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4<title>vorbisfile - Example Code</title>
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11<td><p class=tiny>Vorbisfile documentation</p></td>
12<td align=right><p class=tiny>vorbisfile version 1.2.0 - 20070723</p></td>
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14</table>
15
16<h1>Chaining Example Code</h1>
17
18<p>
19The following is a run-through of the chaining example program supplied
20with vorbisfile - <a href="chaining_example_c.html">chaining_example.c</a>.
21This program demonstrates how to work with a chained bitstream.
22
23<p>
24First, relevant headers, including vorbis-specific "codec.h" and "vorbisfile.h" have to be included.
25
26<br><br>
27<table border=0 width=100% color=black cellspacing=0 cellpadding=7>
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29	<td>
30<pre><b>
31#include "vorbis/codec.h"
32#include "vorbis/vorbisfile.h"
33#include "../lib/misc.h"
34</b></pre>
35	</td>
36</tr>
37</table>
38
39<p>Inside main(), we declare our primary OggVorbis_File structure.  We also declare a other helpful variables to track our progress within the file.
40<br><br>
41<table border=0 width=100% color=black cellspacing=0 cellpadding=7>
42<tr bgcolor=#cccccc>
43        <td>
44<pre><b>
45int main(){
46  OggVorbis_File ov;
47  int i;
48</b></pre>
49        </td>
50</tr>
51</table>
52
53<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.
54<br><br>
55<table border=0 width=100% color=black cellspacing=0 cellpadding=7>
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57        <td>
58<pre><b>
59#ifdef _WIN32 /* We need to set stdin to binary mode under Windows */
60  _setmode( _fileno( stdin ), _O_BINARY );
61#endif
62</b></pre>
63        </td>
64</tr>
65</table>
66
67<p>We call <a href="ov_open_callbacks.html">ov_open_callbacks()</a> to
68initialize the <a href="OggVorbis_File.html">OggVorbis_File</a>
69structure.  <a href="ov_open_callbacks.html">ov_open_callbacks()</a>
70also checks to ensure that we're reading Vorbis format and not
71something else. The OV_CALLBACKS_NOCLOSE callbacks instruct
72libvorbisfile not to close stdin later during cleanup.<p>
73
74<br><br>
75<table border=0 width=100% color=black cellspacing=0 cellpadding=7>
76<tr bgcolor=#cccccc>
77        <td>
78<pre><b>
79  if(ov_open_callbacks(stdin,&ov,NULL,-1,OV_CALLBACKS_NOCLOSE)<0){
80    printf("Could not open input as an OggVorbis file.\n\n");
81    exit(1);
82  }
83
84</b></pre>
85        </td>
86</tr>
87</table>
88
89<p>
90First we check to make sure the stream is seekable using <a href="ov_seekable.html">ov_seekable</a>.
91
92<p>Then we're going to find the number of logical bitstreams in the physical bitstream using <a href="ov_streams.html">ov_streams</a>.
93
94<p>We use <a href="ov_time_total.html">ov_time_total</a> to determine the total length of the physical bitstream.  We specify that we want the entire bitstream by using the argument <tt>-1</tt>.
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96<br><br>
97<table border=0 width=100% color=black cellspacing=0 cellpadding=7>
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100<pre><b>
101  if(ov_seekable(&amp;ov)){
102    printf("Input bitstream contained %ld logical bitstream section(s).\n",
103	   ov_streams(&amp;ov));
104    printf("Total bitstream playing time: %ld seconds\n\n",
105	   (long)ov_time_total(&amp;ov,-1));
106
107  }else{
108    printf("Standard input was not seekable.\n"
109	   "First logical bitstream information:\n\n");
110  }
111
112</b></pre>
113        </td>
114</tr>
115</table>
116
117<p>Now we're going to iterate through each logical bitstream and print information about that bitstream.
118
119<p>We use <a href="ov_info.html">ov_info</a> to pull out the <a href="vorbis_info.html">vorbis_info</a> struct for each logical bitstream.  This struct contains bitstream-specific info.
120
121<p><a href="ov_serialnumber.html">ov_serialnumber</a> retrieves the unique serial number for the logical bistream.  <a href="ov_raw_total.html">ov_raw_total</a> gives the total compressed bytes for the logical bitstream, and <a href="ov_time_total.html">ov_time_total</a> gives the total time in the logical bitstream.
122
123<br><br>
124<table border=0 width=100% color=black cellspacing=0 cellpadding=7>
125<tr bgcolor=#cccccc>
126        <td>
127<pre><b>
128  for(i=0;i&lt;ov_streams(&amp;ov);i++){
129    vorbis_info *vi=ov_info(&amp;ov,i);
130    printf("\tlogical bitstream section %d information:\n",i+1);
131    printf("\t\t%ldHz %d channels bitrate %ldkbps serial number=%ld\n",
132	   vi-&gt;rate,vi-&gt;channels,ov_bitrate(&amp;ov,i)/1000,
133	   ov_serialnumber(&amp;ov,i));
134    printf("\t\tcompressed length: %ld bytes ",(long)(ov_raw_total(&amp;ov,i)));
135    printf(" play time: %lds\n",(long)ov_time_total(&amp;ov,i));
136  }
137</b></pre>
138        </td>
139</tr>
140</table>
141<p>
142When we're done with the entire physical bitstream, we need to call <a href="ov_clear.html">ov_clear()</a> to release the bitstream.
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144<br><br>
145<table border=0 width=100% color=black cellspacing=0 cellpadding=7>
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148<pre><b>
149  ov_clear(&amp;ov);
150  return 0;
151}
152</b></pre>
153        </td>
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155</table>
156
157<p>
158The full source for chaining_example.c can be found with the vorbis
159distribution in <a href="chaining_example_c.html">chaining_example.c</a>.
160
161<br><br>
162<hr noshade>
163<table border=0 width=100%>
164<tr valign=top>
165<td><p class=tiny>copyright &copy; 2007 Xiph.org</p></td>
166<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>
167</tr><tr>
168<td><p class=tiny>Vorbisfile documentation</p></td>
169<td align=right><p class=tiny>vorbisfile version 1.2.0 - 20070723</p></td>
170</tr>
171</table>
172
173</body>
174
175</html>
176