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72 | CLASS="SECT1" |
73 | ><H1 |
74 | CLASS="SECT1" |
75 | ><A |
76 | NAME="GUIDEAUDIOEXAMPLES" |
77 | ></A |
78 | >Audio Examples</H1 |
79 | ><P |
80 | ></P |
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82 | CLASS="SECT2" |
83 | ><H2 |
84 | CLASS="SECT2" |
85 | ><A |
86 | NAME="AEN382" |
87 | ></A |
88 | >Opening the audio device</H2 |
89 | ><P |
90 | ><PRE |
91 | CLASS="PROGRAMLISTING" |
92 | > SDL_AudioSpec wanted; |
93 | extern void fill_audio(void *udata, Uint8 *stream, int len); |
94 | |
95 | /* Set the audio format */ |
96 | wanted.freq = 22050; |
97 | wanted.format = AUDIO_S16; |
98 | wanted.channels = 2; /* 1 = mono, 2 = stereo */ |
99 | wanted.samples = 1024; /* Good low-latency value for callback */ |
100 | wanted.callback = fill_audio; |
101 | wanted.userdata = NULL; |
102 | |
103 | /* Open the audio device, forcing the desired format */ |
104 | if ( SDL_OpenAudio(&wanted, NULL) < 0 ) { |
105 | fprintf(stderr, "Couldn't open audio: %s\n", SDL_GetError()); |
106 | return(-1); |
107 | } |
108 | return(0);</PRE |
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112 | CLASS="SECT2" |
113 | ><H2 |
114 | CLASS="SECT2" |
115 | ><A |
116 | NAME="AEN386" |
117 | ></A |
118 | >Playing audio</H2 |
119 | ><P |
120 | ><PRE |
121 | CLASS="PROGRAMLISTING" |
122 | > static Uint8 *audio_chunk; |
123 | static Uint32 audio_len; |
124 | static Uint8 *audio_pos; |
125 | |
126 | /* The audio function callback takes the following parameters: |
127 | stream: A pointer to the audio buffer to be filled |
128 | len: The length (in bytes) of the audio buffer |
129 | */ |
130 | void fill_audio(void *udata, Uint8 *stream, int len) |
131 | { |
132 | /* Only play if we have data left */ |
133 | if ( audio_len == 0 ) |
134 | return; |
135 | |
136 | /* Mix as much data as possible */ |
137 | len = ( len > audio_len ? audio_len : len ); |
138 | SDL_MixAudio(stream, audio_pos, len, SDL_MIX_MAXVOLUME); |
139 | audio_pos += len; |
140 | audio_len -= len; |
141 | } |
142 | |
143 | /* Load the audio data ... */ |
144 | |
145 | ;;;;; |
146 | |
147 | audio_pos = audio_chunk; |
148 | |
149 | /* Let the callback function play the audio chunk */ |
150 | SDL_PauseAudio(0); |
151 | |
152 | /* Do some processing */ |
153 | |
154 | ;;;;; |
155 | |
156 | /* Wait for sound to complete */ |
157 | while ( audio_len > 0 ) { |
158 | SDL_Delay(100); /* Sleep 1/10 second */ |
159 | } |
160 | SDL_CloseAudio();</PRE |
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