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4<title>Vorbisfile - function - ov_pcm_seek_page_lap</title>
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11<td><p class=tiny>Vorbisfile documentation</p></td>
12<td align=right><p class=tiny>vorbisfile version 1.2.0 - 20070723</p></td>
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16<h1>ov_pcm_seek_page_lap</h1>
17
18<p><i>declared in "vorbis/vorbisfile.h";</i></p>
19
20<p>Seeks to the closest page preceding the specified location (in pcm
21samples) within the physical bitstream.  This variant of <a
22href="ov_pcm_seek_page.html">ov_pcm_seek_page</a> also automatically
23crosslaps the transition from the previous playback position into the
24new playback position in order to eliminate clicking and boundary
25discontinuities.  Otherwise, usage and behavior is identical to <a
26href="ov_pcm_seek_page.html">ov_pcm_seek_page</a>.
27
28<p>This function is faster than <a
29href="ov_pcm_seek_lap.html">ov_pcm_seek_lap</a> because the function
30can begin decoding at a page boundary rather than seeking through any
31remaining samples before the specified location.  However, it is less
32accurate.
33
34<p>ov_pcm_seek_page_lap also updates everything needed within the
35decoder, so you can immediately call <a
36href="ov_read.html">ov_read()</a> and get data from the newly seeked
37to position.
38
39<p>ov_pcm_seek_page_lap will lap between logical stream links of
40differing numbers of channels. Any extra channels from the origin of
41the seek are ignored; playback of these channels simply ends. Extra
42channels at the destination are lapped from silence.
43ov_pcm_seek_page_lap will also lap between logical stream links of
44differing sample rates.  In this case, the sample rates are ignored
45(no implicit resampling is done to match playback). It is up to the
46application developer to decide if this behavior makes any sense in a
47given context; in practical use, these default behaviors perform
48sensibly.
49
50<p>This function only works for seekable streams.
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56<pre><b>
57int ov_pcm_seek_page_lap(OggVorbis_File *vf,ogg_int64_t pos);
58</b></pre>
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63<h3>Parameters</h3>
64<dl>
65<dt><i>vf</i></dt>
66<dd>A pointer to the OggVorbis_File structure--this is used for ALL the externally visible libvorbisfile
67functions.</dd>
68<dt><i>pos</i></dt>
69<dd>Position in pcm samples to seek to in the bitstream.</dd>
70</dl>
71
72
73<h3>Return Values</h3>
74<blockquote>
75<ul>
76<li>0 for success</li>
77
78<li>
79nonzero indicates failure, described by several error codes:
80  <ul>
81  <li>OV_ENOSEEK - Bitstream is not seekable.
82  </li>
83  <li>OV_EINVAL - Invalid argument value; possibly called with an OggVorbis_File structure that isn't open.
84  </li>
85  <li>OV_EREAD - A read from media returned an error.
86  </li>
87  <li>OV_EFAULT - Internal logic fault; indicates a bug or heap/stack 
88		corruption.
89  </li>
90  <li>OV_EOF - Indicates stream is at end of file immediately after a seek 
91  (making crosslap impossible as there's no preceeding decode state to crosslap).
92  </li>
93  <li>OV_EBADLINK - Invalid stream section supplied to libvorbisfile, or the requested link is corrupt. 
94  </li>
95  </ul></li>
96</ul></blockquote>
97
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102<td><p class=tiny>copyright &copy; 2007 Xiph.org</p></td>
103<td align=right><p class=tiny><a href="http://www.xiph.org/ogg/vorbis/">Ogg Vorbis</a></p></td>
104</tr><tr>
105<td><p class=tiny>Vorbisfile documentation</p></td>
106<td align=right><p class=tiny>vorbisfile version 1.2.0 - 20070723</p></td>
107</tr>
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