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