4 <title>vorbisfile - Example Code</title>
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8 <body bgcolor=white text=black link="#5555ff" alink="#5555ff" vlink="#5555ff">
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11 <td><p class=tiny>vorbisfile documentation</p></td>
12 <td align=right><p class=tiny>vorbisfile version 1.25 - 20000615</p></td>
19 The following is a run-through of the decoding example program supplied
20 with vorbisfile - <a href="vorbisfile_example_c.html">vorbisfile_example.c</a>.
21 This program takes a vorbis bitstream from stdin and writes raw pcm to stdout.
24 First, relevant headers, including vorbis-specific "codec.h" and "vorbisfile.h" have to be included.
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31 #include <stdio.h>
32 #include <stdlib.h>
33 #include <math.h>
34 #include "vorbis/codec.h"
35 #include "vorbis/vorbisfile.h"
41 We also have to make a concession to Windows users here. If we are using windows for decoding, we must declare these libraries so that we can set stdin/stdout to binary.
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49 #include <fcntl.h>
56 Next, a buffer for the pcm audio output is declared.
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69 <p>Inside main(), we declare our primary OggVorbis_File structure. We also declare a few other helpful variables to track out progress within the file.
70 Also, we make our final concession to Windows users by setting the stdin and stdout to binary mode.
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76 int main(int argc, char **argv){
82 _setmode( _fileno( stdin ), _O_BINARY );
83 _setmode( _fileno( stdout ), _O_BINARY );
90 <p><a href="ov_open.html">ov_open()</a> must be
91 called to initialize the <b>OggVorbis_File</b> structure with default values.
92 <a href="ov_open.html">ov_open()</a> also checks to ensure that we're reading Vorbis format and not something else.
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99 if(ov_open(stdin, &vf, NULL, 0) < 0) {
100 fprintf(stderr,"Input does not appear to be an Ogg bitstream.\n");
110 We're going to pull the channel and bitrate info from the file using <a href="ov_info.html">ov_info()</a> and show them to the user.
111 We also want to pull out and show the user a comment attached to the file using <a href="ov_comment.html">ov_comment()</a>.
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119 char **ptr=ov_comment(&vf,-1)->user_comments;
120 vorbis_info *vi=ov_info(&vf,-1);
122 fprintf(stderr,"%s\n",*ptr);
125 fprintf(stderr,"\nBitstream is %d channel, %ldHz\n",vi->channels,vi->rate);
126 fprintf(stderr,"Encoded by: %s\n\n",ov_comment(&vf,-1)->vendor);
135 Here's the read loop:
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144 long ret=ov_read(&vf,pcmout,sizeof(pcmout),0,2,1,¤t_section);
153 fwrite(pcmout,1,ret,stdout);
164 The code is reading blocks of data using <a href="ov_read.html">ov_read()</a>.
165 Based on the value returned, we know if we're at the end of the file or have invalid data. If we have valid data, we write it to the pcm output.
168 Now that we've finished playing, we can pack up and go home. It's important to call <a href="ov_clear.html">ov_clear()</a> when we're finished.
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178 fprintf(stderr,"Done.\n");
187 The full source for vorbisfile_example.c can be found with the vorbis
188 distribution in <a href="vorbisfile_example_c.html">vorbisfile_example.c</a>.
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194 <td><p class=tiny>copyright © 2000 vorbis team</p></td>
195 <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>
197 <td><p class=tiny>vorbisfile documentation</p></td>
198 <td align=right><p class=tiny>vorbisfile version 1.25 - 20000615</p></td>