1 <html> 2 3 <head> 4 <title>Vorbisfile - function - ov_fopen</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_fopen</h1> 17 18 <p><i>declared in "vorbis/vorbisfile.h";</i></p> 19 20 <p>This is the simplest function used to open and initialize an OggVorbis_File 21 structure. It sets up all the related decoding structure. 22 <p>The first argument is a file path suitable 23 for passing to fopen(). <tt>vf</tt> should be a pointer to an empty 24 OggVorbis_File structure -- this is used for ALL the externally visible 25 libvorbisfile functions. Once this has been called, the same <a 26 href="OggVorbis_File.html">OggVorbis_File</a> struct should be passed 27 to all the libvorbisfile functions. 28 <p>The <tt>vf</tt> structure initialized using ov_fopen() must 29 eventually be cleaned using <a href="ov_clear.html">ov_clear()</a>. 30 31 <p> 32 It is often useful to call <tt>ov_fopen()</tt> simply to determine 33 whether a given file is a Vorbis bitstream. If the <tt>ov_fopen()</tt> 34 call fails, then the file is either inaccessable (errno is set) or not 35 recognizable as Vorbis (errno unchanged). If the call succeeds but 36 the initialized <tt>vf</tt> structure will not be used, the 37 application is responsible for calling <a 38 href="ov_clear.html">ov_clear()</a> to clear the decoder's buffers and 39 close the file.<p> 40 41 <br><br> 42 <table border=0 color=black cellspacing=0 cellpadding=7> 43 <tr bgcolor=#cccccc> 44 <td> 45 <pre><b> 46 int ov_fopen(char *path,<a href="OggVorbis_File.html">OggVorbis_File</a> *vf); 47 </b></pre> 48 </td> 49 </tr> 50 </table> 51 52 <h3>Parameters</h3> 53 <dl> 54 <dt><i>path</i></dt> 55 <dd>Null terminated string containing a file path suitable for passing to <tt>fopen()</tt>. 56 </dd> 57 <dt><i>vf</i></dt> 58 <dd>A pointer to the OggVorbis_File structure--this is used for ALL the externally visible libvorbisfile 59 functions. Once this has been called, the same <tt>OggVorbis_File</tt> 60 struct should be passed to all the libvorbisfile functions.</dd> 61 </dl> 62 63 64 <h3>Return Values</h3> 65 <blockquote> 66 <li>0 indicates success</li> 67 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 does not contain any 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] Threaded decode</b><p> 83 <dd>If your decoder is threaded, it is recommended that you NOT call 84 <tt>ov_open_callbacks()</tt> 85 in the main control thread--instead, call <tt>ov_open_callbacks()</tt> in your decode/playback 86 thread. This is important because <tt>ov_open_callbacks()</tt> may be a fairly time-consuming 87 call, given that the full structure of the file is determined at this point, 88 which may require reading large parts of the file under certain circumstances 89 (determining all the logical bitstreams in one physical bitstream, for 90 example). See <a href="threads.html">Thread Safety</a> for other information on using libvorbisfile with threads. 91 <p> 92 93 <dt><b>[b] Mixed media streams</b><p> 94 <dd> 95 As of Vorbisfile release 1.2.0, Vorbisfile is able to access the 96 Vorbis content in mixed-media Ogg streams, not just Vorbis-only 97 streams. For example, Vorbisfile may be used to open and access the 98 audio from an Ogg stream consisting of Theora video and Vorbis audio. 99 Vorbisfile 1.2.0 decodes the first logical audio stream of each 100 physical stream section.<p> 101 102 <dt><b>[c] Faster testing for Vorbis files</b><p> 103 <dd><a href="ov_test.html">ov_test()</a> and <a 104 href="ov_test_callbacks.html">ov_test_callbacks()</a> provide less 105 computationally expensive ways to test a file for Vorbisness, but 106 require more setup code.<p> 107 108 </dl> 109 110 <br><br> 111 <hr noshade> 112 <table border=0 width=100%> 113 <tr valign=top> 114 <td><p class=tiny>copyright © 2007 Xiph.org</p></td> 115 <td align=right><p class=tiny><a href="http://www.xiph.org/ogg/vorbis/">Ogg Vorbis</a></p></td> 116 </tr><tr> 117 <td><p class=tiny>Vorbisfile documentation</p></td> 118 <td align=right><p class=tiny>vorbisfile version 1.2.0 - 20070723</p></td> 119 </tr> 120 </table> 121 122 </body> 123 124 </html> 125
