| [16] | 1 | <html> |
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| 2 | |
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| 3 | <head> |
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| 4 | <title>Vorbisfile - function - ov_fopen</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_fopen</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 the simplest function used to open and initialize an OggVorbis_File |
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| 21 | structure. It sets up all the related decoding structure. |
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| 22 | <p>The first argument is a file path suitable |
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| 23 | for passing to fopen(). <tt>vf</tt> should be a pointer to an empty |
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| 24 | OggVorbis_File structure -- this is used for ALL the externally visible |
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| 25 | libvorbisfile functions. Once this has been called, the same <a |
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| 26 | href="OggVorbis_File.html">OggVorbis_File</a> struct should be passed |
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| 27 | to all the libvorbisfile functions. |
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| 28 | <p>The <tt>vf</tt> structure initialized using ov_fopen() must |
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| 29 | eventually be cleaned using <a href="ov_clear.html">ov_clear()</a>. |
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| 30 | |
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| 31 | <p> |
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| 32 | It is often useful to call <tt>ov_fopen()</tt> simply to determine |
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| 33 | whether a given file is a Vorbis bitstream. If the <tt>ov_fopen()</tt> |
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| 34 | call fails, then the file is either inaccessable (errno is set) or not |
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| 35 | recognizable as Vorbis (errno unchanged). If the call succeeds but |
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| 36 | the initialized <tt>vf</tt> structure will not be used, the |
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| 37 | application is responsible for calling <a |
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| 38 | href="ov_clear.html">ov_clear()</a> to clear the decoder's buffers and |
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| 39 | close the file.<p> |
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| 40 | |
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| 41 | <br><br> |
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| 42 | <table border=0 color=black cellspacing=0 cellpadding=7> |
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| 43 | <tr bgcolor=#cccccc> |
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| 44 | <td> |
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| 45 | <pre><b> |
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| 46 | int ov_fopen(char *path,<a href="OggVorbis_File.html">OggVorbis_File</a> *vf); |
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| 47 | </b></pre> |
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| 48 | </td> |
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| 49 | </tr> |
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| 50 | </table> |
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| 51 | |
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| 52 | <h3>Parameters</h3> |
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| 53 | <dl> |
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| 54 | <dt><i>path</i></dt> |
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| 55 | <dd>Null terminated string containing a file path suitable for passing to <tt>fopen()</tt>. |
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| 56 | </dd> |
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| 57 | <dt><i>vf</i></dt> |
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| 58 | <dd>A pointer to the OggVorbis_File structure--this is used for ALL the externally visible libvorbisfile |
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| 59 | functions. Once this has been called, the same <tt>OggVorbis_File</tt> |
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| 60 | struct should be passed to all the libvorbisfile functions.</dd> |
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| 61 | </dl> |
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| 62 | |
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| 63 | |
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| 64 | <h3>Return Values</h3> |
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| 65 | <blockquote> |
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| 66 | <li>0 indicates success</li> |
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| 67 | |
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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 does not contain any 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] Threaded decode</b><p> |
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| 83 | <dd>If your decoder is threaded, it is recommended that you NOT call |
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| 84 | <tt>ov_open_callbacks()</tt> |
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| 85 | in the main control thread--instead, call <tt>ov_open_callbacks()</tt> in your decode/playback |
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| 86 | thread. This is important because <tt>ov_open_callbacks()</tt> may be a fairly time-consuming |
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| 87 | call, given that the full structure of the file is determined at this point, |
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| 88 | which may require reading large parts of the file under certain circumstances |
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| 89 | (determining all the logical bitstreams in one physical bitstream, for |
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| 90 | example). See <a href="threads.html">Thread Safety</a> for other information on using libvorbisfile with threads. |
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| 91 | <p> |
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| 92 | |
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| 93 | <dt><b>[b] Mixed media streams</b><p> |
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| 94 | <dd> |
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| 95 | As of Vorbisfile release 1.2.0, Vorbisfile is able to access the |
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| 96 | Vorbis content in mixed-media Ogg streams, not just Vorbis-only |
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| 97 | streams. For example, Vorbisfile may be used to open and access the |
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| 98 | audio from an Ogg stream consisting of Theora video and Vorbis audio. |
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| 99 | Vorbisfile 1.2.0 decodes the first logical audio stream of each |
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| 100 | physical stream section.<p> |
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| 101 | |
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| 102 | <dt><b>[c] Faster testing for Vorbis files</b><p> |
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| 103 | <dd><a href="ov_test.html">ov_test()</a> and <a |
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| 104 | href="ov_test_callbacks.html">ov_test_callbacks()</a> provide less |
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| 105 | computationally expensive ways to test a file for Vorbisness, but |
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| 106 | require more setup code.<p> |
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| 107 | |
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| 108 | </dl> |
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| 109 | |
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| 110 | <br><br> |
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| 111 | <hr noshade> |
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| 112 | <table border=0 width=100%> |
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| 113 | <tr valign=top> |
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| 114 | <td><p class=tiny>copyright © 2007 Xiph.org</p></td> |
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| 115 | <td align=right><p class=tiny><a href="http://www.xiph.org/ogg/vorbis/">Ogg Vorbis</a></p></td> |
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| 116 | </tr><tr> |
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| 117 | <td><p class=tiny>Vorbisfile documentation</p></td> |
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| 118 | <td align=right><p class=tiny>vorbisfile version 1.2.0 - 20070723</p></td> |
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| 119 | </tr> |
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| 120 | </table> |
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| 121 | |
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| 122 | </body> |
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| 123 | |
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| 124 | </html> |
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