116 lines
4.5 KiB
HTML
116 lines
4.5 KiB
HTML
|
<html>
|
||
|
|
|
||
|
|
<head>
|
||
|
|
<title>Tremor - function - ov_open</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>ov_open</h1>
|
||
|
|
|
||
|
|
<p><i>declared in "ivorbisfile.h";</i></p>
|
||
|
|
|
||
|
|
<p>This is the main function used to open and initialize an OggVorbis_File
|
||
|
|
structure. It sets up all the related decoding structure.
|
||
|
|
<p>The first argument must be a file pointer to an already opened file
|
||
|
|
or pipe (it need not be seekable--though this obviously restricts what
|
||
|
|
can be done with the bitstream). <tt>vf</tt> should be a pointer to the
|
||
|
|
OggVorbis_File structure--this is used for ALL the externally visible libvorbisidec
|
||
|
|
functions. Once this has been called, the same <a href="OggVorbis_File.html">OggVorbis_File</a>
|
||
|
|
struct should be passed to all the libvorbisidec functions.
|
||
|
|
<p>Also, you should be aware that ov_open(), once successful, takes complete possession of the file resource. After you have opened a file using ov_open(), you MUST close it using <a href="ov_clear.html">ov_clear()</a>, not fclose() or any other function.
|
||
|
|
<p>
|
||
|
|
It is often useful to call <tt>ov_open()</tt>
|
||
|
|
simply to determine whether a given file is a vorbis bitstream. If the
|
||
|
|
<tt>ov_open()</tt>
|
||
|
|
call fails, then the file is not recognizable as such.
|
||
|
|
When you use <tt>ov_open()
|
||
|
|
</tt>for
|
||
|
|
this, you should <tt>fclose()</tt> the file pointer if, and only if, the
|
||
|
|
<tt>ov_open()</tt>
|
||
|
|
call fails. If it succeeds, you must call <a href="ov_clear.html">ov_clear()</a> to clear
|
||
|
|
the decoder's buffers and close the file for you.<p>
|
||
|
|
|
||
|
|
(Note that <a href="ov_test.html">ov_test()</a> provides a less expensive way to test a file for Vorbisness.)<p>
|
||
|
|
|
||
|
|
<br><br>
|
||
|
|
<table border=0 color=black cellspacing=0 cellpadding=7>
|
||
|
|
<tr bgcolor=#cccccc>
|
||
|
|
<td>
|
||
|
|
<pre><b>
|
||
|
|
int ov_open(FILE *f,<a href="OggVorbis_File.html">OggVorbis_File</a> *vf,char *initial,long ibytes);
|
||
|
|
</b></pre>
|
||
|
|
</td>
|
||
|
|
</tr>
|
||
|
|
</table>
|
||
|
|
|
||
|
|
<h3>Parameters</h3>
|
||
|
|
<dl>
|
||
|
|
<dt><i>f</i></dt>
|
||
|
|
<dd>File pointer to an already opened file
|
||
|
|
or pipe (it need not be seekable--though this obviously restricts what
|
||
|
|
can be done with the bitstream).</dd>
|
||
|
|
<dt><i>vf</i></dt>
|
||
|
|
<dd>A pointer to the OggVorbis_File structure--this is used for ALL the externally visible libvorbisidec
|
||
|
|
functions. Once this has been called, the same <tt>OggVorbis_File</tt>
|
||
|
|
struct should be passed to all the libvorbisidec functions.</dd>
|
||
|
|
<dt><i>initial</i></dt>
|
||
|
|
<dd>Typically set to NULL. This parameter is useful if some data has already been
|
||
|
|
read from the file and the stream is not seekable. It is used in conjunction with <tt>ibytes</tt>. In this case, <tt>initial</tt>
|
||
|
|
should be a pointer to a buffer containing the data read.</dd>
|
||
|
|
<dt><i>ibytes</i></dt>
|
||
|
|
<dd>Typically set to 0. This parameter is useful if some data has already been
|
||
|
|
read from the file and the stream is not seekable. In this case, <tt>ibytes</tt>
|
||
|
|
should contain the length (in bytes) of the buffer. Used together with <tt>initial</tt></dd>
|
||
|
|
</dl>
|
||
|
|
|
||
|
|
|
||
|
|
<h3>Return Values</h3>
|
||
|
|
<blockquote>
|
||
|
|
<li>0 indicates success</li>
|
||
|
|
|
||
|
|
<li>less than zero for failure:</li>
|
||
|
|
<ul>
|
||
|
|
<li>OV_EREAD - A read from media returned an error.</li>
|
||
|
|
<li>OV_ENOTVORBIS - Bitstream is not Vorbis data.</li>
|
||
|
|
<li>OV_EVERSION - Vorbis version mismatch.</li>
|
||
|
|
<li>OV_EBADHEADER - Invalid Vorbis bitstream header.</li>
|
||
|
|
<li>OV_EFAULT - Internal logic fault; indicates a bug or heap/stack corruption.</li>
|
||
|
|
</ul>
|
||
|
|
</blockquote>
|
||
|
|
<p>
|
||
|
|
|
||
|
|
<h3>Notes</h3>
|
||
|
|
<p>If your decoder is threaded, it is recommended that you NOT call
|
||
|
|
<tt>ov_open()</tt>
|
||
|
|
in the main control thread--instead, call <tt>ov_open()</tt> IN your decode/playback
|
||
|
|
thread. This is important because <tt>ov_open()</tt> may be a fairly time-consuming
|
||
|
|
call, given that the full structure of the file is determined at this point,
|
||
|
|
which may require reading large parts of the file under certain circumstances
|
||
|
|
(determining all the logical bitstreams in one physical bitstream, for
|
||
|
|
example). See <a href="threads.html">Thread Safety</a> for other information on using libvorbisidec with threads.
|
||
|
|
|
||
|
|
|
||
|
|
<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>
|