2 Simple DirectMedia Layer
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.
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:
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.
25 * Access to the raw audio mixing buffer for the SDL library.
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"
38 #include "begin_code.h"
39 /* Set up for C function definitions, even when using C++ */
45 * \brief Audio format flags.
47 * These are what the 16 bits in SDL_AudioFormat currently mean...
48 * (Unspecified bits are always zero).
51 ++-----------------------sample is signed if set
53 || ++-----------sample is bigendian if set
55 || || ++---sample is float if set
57 || || || +---sample bit size---+
59 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
62 * There are macros in SDL 2.0 and later to query these bits.
64 typedef Uint16 SDL_AudioFormat;
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))
84 * \name Audio format flags
86 * Defaults to LSB byte order.
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
100 * \name int32 support
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
109 * \name float32 support
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
118 * \name Native audio byte ordering
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
127 #define AUDIO_U16SYS AUDIO_U16MSB
128 #define AUDIO_S16SYS AUDIO_S16MSB
129 #define AUDIO_S32SYS AUDIO_S32MSB
130 #define AUDIO_F32SYS AUDIO_F32MSB
135 * \name Allow change flags
137 * Which audio format changes are allowed when opening a device.
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)
146 /* @} *//* Audio flags */
149 * This function is called when the audio device needs more data.
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.
156 * Once the callback returns, the buffer will no longer be valid.
157 * Stereo samples are stored in a LRLRLR ordering.
159 typedef void (SDLCALL * SDL_AudioCallback) (void *userdata, Uint8 * stream,
163 * The calculated values in this structure are calculated by SDL_OpenAudio().
165 typedef struct SDL_AudioSpec
167 int freq; /**< DSP frequency -- samples per second */
168 SDL_AudioFormat format; /**< Audio data format */
169 Uint8 channels; /**< Number of channels: 1 mono, 2 stereo */
170 Uint8 silence; /**< Audio buffer silence value (calculated) */
171 Uint16 samples; /**< Audio buffer size in samples (power of 2) */
172 Uint16 padding; /**< Necessary for some compile environments */
173 Uint32 size; /**< Audio buffer size in bytes (calculated) */
174 SDL_AudioCallback callback;
180 typedef void (SDLCALL * SDL_AudioFilter) (struct SDL_AudioCVT * cvt,
181 SDL_AudioFormat format);
184 * A structure to hold a set of audio conversion filters and buffers.
187 /* This structure is 84 bytes on 32-bit architectures, make sure GCC doesn't
188 pad it out to 88 bytes to guarantee ABI compatibility between compilers.
190 The next time we rev the ABI, make sure to size the ints and add padding.
192 #define SDL_AUDIOCVT_PACKED __attribute__((packed))
194 #define SDL_AUDIOCVT_PACKED
197 typedef struct SDL_AudioCVT
199 int needed; /**< Set to 1 if conversion possible */
200 SDL_AudioFormat src_format; /**< Source audio format */
201 SDL_AudioFormat dst_format; /**< Target audio format */
202 double rate_incr; /**< Rate conversion increment */
203 Uint8 *buf; /**< Buffer to hold entire audio data */
204 int len; /**< Length of original audio buffer */
205 int len_cvt; /**< Length of converted audio buffer */
206 int len_mult; /**< buffer must be len*len_mult big */
207 double len_ratio; /**< Given len, final size is len*len_ratio */
208 SDL_AudioFilter filters[10]; /**< Filter list */
209 int filter_index; /**< Current audio conversion function */
210 } SDL_AUDIOCVT_PACKED SDL_AudioCVT;
213 /* Function prototypes */
216 * \name Driver discovery functions
218 * These functions return the list of built in audio drivers, in the
219 * order that they are normally initialized by default.
222 extern DECLSPEC int SDLCALL SDL_GetNumAudioDrivers(void);
223 extern DECLSPEC const char *SDLCALL SDL_GetAudioDriver(int index);
227 * \name Initialization and cleanup
229 * \internal These functions are used internally, and should not be used unless
230 * you have a specific need to specify the audio driver you want to
231 * use. You should normally use SDL_Init() or SDL_InitSubSystem().
234 extern DECLSPEC int SDLCALL SDL_AudioInit(const char *driver_name);
235 extern DECLSPEC void SDLCALL SDL_AudioQuit(void);
239 * This function returns the name of the current audio driver, or NULL
240 * if no driver has been initialized.
242 extern DECLSPEC const char *SDLCALL SDL_GetCurrentAudioDriver(void);
245 * This function opens the audio device with the desired parameters, and
246 * returns 0 if successful, placing the actual hardware parameters in the
247 * structure pointed to by \c obtained. If \c obtained is NULL, the audio
248 * data passed to the callback function will be guaranteed to be in the
249 * requested format, and will be automatically converted to the hardware
250 * audio format if necessary. This function returns -1 if it failed
251 * to open the audio device, or couldn't set up the audio thread.
253 * When filling in the desired audio spec structure,
254 * - \c desired->freq should be the desired audio frequency in samples-per-
256 * - \c desired->format should be the desired audio format.
257 * - \c desired->samples is the desired size of the audio buffer, in
258 * samples. This number should be a power of two, and may be adjusted by
259 * the audio driver to a value more suitable for the hardware. Good values
260 * seem to range between 512 and 8096 inclusive, depending on the
261 * application and CPU speed. Smaller values yield faster response time,
262 * but can lead to underflow if the application is doing heavy processing
263 * and cannot fill the audio buffer in time. A stereo sample consists of
264 * both right and left channels in LR ordering.
265 * Note that the number of samples is directly related to time by the
266 * following formula: \code ms = (samples*1000)/freq \endcode
267 * - \c desired->size is the size in bytes of the audio buffer, and is
268 * calculated by SDL_OpenAudio().
269 * - \c desired->silence is the value used to set the buffer to silence,
270 * and is calculated by SDL_OpenAudio().
271 * - \c desired->callback should be set to a function that will be called
272 * when the audio device is ready for more data. It is passed a pointer
273 * to the audio buffer, and the length in bytes of the audio buffer.
274 * This function usually runs in a separate thread, and so you should
275 * protect data structures that it accesses by calling SDL_LockAudio()
276 * and SDL_UnlockAudio() in your code.
277 * - \c desired->userdata is passed as the first parameter to your callback
280 * The audio device starts out playing silence when it's opened, and should
281 * be enabled for playing by calling \c SDL_PauseAudio(0) when you are ready
282 * for your audio callback function to be called. Since the audio driver
283 * may modify the requested size of the audio buffer, you should allocate
284 * any local mixing buffers after you open the audio device.
286 extern DECLSPEC int SDLCALL SDL_OpenAudio(SDL_AudioSpec * desired,
287 SDL_AudioSpec * obtained);
290 * SDL Audio Device IDs.
292 * A successful call to SDL_OpenAudio() is always device id 1, and legacy
293 * SDL audio APIs assume you want this device ID. SDL_OpenAudioDevice() calls
294 * always returns devices >= 2 on success. The legacy calls are good both
295 * for backwards compatibility and when you don't care about multiple,
296 * specific, or capture devices.
298 typedef Uint32 SDL_AudioDeviceID;
301 * Get the number of available devices exposed by the current driver.
302 * Only valid after a successfully initializing the audio subsystem.
303 * Returns -1 if an explicit list of devices can't be determined; this is
304 * not an error. For example, if SDL is set up to talk to a remote audio
305 * server, it can't list every one available on the Internet, but it will
306 * still allow a specific host to be specified to SDL_OpenAudioDevice().
308 * In many common cases, when this function returns a value <= 0, it can still
309 * successfully open the default device (NULL for first argument of
310 * SDL_OpenAudioDevice()).
312 extern DECLSPEC int SDLCALL SDL_GetNumAudioDevices(int iscapture);
315 * Get the human-readable name of a specific audio device.
316 * Must be a value between 0 and (number of audio devices-1).
317 * Only valid after a successfully initializing the audio subsystem.
318 * The values returned by this function reflect the latest call to
319 * SDL_GetNumAudioDevices(); recall that function to redetect available
322 * The string returned by this function is UTF-8 encoded, read-only, and
323 * managed internally. You are not to free it. If you need to keep the
324 * string for any length of time, you should make your own copy of it, as it
325 * will be invalid next time any of several other SDL functions is called.
327 extern DECLSPEC const char *SDLCALL SDL_GetAudioDeviceName(int index,
332 * Open a specific audio device. Passing in a device name of NULL requests
333 * the most reasonable default (and is equivalent to calling SDL_OpenAudio()).
335 * The device name is a UTF-8 string reported by SDL_GetAudioDeviceName(), but
336 * some drivers allow arbitrary and driver-specific strings, such as a
337 * hostname/IP address for a remote audio server, or a filename in the
340 * \return 0 on error, a valid device ID that is >= 2 on success.
342 * SDL_OpenAudio(), unlike this function, always acts on device ID 1.
344 extern DECLSPEC SDL_AudioDeviceID SDLCALL SDL_OpenAudioDevice(const char
360 * Get the current audio state.
365 SDL_AUDIO_STOPPED = 0,
369 extern DECLSPEC SDL_AudioStatus SDLCALL SDL_GetAudioStatus(void);
371 extern DECLSPEC SDL_AudioStatus SDLCALL
372 SDL_GetAudioDeviceStatus(SDL_AudioDeviceID dev);
373 /* @} *//* Audio State */
376 * \name Pause audio functions
378 * These functions pause and unpause the audio callback processing.
379 * They should be called with a parameter of 0 after opening the audio
380 * device to start playing sound. This is so you can safely initialize
381 * data for your callback function after opening the audio device.
382 * Silence will be written to the audio device during the pause.
385 extern DECLSPEC void SDLCALL SDL_PauseAudio(int pause_on);
386 extern DECLSPEC void SDLCALL SDL_PauseAudioDevice(SDL_AudioDeviceID dev,
388 /* @} *//* Pause audio functions */
391 * This function loads a WAVE from the data source, automatically freeing
392 * that source if \c freesrc is non-zero. For example, to load a WAVE file,
395 * SDL_LoadWAV_RW(SDL_RWFromFile("sample.wav", "rb"), 1, ...);
398 * If this function succeeds, it returns the given SDL_AudioSpec,
399 * filled with the audio data format of the wave data, and sets
400 * \c *audio_buf to a malloc()'d buffer containing the audio data,
401 * and sets \c *audio_len to the length of that audio buffer, in bytes.
402 * You need to free the audio buffer with SDL_FreeWAV() when you are
405 * This function returns NULL and sets the SDL error message if the
406 * wave file cannot be opened, uses an unknown data format, or is
407 * corrupt. Currently raw and MS-ADPCM WAVE files are supported.
409 extern DECLSPEC SDL_AudioSpec *SDLCALL SDL_LoadWAV_RW(SDL_RWops * src,
411 SDL_AudioSpec * spec,
416 * Loads a WAV from a file.
417 * Compatibility convenience function.
419 #define SDL_LoadWAV(file, spec, audio_buf, audio_len) \
420 SDL_LoadWAV_RW(SDL_RWFromFile(file, "rb"),1, spec,audio_buf,audio_len)
423 * This function frees data previously allocated with SDL_LoadWAV_RW()
425 extern DECLSPEC void SDLCALL SDL_FreeWAV(Uint8 * audio_buf);
428 * This function takes a source format and rate and a destination format
429 * and rate, and initializes the \c cvt structure with information needed
430 * by SDL_ConvertAudio() to convert a buffer of audio data from one format
433 * \return -1 if the format conversion is not supported, 0 if there's
434 * no conversion needed, or 1 if the audio filter is set up.
436 extern DECLSPEC int SDLCALL SDL_BuildAudioCVT(SDL_AudioCVT * cvt,
437 SDL_AudioFormat src_format,
440 SDL_AudioFormat dst_format,
445 * Once you have initialized the \c cvt structure using SDL_BuildAudioCVT(),
446 * created an audio buffer \c cvt->buf, and filled it with \c cvt->len bytes of
447 * audio data in the source format, this function will convert it in-place
448 * to the desired format.
450 * The data conversion may expand the size of the audio data, so the buffer
451 * \c cvt->buf should be allocated after the \c cvt structure is initialized by
452 * SDL_BuildAudioCVT(), and should be \c cvt->len*cvt->len_mult bytes long.
454 extern DECLSPEC int SDLCALL SDL_ConvertAudio(SDL_AudioCVT * cvt);
456 #define SDL_MIX_MAXVOLUME 128
458 * This takes two audio buffers of the playing audio format and mixes
459 * them, performing addition, volume adjustment, and overflow clipping.
460 * The volume ranges from 0 - 128, and should be set to ::SDL_MIX_MAXVOLUME
461 * for full audio volume. Note this does not change hardware volume.
462 * This is provided for convenience -- you can mix your own audio data.
464 extern DECLSPEC void SDLCALL SDL_MixAudio(Uint8 * dst, const Uint8 * src,
465 Uint32 len, int volume);
468 * This works like SDL_MixAudio(), but you specify the audio format instead of
469 * using the format of audio device 1. Thus it can be used when no audio
470 * device is open at all.
472 extern DECLSPEC void SDLCALL SDL_MixAudioFormat(Uint8 * dst,
474 SDL_AudioFormat format,
475 Uint32 len, int volume);
478 * \name Audio lock functions
480 * The lock manipulated by these functions protects the callback function.
481 * During a SDL_LockAudio()/SDL_UnlockAudio() pair, you can be guaranteed that
482 * the callback function is not running. Do not call these from the callback
483 * function or you will cause deadlock.
486 extern DECLSPEC void SDLCALL SDL_LockAudio(void);
487 extern DECLSPEC void SDLCALL SDL_LockAudioDevice(SDL_AudioDeviceID dev);
488 extern DECLSPEC void SDLCALL SDL_UnlockAudio(void);
489 extern DECLSPEC void SDLCALL SDL_UnlockAudioDevice(SDL_AudioDeviceID dev);
490 /* @} *//* Audio lock functions */
493 * This function shuts down audio processing and closes the audio device.
495 extern DECLSPEC void SDLCALL SDL_CloseAudio(void);
496 extern DECLSPEC void SDLCALL SDL_CloseAudioDevice(SDL_AudioDeviceID dev);
498 /* Ends C function definitions when using C++ */
502 #include "close_code.h"
504 #endif /* _SDL_audio_h */
506 /* vi: set ts=4 sw=4 expandtab: */