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<title>Vorbisfile - function - ov_test</title>
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<td><p class=tiny>Vorbisfile documentation</p></td>
<td align=right><p class=tiny>vorbisfile version 1.3.2 - 20101101</p></td>
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<h1>ov_test</h1>

<p><i>declared in "vorbis/vorbisfile.h";</i></p>

<p>
This partially opens a vorbis file to test for Vorbis-ness.  It loads
the headers for the first chain and tests for seekability (but does not seek).
Use <a href="ov_test_open.html">ov_test_open()</a> to finish opening the file
or <a href="ov_clear.html">ov_clear</a> to close/free it.
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<p><em><b> WARNING for Windows developers: </b> Do not use ov_test()
in Windows applications; Windows linking places restrictions on
passing <tt>FILE *</tt> handles successfully, and ov_test() runs afoul
of these restrictions <a href="#winfoot">[a]</a> in exactly the same
way as <a href="ov_open.html">ov_open()</a>.  See the <a
href="ov_test_callbacks.html">ov_test_callbacks() page </a> for
details on using <a
href="ov_test_callbacks.html">ov_test_callbacks()</a> instead. </em>
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<pre><b>
int ov_test(FILE *f,<a href="OggVorbis_File.html">OggVorbis_File</a> *vf,char *initial,long ibytes);
</b></pre>
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<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 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 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 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 contains no 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>
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<h3>Notes</h3>

All the <a href="ov_open.html#notes">notes from ov_open()</a> apply to ov_test().

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<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>
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author	Chris Cannam
date	Fri, 07 Feb 2020 11:51:13 +0000
parents	05aa0afa9217
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