You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
82 lines
2.6 KiB
82 lines
2.6 KiB
<html>
|
|
|
|
<head>
|
|
<title>Tremor - Decoding</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>Decoding</h1>
|
|
|
|
<p>
|
|
All libivorbisdec decoding routines are declared in "ivorbisfile.h".
|
|
<p>
|
|
|
|
After <a href="initialization.html">initialization</a>, decoding audio
|
|
is as simple as calling <a href="ov_read.html">ov_read()</a>. This
|
|
function works similarly to reading from a normal file using
|
|
<tt>read()</tt>.<p>
|
|
|
|
However, a few differences are worth noting:
|
|
|
|
<h2>multiple stream links</h2>
|
|
|
|
A Vorbis stream may consist of multiple sections (called links) that
|
|
encode differing numbers of channels or sample rates. It is vitally
|
|
important to pay attention to the link numbers returned by <a
|
|
href="ov_read.html">ov_read</a> and handle audio changes that may
|
|
occur at link boundaries. Such multi-section files do exist in the
|
|
wild and are not merely a specification curiosity.
|
|
|
|
<h2>returned data amount</h2>
|
|
|
|
<a href="ov_read.html">ov_read</a> does not attempt to completely fill
|
|
a large, passed in data buffer; it merely guarantees that the passed
|
|
back data does not overflow the passed in buffer size. Large buffers
|
|
may be filled by iteratively looping over calls to <a
|
|
href="ov_read.html">ov_read</a> (incrementing the buffer pointer)
|
|
until the original buffer is filled.
|
|
|
|
<h2>file cursor position</h2>
|
|
|
|
Vorbis files do not necessarily start at a sample number or time offset
|
|
of zero. Do not be surprised if a file begins at a positive offset of
|
|
several minutes or hours, such as would happen if a large stream (such
|
|
as a concert recording) is chopped into multiple seperate files.
|
|
|
|
<p>
|
|
<table border=1 color=black width=50% cellspacing=0 cellpadding=7>
|
|
<tr bgcolor=#cccccc>
|
|
<td><b>function</b></td>
|
|
<td><b>purpose</b></td>
|
|
</tr>
|
|
<tr valign=top>
|
|
<td><a href="ov_read.html">ov_read</a></td>
|
|
<td>This function makes up the main chunk of a decode loop. It takes an
|
|
OggVorbis_File structure, which must have been initialized by a previous
|
|
call to <a href="ov_open.html"><tt>ov_open()</tt></a>.</td>
|
|
</tr>
|
|
</table>
|
|
|
|
<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>
|
|
|