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1 <html>
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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 1.3.2 - 20101101</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 © 2000-2010 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 1.3.2 - 20101101</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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