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+<html>
+
+<head>
+<title>Vorbisfile - function - ov_open_callbacks</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>Vorbisfile documentation</p></td>
+<td align=right><p class=tiny>vorbisfile version 1.3.2 - 20101101</p></td>
+</tr>
+</table>
+
+<h1>ov_open_callbacks</h1>
+
+<p><i>declared in "vorbis/vorbisfile.h";</i></p>
+
+<p>This is an alternative function used to open and initialize an
+OggVorbis_File structure when using a data source other than a file,
+when its necessary to modify default file access behavior, or to
+initialize a Vorbis decode from a <tt>FILE *</tt> pointer under
+Windows where <a href="ov_open.html">ov_open()</a> cannot be used. It
+allows the application to specify custom file manipulation routines
+and sets up all the related decoding structures.
+
+<p>Once ov_open_callbacks() has been called, the same
+<tt>OggVorbis_File</tt> struct should be passed to all the
+libvorbisfile functions. Unlike <a
+href="ov_fopen.html">ov_fopen()</a> and <a
+href="ov_open.html">ov_open()</a>, ov_open_callbacks() may be used to
+instruct vorbisfile to either automatically close or not to close the
+file/data access handle in <a href="ov_clear.html">ov_clear()</a>.
+Automatic closure is disabled by passing NULL as the close callback,
+or using one of the predefined callback sets that specify a NULL close
+callback. The application is responsible for closing a file when a
+call to ov_open_callbacks() is unsuccessful.<p>
+
+See also <a href="callbacks.html">Callbacks and Non-stdio I/O</a> for
+information on designing and specifying custom callback functions.<p>
+
+<br><br>
+<table border=0 color=black cellspacing=0 cellpadding=7>
+<tr bgcolor=#cccccc>
+ <td>
+<pre><b>
+int ov_open_callbacks(void *datasource, <a href="OggVorbis_File.html">OggVorbis_File</a> *vf, char *initial, long ibytes, <a href="ov_callbacks.html">ov_callbacks</a> callbacks);
+</b></pre>
+ </td>
+</tr>
+</table>
+
+<h3>Parameters</h3>
+<dl>
+<dt><i>datasource</i></dt>
+<dd>Pointer to a data structure allocated by the calling application, containing any state needed by the callbacks provided.</dd>
+<dt><i>vf</i></dt>
+<dd>A pointer to the OggVorbis_File structure--this is used for ALL the externally visible libvorbisfile
+functions. Once this has been called, the same <tt>OggVorbis_File</tt>
+struct should be passed to all the libvorbisfile 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 stream 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 stream 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>
+<dt><i>callbacks</i></dt>
+<dd>A completed <a href="ov_callbacks.html">ov_callbacks</a> struct which indicates desired custom file manipulation routines. vorbisfile.h defines several preprovided callback sets; see <a href="ov_callbacks.html">ov_callbacks</a> for details.</dd>
+</dl>
+
+
+<h3>Return Values</h3>
+<blockquote>
+<li>0 for 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 does not contain any 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>
+<dl>
+
+<dt><b>[a] Windows and use as an ov_open() substitute</b><p> Windows
+applications should not use <a href="ov_open.html">ov_open()</a> due
+to the likelihood of <a href="ov_open.html#winfoot">CRT linking
+mismatches and runtime protection faults
+[ov_open:a]</a>. ov_open_callbacks() is a safe substitute; specifically:
+
+<pre><tt>ov_open_callbacks(f, vf, initial, ibytes, OV_CALLBACKS_DEFAULT);</tt>
+</pre>
+
+... provides exactly the same functionality as <a
+href="ov_open.html">ov_open()</a> but will always work correctly under
+Windows, regardless of linking setup details.<p>
+
+<dt><b>[b] Threaded decode</b><p>
+<dd>If your decoder is threaded, it is recommended that you NOT call
+<tt>ov_open_callbacks()</tt>
+in the main control thread--instead, call <tt>ov_open_callbacks()</tt> in your decode/playback
+thread. This is important because <tt>ov_open_callbacks()</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 libvorbisfile with threads.
+<p>
+
+<dt><b>[c] Mixed media streams</b><p>
+<dd>
+As of Vorbisfile release 1.2.0, Vorbisfile is able to access the
+Vorbis content in mixed-media Ogg streams, not just Vorbis-only
+streams. For example, Vorbisfile may be used to open and access the
+audio from an Ogg stream consisting of Theora video and Vorbis audio.
+Vorbisfile 1.2.0 decodes the first logical audio stream of each
+physical stream section.<p>
+
+<dt><b>[d] Faster testing for Vorbis files</b><p>
+<dd><a href="ov_test.html">ov_test()</a> and <a
+href="ov_test_callbacks.html">ov_test_callbacks()</a> provide less
+computationally expensive ways to test a file for Vorbisness, but
+require more setup code.<p>
+
+</dl>
+
+<br><br>
+<hr noshade>
+<table border=0 width=100%>
+<tr valign=top>
+<td><p class=tiny>copyright &copy; 2000-2010 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>Vorbisfile documentation</p></td>
+<td align=right><p class=tiny>vorbisfile version 1.3.2 - 20101101</p></td>
+</tr>
+</table>
+
+</body>
+
+</html>