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<title>libvorbisenc - function - vorbis_encode_ctl</title>
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<td><p class=tiny>libvorbisenc documentation</p></td>
<td align=right><p class=tiny>libvorbisenc release 1.1 - 20040709</p></td>
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<h1>vorbis_encode_ctl</h1>

<p><i>declared in "vorbis/libvorbisenc.h";</i></p>

<p>This function implements a generic interface to miscellaneous
encoder settings similar to the clasasic UNIX 'ioctl()' system call.
Applications may use vorbis_encode_ctl() to query or set bitrate
management or quality mode details by using one of several
<i>request</i> arguments detailed below.  Vorbis_encode_ctl() must be
called after one of <a
href="vorbis_encode_setup_managed.html">vorbis_encode_setup_managed()</a>
or <a
href="vorbis_encode_setup_vbr.html">vorbis_encode_setup_vbr()</a>.
When used to modify settings, vorbis_encode_ctl() must be called
before <a
href="vorbis_encode_setup_init.html">vorbis_encode_setup_init()</a>.

<p>
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<pre><b>
extern int vorbis_encode_ctl(vorbis_info *vi,int request,void *arg);

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<h3>Parameters</h3>
<dl>
<dt><i>vi</i></dt>
<dd>File pointer to an initialized <a href="vorbis_info.html">vorbis_info</a> struct.</dd><p>
<dt><i>request</i></dt>
<dd>Specifies the desired action; possible request fields are detailed below.</dd><p>
<dt><i>arg</i></dt>
<dd>void * pointing to a data structure matching the request argument.</dd><p>
</dl><p>

<h3>Requests</h3>
<dl>

<dt><i>OV_ECTL_RATEMANAGE2_GET</i></dt>

<dd><b>Argument: <a href="ovectl_ratemanage2_arg.html">struct
ovectl_ratemanage2_arg *</a></b><br> Used to query the current
encoder bitrate management setting.  Also used to initialize fields of
an ovectl_ratemanage2_arg structure for use with
OV_ECTL_RATEMANAGE2_SET.</dd><p>

<dt><i>OV_ECTL_RATEMANAGE2_SET</i></dt>
<dd><b>Argument: <a href="ovectl_ratemanage2_arg.html">struct
ovectl_ratemanage2_arg *</a></b><br> Used to set the current
encoder bitrate management settings to the values listed in the
ovectl_ratemanage2_arg.  Passing a NULL pointer will disable bitrate
management.
</dd><p>

<dt><i>OV_ECTL_LOWPASS_GET</i></dt>
<dd><b>Argument: double *</b><br> Returns the current encoder hard-lowpass
setting (kHz) in the double pointed to by arg.
</dd><p>

<dt><i>OV_ECTL_LOWPASS_SET</i></dt>
<dd><b>Argument: double *</b><br> Sets the encoder hard-lowpass to the value
(kHz) pointed to by arg. Valid lowpass settings range from 2 to 99.
</dd><p>

<dt><i>OV_ECTL_IBLOCK_GET</i></dt>
<dd><b>Argument: double *</b><br> Returns the current encoder impulse
block setting in the double pointed to by arg.</dd><p>

<dt><i>OV_ECTL_IBLOCK_SET</i></dt> <dd><b>Argument: double *</b><br> Sets
the impulse block bias to the the value pointed to by arg; valid range
is -15.0 to 0.0 [default].  A negative impulse block bias will direct
to encoder to use more bits when incoding short blocks that contain
strong impulses, thus improving the accuracy of impulse encoding.</dd><p>

<dt><i>OV_ECTL_RATEMANAGE_GET [deprecated]</i></dt>
<dd>

<b>Argument: <a href="ovectl_ratemanage_arg.html">struct
ovectl_ratemanage_arg *</a></b><br> Old interface to querying bitrate
management settings; deprecated after move to bit-reservoir style
management in 1.1 rendered this interface partially obsolete.  Please
use OV_ECTL_RATEMANGE2_GET instead.

</dd><p>

<dt><i>OV_ECTL_RATEMANAGE_SET [deprecated]</i></dt>
<dd>
<b>Argument: <a href="ovectl_ratemanage_arg.html">struct
ovectl_ratemanage_arg *</a></b><br> Old interface to modifying bitrate
management settings; deprecated after move to bit-reservoir style
management in 1.1 rendered this interface partially obsolete.  Please
use OV_ECTL_RATEMANGE2_SET instead.
</dd><p>

<dt><i>OV_ECTL_RATEMANAGE_AVG [deprecated]</i></dt>
<dd>
<b>Argument: <a href="ovectl_ratemanage_arg.html">struct
ovectl_ratemanage_arg *</a></b><br> Old interface to setting
average-bitrate encoding mode; deprecated after move to bit-reservoir
style management in 1.1 rendered this interface partially obsolete.
Please use OV_ECTL_RATEMANGE2_SET instead.  
</dd><p>

<dt><i>OV_ECTL_RATEMANAGE_HARD [deprecated]</i></dt>
<dd>
<b>Argument: <a href="ovectl_ratemanage_arg.html">struct
ovectl_ratemanage_arg *</a></b><br> Old interface to setting
bounded-bitrate encoding modes; deprecated after move to bit-reservoir
style management in 1.1 rendered this interface partially obsolete.
Please use OV_ECTL_RATEMANGE2_SET instead.  
</dd><p>


</dl>


<h3>Return Values</h3> vorbis_encode_ctl() returns zero on success,
placing any further return information (such as the result of a query)
into the storage pointed to by <i>*arg</i>.  On error,
vorbis_encode_ctl() may return one of the following error codes:

<dl>

<dt>OV_EINVAL</dt><dd>Invalid argument, or an attempt to modify a
setting after calling <a
href="vorbis_encode_setup_init.html">vorbis_encode_setup_init()</a>.</dd><p>

<dt>OV_EIMPL</dt><dd>Unimplemented or unknown request</dd><p>

</dl>

<p>

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<td><p class=tiny>copyright &copy; 2004 xiph.org</p></td>
<td align=right><p class=tiny><a href="http://www.xiph.org/ogg/vorbis/index.html">Ogg Vorbis</a><br><a href="mailto:team@vorbis.org">team@vorbis.org</a></p></td>
</tr><tr>
<td><p class=tiny>libvorbisenc documentation</p></td>
<td align=right><p class=tiny>libvorbisenc release 1.1 - 20040709</p></td>
</tr>
</table>


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