1 <html> 2 3 <head> 4 <title>Vorbisfile - function - ov_test_callbacks</title> 5 <link rel=stylesheet href="style.css" type="text/css"> 6 </head> 7 8 <body bgcolor=white text=black link="#5555ff" alink="#5555ff" vlink="#5555ff"> 9 <table border=0 width=100%> 10 <tr> 11 <td><p class=tiny>Vorbisfile documentation</p></td> 12 <td align=right><p class=tiny>vorbisfile version 1.2.0 - 20070723</p></td> 13 </tr> 14 </table> 15 16 <h1>ov_test_callbacks</h1> 17 18 <p><i>declared in "vorbis/vorbisfile.h";</i></p> 19 20 <p>This is an alternative function used to open and test an OggVorbis_File 21 structure when using a data source other than a file, 22 when its necessary to modify default file access behavior, or to 23 test for Vorbis content from a <tt>FILE *</tt> pointer under 24 Windows where <a href="ov_open.html">ov_test()</a> cannot be used. It 25 allows the application to specify custom file manipulation routines 26 and sets up all the related decoding structures. 27 28 <p>Once this has been called, the same <tt>OggVorbis_File</tt> 29 struct should be passed to all the libvorbisfile functions. 30 <p> 31 <br><br> 32 <table border=0 color=black cellspacing=0 cellpadding=7> 33 <tr bgcolor=#cccccc> 34 <td> 35 <pre><b> 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); 37 </b></pre> 38 </td> 39 </tr> 40 </table> 41 42 <h3>Parameters</h3> 43 <dl> 44 <dt><i>f</i></dt> 45 <dd>File pointer to an already opened file 46 or pipe (it need not be seekable--though this obviously restricts what 47 can be done with the bitstream).</dd> 48 <dt><i>vf</i></dt> 49 <dd>A pointer to the OggVorbis_File structure--this is used for ALL the externally visible libvorbisfile 50 functions. Once this has been called, the same <tt>OggVorbis_File</tt> 51 struct should be passed to all the libvorbisfile functions.</dd> 52 <dt><i>initial</i></dt> 53 <dd>Typically set to NULL. This parameter is useful if some data has already been 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> 55 should be a pointer to a buffer containing the data read.</dd> 56 <dt><i>ibytes</i></dt> 57 <dd>Typically set to 0. This parameter is useful if some data has already been 58 read from the file and the stream is not seekable. In this case, <tt>ibytes</tt> 59 should contain the length (in bytes) of the buffer. Used together with <tt>initial</tt>.</dd> 60 <dt><i>callbacks</i></dt> 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> 62 </dl> 63 64 65 <h3>Return Values</h3> 66 <blockquote> 67 <li>0 for success</li> 68 <li>less than zero for failure:</li> 69 <ul> 70 <li>OV_EREAD - A read from media returned an error.</li> 71 <li>OV_ENOTVORBIS - Bitstream contains no Vorbis data.</li> 72 <li>OV_EVERSION - Vorbis version mismatch.</li> 73 <li>OV_EBADHEADER - Invalid Vorbis bitstream header.</li> 74 <li>OV_EFAULT - Internal logic fault; indicates a bug or heap/stack corruption.</li> 75 </ul> 76 </blockquote> 77 <p> 78 79 <h3>Notes</h3> 80 <dl> 81 82 <dt><b>[a] Windows and use as an ov_test() substitute</b><p> Windows 83 applications should not use <a href="ov_test.html">ov_test()</a> due 84 to the likelihood of <a href="ov_open.html#winfoot">CRT linking 85 mismatches and runtime protection faults 86 [ov_open:a]</a>. ov_test_callbacks() is a safe substitute; specifically: 87 88 <pre><tt>ov_test_callbacks(f, vf, initial, ibytes, OV_CALLBACKS_DEFAULT);</tt> 89 </pre> 90 91 ... provides exactly the same functionality as <a 92 href="ov_test.html">ov_test()</a> but will always work correctly under 93 Windows, regardless of linking setup details.<p> 94 95 </dl> 96 97 <br><br> 98 <hr noshade> 99 <table border=0 width=100%> 100 <tr valign=top> 101 <td><p class=tiny>copyright © 2007 Xiph.org</p></td> 102 <td align=right><p class=tiny><a href="http://www.xiph.org/ogg/vorbis/">Ogg Vorbis</a></p></td> 103 </tr><tr> 104 <td><p class=tiny>Vorbisfile documentation</p></td> 105 <td align=right><p class=tiny>vorbisfile version 1.2.0 - 20070723</p></td> 106 </tr> 107 </table> 108 109 </body> 110 111 </html> 112
