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1 <HTML
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2 ><HEAD
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3 ><TITLE
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4 >Audio Examples</TITLE
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5 ><META
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6 NAME="GENERATOR"
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7 CONTENT="Modular DocBook HTML Stylesheet Version 1.61
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8 "><LINK
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9 REL="HOME"
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10 TITLE="SDL Library Documentation"
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11 HREF="index.html"><LINK
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12 REL="UP"
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13 TITLE="Examples"
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14 HREF="guideexamples.html"><LINK
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15 REL="PREVIOUS"
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16 TITLE="Event Examples"
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17 HREF="guideeventexamples.html"><LINK
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18 REL="NEXT"
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19 TITLE="CDROM Examples"
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20 HREF="guidecdromexamples.html"></HEAD
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21 ><BODY
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22 CLASS="SECT1"
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23 BGCOLOR="#FFF8DC"
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24 TEXT="#000000"
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25 LINK="#0000ee"
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26 VLINK="#551a8b"
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27 ALINK="#ff0000"
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28 ><DIV
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29 CLASS="NAVHEADER"
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30 ><TABLE
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31 WIDTH="100%"
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32 BORDER="0"
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33 CELLPADDING="0"
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34 CELLSPACING="0"
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35 ><TR
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36 ><TH
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37 COLSPAN="3"
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38 ALIGN="center"
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39 >SDL Library Documentation</TH
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40 ></TR
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41 ><TR
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42 ><TD
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43 WIDTH="10%"
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44 ALIGN="left"
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45 VALIGN="bottom"
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46 ><A
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47 HREF="guideeventexamples.html"
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48 >Prev</A
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49 ></TD
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50 ><TD
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51 WIDTH="80%"
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52 ALIGN="center"
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53 VALIGN="bottom"
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54 >Chapter 4. Examples</TD
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55 ><TD
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56 WIDTH="10%"
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57 ALIGN="right"
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58 VALIGN="bottom"
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59 ><A
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60 HREF="guidecdromexamples.html"
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61 >Next</A
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62 ></TD
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63 ></TR
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64 ></TABLE
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65 ><HR
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66 ALIGN="LEFT"
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67 WIDTH="100%"></DIV
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68 ><DIV
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69 CLASS="SECT1"
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70 ><H1
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71 CLASS="SECT1"
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72 ><A
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73 NAME="GUIDEAUDIOEXAMPLES"
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74 >Audio Examples</A
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75 ></H1
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76 ><P
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77 ></P
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78 ><DIV
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79 CLASS="SECT2"
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80 ><H2
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81 CLASS="SECT2"
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82 ><A
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83 NAME="AEN343"
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84 >Opening the audio device</A
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85 ></H2
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86 ><P
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87 ><PRE
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88 CLASS="PROGRAMLISTING"
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89 > SDL_AudioSpec wanted;
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90 extern void fill_audio(void *udata, Uint8 *stream, int len);
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91
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92 /* Set the audio format */
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93 wanted.freq = 22050;
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94 wanted.format = AUDIO_S16;
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95 wanted.channels = 2; /* 1 = mono, 2 = stereo */
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96 wanted.samples = 1024; /* Good low-latency value for callback */
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97 wanted.callback = fill_audio;
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98 wanted.userdata = NULL;
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99
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100 /* Open the audio device, forcing the desired format */
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101 if ( SDL_OpenAudio(&wanted, NULL) < 0 ) {
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102 fprintf(stderr, "Couldn't open audio: %s\n", SDL_GetError());
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103 return(-1);
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104 }
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105 return(0);</PRE
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106 ></P
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107 ></DIV
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108 ><DIV
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109 CLASS="SECT2"
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110 ><H2
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111 CLASS="SECT2"
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112 ><A
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113 NAME="AEN347"
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114 >Playing audio</A
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115 ></H2
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116 ><P
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117 ><PRE
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118 CLASS="PROGRAMLISTING"
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119 > static Uint8 *audio_chunk;
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120 static Uint32 audio_len;
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121 static Uint8 *audio_pos;
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122
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123 /* The audio function callback takes the following parameters:
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124 stream: A pointer to the audio buffer to be filled
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125 len: The length (in bytes) of the audio buffer
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126 */
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127 void fill_audio(void *udata, Uint8 *stream, int len)
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128 {
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129 /* Only play if we have data left */
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130 if ( audio_len == 0 )
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131 return;
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132
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133 /* Mix as much data as possible */
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134 len = ( len > audio_len ? audio_len : len );
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135 SDL_MixAudio(stream, audio_pos, len, SDL_MIX_MAXVOLUME)
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136 audio_pos += len;
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137 audio_len -= len;
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138 }
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139
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140 /* Load the audio data ... */
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141
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142 ;;;;;
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143
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144 audio_pos = audio_chunk;
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145
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146 /* Let the callback function play the audio chunk */
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147 SDL_PauseAudio(0);
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148
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149 /* Do some processing */
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150
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151 ;;;;;
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152
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153 /* Wait for sound to complete */
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154 while ( audio_len > 0 ) {
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155 SDL_Delay(100); /* Sleep 1/10 second */
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156 }
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157 SDL_CloseAudio();</PRE
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158 ></P
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159 ></DIV
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160 ></DIV
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161 ><DIV
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162 CLASS="NAVFOOTER"
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163 ><HR
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164 ALIGN="LEFT"
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165 WIDTH="100%"><TABLE
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166 WIDTH="100%"
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167 BORDER="0"
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168 CELLPADDING="0"
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169 CELLSPACING="0"
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170 ><TR
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171 ><TD
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172 WIDTH="33%"
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173 ALIGN="left"
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174 VALIGN="top"
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175 ><A
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176 HREF="guideeventexamples.html"
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177 >Prev</A
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178 ></TD
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179 ><TD
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180 WIDTH="34%"
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181 ALIGN="center"
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182 VALIGN="top"
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183 ><A
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184 HREF="index.html"
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185 >Home</A
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186 ></TD
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187 ><TD
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188 WIDTH="33%"
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189 ALIGN="right"
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190 VALIGN="top"
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191 ><A
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192 HREF="guidecdromexamples.html"
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193 >Next</A
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194 ></TD
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195 ></TR
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196 ><TR
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197 ><TD
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198 WIDTH="33%"
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199 ALIGN="left"
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200 VALIGN="top"
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201 >Event Examples</TD
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202 ><TD
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203 WIDTH="34%"
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204 ALIGN="center"
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205 VALIGN="top"
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206 ><A
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207 HREF="guideexamples.html"
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208 >Up</A
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209 ></TD
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210 ><TD
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211 WIDTH="33%"
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212 ALIGN="right"
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213 VALIGN="top"
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214 >CDROM Examples</TD
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215 ></TR
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216 ></TABLE
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217 ></DIV
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218 ></BODY
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219 ></HTML
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220 > |
