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1 | <HTML |
| 2 | ><HEAD |
| 3 | ><TITLE |
| 4 | >Audio Examples</TITLE |
| 5 | ><META |
| 6 | NAME="GENERATOR" |
| 7 | CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+ |
| 8 | "><LINK |
| 9 | REL="HOME" |
| 10 | TITLE="SDL Library Documentation" |
| 11 | HREF="index.html"><LINK |
| 12 | REL="UP" |
| 13 | TITLE="Examples" |
| 14 | HREF="guideexamples.html"><LINK |
| 15 | REL="PREVIOUS" |
| 16 | TITLE="Event Examples" |
| 17 | HREF="guideeventexamples.html"><LINK |
| 18 | REL="NEXT" |
| 19 | TITLE="CDROM Examples" |
| 20 | HREF="guidecdromexamples.html"></HEAD |
| 21 | ><BODY |
| 22 | CLASS="SECT1" |
| 23 | BGCOLOR="#FFF8DC" |
| 24 | TEXT="#000000" |
| 25 | LINK="#0000ee" |
| 26 | VLINK="#551a8b" |
| 27 | ALINK="#ff0000" |
| 28 | ><DIV |
| 29 | CLASS="NAVHEADER" |
| 30 | ><TABLE |
| 31 | SUMMARY="Header navigation table" |
| 32 | WIDTH="100%" |
| 33 | BORDER="0" |
| 34 | CELLPADDING="0" |
| 35 | CELLSPACING="0" |
| 36 | ><TR |
| 37 | ><TH |
| 38 | COLSPAN="3" |
| 39 | ALIGN="center" |
| 40 | >SDL Library Documentation</TH |
| 41 | ></TR |
| 42 | ><TR |
| 43 | ><TD |
| 44 | WIDTH="10%" |
| 45 | ALIGN="left" |
| 46 | VALIGN="bottom" |
| 47 | ><A |
| 48 | HREF="guideeventexamples.html" |
| 49 | ACCESSKEY="P" |
| 50 | >Prev</A |
| 51 | ></TD |
| 52 | ><TD |
| 53 | WIDTH="80%" |
| 54 | ALIGN="center" |
| 55 | VALIGN="bottom" |
| 56 | >Chapter 4. Examples</TD |
| 57 | ><TD |
| 58 | WIDTH="10%" |
| 59 | ALIGN="right" |
| 60 | VALIGN="bottom" |
| 61 | ><A |
| 62 | HREF="guidecdromexamples.html" |
| 63 | ACCESSKEY="N" |
| 64 | >Next</A |
| 65 | ></TD |
| 66 | ></TR |
| 67 | ></TABLE |
| 68 | ><HR |
| 69 | ALIGN="LEFT" |
| 70 | WIDTH="100%"></DIV |
| 71 | ><DIV |
| 72 | CLASS="SECT1" |
| 73 | ><H1 |
| 74 | CLASS="SECT1" |
| 75 | ><A |
| 76 | NAME="GUIDEAUDIOEXAMPLES" |
| 77 | ></A |
| 78 | >Audio Examples</H1 |
| 79 | ><P |
| 80 | ></P |
| 81 | ><DIV |
| 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 |
| 109 | ></P |
| 110 | ></DIV |
| 111 | ><DIV |
| 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 |
| 161 | ></P |
| 162 | ></DIV |
| 163 | ></DIV |
| 164 | ><DIV |
| 165 | CLASS="NAVFOOTER" |
| 166 | ><HR |
| 167 | ALIGN="LEFT" |
| 168 | WIDTH="100%"><TABLE |
| 169 | SUMMARY="Footer navigation table" |
| 170 | WIDTH="100%" |
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| 173 | CELLSPACING="0" |
| 174 | ><TR |
| 175 | ><TD |
| 176 | WIDTH="33%" |
| 177 | ALIGN="left" |
| 178 | VALIGN="top" |
| 179 | ><A |
| 180 | HREF="guideeventexamples.html" |
| 181 | ACCESSKEY="P" |
| 182 | >Prev</A |
| 183 | ></TD |
| 184 | ><TD |
| 185 | WIDTH="34%" |
| 186 | ALIGN="center" |
| 187 | VALIGN="top" |
| 188 | ><A |
| 189 | HREF="index.html" |
| 190 | ACCESSKEY="H" |
| 191 | >Home</A |
| 192 | ></TD |
| 193 | ><TD |
| 194 | WIDTH="33%" |
| 195 | ALIGN="right" |
| 196 | VALIGN="top" |
| 197 | ><A |
| 198 | HREF="guidecdromexamples.html" |
| 199 | ACCESSKEY="N" |
| 200 | >Next</A |
| 201 | ></TD |
| 202 | ></TR |
| 203 | ><TR |
| 204 | ><TD |
| 205 | WIDTH="33%" |
| 206 | ALIGN="left" |
| 207 | VALIGN="top" |
| 208 | >Event Examples</TD |
| 209 | ><TD |
| 210 | WIDTH="34%" |
| 211 | ALIGN="center" |
| 212 | VALIGN="top" |
| 213 | ><A |
| 214 | HREF="guideexamples.html" |
| 215 | ACCESSKEY="U" |
| 216 | >Up</A |
| 217 | ></TD |
| 218 | ><TD |
| 219 | WIDTH="33%" |
| 220 | ALIGN="right" |
| 221 | VALIGN="top" |
| 222 | >CDROM Examples</TD |
| 223 | ></TR |
| 224 | ></TABLE |
| 225 | ></DIV |
| 226 | ></BODY |
| 227 | ></HTML |
| 228 | > |
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