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| <title>Vorbisfile - function - ov_test_callbacks</title> |
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| <td><p class=tiny>Vorbisfile documentation</p></td> |
| <td align=right><p class=tiny>vorbisfile version 1.2.0 - 20070723</p></td> |
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| </table> |
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| <h1>ov_test_callbacks</h1> |
| |
| <p><i>declared in "vorbis/vorbisfile.h";</i></p> |
| |
| <p>This is an alternative function used to open and test an OggVorbis_File |
| structure when using a data source other than a file, |
| when its necessary to modify default file access behavior, or to |
| test for Vorbis content from a <tt>FILE *</tt> pointer under |
| Windows where <a href="ov_open.html">ov_test()</a> cannot be used. It |
| allows the application to specify custom file manipulation routines |
| and sets up all the related decoding structures. |
| |
| <p>Once this has been called, the same <tt>OggVorbis_File</tt> |
| struct should be passed to all the libvorbisfile functions. |
| <p> |
| <br><br> |
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| <pre><b> |
| int ov_test_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> |
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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> |
| <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 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> |
| <p> |
| |
| <h3>Notes</h3> |
| <dl> |
| |
| <dt><b>[a] Windows and use as an ov_test() substitute</b><p> Windows |
| applications should not use <a href="ov_test.html">ov_test()</a> due |
| to the likelihood of <a href="ov_open.html#winfoot">CRT linking |
| mismatches and runtime protection faults |
| [ov_open:a]</a>. ov_test_callbacks() is a safe substitute; specifically: |
| |
| <pre><tt>ov_test_callbacks(f, vf, initial, ibytes, OV_CALLBACKS_DEFAULT);</tt> |
| </pre> |
| |
| ... provides exactly the same functionality as <a |
| href="ov_test.html">ov_test()</a> but will always work correctly under |
| Windows, regardless of linking setup details.<p> |
| |
| </dl> |
| |
| <br><br> |
| <hr noshade> |
| <table border=0 width=100%> |
| <tr valign=top> |
| <td><p class=tiny>copyright © 2007 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 1.2.0 - 20070723</p></td> |
| </tr> |
| </table> |
| |
| </body> |
| |
| </html> |
