]>
Commit | Line | Data |
---|---|---|
1 | /* | |
2 | SDL - Simple DirectMedia Layer | |
3 | Copyright (C) 1997-2006 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 | /* Access to the raw audio mixing buffer for the SDL library */ | |
24 | ||
25 | #ifndef _SDL_audio_h | |
26 | #define _SDL_audio_h | |
27 | ||
28 | #include "SDL_stdinc.h" | |
29 | #include "SDL_error.h" | |
30 | #include "SDL_endian.h" | |
31 | #include "SDL_mutex.h" | |
32 | #include "SDL_thread.h" | |
33 | #include "SDL_rwops.h" | |
34 | ||
35 | #include "begin_code.h" | |
36 | /* Set up for C function definitions, even when using C++ */ | |
37 | #ifdef __cplusplus | |
38 | extern "C" { | |
39 | #endif | |
40 | ||
41 | /* The calculated values in this structure are calculated by SDL_OpenAudio() */ | |
42 | typedef struct SDL_AudioSpec { | |
43 | int freq; /* DSP frequency -- samples per second */ | |
44 | Uint16 format; /* Audio data format */ | |
45 | Uint8 channels; /* Number of channels: 1 mono, 2 stereo */ | |
46 | Uint8 silence; /* Audio buffer silence value (calculated) */ | |
47 | Uint16 samples; /* Audio buffer size in samples (power of 2) */ | |
48 | Uint16 padding; /* Necessary for some compile environments */ | |
49 | Uint32 size; /* Audio buffer size in bytes (calculated) */ | |
50 | /* This function is called when the audio device needs more data. | |
51 | 'stream' is a pointer to the audio data buffer | |
52 | 'len' is the length of that buffer in bytes. | |
53 | Once the callback returns, the buffer will no longer be valid. | |
54 | Stereo samples are stored in a LRLRLR ordering. | |
55 | */ | |
56 | void (SDLCALL *callback)(void *userdata, Uint8 *stream, int len); | |
57 | void *userdata; | |
58 | } SDL_AudioSpec; | |
59 | ||
60 | /* Audio format flags (defaults to LSB byte order) */ | |
61 | #define AUDIO_U8 0x0008 /* Unsigned 8-bit samples */ | |
62 | #define AUDIO_S8 0x8008 /* Signed 8-bit samples */ | |
63 | #define AUDIO_U16LSB 0x0010 /* Unsigned 16-bit samples */ | |
64 | #define AUDIO_S16LSB 0x8010 /* Signed 16-bit samples */ | |
65 | #define AUDIO_U16MSB 0x1010 /* As above, but big-endian byte order */ | |
66 | #define AUDIO_S16MSB 0x9010 /* As above, but big-endian byte order */ | |
67 | #define AUDIO_U16 AUDIO_U16LSB | |
68 | #define AUDIO_S16 AUDIO_S16LSB | |
69 | ||
70 | /* Native audio byte ordering */ | |
71 | #if SDL_BYTEORDER == SDL_LIL_ENDIAN | |
72 | #define AUDIO_U16SYS AUDIO_U16LSB | |
73 | #define AUDIO_S16SYS AUDIO_S16LSB | |
74 | #else | |
75 | #define AUDIO_U16SYS AUDIO_U16MSB | |
76 | #define AUDIO_S16SYS AUDIO_S16MSB | |
77 | #endif | |
78 | ||
79 | ||
80 | /* A structure to hold a set of audio conversion filters and buffers */ | |
81 | typedef struct SDL_AudioCVT { | |
82 | int needed; /* Set to 1 if conversion possible */ | |
83 | Uint16 src_format; /* Source audio format */ | |
84 | Uint16 dst_format; /* Target audio format */ | |
85 | double rate_incr; /* Rate conversion increment */ | |
86 | Uint8 *buf; /* Buffer to hold entire audio data */ | |
87 | int len; /* Length of original audio buffer */ | |
88 | int len_cvt; /* Length of converted audio buffer */ | |
89 | int len_mult; /* buffer must be len*len_mult big */ | |
90 | double len_ratio; /* Given len, final size is len*len_ratio */ | |
91 | void (SDLCALL *filters[10])(struct SDL_AudioCVT *cvt, Uint16 format); | |
92 | int filter_index; /* Current audio conversion function */ | |
93 | } SDL_AudioCVT; | |
94 | ||
95 | ||
96 | /* Function prototypes */ | |
97 | ||
98 | /* These functions are used internally, and should not be used unless you | |
99 | * have a specific need to specify the audio driver you want to use. | |
100 | * You should normally use SDL_Init() or SDL_InitSubSystem(). | |
101 | */ | |
102 | extern DECLSPEC int SDLCALL SDL_AudioInit(const char *driver_name); | |
103 | extern DECLSPEC void SDLCALL SDL_AudioQuit(void); | |
104 | ||
105 | /* This function fills the given character buffer with the name of the | |
106 | * current audio driver, and returns a pointer to it if the audio driver has | |
107 | * been initialized. It returns NULL if no driver has been initialized. | |
108 | */ | |
109 | extern DECLSPEC char * SDLCALL SDL_AudioDriverName(char *namebuf, int maxlen); | |
110 | ||
111 | /* | |
112 | * This function opens the audio device with the desired parameters, and | |
113 | * returns 0 if successful, placing the actual hardware parameters in the | |
114 | * structure pointed to by 'obtained'. If 'obtained' is NULL, the audio | |
115 | * data passed to the callback function will be guaranteed to be in the | |
116 | * requested format, and will be automatically converted to the hardware | |
117 | * audio format if necessary. This function returns -1 if it failed | |
118 | * to open the audio device, or couldn't set up the audio thread. | |
119 | * | |
120 | * When filling in the desired audio spec structure, | |
121 | * 'desired->freq' should be the desired audio frequency in samples-per-second. | |
122 | * 'desired->format' should be the desired audio format. | |
123 | * 'desired->samples' is the desired size of the audio buffer, in samples. | |
124 | * This number should be a power of two, and may be adjusted by the audio | |
125 | * driver to a value more suitable for the hardware. Good values seem to | |
126 | * range between 512 and 8096 inclusive, depending on the application and | |
127 | * CPU speed. Smaller values yield faster response time, but can lead | |
128 | * to underflow if the application is doing heavy processing and cannot | |
129 | * fill the audio buffer in time. A stereo sample consists of both right | |
130 | * and left channels in LR ordering. | |
131 | * Note that the number of samples is directly related to time by the | |
132 | * following formula: ms = (samples*1000)/freq | |
133 | * 'desired->size' is the size in bytes of the audio buffer, and is | |
134 | * calculated by SDL_OpenAudio(). | |
135 | * 'desired->silence' is the value used to set the buffer to silence, | |
136 | * and is calculated by SDL_OpenAudio(). | |
137 | * 'desired->callback' should be set to a function that will be called | |
138 | * when the audio device is ready for more data. It is passed a pointer | |
139 | * to the audio buffer, and the length in bytes of the audio buffer. | |
140 | * This function usually runs in a separate thread, and so you should | |
141 | * protect data structures that it accesses by calling SDL_LockAudio() | |
142 | * and SDL_UnlockAudio() in your code. | |
143 | * 'desired->userdata' is passed as the first parameter to your callback | |
144 | * function. | |
145 | * | |
146 | * The audio device starts out playing silence when it's opened, and should | |
147 | * be enabled for playing by calling SDL_PauseAudio(0) when you are ready | |
148 | * for your audio callback function to be called. Since the audio driver | |
149 | * may modify the requested size of the audio buffer, you should allocate | |
150 | * any local mixing buffers after you open the audio device. | |
151 | */ | |
152 | extern DECLSPEC int SDLCALL SDL_OpenAudio(SDL_AudioSpec *desired, SDL_AudioSpec *obtained); | |
153 | ||
154 | /* | |
155 | * Get the current audio state: | |
156 | */ | |
157 | typedef enum { | |
158 | SDL_AUDIO_STOPPED = 0, | |
159 | SDL_AUDIO_PLAYING, | |
160 | SDL_AUDIO_PAUSED | |
161 | } SDL_audiostatus; | |
162 | extern DECLSPEC SDL_audiostatus SDLCALL SDL_GetAudioStatus(void); | |
163 | ||
164 | /* | |
165 | * This function pauses and unpauses the audio callback processing. | |
166 | * It should be called with a parameter of 0 after opening the audio | |
167 | * device to start playing sound. This is so you can safely initialize | |
168 | * data for your callback function after opening the audio device. | |
169 | * Silence will be written to the audio device during the pause. | |
170 | */ | |
171 | extern DECLSPEC void SDLCALL SDL_PauseAudio(int pause_on); | |
172 | ||
173 | /* | |
174 | * This function loads a WAVE from the data source, automatically freeing | |
175 | * that source if 'freesrc' is non-zero. For example, to load a WAVE file, | |
176 | * you could do: | |
177 | * SDL_LoadWAV_RW(SDL_RWFromFile("sample.wav", "rb"), 1, ...); | |
178 | * | |
179 | * If this function succeeds, it returns the given SDL_AudioSpec, | |
180 | * filled with the audio data format of the wave data, and sets | |
181 | * 'audio_buf' to a malloc()'d buffer containing the audio data, | |
182 | * and sets 'audio_len' to the length of that audio buffer, in bytes. | |
183 | * You need to free the audio buffer with SDL_FreeWAV() when you are | |
184 | * done with it. | |
185 | * | |
186 | * This function returns NULL and sets the SDL error message if the | |
187 | * wave file cannot be opened, uses an unknown data format, or is | |
188 | * corrupt. Currently raw and MS-ADPCM WAVE files are supported. | |
189 | */ | |
190 | extern DECLSPEC SDL_AudioSpec * SDLCALL SDL_LoadWAV_RW(SDL_RWops *src, int freesrc, SDL_AudioSpec *spec, Uint8 **audio_buf, Uint32 *audio_len); | |
191 | ||
192 | /* Compatibility convenience function -- loads a WAV from a file */ | |
193 | #define SDL_LoadWAV(file, spec, audio_buf, audio_len) \ | |
194 | SDL_LoadWAV_RW(SDL_RWFromFile(file, "rb"),1, spec,audio_buf,audio_len) | |
195 | ||
196 | /* | |
197 | * This function frees data previously allocated with SDL_LoadWAV_RW() | |
198 | */ | |
199 | extern DECLSPEC void SDLCALL SDL_FreeWAV(Uint8 *audio_buf); | |
200 | ||
201 | /* | |
202 | * This function takes a source format and rate and a destination format | |
203 | * and rate, and initializes the 'cvt' structure with information needed | |
204 | * by SDL_ConvertAudio() to convert a buffer of audio data from one format | |
205 | * to the other. | |
206 | * This function returns 0, or -1 if there was an error. | |
207 | */ | |
208 | extern DECLSPEC int SDLCALL SDL_BuildAudioCVT(SDL_AudioCVT *cvt, | |
209 | Uint16 src_format, Uint8 src_channels, int src_rate, | |
210 | Uint16 dst_format, Uint8 dst_channels, int dst_rate); | |
211 | ||
212 | /* Once you have initialized the 'cvt' structure using SDL_BuildAudioCVT(), | |
213 | * created an audio buffer cvt->buf, and filled it with cvt->len bytes of | |
214 | * audio data in the source format, this function will convert it in-place | |
215 | * to the desired format. | |
216 | * The data conversion may expand the size of the audio data, so the buffer | |
217 | * cvt->buf should be allocated after the cvt structure is initialized by | |
218 | * SDL_BuildAudioCVT(), and should be cvt->len*cvt->len_mult bytes long. | |
219 | */ | |
220 | extern DECLSPEC int SDLCALL SDL_ConvertAudio(SDL_AudioCVT *cvt); | |
221 | ||
222 | /* | |
223 | * This takes two audio buffers of the playing audio format and mixes | |
224 | * them, performing addition, volume adjustment, and overflow clipping. | |
225 | * The volume ranges from 0 - 128, and should be set to SDL_MIX_MAXVOLUME | |
226 | * for full audio volume. Note this does not change hardware volume. | |
227 | * This is provided for convenience -- you can mix your own audio data. | |
228 | */ | |
229 | #define SDL_MIX_MAXVOLUME 128 | |
230 | extern DECLSPEC void SDLCALL SDL_MixAudio(Uint8 *dst, const Uint8 *src, Uint32 len, int volume); | |
231 | ||
232 | /* | |
233 | * The lock manipulated by these functions protects the callback function. | |
234 | * During a LockAudio/UnlockAudio pair, you can be guaranteed that the | |
235 | * callback function is not running. Do not call these from the callback | |
236 | * function or you will cause deadlock. | |
237 | */ | |
238 | extern DECLSPEC void SDLCALL SDL_LockAudio(void); | |
239 | extern DECLSPEC void SDLCALL SDL_UnlockAudio(void); | |
240 | ||
241 | /* | |
242 | * This function shuts down audio processing and closes the audio device. | |
243 | */ | |
244 | extern DECLSPEC void SDLCALL SDL_CloseAudio(void); | |
245 | ||
246 | ||
247 | /* Ends C function definitions when using C++ */ | |
248 | #ifdef __cplusplus | |
249 | } | |
250 | #endif | |
251 | #include "close_code.h" | |
252 | ||
253 | #endif /* _SDL_audio_h */ |