e14743d1 |
1 | /* |
2 | SDL - Simple DirectMedia Layer |
3 | Copyright (C) 1997-2009 Sam Lantinga |
4 | |
5 | This library is free software; you can redistribute it and/or |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either |
8 | version 2.1 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 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with this library; if not, write to the Free Software |
17 | Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
18 | |
19 | Sam Lantinga |
20 | slouken@libsdl.org |
21 | */ |
22 | |
23 | /** |
24 | * @file SDL_audio.h |
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 | * When filling in the desired audio spec structure, |
46 | * - 'desired->freq' should be the desired audio frequency in samples-per-second. |
47 | * - 'desired->format' should be the desired audio format. |
48 | * - 'desired->samples' is the desired size of the audio buffer, in samples. |
49 | * This number should be a power of two, and may be adjusted by the audio |
50 | * driver to a value more suitable for the hardware. Good values seem to |
51 | * range between 512 and 8096 inclusive, depending on the application and |
52 | * CPU speed. Smaller values yield faster response time, but can lead |
53 | * to underflow if the application is doing heavy processing and cannot |
54 | * fill the audio buffer in time. A stereo sample consists of both right |
55 | * and left channels in LR ordering. |
56 | * Note that the number of samples is directly related to time by the |
57 | * following formula: ms = (samples*1000)/freq |
58 | * - 'desired->size' is the size in bytes of the audio buffer, and is |
59 | * calculated by SDL_OpenAudio(). |
60 | * - 'desired->silence' is the value used to set the buffer to silence, |
61 | * and is calculated by SDL_OpenAudio(). |
62 | * - 'desired->callback' should be set to a function that will be called |
63 | * when the audio device is ready for more data. It is passed a pointer |
64 | * to the audio buffer, and the length in bytes of the audio buffer. |
65 | * This function usually runs in a separate thread, and so you should |
66 | * protect data structures that it accesses by calling SDL_LockAudio() |
67 | * and SDL_UnlockAudio() in your code. |
68 | * - 'desired->userdata' is passed as the first parameter to your callback |
69 | * function. |
70 | * |
71 | * @note The calculated values in this structure are calculated by SDL_OpenAudio() |
72 | * |
73 | */ |
74 | typedef struct SDL_AudioSpec { |
75 | int freq; /**< DSP frequency -- samples per second */ |
76 | Uint16 format; /**< Audio data format */ |
77 | Uint8 channels; /**< Number of channels: 1 mono, 2 stereo */ |
78 | Uint8 silence; /**< Audio buffer silence value (calculated) */ |
79 | Uint16 samples; /**< Audio buffer size in samples (power of 2) */ |
80 | Uint16 padding; /**< Necessary for some compile environments */ |
81 | Uint32 size; /**< Audio buffer size in bytes (calculated) */ |
82 | /** |
83 | * This function is called when the audio device needs more data. |
84 | * |
85 | * @param[out] stream A pointer to the audio data buffer |
86 | * @param[in] len The length of the audio buffer in bytes. |
87 | * |
88 | * Once the callback returns, the buffer will no longer be valid. |
89 | * Stereo samples are stored in a LRLRLR ordering. |
90 | */ |
91 | void (SDLCALL *callback)(void *userdata, Uint8 *stream, int len); |
92 | void *userdata; |
93 | } SDL_AudioSpec; |
94 | |
95 | /** |
96 | * @name Audio format flags |
97 | * defaults to LSB byte order |
98 | */ |
99 | /*@{*/ |
100 | #define AUDIO_U8 0x0008 /**< Unsigned 8-bit samples */ |
101 | #define AUDIO_S8 0x8008 /**< Signed 8-bit samples */ |
102 | #define AUDIO_U16LSB 0x0010 /**< Unsigned 16-bit samples */ |
103 | #define AUDIO_S16LSB 0x8010 /**< Signed 16-bit samples */ |
104 | #define AUDIO_U16MSB 0x1010 /**< As above, but big-endian byte order */ |
105 | #define AUDIO_S16MSB 0x9010 /**< As above, but big-endian byte order */ |
106 | #define AUDIO_U16 AUDIO_U16LSB |
107 | #define AUDIO_S16 AUDIO_S16LSB |
108 | |
109 | /** |
110 | * @name Native audio byte ordering |
111 | */ |
112 | /*@{*/ |
113 | #if SDL_BYTEORDER == SDL_LIL_ENDIAN |
114 | #define AUDIO_U16SYS AUDIO_U16LSB |
115 | #define AUDIO_S16SYS AUDIO_S16LSB |
116 | #else |
117 | #define AUDIO_U16SYS AUDIO_U16MSB |
118 | #define AUDIO_S16SYS AUDIO_S16MSB |
119 | #endif |
120 | /*@}*/ |
121 | |
122 | /*@}*/ |
123 | |
124 | |
125 | /** A structure to hold a set of audio conversion filters and buffers */ |
126 | typedef struct SDL_AudioCVT { |
127 | int needed; /**< Set to 1 if conversion possible */ |
128 | Uint16 src_format; /**< Source audio format */ |
129 | Uint16 dst_format; /**< Target audio format */ |
130 | double rate_incr; /**< Rate conversion increment */ |
131 | Uint8 *buf; /**< Buffer to hold entire audio data */ |
132 | int len; /**< Length of original audio buffer */ |
133 | int len_cvt; /**< Length of converted audio buffer */ |
134 | int len_mult; /**< buffer must be len*len_mult big */ |
135 | double len_ratio; /**< Given len, final size is len*len_ratio */ |
136 | void (SDLCALL *filters[10])(struct SDL_AudioCVT *cvt, Uint16 format); |
137 | int filter_index; /**< Current audio conversion function */ |
138 | } SDL_AudioCVT; |
139 | |
140 | |
141 | /* Function prototypes */ |
142 | |
143 | /** |
144 | * @name Audio Init and Quit |
145 | * These functions are used internally, and should not be used unless you |
146 | * have a specific need to specify the audio driver you want to use. |
147 | * You should normally use SDL_Init() or SDL_InitSubSystem(). |
148 | */ |
149 | /*@{*/ |
150 | extern DECLSPEC int SDLCALL SDL_AudioInit(const char *driver_name); |
151 | extern DECLSPEC void SDLCALL SDL_AudioQuit(void); |
152 | /*@}*/ |
153 | |
154 | /** |
155 | * This function fills the given character buffer with the name of the |
156 | * current audio driver, and returns a pointer to it if the audio driver has |
157 | * been initialized. It returns NULL if no driver has been initialized. |
158 | */ |
159 | extern DECLSPEC char * SDLCALL SDL_AudioDriverName(char *namebuf, int maxlen); |
160 | |
161 | /** |
162 | * This function opens the audio device with the desired parameters, and |
163 | * returns 0 if successful, placing the actual hardware parameters in the |
164 | * structure pointed to by 'obtained'. If 'obtained' is NULL, the audio |
165 | * data passed to the callback function will be guaranteed to be in the |
166 | * requested format, and will be automatically converted to the hardware |
167 | * audio format if necessary. This function returns -1 if it failed |
168 | * to open the audio device, or couldn't set up the audio thread. |
169 | * |
170 | * The audio device starts out playing silence when it's opened, and should |
171 | * be enabled for playing by calling SDL_PauseAudio(0) when you are ready |
172 | * for your audio callback function to be called. Since the audio driver |
173 | * may modify the requested size of the audio buffer, you should allocate |
174 | * any local mixing buffers after you open the audio device. |
175 | * |
176 | * @sa SDL_AudioSpec |
177 | */ |
178 | extern DECLSPEC int SDLCALL SDL_OpenAudio(SDL_AudioSpec *desired, SDL_AudioSpec *obtained); |
179 | |
180 | typedef enum { |
181 | SDL_AUDIO_STOPPED = 0, |
182 | SDL_AUDIO_PLAYING, |
183 | SDL_AUDIO_PAUSED |
184 | } SDL_audiostatus; |
185 | |
186 | /** Get the current audio state */ |
187 | extern DECLSPEC SDL_audiostatus SDLCALL SDL_GetAudioStatus(void); |
188 | |
189 | /** |
190 | * This function pauses and unpauses the audio callback processing. |
191 | * It should be called with a parameter of 0 after opening the audio |
192 | * device to start playing sound. This is so you can safely initialize |
193 | * data for your callback function after opening the audio device. |
194 | * Silence will be written to the audio device during the pause. |
195 | */ |
196 | extern DECLSPEC void SDLCALL SDL_PauseAudio(int pause_on); |
197 | |
198 | /** |
199 | * This function loads a WAVE from the data source, automatically freeing |
200 | * that source if 'freesrc' is non-zero. For example, to load a WAVE file, |
201 | * you could do: |
202 | * @code SDL_LoadWAV_RW(SDL_RWFromFile("sample.wav", "rb"), 1, ...); @endcode |
203 | * |
204 | * If this function succeeds, it returns the given SDL_AudioSpec, |
205 | * filled with the audio data format of the wave data, and sets |
206 | * 'audio_buf' to a malloc()'d buffer containing the audio data, |
207 | * and sets 'audio_len' to the length of that audio buffer, in bytes. |
208 | * You need to free the audio buffer with SDL_FreeWAV() when you are |
209 | * done with it. |
210 | * |
211 | * This function returns NULL and sets the SDL error message if the |
212 | * wave file cannot be opened, uses an unknown data format, or is |
213 | * corrupt. Currently raw and MS-ADPCM WAVE files are supported. |
214 | */ |
215 | extern DECLSPEC SDL_AudioSpec * SDLCALL SDL_LoadWAV_RW(SDL_RWops *src, int freesrc, SDL_AudioSpec *spec, Uint8 **audio_buf, Uint32 *audio_len); |
216 | |
217 | /** Compatibility convenience function -- loads a WAV from a file */ |
218 | #define SDL_LoadWAV(file, spec, audio_buf, audio_len) \ |
219 | SDL_LoadWAV_RW(SDL_RWFromFile(file, "rb"),1, spec,audio_buf,audio_len) |
220 | |
221 | /** |
222 | * This function frees data previously allocated with SDL_LoadWAV_RW() |
223 | */ |
224 | extern DECLSPEC void SDLCALL SDL_FreeWAV(Uint8 *audio_buf); |
225 | |
226 | /** |
227 | * This function takes a source format and rate and a destination format |
228 | * and rate, and initializes the 'cvt' structure with information needed |
229 | * by SDL_ConvertAudio() to convert a buffer of audio data from one format |
230 | * to the other. |
231 | * |
232 | * @return This function returns 0, or -1 if there was an error. |
233 | */ |
234 | extern DECLSPEC int SDLCALL SDL_BuildAudioCVT(SDL_AudioCVT *cvt, |
235 | Uint16 src_format, Uint8 src_channels, int src_rate, |
236 | Uint16 dst_format, Uint8 dst_channels, int dst_rate); |
237 | |
238 | /** |
239 | * Once you have initialized the 'cvt' structure using SDL_BuildAudioCVT(), |
240 | * created an audio buffer cvt->buf, and filled it with cvt->len bytes of |
241 | * audio data in the source format, this function will convert it in-place |
242 | * to the desired format. |
243 | * The data conversion may expand the size of the audio data, so the buffer |
244 | * cvt->buf should be allocated after the cvt structure is initialized by |
245 | * SDL_BuildAudioCVT(), and should be cvt->len*cvt->len_mult bytes long. |
246 | */ |
247 | extern DECLSPEC int SDLCALL SDL_ConvertAudio(SDL_AudioCVT *cvt); |
248 | |
249 | |
250 | #define SDL_MIX_MAXVOLUME 128 |
251 | /** |
252 | * This takes two audio buffers of the playing audio format and mixes |
253 | * them, performing addition, volume adjustment, and overflow clipping. |
254 | * The volume ranges from 0 - 128, and should be set to SDL_MIX_MAXVOLUME |
255 | * for full audio volume. Note this does not change hardware volume. |
256 | * This is provided for convenience -- you can mix your own audio data. |
257 | */ |
258 | extern DECLSPEC void SDLCALL SDL_MixAudio(Uint8 *dst, const Uint8 *src, Uint32 len, int volume); |
259 | |
260 | /** |
261 | * @name Audio Locks |
262 | * The lock manipulated by these functions protects the callback function. |
263 | * During a LockAudio/UnlockAudio pair, you can be guaranteed that the |
264 | * callback function is not running. Do not call these from the callback |
265 | * function or you will cause deadlock. |
266 | */ |
267 | /*@{*/ |
268 | extern DECLSPEC void SDLCALL SDL_LockAudio(void); |
269 | extern DECLSPEC void SDLCALL SDL_UnlockAudio(void); |
270 | /*@}*/ |
271 | |
272 | /** |
273 | * This function shuts down audio processing and closes the audio device. |
274 | */ |
275 | extern DECLSPEC void SDLCALL SDL_CloseAudio(void); |
276 | |
277 | |
278 | /* Ends C function definitions when using C++ */ |
279 | #ifdef __cplusplus |
280 | } |
281 | #endif |
282 | #include "close_code.h" |
283 | |
284 | #endif /* _SDL_audio_h */ |