452
int SDL_GetNumAudioDevices(int iscapture)
Definition: SDL_audio.c:978
SDL_AudioCallback callback
Definition: SDL_audio.h:177
SDL_AudioFormat src_format
Definition: SDL_audio.h:219
GLuint index
Uint16 padding
Definition: SDL_audio.h:175
Uint32 size
Definition: SDL_audio.h:176
SDL_AudioFormat dst_format
Definition: SDL_audio.h:220
Uint32 SDL_AudioDeviceID
Definition: SDL_audio.h:320
void SDL_ClearQueuedAudio(SDL_AudioDeviceID dev)
Definition: SDL_audio.c:620
SDL_AudioFormat format
Definition: SDL_audio.h:171
SDL_PRINTF_FORMAT_STRING const char int SDL_PRINTF_FORMAT_STRING const char int SDL_PRINTF_FORMAT_STRING const char int SDL_PRINTF_FORMAT_STRING const char const char SDL_SCANF_FORMAT_STRING const char return SDL_ThreadFunction const char void return Uint32 return Uint32 void
const char * SDL_GetAudioDeviceName(int index, int iscapture)
Definition: SDL_audio.c:1004
void(* SDL_AudioFilter)(struct SDL_AudioCVT *cvt, SDL_AudioFormat format)
Definition: SDL_audio.h:183
double rate_incr
Definition: SDL_audio.h:221
void SDL_CloseAudioDevice(SDL_AudioDeviceID dev)
Definition: SDL_audio.c:1508
void SDL_UnlockAudio(void)
Definition: SDL_audio.c:1502
uint16_t Uint16
Definition: SDL_stdinc.h:169
void * userdata
Definition: SDL_audio.h:178
void SDL_CloseAudio(void)
Definition: SDL_audio.c:1514
int SDL_ConvertAudio(SDL_AudioCVT *cvt)
Definition: SDL_audiocvt.c:530
#define SDLCALL
Definition: SDL_internal.h:45
int SDL_AudioInit(const char *driver_name)
Definition: SDL_audio.c:878
int SDL_OpenAudio(SDL_AudioSpec *desired, SDL_AudioSpec *obtained)
Definition: SDL_audio.c:1391
void SDL_LockAudioDevice(SDL_AudioDeviceID dev)
Definition: SDL_audio.c:1476