| 1 | <html> |
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| 3 | <head> |
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| 4 | <title>Vorbisfile - function - ov_test_callbacks</title> |
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| 5 | <link rel=stylesheet href="style.css" type="text/css"> |
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| 6 | </head> |
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| 7 | |
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| 8 | <body bgcolor=white text=black link="#5555ff" alink="#5555ff" vlink="#5555ff"> |
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| 9 | <table border=0 width=100%> |
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| 10 | <tr> |
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| 11 | <td><p class=tiny>Vorbisfile documentation</p></td> |
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| 12 | <td align=right><p class=tiny>vorbisfile version 1.2.0 - 20070723</p></td> |
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| 13 | </tr> |
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| 14 | </table> |
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| 15 | |
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| 16 | <h1>ov_test_callbacks</h1> |
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| 17 | |
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| 18 | <p><i>declared in "vorbis/vorbisfile.h";</i></p> |
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| 19 | |
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| 20 | <p>This is an alternative function used to open and test an OggVorbis_File |
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| 21 | structure when using a data source other than a file, |
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| 22 | when its necessary to modify default file access behavior, or to |
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| 23 | test for Vorbis content from a <tt>FILE *</tt> pointer under |
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| 24 | Windows where <a href="ov_open.html">ov_test()</a> cannot be used. It |
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| 25 | allows the application to specify custom file manipulation routines |
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| 26 | and sets up all the related decoding structures. |
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| 27 | |
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| 28 | <p>Once this has been called, the same <tt>OggVorbis_File</tt> |
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| 29 | struct should be passed to all the libvorbisfile functions. |
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| 30 | <p> |
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| 31 | <br><br> |
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| 32 | <table border=0 color=black cellspacing=0 cellpadding=7> |
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| 33 | <tr bgcolor=#cccccc> |
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| 34 | <td> |
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| 35 | <pre><b> |
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| 36 | 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); |
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| 37 | </b></pre> |
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| 38 | </td> |
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| 39 | </tr> |
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| 40 | </table> |
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| 41 | |
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| 42 | <h3>Parameters</h3> |
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| 43 | <dl> |
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| 44 | <dt><i>f</i></dt> |
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| 45 | <dd>File pointer to an already opened file |
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| 46 | or pipe (it need not be seekable--though this obviously restricts what |
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| 47 | can be done with the bitstream).</dd> |
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| 48 | <dt><i>vf</i></dt> |
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| 49 | <dd>A pointer to the OggVorbis_File structure--this is used for ALL the externally visible libvorbisfile |
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| 50 | functions. Once this has been called, the same <tt>OggVorbis_File</tt> |
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| 51 | struct should be passed to all the libvorbisfile functions.</dd> |
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| 52 | <dt><i>initial</i></dt> |
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| 53 | <dd>Typically set to NULL. This parameter is useful if some data has already been |
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| 54 | 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> |
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| 55 | should be a pointer to a buffer containing the data read.</dd> |
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| 56 | <dt><i>ibytes</i></dt> |
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| 57 | <dd>Typically set to 0. This parameter is useful if some data has already been |
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| 58 | read from the file and the stream is not seekable. In this case, <tt>ibytes</tt> |
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| 59 | should contain the length (in bytes) of the buffer. Used together with <tt>initial</tt>.</dd> |
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| 60 | <dt><i>callbacks</i></dt> |
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| 61 | <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> |
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| 62 | </dl> |
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| 63 | |
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| 64 | |
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| 65 | <h3>Return Values</h3> |
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| 66 | <blockquote> |
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| 67 | <li>0 for success</li> |
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| 68 | <li>less than zero for failure:</li> |
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| 69 | <ul> |
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| 70 | <li>OV_EREAD - A read from media returned an error.</li> |
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| 71 | <li>OV_ENOTVORBIS - Bitstream contains no Vorbis data.</li> |
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| 72 | <li>OV_EVERSION - Vorbis version mismatch.</li> |
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| 73 | <li>OV_EBADHEADER - Invalid Vorbis bitstream header.</li> |
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| 74 | <li>OV_EFAULT - Internal logic fault; indicates a bug or heap/stack corruption.</li> |
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| 75 | </ul> |
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| 76 | </blockquote> |
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| 77 | <p> |
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| 78 | |
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| 79 | <h3>Notes</h3> |
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| 80 | <dl> |
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| 81 | |
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| 82 | <dt><b>[a] Windows and use as an ov_test() substitute</b><p> Windows |
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| 83 | applications should not use <a href="ov_test.html">ov_test()</a> due |
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| 84 | to the likelihood of <a href="ov_open.html#winfoot">CRT linking |
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| 85 | mismatches and runtime protection faults |
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| 86 | [ov_open:a]</a>. ov_test_callbacks() is a safe substitute; specifically: |
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| 87 | |
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| 88 | <pre><tt>ov_test_callbacks(f, vf, initial, ibytes, OV_CALLBACKS_DEFAULT);</tt> |
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| 89 | </pre> |
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| 90 | |
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| 91 | ... provides exactly the same functionality as <a |
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| 92 | href="ov_test.html">ov_test()</a> but will always work correctly under |
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| 93 | Windows, regardless of linking setup details.<p> |
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| 94 | |
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| 95 | </dl> |
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| 96 | |
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| 97 | <br><br> |
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| 98 | <hr noshade> |
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| 99 | <table border=0 width=100%> |
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| 100 | <tr valign=top> |
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| 101 | <td><p class=tiny>copyright © 2007 Xiph.org</p></td> |
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| 102 | <td align=right><p class=tiny><a href="http://www.xiph.org/ogg/vorbis/">Ogg Vorbis</a></p></td> |
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| 103 | </tr><tr> |
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| 104 | <td><p class=tiny>Vorbisfile documentation</p></td> |
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| 105 | <td align=right><p class=tiny>vorbisfile version 1.2.0 - 20070723</p></td> |
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| 106 | </tr> |
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| 107 | </table> |
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| 108 | |
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| 109 | </body> |
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| 110 | |
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| 111 | </html> |
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