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annotate include/SDL_audio.h @ 591:9c9598e4b904
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| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Sat, 01 Feb 2003 20:32:44 +0000 |
| parents | 9154ec9ca3d2 |
| children | b8d311d90021 |
| rev | line source |
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| 0 | 1 /* |
| 2 SDL - Simple DirectMedia Layer | |
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3 Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002 Sam Lantinga |
| 0 | 4 |
| 5 This library is free software; you can redistribute it and/or | |
| 6 modify it under the terms of the GNU Library General Public | |
| 7 License as published by the Free Software Foundation; either | |
| 8 version 2 of the License, or (at your option) any later version. | |
| 9 | |
| 10 This library is distributed in the hope that it will be useful, | |
| 11 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 13 Library General Public License for more details. | |
| 14 | |
| 15 You should have received a copy of the GNU Library General Public | |
| 16 License along with this library; if not, write to the Free | |
| 17 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
| 18 | |
| 19 Sam Lantinga | |
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20 slouken@libsdl.org |
| 0 | 21 */ |
| 22 | |
| 23 #ifdef SAVE_RCSID | |
| 24 static char rcsid = | |
| 25 "@(#) $Id$"; | |
| 26 #endif | |
| 27 | |
| 28 /* Access to the raw audio mixing buffer for the SDL library */ | |
| 29 | |
| 30 #ifndef _SDL_audio_h | |
| 31 #define _SDL_audio_h | |
| 32 | |
| 33 #include <stdio.h> | |
| 34 | |
| 35 #include "SDL_main.h" | |
| 36 #include "SDL_types.h" | |
| 37 #include "SDL_error.h" | |
| 38 #include "SDL_rwops.h" | |
| 39 #include "SDL_byteorder.h" | |
| 40 | |
| 41 #include "begin_code.h" | |
| 42 /* Set up for C function definitions, even when using C++ */ | |
| 43 #ifdef __cplusplus | |
| 44 extern "C" { | |
| 45 #endif | |
| 46 | |
| 47 /* The calculated values in this structure are calculated by SDL_OpenAudio() */ | |
| 48 typedef struct { | |
| 49 int freq; /* DSP frequency -- samples per second */ | |
| 50 Uint16 format; /* Audio data format */ | |
| 51 Uint8 channels; /* Number of channels: 1 mono, 2 stereo */ | |
| 52 Uint8 silence; /* Audio buffer silence value (calculated) */ | |
| 188 | 53 Uint16 samples; /* Audio buffer size in samples (power of 2) */ |
| 0 | 54 Uint16 padding; /* Necessary for some compile environments */ |
| 55 Uint32 size; /* Audio buffer size in bytes (calculated) */ | |
| 56 /* This function is called when the audio device needs more data. | |
| 57 'stream' is a pointer to the audio data buffer | |
| 58 'len' is the length of that buffer in bytes. | |
| 59 Once the callback returns, the buffer will no longer be valid. | |
| 60 Stereo samples are stored in a LRLRLR ordering. | |
| 61 */ | |
| 62 void (*callback)(void *userdata, Uint8 *stream, int len); | |
| 63 void *userdata; | |
| 64 } SDL_AudioSpec; | |
| 65 | |
| 66 /* Audio format flags (defaults to LSB byte order) */ | |
| 67 #define AUDIO_U8 0x0008 /* Unsigned 8-bit samples */ | |
| 68 #define AUDIO_S8 0x8008 /* Signed 8-bit samples */ | |
| 69 #define AUDIO_U16LSB 0x0010 /* Unsigned 16-bit samples */ | |
| 70 #define AUDIO_S16LSB 0x8010 /* Signed 16-bit samples */ | |
| 71 #define AUDIO_U16MSB 0x1010 /* As above, but big-endian byte order */ | |
| 72 #define AUDIO_S16MSB 0x9010 /* As above, but big-endian byte order */ | |
| 73 #define AUDIO_U16 AUDIO_U16LSB | |
| 74 #define AUDIO_S16 AUDIO_S16LSB | |
| 75 | |
| 76 /* Native audio byte ordering */ | |
| 77 #if SDL_BYTEORDER == SDL_LIL_ENDIAN | |
| 78 #define AUDIO_U16SYS AUDIO_U16LSB | |
| 79 #define AUDIO_S16SYS AUDIO_S16LSB | |
| 80 #else | |
| 81 #define AUDIO_U16SYS AUDIO_U16MSB | |
| 82 #define AUDIO_S16SYS AUDIO_S16MSB | |
| 83 #endif | |
| 84 | |
| 85 | |
| 86 /* A structure to hold a set of audio conversion filters and buffers */ | |
| 87 typedef struct SDL_AudioCVT { | |
| 88 int needed; /* Set to 1 if conversion possible */ | |
| 89 Uint16 src_format; /* Source audio format */ | |
| 90 Uint16 dst_format; /* Target audio format */ | |
| 91 double rate_incr; /* Rate conversion increment */ | |
| 92 Uint8 *buf; /* Buffer to hold entire audio data */ | |
| 93 int len; /* Length of original audio buffer */ | |
| 94 int len_cvt; /* Length of converted audio buffer */ | |
| 95 int len_mult; /* buffer must be len*len_mult big */ | |
| 96 double len_ratio; /* Given len, final size is len*len_ratio */ | |
| 97 void (*filters[10])(struct SDL_AudioCVT *cvt, Uint16 format); | |
| 98 int filter_index; /* Current audio conversion function */ | |
| 99 } SDL_AudioCVT; | |
| 100 | |
| 101 | |
| 102 /* Function prototypes */ | |
| 103 | |
| 104 /* These functions are used internally, and should not be used unless you | |
| 105 * have a specific need to specify the audio driver you want to use. | |
| 106 * You should normally use SDL_Init() or SDL_InitSubSystem(). | |
| 107 */ | |
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108 extern DECLSPEC int SDLCALL SDL_AudioInit(const char *driver_name); |
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109 extern DECLSPEC void SDLCALL SDL_AudioQuit(void); |
| 0 | 110 |
| 111 /* This function fills the given character buffer with the name of the | |
| 112 * current audio driver, and returns a pointer to it if the audio driver has | |
| 113 * been initialized. It returns NULL if no driver has been initialized. | |
| 114 */ | |
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115 extern DECLSPEC char * SDLCALL SDL_AudioDriverName(char *namebuf, int maxlen); |
| 0 | 116 |
| 117 /* | |
| 118 * This function opens the audio device with the desired parameters, and | |
| 119 * returns 0 if successful, placing the actual hardware parameters in the | |
| 120 * structure pointed to by 'obtained'. If 'obtained' is NULL, the audio | |
| 121 * data passed to the callback function will be guaranteed to be in the | |
| 122 * requested format, and will be automatically converted to the hardware | |
| 123 * audio format if necessary. This function returns -1 if it failed | |
| 124 * to open the audio device, or couldn't set up the audio thread. | |
| 125 * | |
| 126 * When filling in the desired audio spec structure, | |
| 127 * 'desired->freq' should be the desired audio frequency in samples-per-second. | |
| 128 * 'desired->format' should be the desired audio format. | |
| 129 * 'desired->samples' is the desired size of the audio buffer, in samples. | |
| 130 * This number should be a power of two, and may be adjusted by the audio | |
| 131 * driver to a value more suitable for the hardware. Good values seem to | |
| 132 * range between 512 and 8096 inclusive, depending on the application and | |
| 133 * CPU speed. Smaller values yield faster response time, but can lead | |
| 134 * to underflow if the application is doing heavy processing and cannot | |
| 135 * fill the audio buffer in time. A stereo sample consists of both right | |
| 136 * and left channels in LR ordering. | |
| 137 * Note that the number of samples is directly related to time by the | |
| 138 * following formula: ms = (samples*1000)/freq | |
| 139 * 'desired->size' is the size in bytes of the audio buffer, and is | |
| 140 * calculated by SDL_OpenAudio(). | |
| 141 * 'desired->silence' is the value used to set the buffer to silence, | |
| 142 * and is calculated by SDL_OpenAudio(). | |
| 143 * 'desired->callback' should be set to a function that will be called | |
| 144 * when the audio device is ready for more data. It is passed a pointer | |
| 145 * to the audio buffer, and the length in bytes of the audio buffer. | |
| 146 * This function usually runs in a separate thread, and so you should | |
| 147 * protect data structures that it accesses by calling SDL_LockAudio() | |
| 148 * and SDL_UnlockAudio() in your code. | |
| 149 * 'desired->userdata' is passed as the first parameter to your callback | |
| 150 * function. | |
| 151 * | |
| 152 * The audio device starts out playing silence when it's opened, and should | |
| 153 * be enabled for playing by calling SDL_PauseAudio(0) when you are ready | |
| 154 * for your audio callback function to be called. Since the audio driver | |
| 155 * may modify the requested size of the audio buffer, you should allocate | |
| 156 * any local mixing buffers after you open the audio device. | |
| 157 */ | |
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158 extern DECLSPEC int SDLCALL SDL_OpenAudio(SDL_AudioSpec *desired, SDL_AudioSpec *obtained); |
| 0 | 159 |
| 160 /* | |
| 161 * Get the current audio state: | |
| 162 */ | |
| 163 typedef enum { | |
| 164 SDL_AUDIO_STOPPED = 0, | |
| 165 SDL_AUDIO_PLAYING, | |
| 166 SDL_AUDIO_PAUSED | |
| 167 } SDL_audiostatus; | |
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168 extern DECLSPEC SDL_audiostatus SDLCALL SDL_GetAudioStatus(void); |
| 0 | 169 |
| 170 /* | |
| 171 * This function pauses and unpauses the audio callback processing. | |
| 172 * It should be called with a parameter of 0 after opening the audio | |
| 173 * device to start playing sound. This is so you can safely initialize | |
| 174 * data for your callback function after opening the audio device. | |
| 175 * Silence will be written to the audio device during the pause. | |
| 176 */ | |
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177 extern DECLSPEC void SDLCALL SDL_PauseAudio(int pause_on); |
| 0 | 178 |
| 179 /* | |
| 180 * This function loads a WAVE from the data source, automatically freeing | |
| 181 * that source if 'freesrc' is non-zero. For example, to load a WAVE file, | |
| 182 * you could do: | |
| 183 * SDL_LoadWAV_RW(SDL_RWFromFile("sample.wav", "rb"), 1, ...); | |
| 184 * | |
| 185 * If this function succeeds, it returns the given SDL_AudioSpec, | |
| 186 * filled with the audio data format of the wave data, and sets | |
| 187 * 'audio_buf' to a malloc()'d buffer containing the audio data, | |
| 188 * and sets 'audio_len' to the length of that audio buffer, in bytes. | |
| 189 * You need to free the audio buffer with SDL_FreeWAV() when you are | |
| 190 * done with it. | |
| 191 * | |
| 192 * This function returns NULL and sets the SDL error message if the | |
| 193 * wave file cannot be opened, uses an unknown data format, or is | |
| 194 * corrupt. Currently raw and MS-ADPCM WAVE files are supported. | |
| 195 */ | |
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196 extern DECLSPEC SDL_AudioSpec * SDLCALL SDL_LoadWAV_RW(SDL_RWops *src, int freesrc, SDL_AudioSpec *spec, Uint8 **audio_buf, Uint32 *audio_len); |
| 0 | 197 |
| 198 /* Compatibility convenience function -- loads a WAV from a file */ | |
| 199 #define SDL_LoadWAV(file, spec, audio_buf, audio_len) \ | |
| 200 SDL_LoadWAV_RW(SDL_RWFromFile(file, "rb"),1, spec,audio_buf,audio_len) | |
| 201 | |
| 202 /* | |
| 203 * This function frees data previously allocated with SDL_LoadWAV_RW() | |
| 204 */ | |
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205 extern DECLSPEC void SDLCALL SDL_FreeWAV(Uint8 *audio_buf); |
| 0 | 206 |
| 207 /* | |
| 208 * This function takes a source format and rate and a destination format | |
| 209 * and rate, and initializes the 'cvt' structure with information needed | |
| 210 * by SDL_ConvertAudio() to convert a buffer of audio data from one format | |
| 211 * to the other. | |
| 212 * This function returns 0, or -1 if there was an error. | |
| 213 */ | |
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214 extern DECLSPEC int SDLCALL SDL_BuildAudioCVT(SDL_AudioCVT *cvt, |
| 0 | 215 Uint16 src_format, Uint8 src_channels, int src_rate, |
| 216 Uint16 dst_format, Uint8 dst_channels, int dst_rate); | |
| 217 | |
| 218 /* Once you have initialized the 'cvt' structure using SDL_BuildAudioCVT(), | |
| 219 * created an audio buffer cvt->buf, and filled it with cvt->len bytes of | |
| 220 * audio data in the source format, this function will convert it in-place | |
| 221 * to the desired format. | |
| 222 * The data conversion may expand the size of the audio data, so the buffer | |
| 223 * cvt->buf should be allocated after the cvt structure is initialized by | |
| 224 * SDL_BuildAudioCVT(), and should be cvt->len*cvt->len_mult bytes long. | |
| 225 */ | |
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226 extern DECLSPEC int SDLCALL SDL_ConvertAudio(SDL_AudioCVT *cvt); |
| 0 | 227 |
| 228 /* | |
| 229 * This takes two audio buffers of the playing audio format and mixes | |
| 230 * them, performing addition, volume adjustment, and overflow clipping. | |
| 231 * The volume ranges from 0 - 128, and should be set to SDL_MIX_MAXVOLUME | |
| 232 * for full audio volume. Note this does not change hardware volume. | |
| 233 * This is provided for convenience -- you can mix your own audio data. | |
| 234 */ | |
| 235 #define SDL_MIX_MAXVOLUME 128 | |
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236 extern DECLSPEC void SDLCALL SDL_MixAudio(Uint8 *dst, const Uint8 *src, Uint32 len, int volume); |
| 0 | 237 |
| 238 /* | |
| 239 * The lock manipulated by these functions protects the callback function. | |
| 240 * During a LockAudio/UnlockAudio pair, you can be guaranteed that the | |
| 241 * callback function is not running. Do not call these from the callback | |
| 242 * function or you will cause deadlock. | |
| 243 */ | |
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244 extern DECLSPEC void SDLCALL SDL_LockAudio(void); |
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245 extern DECLSPEC void SDLCALL SDL_UnlockAudio(void); |
| 0 | 246 |
| 247 /* | |
| 248 * This function shuts down audio processing and closes the audio device. | |
| 249 */ | |
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250 extern DECLSPEC void SDLCALL SDL_CloseAudio(void); |
| 0 | 251 |
| 252 | |
| 253 /* Ends C function definitions when using C++ */ | |
| 254 #ifdef __cplusplus | |
| 255 } | |
| 256 #endif | |
| 257 #include "close_code.h" | |
| 258 | |
| 259 #endif /* _SDL_audio_h */ |