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<html>
<head>
<title>vorbisfile - Example Code</title>
<link rel=stylesheet href="style.css" type="text/css">
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<body bgcolor=white text=black link="#5555ff" alink="#5555ff" vlink="#5555ff">
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<td><p class=tiny>Vorbisfile documentation</p></td>
<td align=right><p class=tiny>vorbisfile version 1.3.2 - 20101101</p></td>
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</table>
<h1>Example Code: seeking</h1>
<p>
The following is a run-through of the seeking example program supplied
with vorbisfile - <a href="seeking_test_c.html">seeking_test.c</a>.
This program tests the vorbisfile <a href="ov_time_seek.html">ov_time_seek</a> function by seeking to random points within the file.
<p>
First, relevant headers, including vorbis-specific "codec.h" and "vorbisfile.h" have to be included.
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<pre><b>
#include <stdlib.h>
#include <stdio.h>
#include "vorbis/codec.h"
#include "vorbis/vorbisfile.h"
</b></pre>
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<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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<pre><b>
int main(){
OggVorbis_File ov;
int i;
</b></pre>
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<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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<pre><b>
#ifdef _WIN32 /* We need to set stdin to binary mode under Windows */
_setmode( _fileno( stdin ), _O_BINARY );
#endif
</b></pre>
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<p><a href="ov_open_callbacks.html">ov_open()</a> must be
called to initialize the <a href="OggVorbis_File.html">OggVorbis_File</a> structure with default values.
<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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<pre><b>
if(ov_open_callbacks(stdin,&ov,NULL,-1, OV_CALLBACKS_NOCLOSE)<0){
printf("Could not open input as an OggVorbis file.\n\n");
exit(1);
}
</b></pre>
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<p>
First we check to make sure the stream is seekable using <a href="ov_seekable.html">ov_seekable</a>.
<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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<pre><b>
/* print details about each logical bitstream in the input */
if(ov_seekable(&ov)){
double length=ov_time_total(&ov,-1);
printf("testing seeking to random places in %g seconds....\n",length);
for(i=0;i<100;i++){
double val=(double)rand()/RAND_MAX*length;
ov_time_seek(&ov,val);
printf("\r\t%d [%gs]... ",i,val);
fflush(stdout);
}
printf("\r \nOK.\n\n");
}else{
printf("Standard input was not seekable.\n");
}
</b></pre>
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<p>
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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<pre><b>
ov_clear(&ov);
return 0;
}
</b></pre>
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<p>
The full source for seeking_test.c can be found with the vorbis
distribution in <a href="seeking_test_c.html">seeking_test.c</a>.
<br><br>
<hr noshade>
<table border=0 width=100%>
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<td><p class=tiny>copyright © 2000-2010 Xiph.Org</p></td>
<td align=right><p class=tiny><a href="http://www.xiph.org/ogg/vorbis/">Ogg Vorbis</a></p></td>
</tr><tr>
<td><p class=tiny>Vorbisfile documentation</p></td>
<td align=right><p class=tiny>vorbisfile version 1.3.2 - 20101101</p></td>
</tr>
</table>
</body>
</html>
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