125 lines
4.3 KiB
HTML
125 lines
4.3 KiB
HTML
<html>
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<head>
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<title>Vorbisfile - function - ov_fopen</title>
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<link rel=stylesheet href="style.css" type="text/css">
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</head>
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<body bgcolor=white text=black link="#5555ff" alink="#5555ff" vlink="#5555ff">
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<table border=0 width=100%>
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<tr>
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<td><p class=tiny>Vorbisfile documentation</p></td>
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<td align=right><p class=tiny>vorbisfile version 1.3.2 - 20101101</p></td>
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</tr>
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</table>
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<h1>ov_fopen</h1>
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<p><i>declared in "vorbis/vorbisfile.h";</i></p>
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<p>This is the simplest function used to open and initialize an OggVorbis_File
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structure. It sets up all the related decoding structure.
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<p>The first argument is a file path suitable
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for passing to fopen(). <tt>vf</tt> should be a pointer to an empty
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OggVorbis_File structure -- this is used for ALL the externally visible
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libvorbisfile functions. Once this has been called, the same <a
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href="OggVorbis_File.html">OggVorbis_File</a> struct should be passed
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to all the libvorbisfile functions.
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<p>The <tt>vf</tt> structure initialized using ov_fopen() must
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eventually be cleaned using <a href="ov_clear.html">ov_clear()</a>.
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<p>
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It is often useful to call <tt>ov_fopen()</tt> simply to determine
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whether a given file is a Vorbis bitstream. If the <tt>ov_fopen()</tt>
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call fails, then the file is either inaccessable (errno is set) or not
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recognizable as Vorbis (errno unchanged). If the call succeeds but
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the initialized <tt>vf</tt> structure will not be used, the
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application is responsible for calling <a
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href="ov_clear.html">ov_clear()</a> to clear the decoder's buffers and
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close the file.<p>
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<br><br>
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<table border=0 color=black cellspacing=0 cellpadding=7>
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<tr bgcolor=#cccccc>
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<td>
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<pre><b>
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int ov_fopen(const char *path,<a href="OggVorbis_File.html">OggVorbis_File</a> *vf);
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</b></pre>
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</td>
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</tr>
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</table>
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<h3>Parameters</h3>
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<dl>
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<dt><i>path</i></dt>
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<dd>Null terminated string containing a file path suitable for passing to <tt>fopen()</tt>.
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</dd>
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<dt><i>vf</i></dt>
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<dd>A pointer to the OggVorbis_File structure--this is used for ALL the externally visible libvorbisfile
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functions. Once this has been called, the same <tt>OggVorbis_File</tt>
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struct should be passed to all the libvorbisfile functions.</dd>
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</dl>
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<h3>Return Values</h3>
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<blockquote>
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<li>0 indicates success</li>
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<li>less than zero for failure:</li>
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<ul>
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<li>OV_EREAD - A read from media returned an error.</li>
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<li>OV_ENOTVORBIS - Bitstream does not contain any Vorbis data.</li>
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<li>OV_EVERSION - Vorbis version mismatch.</li>
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<li>OV_EBADHEADER - Invalid Vorbis bitstream header.</li>
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<li>OV_EFAULT - Internal logic fault; indicates a bug or heap/stack corruption.</li>
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</ul>
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</blockquote>
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<p>
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<h3>Notes</h3>
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<dl>
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<dt><b>[a] Threaded decode</b><p>
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<dd>If your decoder is threaded, it is recommended that you NOT call
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<tt>ov_open_callbacks()</tt>
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in the main control thread--instead, call <tt>ov_open_callbacks()</tt> in your decode/playback
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thread. This is important because <tt>ov_open_callbacks()</tt> may be a fairly time-consuming
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call, given that the full structure of the file is determined at this point,
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which may require reading large parts of the file under certain circumstances
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(determining all the logical bitstreams in one physical bitstream, for
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example). See <a href="threads.html">Thread Safety</a> for other information on using libvorbisfile with threads.
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<p>
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<dt><b>[b] Mixed media streams</b><p>
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<dd>
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As of Vorbisfile release 1.2.0, Vorbisfile is able to access the
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Vorbis content in mixed-media Ogg streams, not just Vorbis-only
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streams. For example, Vorbisfile may be used to open and access the
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audio from an Ogg stream consisting of Theora video and Vorbis audio.
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Vorbisfile 1.2.0 decodes the first logical audio stream of each
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physical stream section.<p>
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<dt><b>[c] Faster testing for Vorbis files</b><p>
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<dd><a href="ov_test.html">ov_test()</a> and <a
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href="ov_test_callbacks.html">ov_test_callbacks()</a> provide less
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computationally expensive ways to test a file for Vorbisness, but
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require more setup code.<p>
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</dl>
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<br><br>
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<hr noshade>
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<table border=0 width=100%>
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<tr valign=top>
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<td><p class=tiny>copyright © 2000-2010 Xiph.Org</p></td>
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<td align=right><p class=tiny><a href="http://www.xiph.org/ogg/vorbis/">Ogg Vorbis</a></p></td>
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</tr><tr>
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<td><p class=tiny>Vorbisfile documentation</p></td>
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<td align=right><p class=tiny>vorbisfile version 1.3.2 - 20101101</p></td>
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</tr>
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</table>
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</body>
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</html>
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