1 /* 2 * SDL_audio.h 3 * 4 * Written by 5 * Sam Lantinga <slouken@libsdl.org> 6 * 7 * This file is a modified SDL header. 8 * 9 * This file is part of VICE, the Versatile Commodore Emulator. 10 * See README for copyright notice. 11 * 12 * This program is free software; you can redistribute it and/or modify 13 * it under the terms of the GNU General Public License as published by 14 * the Free Software Foundation; either version 2 of the License, or 15 * (at your option) any later version. 16 * 17 * This program is distributed in the hope that it will be useful, 18 * but WITHOUT ANY WARRANTY; without even the implied warranty of 19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 20 * GNU General Public License for more details. 21 * 22 * You should have received a copy of the GNU General Public License 23 * along with this program; if not, write to the Free Software 24 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 25 * 02111-1307 USA. 26 * 27 */ 28 29 /** 30 * @file SDL_audio.h 31 * Access to the raw audio mixing buffer for the SDL library 32 */ 33 34 #ifndef _SDL_audio_h 35 #define _SDL_audio_h 36 37 #include "SDL_stdinc.h" 38 #include "SDL_error.h" 39 #include "SDL_endian.h" 40 #include "SDL_mutex.h" 41 #include "SDL_thread.h" 42 #include "SDL_rwops.h" 43 44 #include "begin_code.h" 45 /* Set up for C function definitions, even when using C++ */ 46 #ifdef __cplusplus 47 extern "C" { 48 #endif 49 50 /** 51 * When filling in the desired audio spec structure, 52 * - 'desired->freq' should be the desired audio frequency in samples-per-second. 53 * - 'desired->format' should be the desired audio format. 54 * - 'desired->samples' is the desired size of the audio buffer, in samples. 55 * This number should be a power of two, and may be adjusted by the audio 56 * driver to a value more suitable for the hardware. Good values seem to 57 * range between 512 and 8096 inclusive, depending on the application and 58 * CPU speed. Smaller values yield faster response time, but can lead 59 * to underflow if the application is doing heavy processing and cannot 60 * fill the audio buffer in time. A stereo sample consists of both right 61 * and left channels in LR ordering. 62 * Note that the number of samples is directly related to time by the 63 * following formula: ms = (samples*1000)/freq 64 * - 'desired->size' is the size in bytes of the audio buffer, and is 65 * calculated by SDL_OpenAudio(). 66 * - 'desired->silence' is the value used to set the buffer to silence, 67 * and is calculated by SDL_OpenAudio(). 68 * - 'desired->callback' should be set to a function that will be called 69 * when the audio device is ready for more data. It is passed a pointer 70 * to the audio buffer, and the length in bytes of the audio buffer. 71 * This function usually runs in a separate thread, and so you should 72 * protect data structures that it accesses by calling SDL_LockAudio() 73 * and SDL_UnlockAudio() in your code. 74 * - 'desired->userdata' is passed as the first parameter to your callback 75 * function. 76 * 77 * @note The calculated values in this structure are calculated by SDL_OpenAudio() 78 * 79 */ 80 typedef struct SDL_AudioSpec { 81 int freq; /**< DSP frequency -- samples per second */ 82 Uint16 format; /**< Audio data format */ 83 Uint8 channels; /**< Number of channels: 1 mono, 2 stereo */ 84 Uint8 silence; /**< Audio buffer silence value (calculated) */ 85 Uint16 samples; /**< Audio buffer size in samples (power of 2) */ 86 Uint16 padding; /**< Necessary for some compile environments */ 87 Uint32 size; /**< Audio buffer size in bytes (calculated) */ 88 /** 89 * This function is called when the audio device needs more data. 90 * 91 * @param[out] stream A pointer to the audio data buffer 92 * @param[in] len The length of the audio buffer in bytes. 93 * 94 * Once the callback returns, the buffer will no longer be valid. 95 * Stereo samples are stored in a LRLRLR ordering. 96 */ 97 void (SDLCALL *callback)(void *userdata, Uint8 *stream, int len); 98 void *userdata; 99 } SDL_AudioSpec; 100 101 /** 102 * @name Audio format flags 103 * defaults to LSB byte order 104 */ 105 /*@{*/ 106 #define AUDIO_U8 0x0008 /**< Unsigned 8-bit samples */ 107 #define AUDIO_S8 0x8008 /**< Signed 8-bit samples */ 108 #define AUDIO_U16LSB 0x0010 /**< Unsigned 16-bit samples */ 109 #define AUDIO_S16LSB 0x8010 /**< Signed 16-bit samples */ 110 #define AUDIO_U16MSB 0x1010 /**< As above, but big-endian byte order */ 111 #define AUDIO_S16MSB 0x9010 /**< As above, but big-endian byte order */ 112 #define AUDIO_U16 AUDIO_U16LSB 113 #define AUDIO_S16 AUDIO_S16LSB 114 115 /** 116 * @name Native audio byte ordering 117 */ 118 /*@{*/ 119 #if SDL_BYTEORDER == SDL_LIL_ENDIAN 120 # define AUDIO_U16SYS AUDIO_U16LSB 121 # define AUDIO_S16SYS AUDIO_S16LSB 122 #else 123 # define AUDIO_U16SYS AUDIO_U16MSB 124 # define AUDIO_S16SYS AUDIO_S16MSB 125 #endif 126 /*@}*/ 127 128 /*@}*/ 129 130 131 /** A structure to hold a set of audio conversion filters and buffers */ 132 typedef struct SDL_AudioCVT { 133 int needed; /**< Set to 1 if conversion possible */ 134 Uint16 src_format; /**< Source audio format */ 135 Uint16 dst_format; /**< Target audio format */ 136 double rate_incr; /**< Rate conversion increment */ 137 Uint8 *buf; /**< Buffer to hold entire audio data */ 138 int len; /**< Length of original audio buffer */ 139 int len_cvt; /**< Length of converted audio buffer */ 140 int len_mult; /**< buffer must be len*len_mult big */ 141 double len_ratio; /**< Given len, final size is len*len_ratio */ 142 void (SDLCALL *filters[10])(struct SDL_AudioCVT *cvt, Uint16 format); 143 int filter_index; /**< Current audio conversion function */ 144 } SDL_AudioCVT; 145 146 147 /* Function prototypes */ 148 149 /** 150 * @name Audio Init and Quit 151 * These functions are used internally, and should not be used unless you 152 * have a specific need to specify the audio driver you want to use. 153 * You should normally use SDL_Init() or SDL_InitSubSystem(). 154 */ 155 /*@{*/ 156 extern DECLSPEC int SDLCALL SDL_AudioInit(const char *driver_name); 157 extern DECLSPEC void SDLCALL SDL_AudioQuit(void); 158 /*@}*/ 159 160 /** 161 * This function fills the given character buffer with the name of the 162 * current audio driver, and returns a pointer to it if the audio driver has 163 * been initialized. It returns NULL if no driver has been initialized. 164 */ 165 extern DECLSPEC char * SDLCALL SDL_AudioDriverName(char *namebuf, int maxlen); 166 167 /** 168 * This function opens the audio device with the desired parameters, and 169 * returns 0 if successful, placing the actual hardware parameters in the 170 * structure pointed to by 'obtained'. If 'obtained' is NULL, the audio 171 * data passed to the callback function will be guaranteed to be in the 172 * requested format, and will be automatically converted to the hardware 173 * audio format if necessary. This function returns -1 if it failed 174 * to open the audio device, or couldn't set up the audio thread. 175 * 176 * The audio device starts out playing silence when it's opened, and should 177 * be enabled for playing by calling SDL_PauseAudio(0) when you are ready 178 * for your audio callback function to be called. Since the audio driver 179 * may modify the requested size of the audio buffer, you should allocate 180 * any local mixing buffers after you open the audio device. 181 * 182 * @sa SDL_AudioSpec 183 */ 184 extern DECLSPEC int SDLCALL SDL_OpenAudio(SDL_AudioSpec *desired, SDL_AudioSpec *obtained); 185 186 typedef enum { 187 SDL_AUDIO_STOPPED = 0, 188 SDL_AUDIO_PLAYING, 189 SDL_AUDIO_PAUSED 190 } SDL_audiostatus; 191 192 /** Get the current audio state */ 193 extern DECLSPEC SDL_audiostatus SDLCALL SDL_GetAudioStatus(void); 194 195 /** 196 * This function pauses and unpauses the audio callback processing. 197 * It should be called with a parameter of 0 after opening the audio 198 * device to start playing sound. This is so you can safely initialize 199 * data for your callback function after opening the audio device. 200 * Silence will be written to the audio device during the pause. 201 */ 202 extern DECLSPEC void SDLCALL SDL_PauseAudio(int pause_on); 203 204 /** 205 * This function loads a WAVE from the data source, automatically freeing 206 * that source if 'freesrc' is non-zero. For example, to load a WAVE file, 207 * you could do: 208 * @code SDL_LoadWAV_RW(SDL_RWFromFile("sample.wav", "rb"), 1, ...); @endcode 209 * 210 * If this function succeeds, it returns the given SDL_AudioSpec, 211 * filled with the audio data format of the wave data, and sets 212 * 'audio_buf' to a malloc()'d buffer containing the audio data, 213 * and sets 'audio_len' to the length of that audio buffer, in bytes. 214 * You need to free the audio buffer with SDL_FreeWAV() when you are 215 * done with it. 216 * 217 * This function returns NULL and sets the SDL error message if the 218 * wave file cannot be opened, uses an unknown data format, or is 219 * corrupt. Currently raw and MS-ADPCM WAVE files are supported. 220 */ 221 extern DECLSPEC SDL_AudioSpec * SDLCALL SDL_LoadWAV_RW(SDL_RWops *src, int freesrc, SDL_AudioSpec *spec, Uint8 **audio_buf, Uint32 *audio_len); 222 223 /** Compatibility convenience function -- loads a WAV from a file */ 224 #define SDL_LoadWAV(file, spec, audio_buf, audio_len) \ 225 SDL_LoadWAV_RW(SDL_RWFromFile(file, "rb"),1, spec,audio_buf,audio_len) 226 227 /** 228 * This function frees data previously allocated with SDL_LoadWAV_RW() 229 */ 230 extern DECLSPEC void SDLCALL SDL_FreeWAV(Uint8 *audio_buf); 231 232 /** 233 * This function takes a source format and rate and a destination format 234 * and rate, and initializes the 'cvt' structure with information needed 235 * by SDL_ConvertAudio() to convert a buffer of audio data from one format 236 * to the other. 237 * 238 * @return This function returns 0, or -1 if there was an error. 239 */ 240 extern DECLSPEC int SDLCALL SDL_BuildAudioCVT(SDL_AudioCVT *cvt, 241 Uint16 src_format, Uint8 src_channels, int src_rate, 242 Uint16 dst_format, Uint8 dst_channels, int dst_rate); 243 244 /** 245 * Once you have initialized the 'cvt' structure using SDL_BuildAudioCVT(), 246 * created an audio buffer cvt->buf, and filled it with cvt->len bytes of 247 * audio data in the source format, this function will convert it in-place 248 * to the desired format. 249 * The data conversion may expand the size of the audio data, so the buffer 250 * cvt->buf should be allocated after the cvt structure is initialized by 251 * SDL_BuildAudioCVT(), and should be cvt->len*cvt->len_mult bytes long. 252 */ 253 extern DECLSPEC int SDLCALL SDL_ConvertAudio(SDL_AudioCVT *cvt); 254 255 256 #define SDL_MIX_MAXVOLUME 128 257 /** 258 * This takes two audio buffers of the playing audio format and mixes 259 * them, performing addition, volume adjustment, and overflow clipping. 260 * The volume ranges from 0 - 128, and should be set to SDL_MIX_MAXVOLUME 261 * for full audio volume. Note this does not change hardware volume. 262 * This is provided for convenience -- you can mix your own audio data. 263 */ 264 extern DECLSPEC void SDLCALL SDL_MixAudio(Uint8 *dst, const Uint8 *src, Uint32 len, int volume); 265 266 /** 267 * @name Audio Locks 268 * The lock manipulated by these functions protects the callback function. 269 * During a LockAudio/UnlockAudio pair, you can be guaranteed that the 270 * callback function is not running. Do not call these from the callback 271 * function or you will cause deadlock. 272 */ 273 /*@{*/ 274 extern DECLSPEC void SDLCALL SDL_LockAudio(void); 275 extern DECLSPEC void SDLCALL SDL_UnlockAudio(void); 276 /*@}*/ 277 278 /** 279 * This function shuts down audio processing and closes the audio device. 280 */ 281 extern DECLSPEC void SDLCALL SDL_CloseAudio(void); 282 283 284 /* Ends C function definitions when using C++ */ 285 #ifdef __cplusplus 286 } 287 #endif 288 #include "close_code.h" 289 290 #endif /* _SDL_audio_h */ 291