Mercurial > hg > sv-dependency-builds

comparison src/libvorbis-1.3.3/doc/vorbisfile/chainingexample.html @ 86:98c1576536ae

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Bring in flac, ogg, vorbis
author Chris Cannam <cannam@all-day-breakfast.com>
date Tue, 19 Mar 2013 17:37:49 +0000
parents
children
comparison
equal deleted inserted replaced
85:545efbb81310 86:98c1576536ae
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>Chaining Example Code</h1>
17
18 <p>
19 The following is a run-through of the chaining example program supplied
20 with vorbisfile - <a href="chaining_example_c.html">chaining_example.c</a>.
21 This program demonstrates how to work with a chained bitstream.
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 "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>
45 int 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>
56 <tr bgcolor=#cccccc>
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
68 initialize the <a href="OggVorbis_File.html">OggVorbis_File</a>
69 structure. <a href="ov_open_callbacks.html">ov_open_callbacks()</a>
70 also checks to ensure that we're reading Vorbis format and not
71 something else. The OV_CALLBACKS_NOCLOSE callbacks instruct
72 libvorbisfile 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>
90 First 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>.
95
96 <br><br>
97 <table border=0 width=100% color=black cellspacing=0 cellpadding=7>
98 <tr bgcolor=#cccccc>
99 <td>
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="../libvorbis/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>
142 When we're done with the entire physical bitstream, we need to call <a href="ov_clear.html">ov_clear()</a> to release the bitstream.
143
144 <br><br>
145 <table border=0 width=100% color=black cellspacing=0 cellpadding=7>
146 <tr bgcolor=#cccccc>
147 <td>
148 <pre><b>
149 ov_clear(&amp;ov);
150 return 0;
151 }
152 </b></pre>
153 </td>
154 </tr>
155 </table>
156
157 <p>
158 The full source for chaining_example.c can be found with the vorbis
159 distribution 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; 2000-2010 Xiph.Org</p></td>
166 <td align=right><p class=tiny><a href="http://www.xiph.org/ogg/vorbis/">Ogg Vorbis</a></p></td>
167 </tr><tr>
168 <td><p class=tiny>Vorbisfile documentation</p></td>
169 <td align=right><p class=tiny>vorbisfile version 1.3.2 - 20101101</p></td>
170 </tr>
171 </table>
172
173 </body>
174
175 </html>