ov_read_filter.html
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<title>Vorbisfile - function - ov_read_filter</title>
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<td><p class=tiny>Vorbisfile documentation</p></td>
<td align=right><p class=tiny>vorbisfile version 1.3.2 - 20101101</p></td>
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<h1>ov_read_filter()</h1>
<p><i>declared in "vorbis/vorbisfile.h";</i></p>
<p>
<tt>ov_read_filter()</tt> is a variant of <a
href="ov_read.html">ov_read()</a>, the main function used to decode
a Vorbis file within a loop. It passes the decoded floating point
PCM data to the filter specified in the function arguments before
converting the data to integer output samples. All other aspects of
its behavior are as with <a href="ov_read.html">ov_read()</a>.
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<pre><b>
long ov_read_filter(<a href="OggVorbis_File.html">OggVorbis_File</a> *vf, char *buffer, int length, int bigendianp, int word, int sgned, int *bitstream,
void (*filter)(float **pcm,long channels,long samples,void *filter_param),void *filter_param);
</b></pre>
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<h3>Parameters</h3>
<dl>
<dt><i>vf</i></dt>
<dd>A pointer to the OggVorbis_File structure--this is used for ALL the externally visible libvorbisfile
functions.</dd>
<dt><i>buffer</i></dt>
<dd>A pointer to an output buffer. The decoded output is inserted into this buffer.</dd>
<dt><i>length</i></dt>
<dd>Number of bytes to be read into the buffer. Should be the same size as the buffer. A typical value is 4096.</dd>
<dt><i>bigendianp</i></dt>
<dd>Specifies big or little endian byte packing. 0 for little endian, 1 for b
ig endian. Typical value is 0.</dd>
<dt><i>word</i></dt>
<dd>Specifies word size. Possible arguments are 1 for 8-bit samples, or 2 or
16-bit samples. Typical value is 2.</dd>
<dt><i>sgned</i></dt>
<dd>Signed or unsigned data. 0 for unsigned, 1 for signed. Typically 1.</dd>
<dt><i>bitstream</i></dt>
<dd>A pointer to the number of the current logical bitstream.</dd>
<dt><i>filter</i></dt>
<dd>Filter function to process float PCM data prior to conversion to interleaved integer output.</dd>
<dt><i>filter_param</i></dt>
<dd>Data to pass through to the filter function.</dd>
</dl>
<h3>Return Values</h3>
<blockquote>
<dl>
<dt>OV_HOLE</dt>
<dd>indicates there was an interruption in the data.
<br>(one of: garbage between pages, loss of sync followed by
recapture, or a corrupt page)</dd>
<dt>OV_EBADLINK</dt>
<dd>indicates that an invalid stream section was supplied to
libvorbisfile, or the requested link is corrupt.</dd>
<dt>0</dt>
<dd>indicates EOF</dd>
<dt><i>n</i></dt>
<dd>indicates actual number of bytes read. <tt>ov_read()</tt> will
decode at most one vorbis packet per invocation, so the value
returned will generally be less than <tt>length</tt>.
</dl>
</blockquote>
<h3>Notes</h3>
<p><b>Typical usage:</b>
<blockquote>
<tt>bytes_read = ov_read_filter(&vf,
buffer, 4096,0,2,1,&current_section, filter, (void *)filter_data_ptr)</tt>
</blockquote>
This reads up to 4096 bytes into a buffer, with signed 16-bit
little-endian samples. The decoded data is passed to the function <tt>filter</tt> before integer conversiona nd interleave.
</p>
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<td><p class=tiny>copyright © 2000-2010 Xiph.Org</p></td>
<td align=right><p class=tiny><a href="http://www.xiph.org/ogg/vorbis/">Ogg Vorbis</a></p></td>
</tr><tr>
<td><p class=tiny>Vorbisfile documentation</p></td>
<td align=right><p class=tiny>vorbisfile version 1.3.2 - 20101101</p></td>
</tr>
</table>
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</html>