/usr/share/doc/libvorbisidec-dev/html/example.html is in libvorbisidec-dev 1.0.2+svn18153-1+deb9u1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 | <html>
<head>
<title>Tremor - Example Code</title>
<link rel=stylesheet href="style.css" type="text/css">
</head>
<body bgcolor=white text=black link="#5555ff" alink="#5555ff" vlink="#5555ff">
<table border=0 width=100%>
<tr>
<td><p class=tiny>Tremor documentation</p></td>
<td align=right><p class=tiny>Tremor version 1.0 - 20020403</p></td>
</tr>
</table>
<h1>Example Code</h1>
<p>
The following is a run-through of the decoding example program supplied
with libvorbisidec, ivorbisfile_example.c.
This program takes a vorbis bitstream from stdin and writes raw pcm to stdout.
<p>
First, relevant headers, including vorbis-specific "ivorbiscodec.h" and "ivorbisfile.h" have to be included.
<br><br>
<table border=0 width=100% color=black cellspacing=0 cellpadding=7>
<tr bgcolor=#cccccc>
<td>
<pre><b>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "ivorbiscodec.h"
#include "ivorbisfile.h"
</b></pre>
</td>
</tr>
</table>
<p>
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.
<br><br>
<table border=0 width=100% color=black cellspacing=0 cellpadding=7>
<tr bgcolor=#cccccc>
<td>
<pre><b>
#ifdef _WIN32
#include <io.h>
#include <fcntl.h>
#endif
</b></pre>
</td>
</tr>
</table>
<p>
Next, a buffer for the pcm audio output is declared.
<br><br>
<table border=0 width=100% color=black cellspacing=0 cellpadding=7>
<tr bgcolor=#cccccc>
<td>
<pre><b>
char pcmout[4096];
</b></pre>
</td>
</tr>
</table>
<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.
Also, we make our final concession to Windows users by setting the stdin and stdout to binary mode.
<br><br>
<table border=0 width=100% color=black cellspacing=0 cellpadding=7>
<tr bgcolor=#cccccc>
<td>
<pre><b>
int main(int argc, char **argv){
OggVorbis_File vf;
int eof=0;
int current_section;
#ifdef _WIN32
_setmode( _fileno( stdin ), _O_BINARY );
_setmode( _fileno( stdout ), _O_BINARY );
#endif
</b></pre>
</td>
</tr>
</table>
<p><a href="ov_open.html">ov_open()</a> must be
called to initialize the <b>OggVorbis_File</b> structure with default values.
<a href="ov_open.html">ov_open()</a> also checks to ensure that we're reading Vorbis format and not something else.
<br><br>
<table border=0 width=100% color=black cellspacing=0 cellpadding=7>
<tr bgcolor=#cccccc>
<td>
<pre><b>
if(ov_open(stdin, &vf, NULL, 0) < 0) {
fprintf(stderr,"Input does not appear to be an Ogg bitstream.\n");
exit(1);
}
</b></pre>
</td>
</tr>
</table>
<p>
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.
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>.
<br><br>
<table border=0 width=100% color=black cellspacing=0 cellpadding=7>
<tr bgcolor=#cccccc>
<td>
<pre><b>
{
char **ptr=ov_comment(&vf,-1)->user_comments;
vorbis_info *vi=ov_info(&vf,-1);
while(*ptr){
fprintf(stderr,"%s\n",*ptr);
++ptr;
}
fprintf(stderr,"\nBitstream is %d channel, %ldHz\n",vi->channels,vi->rate);
fprintf(stderr,"\nDecoded length: %ld samples\n",
(long)ov_pcm_total(&vf,-1));
fprintf(stderr,"Encoded by: %s\n\n",ov_comment(&vf,-1)->vendor);
}
</b></pre>
</td>
</tr>
</table>
<p>
Here's the read loop:
<br><br>
<table border=0 width=100% color=black cellspacing=0 cellpadding=7>
<tr bgcolor=#cccccc>
<td>
<pre><b>
while(!eof){
long ret=ov_read(&vf,pcmout,sizeof(pcmout),¤t_section);
if (ret == 0) {
/* EOF */
eof=1;
} else if (ret < 0) {
/* error in the stream. Not a problem, just reporting it in
case we (the app) cares. In this case, we don't. */
} else {
/* we don't bother dealing with sample rate changes, etc, but
you'll have to*/
fwrite(pcmout,1,ret,stdout);
}
}
</b></pre>
</td>
</tr>
</table>
<p>
The code is reading blocks of data using <a href="ov_read.html">ov_read()</a>.
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.
<p>
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.
<br><br>
<table border=0 width=100% color=black cellspacing=0 cellpadding=7>
<tr bgcolor=#cccccc>
<td>
<pre><b>
ov_clear(&vf);
fprintf(stderr,"Done.\n");
return(0);
}
</b></pre>
</td>
</tr>
</table>
<p>
<br><br>
<hr noshade>
<table border=0 width=100%>
<tr valign=top>
<td><p class=tiny>copyright © 2002 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>Tremor documentation</p></td>
<td align=right><p class=tiny>Tremor version 1.0 - 20020403</p></td>
</tr>
</table>
</body>
</html>
|