| [16] | 1 | <html> |
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| 2 | |
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| 3 | <head> |
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| 4 | <title>vorbisfile - Example Code</title> |
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| 5 | <link rel=stylesheet href="style.css" type="text/css"> |
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| 6 | </head> |
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| 7 | |
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| 8 | <body bgcolor=white text=black link="#5555ff" alink="#5555ff" vlink="#5555ff"> |
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| 9 | <table border=0 width=100%> |
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| 10 | <tr> |
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| 11 | <td><p class=tiny>Vorbisfile documentation</p></td> |
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| 12 | <td align=right><p class=tiny>vorbisfile version 1.2.0 - 20070723</p></td> |
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| 13 | </tr> |
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| 14 | </table> |
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| 15 | |
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| 16 | <h1>Chaining Example Code</h1> |
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| 17 | |
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| 18 | <p> |
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| 19 | The following is a run-through of the chaining example program supplied |
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| 20 | with vorbisfile - <a href="chaining_example_c.html">chaining_example.c</a>. |
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| 21 | This program demonstrates how to work with a chained bitstream. |
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| 22 | |
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| 23 | <p> |
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| 24 | First, relevant headers, including vorbis-specific "codec.h" and "vorbisfile.h" have to be included. |
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| 25 | |
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| 26 | <br><br> |
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| 27 | <table border=0 width=100% color=black cellspacing=0 cellpadding=7> |
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| 28 | <tr bgcolor=#cccccc> |
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| 29 | <td> |
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| 30 | <pre><b> |
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| 31 | #include "vorbis/codec.h" |
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| 32 | #include "vorbis/vorbisfile.h" |
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| 33 | #include "../lib/misc.h" |
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| 34 | </b></pre> |
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| 35 | </td> |
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| 36 | </tr> |
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| 37 | </table> |
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| 38 | |
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| 39 | <p>Inside main(), we declare our primary OggVorbis_File structure. We also declare a other helpful variables to track our progress within the file. |
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| 40 | <br><br> |
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| 41 | <table border=0 width=100% color=black cellspacing=0 cellpadding=7> |
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| 42 | <tr bgcolor=#cccccc> |
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| 43 | <td> |
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| 44 | <pre><b> |
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| 45 | int main(){ |
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| 46 | OggVorbis_File ov; |
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| 47 | int i; |
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| 48 | </b></pre> |
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| 49 | </td> |
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| 50 | </tr> |
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| 51 | </table> |
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| 52 | |
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| 53 | <p>This example takes its input on stdin which is in 'text' mode by default under Windows; this will corrupt the input data unless set to binary mode. This applies only to Windows. |
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| 54 | <br><br> |
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| 55 | <table border=0 width=100% color=black cellspacing=0 cellpadding=7> |
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| 56 | <tr bgcolor=#cccccc> |
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| 57 | <td> |
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| 58 | <pre><b> |
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| 59 | #ifdef _WIN32 /* We need to set stdin to binary mode under Windows */ |
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| 60 | _setmode( _fileno( stdin ), _O_BINARY ); |
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| 61 | #endif |
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| 62 | </b></pre> |
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| 63 | </td> |
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| 64 | </tr> |
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| 65 | </table> |
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| 66 | |
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| 67 | <p>We call <a href="ov_open_callbacks.html">ov_open_callbacks()</a> to |
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| 68 | initialize the <a href="OggVorbis_File.html">OggVorbis_File</a> |
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| 69 | structure. <a href="ov_open_callbacks.html">ov_open_callbacks()</a> |
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| 70 | also checks to ensure that we're reading Vorbis format and not |
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| 71 | something else. The OV_CALLBACKS_NOCLOSE callbacks instruct |
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| 72 | libvorbisfile not to close stdin later during cleanup.<p> |
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| 73 | |
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| 74 | <br><br> |
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| 75 | <table border=0 width=100% color=black cellspacing=0 cellpadding=7> |
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| 76 | <tr bgcolor=#cccccc> |
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| 77 | <td> |
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| 78 | <pre><b> |
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| 79 | if(ov_open_callbacks(stdin,&ov,NULL,-1,OV_CALLBACKS_NOCLOSE)<0){ |
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| 80 | printf("Could not open input as an OggVorbis file.\n\n"); |
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| 81 | exit(1); |
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| 82 | } |
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| 83 | |
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| 84 | </b></pre> |
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| 85 | </td> |
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| 86 | </tr> |
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| 87 | </table> |
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| 88 | |
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| 89 | <p> |
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| 90 | First we check to make sure the stream is seekable using <a href="ov_seekable.html">ov_seekable</a>. |
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| 91 | |
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| 92 | <p>Then we're going to find the number of logical bitstreams in the physical bitstream using <a href="ov_streams.html">ov_streams</a>. |
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| 93 | |
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| 94 | <p>We use <a href="ov_time_total.html">ov_time_total</a> to determine the total length of the physical bitstream. We specify that we want the entire bitstream by using the argument <tt>-1</tt>. |
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| 95 | |
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| 96 | <br><br> |
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| 97 | <table border=0 width=100% color=black cellspacing=0 cellpadding=7> |
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| 98 | <tr bgcolor=#cccccc> |
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| 99 | <td> |
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| 100 | <pre><b> |
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| 101 | if(ov_seekable(&ov)){ |
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| 102 | printf("Input bitstream contained %ld logical bitstream section(s).\n", |
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| 103 | ov_streams(&ov)); |
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| 104 | printf("Total bitstream playing time: %ld seconds\n\n", |
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| 105 | (long)ov_time_total(&ov,-1)); |
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| 106 | |
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| 107 | }else{ |
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| 108 | printf("Standard input was not seekable.\n" |
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| 109 | "First logical bitstream information:\n\n"); |
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| 110 | } |
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| 111 | |
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| 112 | </b></pre> |
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| 113 | </td> |
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| 114 | </tr> |
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| 115 | </table> |
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| 116 | |
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| 117 | <p>Now we're going to iterate through each logical bitstream and print information about that bitstream. |
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| 118 | |
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| 119 | <p>We use <a href="ov_info.html">ov_info</a> to pull out the <a href="vorbis_info.html">vorbis_info</a> struct for each logical bitstream. This struct contains bitstream-specific info. |
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| 120 | |
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| 121 | <p><a href="ov_serialnumber.html">ov_serialnumber</a> retrieves the unique serial number for the logical bistream. <a href="ov_raw_total.html">ov_raw_total</a> gives the total compressed bytes for the logical bitstream, and <a href="ov_time_total.html">ov_time_total</a> gives the total time in the logical bitstream. |
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| 122 | |
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| 123 | <br><br> |
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| 124 | <table border=0 width=100% color=black cellspacing=0 cellpadding=7> |
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| 125 | <tr bgcolor=#cccccc> |
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| 126 | <td> |
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| 127 | <pre><b> |
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| 128 | for(i=0;i<ov_streams(&ov);i++){ |
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| 129 | vorbis_info *vi=ov_info(&ov,i); |
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| 130 | printf("\tlogical bitstream section %d information:\n",i+1); |
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| 131 | printf("\t\t%ldHz %d channels bitrate %ldkbps serial number=%ld\n", |
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| 132 | vi->rate,vi->channels,ov_bitrate(&ov,i)/1000, |
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| 133 | ov_serialnumber(&ov,i)); |
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| 134 | printf("\t\tcompressed length: %ld bytes ",(long)(ov_raw_total(&ov,i))); |
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| 135 | printf(" play time: %lds\n",(long)ov_time_total(&ov,i)); |
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| 136 | } |
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| 137 | </b></pre> |
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| 138 | </td> |
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| 139 | </tr> |
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| 140 | </table> |
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| 141 | <p> |
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| 142 | When we're done with the entire physical bitstream, we need to call <a href="ov_clear.html">ov_clear()</a> to release the bitstream. |
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| 143 | |
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| 144 | <br><br> |
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| 145 | <table border=0 width=100% color=black cellspacing=0 cellpadding=7> |
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| 146 | <tr bgcolor=#cccccc> |
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| 147 | <td> |
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| 148 | <pre><b> |
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| 149 | ov_clear(&ov); |
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| 150 | return 0; |
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| 151 | } |
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| 152 | </b></pre> |
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| 153 | </td> |
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| 154 | </tr> |
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| 155 | </table> |
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| 156 | |
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| 157 | <p> |
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| 158 | The full source for chaining_example.c can be found with the vorbis |
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| 159 | distribution in <a href="chaining_example_c.html">chaining_example.c</a>. |
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| 160 | |
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| 161 | <br><br> |
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| 162 | <hr noshade> |
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| 163 | <table border=0 width=100%> |
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| 164 | <tr valign=top> |
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| 165 | <td><p class=tiny>copyright © 2007 Xiph.org</p></td> |
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| 166 | <td align=right><p class=tiny><a href="http://www.xiph.org/ogg/vorbis/">Ogg Vorbis</a><br><a href="mailto:team@vorbis.org">team@vorbis.org</a></p></td> |
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| 167 | </tr><tr> |
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| 168 | <td><p class=tiny>Vorbisfile documentation</p></td> |
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| 169 | <td align=right><p class=tiny>vorbisfile version 1.2.0 - 20070723</p></td> |
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| 170 | </tr> |
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| 171 | </table> |
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| 172 | |
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| 173 | </body> |
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| 174 | |
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| 175 | </html> |
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