153 lines
4.1 KiB
HTML
153 lines
4.1 KiB
HTML
<html>
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<head>
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<title>vorbisfile - Example Code</title>
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<link rel=stylesheet href="style.css" type="text/css">
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</head>
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<body bgcolor=white text=black link="#5555ff" alink="#5555ff" vlink="#5555ff">
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<table border=0 width=100%>
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<tr>
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<td><p class=tiny>Vorbisfile documentation</p></td>
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<td align=right><p class=tiny>vorbisfile version 1.3.2 - 20101101</p></td>
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</tr>
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</table>
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<h1>Example Code: seeking</h1>
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<p>
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The following is a run-through of the seeking example program supplied
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with vorbisfile - <a href="seeking_test_c.html">seeking_test.c</a>.
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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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<p>
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First, relevant headers, including vorbis-specific "codec.h" and "vorbisfile.h" have to be included.
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<br><br>
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<table border=0 width=100% color=black cellspacing=0 cellpadding=7>
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<tr bgcolor=#cccccc>
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<td>
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<pre><b>
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#include <stdlib.h>
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#include <stdio.h>
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#include "vorbis/codec.h"
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#include "vorbis/vorbisfile.h"
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</b></pre>
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</td>
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</tr>
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</table>
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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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<br><br>
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<table border=0 width=100% color=black cellspacing=0 cellpadding=7>
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<tr bgcolor=#cccccc>
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<td>
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<pre><b>
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int main(){
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OggVorbis_File ov;
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int i;
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</b></pre>
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</td>
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</tr>
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</table>
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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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<br><br>
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<table border=0 width=100% color=black cellspacing=0 cellpadding=7>
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<tr bgcolor=#cccccc>
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<td>
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<pre><b>
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#ifdef _WIN32 /* We need to set stdin to binary mode under Windows */
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_setmode( _fileno( stdin ), _O_BINARY );
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#endif
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</b></pre>
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</td>
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</tr>
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</table>
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<p><a href="ov_open_callbacks.html">ov_open()</a> must be
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called to initialize the <a href="OggVorbis_File.html">OggVorbis_File</a> structure with default values.
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<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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<br><br>
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<table border=0 width=100% color=black cellspacing=0 cellpadding=7>
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<tr bgcolor=#cccccc>
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<td>
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<pre><b>
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if(ov_open_callbacks(stdin,&ov,NULL,-1, OV_CALLBACKS_NOCLOSE)<0){
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printf("Could not open input as an OggVorbis file.\n\n");
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exit(1);
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}
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</b></pre>
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</td>
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</tr>
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</table>
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<p>
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First we check to make sure the stream is seekable using <a href="ov_seekable.html">ov_seekable</a>.
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<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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<br><br>
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<table border=0 width=100% color=black cellspacing=0 cellpadding=7>
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<tr bgcolor=#cccccc>
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<td>
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<pre><b>
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/* print details about each logical bitstream in the input */
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if(ov_seekable(&ov)){
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double length=ov_time_total(&ov,-1);
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printf("testing seeking to random places in %g seconds....\n",length);
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for(i=0;i<100;i++){
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double val=(double)rand()/RAND_MAX*length;
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ov_time_seek(&ov,val);
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printf("\r\t%d [%gs]... ",i,val);
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fflush(stdout);
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}
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printf("\r \nOK.\n\n");
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}else{
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printf("Standard input was not seekable.\n");
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}
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</b></pre>
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</td>
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</tr>
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</table>
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<p>
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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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<br><br>
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<table border=0 width=100% color=black cellspacing=0 cellpadding=7>
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<tr bgcolor=#cccccc>
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<td>
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<pre><b>
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ov_clear(&ov);
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return 0;
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}
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</b></pre>
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</td>
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</tr>
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</table>
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<p>
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The full source for seeking_test.c can be found with the vorbis
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distribution in <a href="seeking_test_c.html">seeking_test.c</a>.
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<br><br>
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<hr noshade>
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<table border=0 width=100%>
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<tr valign=top>
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<td><p class=tiny>copyright © 2000-2010 Xiph.Org</p></td>
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<td align=right><p class=tiny><a href="http://www.xiph.org/ogg/vorbis/">Ogg Vorbis</a></p></td>
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</tr><tr>
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<td><p class=tiny>Vorbisfile documentation</p></td>
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<td align=right><p class=tiny>vorbisfile version 1.3.2 - 20101101</p></td>
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</tr>
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</table>
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</body>
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</html>
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