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Bring in flac, ogg, vorbis
author Chris Cannam
date Tue, 19 Mar 2013 17:37:49 +0000
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1 <html>
2
3 <head>
4 <title>vorbisfile - Example Code</title>
5 <link rel=stylesheet href="style.css" type="text/css">
6 </head>
7
8 <body bgcolor=white text=black link="#5555ff" alink="#5555ff" vlink="#5555ff">
9 <table border=0 width=100%>
10 <tr>
11 <td><p class=tiny>Vorbisfile documentation</p></td>
12 <td align=right><p class=tiny>vorbisfile version 1.3.2 - 20101101</p></td>
13 </tr>
14 </table>
15
16 <h1>Example Code: seeking</h1>
17
18 <p>
19 The following is a run-through of the seeking example program supplied
20 with vorbisfile - <a href="seeking_test_c.html">seeking_test.c</a>.
21 This program tests the vorbisfile <a href="ov_time_seek.html">ov_time_seek</a> function by seeking to random points within the file.
22
23 <p>
24 First, 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>
28 <tr bgcolor=#cccccc>
29 <td>
30 <pre><b>
31 #include &lt;stdlib.h>
32 #include &lt;stdio.h>
33 #include "vorbis/codec.h"
34 #include "vorbis/vorbisfile.h"
35 </b></pre>
36 </td>
37 </tr>
38 </table>
39
40 <p>Inside main(), we declare our primary OggVorbis_File structure. We also declare other helpful variables to track our progress within the file.
41 <br><br>
42 <table border=0 width=100% color=black cellspacing=0 cellpadding=7>
43 <tr bgcolor=#cccccc>
44 <td>
45 <pre><b>
46 int main(){
47 OggVorbis_File ov;
48 int i;
49 </b></pre>
50 </td>
51 </tr>
52 </table>
53
54 <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.
55 <br><br>
56 <table border=0 width=100% color=black cellspacing=0 cellpadding=7>
57 <tr bgcolor=#cccccc>
58 <td>
59 <pre><b>
60 #ifdef _WIN32 /* We need to set stdin to binary mode under Windows */
61 _setmode( _fileno( stdin ), _O_BINARY );
62 #endif
63 </b></pre>
64 </td>
65 </tr>
66 </table>
67
68 <p><a href="ov_open_callbacks.html">ov_open()</a> must be
69 called to initialize the <a href="OggVorbis_File.html">OggVorbis_File</a> structure with default values.
70 <a href="ov_open_callbacks.html">ov_open_callbacks()</a> also checks to ensure that we're reading Vorbis format and not something else.
71
72 <br><br>
73 <table border=0 width=100% color=black cellspacing=0 cellpadding=7>
74 <tr bgcolor=#cccccc>
75 <td>
76 <pre><b>
77 if(ov_open_callbacks(stdin,&ov,NULL,-1, OV_CALLBACKS_NOCLOSE)<0){
78 printf("Could not open input as an OggVorbis file.\n\n");
79 exit(1);
80 }
81
82 </b></pre>
83 </td>
84 </tr>
85 </table>
86
87 <p>
88 First we check to make sure the stream is seekable using <a href="ov_seekable.html">ov_seekable</a>.
89
90 <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.
91
92 <br><br>
93 <table border=0 width=100% color=black cellspacing=0 cellpadding=7>
94 <tr bgcolor=#cccccc>
95 <td>
96 <pre><b>
97
98 /* print details about each logical bitstream in the input */
99 if(ov_seekable(&ov)){
100 double length=ov_time_total(&ov,-1);
101 printf("testing seeking to random places in %g seconds....\n",length);
102 for(i=0;i<100;i++){
103 double val=(double)rand()/RAND_MAX*length;
104 ov_time_seek(&ov,val);
105 printf("\r\t%d [%gs]... ",i,val);
106 fflush(stdout);
107 }
108
109 printf("\r \nOK.\n\n");
110 }else{
111 printf("Standard input was not seekable.\n");
112 }
113
114 </b></pre>
115 </td>
116 </tr>
117 </table>
118 <p>
119 When we're done seeking, we need to call <a href="ov_clear.html">ov_clear()</a> to release the bitstream.
120
121 <br><br>
122 <table border=0 width=100% color=black cellspacing=0 cellpadding=7>
123 <tr bgcolor=#cccccc>
124 <td>
125 <pre><b>
126 ov_clear(&ov);
127 return 0;
128 }
129 </b></pre>
130 </td>
131 </tr>
132 </table>
133
134 <p>
135 The full source for seeking_test.c can be found with the vorbis
136 distribution in <a href="seeking_test_c.html">seeking_test.c</a>.
137
138 <br><br>
139 <hr noshade>
140 <table border=0 width=100%>
141 <tr valign=top>
142 <td><p class=tiny>copyright &copy; 2000-2010 Xiph.Org</p></td>
143 <td align=right><p class=tiny><a href="http://www.xiph.org/ogg/vorbis/">Ogg Vorbis</a></p></td>
144 </tr><tr>
145 <td><p class=tiny>Vorbisfile documentation</p></td>
146 <td align=right><p class=tiny>vorbisfile version 1.3.2 - 20101101</p></td>
147 </tr>
148 </table>
149
150 </body>
151
152 </html>