| [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>Example Code: seeking</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 seeking example program supplied |
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| 20 | with vorbisfile - <a href="seeking_test_c.html">seeking_test.c</a>. |
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| 21 | This program tests the vorbisfile <a href="ov_time_seek.html">ov_time_seek</a> function by seeking to random points within the file. |
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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 <stdlib.h> |
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| 32 | #include <stdio.h> |
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| 33 | #include "vorbis/codec.h" |
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| 34 | #include "vorbis/vorbisfile.h" |
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| 35 | </b></pre> |
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| 36 | </td> |
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| 37 | </tr> |
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| 38 | </table> |
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| 39 | |
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| 40 | <p>Inside main(), we declare our primary OggVorbis_File structure. We also declare other helpful variables to track our progress within the file. |
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| 41 | <br><br> |
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| 42 | <table border=0 width=100% color=black cellspacing=0 cellpadding=7> |
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| 43 | <tr bgcolor=#cccccc> |
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| 44 | <td> |
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| 45 | <pre><b> |
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| 46 | int main(){ |
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| 47 | OggVorbis_File ov; |
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| 48 | int i; |
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| 49 | </b></pre> |
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| 50 | </td> |
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| 51 | </tr> |
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| 52 | </table> |
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| 53 | |
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| 54 | <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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| 55 | <br><br> |
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| 56 | <table border=0 width=100% color=black cellspacing=0 cellpadding=7> |
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| 57 | <tr bgcolor=#cccccc> |
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| 58 | <td> |
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| 59 | <pre><b> |
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| 60 | #ifdef _WIN32 /* We need to set stdin to binary mode under Windows */ |
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| 61 | _setmode( _fileno( stdin ), _O_BINARY ); |
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| 62 | #endif |
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| 63 | </b></pre> |
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| 64 | </td> |
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| 65 | </tr> |
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| 66 | </table> |
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| 67 | |
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| 68 | <p><a href="ov_open_callbacks.html">ov_open()</a> must be |
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| 69 | called to initialize the <a href="OggVorbis_File.html">OggVorbis_File</a> structure with default values. |
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| 70 | <a href="ov_open_callbacks.html">ov_open_callbacks()</a> also checks to ensure that we're reading Vorbis format and not something else. |
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| 71 | |
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| 72 | <br><br> |
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| 73 | <table border=0 width=100% color=black cellspacing=0 cellpadding=7> |
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| 74 | <tr bgcolor=#cccccc> |
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| 75 | <td> |
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| 76 | <pre><b> |
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| 77 | if(ov_open_callbacks(stdin,&ov,NULL,-1, OV_CALLBACKS_NOCLOSE)<0){ |
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| 78 | printf("Could not open input as an OggVorbis file.\n\n"); |
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| 79 | exit(1); |
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| 80 | } |
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| 81 | |
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| 82 | </b></pre> |
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| 83 | </td> |
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| 84 | </tr> |
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| 85 | </table> |
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| 86 | |
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| 87 | <p> |
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| 88 | First we check to make sure the stream is seekable using <a href="ov_seekable.html">ov_seekable</a>. |
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| 89 | |
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| 90 | <p>Then we seek to 100 random spots in the bitstream using <a href="ov_time_seek.html">ov_time_seek</a> with randomly generated values. |
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| 91 | |
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| 92 | <br><br> |
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| 93 | <table border=0 width=100% color=black cellspacing=0 cellpadding=7> |
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| 94 | <tr bgcolor=#cccccc> |
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| 95 | <td> |
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| 96 | <pre><b> |
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| 97 | |
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| 98 | /* print details about each logical bitstream in the input */ |
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| 99 | if(ov_seekable(&ov)){ |
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| 100 | double length=ov_time_total(&ov,-1); |
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| 101 | printf("testing seeking to random places in %g seconds....\n",length); |
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| 102 | for(i=0;i<100;i++){ |
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| 103 | double val=(double)rand()/RAND_MAX*length; |
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| 104 | ov_time_seek(&ov,val); |
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| 105 | printf("\r\t%d [%gs]... ",i,val); |
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| 106 | fflush(stdout); |
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| 107 | } |
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| 108 | |
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| 109 | printf("\r \nOK.\n\n"); |
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| 110 | }else{ |
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| 111 | printf("Standard input was not seekable.\n"); |
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| 112 | } |
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| 113 | |
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| 114 | </b></pre> |
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| 115 | </td> |
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| 116 | </tr> |
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| 117 | </table> |
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| 118 | <p> |
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| 119 | When we're done seeking, we need to call <a href="ov_clear.html">ov_clear()</a> to release the bitstream. |
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| 120 | |
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| 121 | <br><br> |
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| 122 | <table border=0 width=100% color=black cellspacing=0 cellpadding=7> |
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| 123 | <tr bgcolor=#cccccc> |
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| 124 | <td> |
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| 125 | <pre><b> |
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| 126 | ov_clear(&ov); |
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| 127 | return 0; |
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| 128 | } |
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| 129 | </b></pre> |
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| 130 | </td> |
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| 131 | </tr> |
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| 132 | </table> |
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| 133 | |
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| 134 | <p> |
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| 135 | The full source for seeking_test.c can be found with the vorbis |
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| 136 | distribution in <a href="seeking_test_c.html">seeking_test.c</a>. |
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| 137 | |
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| 138 | <br><br> |
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| 139 | <hr noshade> |
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| 140 | <table border=0 width=100%> |
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| 141 | <tr valign=top> |
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| 142 | <td><p class=tiny>copyright © 2007 Xiph.org</p></td> |
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| 143 | <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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| 144 | </tr><tr> |
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| 145 | <td><p class=tiny>Vorbisfile documentation</p></td> |
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| 146 | <td align=right><p class=tiny>vorbisfile version 1.2.0 - 20070723</p></td> |
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| 147 | </tr> |
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| 148 | </table> |
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| 149 | |
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| 150 | </body> |
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| 151 | |
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| 152 | </html> |
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