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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968" /><title>Extended Controls</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="LINUX MEDIA INFRASTRUCTURE API" /><link rel="up" href="ch01.html" title="Chapter 1. Common API Elements" /><link rel="prev" href="ch01s08.html" title="User Controls" /><link rel="next" href="ch01s10.html" title="Data Formats" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Extended Controls</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch01s08.html">Prev</a> </td><th width="60%" align="center">Chapter 1. Common API Elements</th><td width="20%" align="right"> <a accesskey="n" href="ch01s10.html">Next</a></td></tr></table><hr /></div><div class="section" title="Extended Controls"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="extended-controls"></a>Extended Controls</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="ch01s09.html#id2580152">Introduction</a></span></dt><dt><span class="section"><a href="ch01s09.html#id2578974">The Extended Control API</a></span></dt><dt><span class="section"><a href="ch01s09.html#id2580473">Enumerating Extended Controls</a></span></dt><dt><span class="section"><a href="ch01s09.html#id2580599">Creating Control Panels</a></span></dt><dt><span class="section"><a href="ch01s09.html#mpeg-controls">MPEG Control Reference</a></span></dt><dt><span class="section"><a href="ch01s09.html#camera-controls">Camera Control Reference</a></span></dt><dt><span class="section"><a href="ch01s09.html#fm-tx-controls">FM Transmitter Control Reference</a></span></dt></dl></div><div class="section" title="Introduction"><div class="titlepage"><div><div><h3 class="title"><a id="id2580152"></a>Introduction</h3></div></div></div><p>The control mechanism as originally designed was meant
to be used for user settings (brightness, saturation, etc). However,
it turned out to be a very useful model for implementing more
complicated driver APIs where each driver implements only a subset of
a larger API.</p><p>The MPEG encoding API was the driving force behind
designing and implementing this extended control mechanism: the MPEG
standard is quite large and the currently supported hardware MPEG
encoders each only implement a subset of this standard. Further more,
many parameters relating to how the video is encoded into an MPEG
stream are specific to the MPEG encoding chip since the MPEG standard
only defines the format of the resulting MPEG stream, not how the
video is actually encoded into that format.</p><p>Unfortunately, the original control API lacked some
features needed for these new uses and so it was extended into the
(not terribly originally named) extended control API.</p><p>Even though the MPEG encoding API was the first effort
to use the Extended Control API, nowadays there are also other classes
of Extended Controls, such as Camera Controls and FM Transmitter Controls.
The Extended Controls API as well as all Extended Controls classes are
described in the following text.</p></div><div class="section" title="The Extended Control API"><div class="titlepage"><div><div><h3 class="title"><a id="id2578974"></a>The Extended Control API</h3></div></div></div><p>Three new ioctls are available: <a class="link" href="re39.html" title="ioctl VIDIOC_G_EXT_CTRLS, VIDIOC_S_EXT_CTRLS, VIDIOC_TRY_EXT_CTRLS"><code class="constant">VIDIOC_G_EXT_CTRLS</code></a>,
<a class="link" href="re39.html" title="ioctl VIDIOC_G_EXT_CTRLS, VIDIOC_S_EXT_CTRLS, VIDIOC_TRY_EXT_CTRLS"><code class="constant">VIDIOC_S_EXT_CTRLS</code></a> and <a class="link" href="re39.html" title="ioctl VIDIOC_G_EXT_CTRLS, VIDIOC_S_EXT_CTRLS, VIDIOC_TRY_EXT_CTRLS"><code class="constant">VIDIOC_TRY_EXT_CTRLS</code></a>. These ioctls act on
arrays of controls (as opposed to the <a class="link" href="re37.html" title="ioctl VIDIOC_G_CTRL, VIDIOC_S_CTRL"><code class="constant">VIDIOC_G_CTRL</code></a> and
<a class="link" href="re37.html" title="ioctl VIDIOC_G_CTRL, VIDIOC_S_CTRL"><code class="constant">VIDIOC_S_CTRL</code></a> ioctls that act on a single control). This is needed
since it is often required to atomically change several controls at
once.</p><p>Each of the new ioctls expects a pointer to a
struct <a class="link" href="re39.html#v4l2-ext-controls" title="Table A.41. struct v4l2_ext_controls">v4l2_ext_controls</a>. This structure contains a pointer to the control
array, a count of the number of controls in that array and a control
class. Control classes are used to group similar controls into a
single class. For example, control class
<code class="constant">V4L2_CTRL_CLASS_USER</code> contains all user controls
(i. e. all controls that can also be set using the old
<code class="constant">VIDIOC_S_CTRL</code> ioctl). Control class
<code class="constant">V4L2_CTRL_CLASS_MPEG</code> contains all controls
relating to MPEG encoding, etc.</p><p>All controls in the control array must belong to the
specified control class. An error is returned if this is not the
case.</p><p>It is also possible to use an empty control array (count
== 0) to check whether the specified control class is
supported.</p><p>The control array is a struct <a class="link" href="re39.html#v4l2-ext-control" title="Table A.40. struct v4l2_ext_control">v4l2_ext_control</a> array. The
<span class="structname">v4l2_ext_control</span> structure is very similar to
struct <a class="link" href="re37.html#v4l2-control" title="Table A.36. struct v4l2_control">v4l2_control</a>, except for the fact that it also allows for 64-bit
values and pointers to be passed.</p><p>It is important to realize that due to the flexibility of
controls it is necessary to check whether the control you want to set
actually is supported in the driver and what the valid range of values
is. So use the <a class="link" href="re57.html" title="ioctl VIDIOC_QUERYCTRL, VIDIOC_QUERYMENU"><code class="constant">VIDIOC_QUERYCTRL</code></a> and <a class="link" href="re57.html" title="ioctl VIDIOC_QUERYCTRL, VIDIOC_QUERYMENU"><code class="constant">VIDIOC_QUERYMENU</code></a> ioctls to
check this. Also note that it is possible that some of the menu
indices in a control of type <code class="constant">V4L2_CTRL_TYPE_MENU</code>
may not be supported (<code class="constant">VIDIOC_QUERYMENU</code> will
return an error). A good example is the list of supported MPEG audio
bitrates. Some drivers only support one or two bitrates, others
support a wider range.</p></div><div class="section" title="Enumerating Extended Controls"><div class="titlepage"><div><div><h3 class="title"><a id="id2580473"></a>Enumerating Extended Controls</h3></div></div></div><p>The recommended way to enumerate over the extended
controls is by using <a class="link" href="re57.html" title="ioctl VIDIOC_QUERYCTRL, VIDIOC_QUERYMENU"><code class="constant">VIDIOC_QUERYCTRL</code></a> in combination with the
<code class="constant">V4L2_CTRL_FLAG_NEXT_CTRL</code> flag:</p><div class="informalexample"><pre class="programlisting">
struct <a class="link" href="re57.html#v4l2-queryctrl" title="Table A.68. struct v4l2_queryctrl">v4l2_queryctrl</a> qctrl;
qctrl.id = V4L2_CTRL_FLAG_NEXT_CTRL;
while (0 == ioctl (fd, <a class="link" href="re57.html" title="ioctl VIDIOC_QUERYCTRL, VIDIOC_QUERYMENU"><code class="constant">VIDIOC_QUERYCTRL</code></a>, &qctrl)) {
/* ... */
qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
}
</pre></div><p>The initial control ID is set to 0 ORed with the
<code class="constant">V4L2_CTRL_FLAG_NEXT_CTRL</code> flag. The
<code class="constant">VIDIOC_QUERYCTRL</code> ioctl will return the first
control with a higher ID than the specified one. When no such controls
are found an error is returned.</p><p>If you want to get all controls within a specific control
class, then you can set the initial
<em class="structfield"><code>qctrl.id</code></em> value to the control class and add
an extra check to break out of the loop when a control of another
control class is found:</p><div class="informalexample"><pre class="programlisting">
qctrl.id = V4L2_CTRL_CLASS_MPEG | V4L2_CTRL_FLAG_NEXT_CTRL;
while (0 == ioctl (fd, <a class="link" href="re57.html" title="ioctl VIDIOC_QUERYCTRL, VIDIOC_QUERYMENU"><code class="constant">VIDIOC_QUERYCTRL</code></a>, &qctrl)) {
if (V4L2_CTRL_ID2CLASS (qctrl.id) != V4L2_CTRL_CLASS_MPEG)
break;
/* ... */
qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
}
</pre></div><p>The 32-bit <em class="structfield"><code>qctrl.id</code></em> value is
subdivided into three bit ranges: the top 4 bits are reserved for
flags (e. g. <code class="constant">V4L2_CTRL_FLAG_NEXT_CTRL</code>) and are not
actually part of the ID. The remaining 28 bits form the control ID, of
which the most significant 12 bits define the control class and the
least significant 16 bits identify the control within the control
class. It is guaranteed that these last 16 bits are always non-zero
for controls. The range of 0x1000 and up are reserved for
driver-specific controls. The macro
<code class="constant">V4L2_CTRL_ID2CLASS(id)</code> returns the control class
ID based on a control ID.</p><p>If the driver does not support extended controls, then
<code class="constant">VIDIOC_QUERYCTRL</code> will fail when used in
combination with <code class="constant">V4L2_CTRL_FLAG_NEXT_CTRL</code>. In
that case the old method of enumerating control should be used (see
1.8). But if it is supported, then it is guaranteed to enumerate over
all controls, including driver-private controls.</p></div><div class="section" title="Creating Control Panels"><div class="titlepage"><div><div><h3 class="title"><a id="id2580599"></a>Creating Control Panels</h3></div></div></div><p>It is possible to create control panels for a graphical
user interface where the user can select the various controls.
Basically you will have to iterate over all controls using the method
described above. Each control class starts with a control of type
<code class="constant">V4L2_CTRL_TYPE_CTRL_CLASS</code>.
<code class="constant">VIDIOC_QUERYCTRL</code> will return the name of this
control class which can be used as the title of a tab page within a
control panel.</p><p>The flags field of struct <a class="link" href="re57.html#v4l2-queryctrl" title="Table A.68. struct v4l2_queryctrl">v4l2_queryctrl</a> also contains hints on
the behavior of the control. See the <a class="link" href="re57.html" title="ioctl VIDIOC_QUERYCTRL, VIDIOC_QUERYMENU"><code class="constant">VIDIOC_QUERYCTRL</code></a> documentation
for more details.</p></div><div class="section" title="MPEG Control Reference"><div class="titlepage"><div><div><h3 class="title"><a id="mpeg-controls"></a>MPEG Control Reference</h3></div></div></div><div class="toc"><dl><dt><span class="section"><a href="ch01s09.html#id2580651">Generic MPEG Controls</a></span></dt><dt><span class="section"><a href="ch01s09.html#id2583138">CX2341x MPEG Controls</a></span></dt></dl></div><p>Below all controls within the MPEG control class are
described. First the generic controls, then controls specific for
certain hardware.</p><div class="section" title="Generic MPEG Controls"><div class="titlepage"><div><div><h4 class="title"><a id="id2580651"></a>Generic MPEG Controls</h4></div></div></div><div class="table"><a id="mpeg-control-id"></a><p class="title"><b>Table 1.2. MPEG Control IDs</b></p><div class="table-contents"><table summary="MPEG Control IDs" width="100%" border="0"><colgroup><col /><col /><col /><col /></colgroup><thead><tr><th colspan="2" align="left">ID</th><th align="left">Type</th><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><th colspan="3" align="left">Description</th></tr></thead><tbody valign="top"><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_MPEG_CLASS</code> </td><td valign="top">class</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">The MPEG class
descriptor. Calling <a class="link" href="re57.html" title="ioctl VIDIOC_QUERYCTRL, VIDIOC_QUERYMENU"><code class="constant">VIDIOC_QUERYCTRL</code></a> for this control will return a
description of this control class. This description can be used as the
caption of a Tab page in a GUI, for example.</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><a id="v4l2-mpeg-stream-type"></a><code class="constant">V4L2_CID_MPEG_STREAM_TYPE</code> </td><td valign="top">enum v4l2_mpeg_stream_type</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">The MPEG-1, -2 or -4
output stream type. One cannot assume anything here. Each hardware
MPEG encoder tends to support different subsets of the available MPEG
stream types. The currently defined stream types are:</td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top"><table width="100%" border="0"><colgroup><col /><col /></colgroup><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_MPEG_STREAM_TYPE_MPEG2_PS</code> </td><td valign="top">MPEG-2 program stream</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_STREAM_TYPE_MPEG2_TS</code> </td><td valign="top">MPEG-2 transport stream</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_STREAM_TYPE_MPEG1_SS</code> </td><td valign="top">MPEG-1 system stream</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_STREAM_TYPE_MPEG2_DVD</code> </td><td valign="top">MPEG-2 DVD-compatible stream</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_STREAM_TYPE_MPEG1_VCD</code> </td><td valign="top">MPEG-1 VCD-compatible stream</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_STREAM_TYPE_MPEG2_SVCD</code> </td><td valign="top">MPEG-2 SVCD-compatible stream</td></tr></tbody></table></td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_MPEG_STREAM_PID_PMT</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Program Map Table
Packet ID for the MPEG transport stream (default 16)</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_MPEG_STREAM_PID_AUDIO</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Audio Packet ID for
the MPEG transport stream (default 256)</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_MPEG_STREAM_PID_VIDEO</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Video Packet ID for
the MPEG transport stream (default 260)</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_MPEG_STREAM_PID_PCR</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Packet ID for the
MPEG transport stream carrying PCR fields (default 259)</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_MPEG_STREAM_PES_ID_AUDIO</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Audio ID for MPEG
PES</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_MPEG_STREAM_PES_ID_VIDEO</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Video ID for MPEG
PES</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><a id="v4l2-mpeg-stream-vbi-fmt"></a><code class="constant">V4L2_CID_MPEG_STREAM_VBI_FMT</code> </td><td valign="top">enum v4l2_mpeg_stream_vbi_fmt</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Some cards can embed
VBI data (e. g. Closed Caption, Teletext) into the MPEG stream. This
control selects whether VBI data should be embedded, and if so, what
embedding method should be used. The list of possible VBI formats
depends on the driver. The currently defined VBI format types
are:</td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top"><table width="100%" border="0"><colgroup><col /><col /></colgroup><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_MPEG_STREAM_VBI_FMT_NONE</code> </td><td valign="top">No VBI in the MPEG stream</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_STREAM_VBI_FMT_IVTV</code> </td><td valign="top">VBI in private packets, IVTV format (documented
in the kernel sources in the file <code class="filename">Documentation/video4linux/cx2341x/README.vbi</code>)</td></tr></tbody></table></td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><a id="v4l2-mpeg-audio-sampling-freq"></a><code class="constant">V4L2_CID_MPEG_AUDIO_SAMPLING_FREQ</code> </td><td valign="top">enum v4l2_mpeg_audio_sampling_freq</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">MPEG Audio sampling
frequency. Possible values are:</td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top"><table width="100%" border="0"><colgroup><col /><col /></colgroup><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_SAMPLING_FREQ_44100</code> </td><td valign="top">44.1 kHz</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_SAMPLING_FREQ_48000</code> </td><td valign="top">48 kHz</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_SAMPLING_FREQ_32000</code> </td><td valign="top">32 kHz</td></tr></tbody></table></td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><a id="v4l2-mpeg-audio-encoding"></a><code class="constant">V4L2_CID_MPEG_AUDIO_ENCODING</code> </td><td valign="top">enum v4l2_mpeg_audio_encoding</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">MPEG Audio encoding.
Possible values are:</td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top"><table width="100%" border="0"><colgroup><col /><col /></colgroup><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_ENCODING_LAYER_1</code> </td><td valign="top">MPEG-1/2 Layer I encoding</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_ENCODING_LAYER_2</code> </td><td valign="top">MPEG-1/2 Layer II encoding</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_ENCODING_LAYER_3</code> </td><td valign="top">MPEG-1/2 Layer III encoding</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_ENCODING_AAC</code> </td><td valign="top">MPEG-2/4 AAC (Advanced Audio Coding)</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_ENCODING_AC3</code> </td><td valign="top">AC-3 aka ATSC A/52 encoding</td></tr></tbody></table></td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><a id="v4l2-mpeg-audio-l1-bitrate"></a><code class="constant">V4L2_CID_MPEG_AUDIO_L1_BITRATE</code> </td><td valign="top">enum v4l2_mpeg_audio_l1_bitrate</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">MPEG-1/2 Layer I bitrate.
Possible values are:</td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top"><table width="100%" border="0"><colgroup><col /><col /></colgroup><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L1_BITRATE_32K</code> </td><td valign="top">32 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L1_BITRATE_64K</code> </td><td valign="top">64 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L1_BITRATE_96K</code> </td><td valign="top">96 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L1_BITRATE_128K</code> </td><td valign="top">128 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L1_BITRATE_160K</code> </td><td valign="top">160 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L1_BITRATE_192K</code> </td><td valign="top">192 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L1_BITRATE_224K</code> </td><td valign="top">224 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L1_BITRATE_256K</code> </td><td valign="top">256 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L1_BITRATE_288K</code> </td><td valign="top">288 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L1_BITRATE_320K</code> </td><td valign="top">320 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L1_BITRATE_352K</code> </td><td valign="top">352 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L1_BITRATE_384K</code> </td><td valign="top">384 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L1_BITRATE_416K</code> </td><td valign="top">416 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L1_BITRATE_448K</code> </td><td valign="top">448 kbit/s</td></tr></tbody></table></td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><a id="v4l2-mpeg-audio-l2-bitrate"></a><code class="constant">V4L2_CID_MPEG_AUDIO_L2_BITRATE</code> </td><td valign="top">enum v4l2_mpeg_audio_l2_bitrate</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">MPEG-1/2 Layer II bitrate.
Possible values are:</td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top"><table width="100%" border="0"><colgroup><col /><col /></colgroup><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L2_BITRATE_32K</code> </td><td valign="top">32 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L2_BITRATE_48K</code> </td><td valign="top">48 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L2_BITRATE_56K</code> </td><td valign="top">56 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L2_BITRATE_64K</code> </td><td valign="top">64 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L2_BITRATE_80K</code> </td><td valign="top">80 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L2_BITRATE_96K</code> </td><td valign="top">96 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L2_BITRATE_112K</code> </td><td valign="top">112 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L2_BITRATE_128K</code> </td><td valign="top">128 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L2_BITRATE_160K</code> </td><td valign="top">160 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L2_BITRATE_192K</code> </td><td valign="top">192 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L2_BITRATE_224K</code> </td><td valign="top">224 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L2_BITRATE_256K</code> </td><td valign="top">256 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L2_BITRATE_320K</code> </td><td valign="top">320 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L2_BITRATE_384K</code> </td><td valign="top">384 kbit/s</td></tr></tbody></table></td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><a id="v4l2-mpeg-audio-l3-bitrate"></a><code class="constant">V4L2_CID_MPEG_AUDIO_L3_BITRATE</code> </td><td valign="top">enum v4l2_mpeg_audio_l3_bitrate</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">MPEG-1/2 Layer III bitrate.
Possible values are:</td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top"><table width="100%" border="0"><colgroup><col /><col /></colgroup><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L3_BITRATE_32K</code> </td><td valign="top">32 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L3_BITRATE_40K</code> </td><td valign="top">40 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L3_BITRATE_48K</code> </td><td valign="top">48 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L3_BITRATE_56K</code> </td><td valign="top">56 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L3_BITRATE_64K</code> </td><td valign="top">64 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L3_BITRATE_80K</code> </td><td valign="top">80 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L3_BITRATE_96K</code> </td><td valign="top">96 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L3_BITRATE_112K</code> </td><td valign="top">112 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L3_BITRATE_128K</code> </td><td valign="top">128 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L3_BITRATE_160K</code> </td><td valign="top">160 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L3_BITRATE_192K</code> </td><td valign="top">192 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L3_BITRATE_224K</code> </td><td valign="top">224 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L3_BITRATE_256K</code> </td><td valign="top">256 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_L3_BITRATE_320K</code> </td><td valign="top">320 kbit/s</td></tr></tbody></table></td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_MPEG_AUDIO_AAC_BITRATE</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">AAC bitrate in bits per second.</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><a id="v4l2-mpeg-audio-ac3-bitrate"></a><code class="constant">V4L2_CID_MPEG_AUDIO_AC3_BITRATE</code> </td><td valign="top">enum v4l2_mpeg_audio_ac3_bitrate</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">AC-3 bitrate.
Possible values are:</td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top"><table width="100%" border="0"><colgroup><col /><col /></colgroup><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_AC3_BITRATE_32K</code> </td><td valign="top">32 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_AC3_BITRATE_40K</code> </td><td valign="top">40 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_AC3_BITRATE_48K</code> </td><td valign="top">48 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_AC3_BITRATE_56K</code> </td><td valign="top">56 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_AC3_BITRATE_64K</code> </td><td valign="top">64 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_AC3_BITRATE_80K</code> </td><td valign="top">80 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_AC3_BITRATE_96K</code> </td><td valign="top">96 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_AC3_BITRATE_112K</code> </td><td valign="top">112 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_AC3_BITRATE_128K</code> </td><td valign="top">128 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_AC3_BITRATE_160K</code> </td><td valign="top">160 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_AC3_BITRATE_192K</code> </td><td valign="top">192 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_AC3_BITRATE_224K</code> </td><td valign="top">224 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_AC3_BITRATE_256K</code> </td><td valign="top">256 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_AC3_BITRATE_320K</code> </td><td valign="top">320 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_AC3_BITRATE_384K</code> </td><td valign="top">384 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_AC3_BITRATE_448K</code> </td><td valign="top">448 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_AC3_BITRATE_512K</code> </td><td valign="top">512 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_AC3_BITRATE_576K</code> </td><td valign="top">576 kbit/s</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_AC3_BITRATE_640K</code> </td><td valign="top">640 kbit/s</td></tr></tbody></table></td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><a id="v4l2-mpeg-audio-mode"></a><code class="constant">V4L2_CID_MPEG_AUDIO_MODE</code> </td><td valign="top">enum v4l2_mpeg_audio_mode</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">MPEG Audio mode.
Possible values are:</td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top"><table width="100%" border="0"><colgroup><col /><col /></colgroup><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_MODE_STEREO</code> </td><td valign="top">Stereo</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_MODE_JOINT_STEREO</code> </td><td valign="top">Joint Stereo</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_MODE_DUAL</code> </td><td valign="top">Bilingual</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_MODE_MONO</code> </td><td valign="top">Mono</td></tr></tbody></table></td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><a id="v4l2-mpeg-audio-mode-extension"></a><code class="constant">V4L2_CID_MPEG_AUDIO_MODE_EXTENSION</code> </td><td valign="top">enum v4l2_mpeg_audio_mode_extension</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Joint Stereo
audio mode extension. In Layer I and II they indicate which subbands
are in intensity stereo. All other subbands are coded in stereo. Layer
III is not (yet) supported. Possible values
are:</td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top"><table width="100%" border="0"><colgroup><col /><col /></colgroup><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_4</code> </td><td valign="top">Subbands 4-31 in intensity stereo</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_8</code> </td><td valign="top">Subbands 8-31 in intensity stereo</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_12</code> </td><td valign="top">Subbands 12-31 in intensity stereo</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_16</code> </td><td valign="top">Subbands 16-31 in intensity stereo</td></tr></tbody></table></td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><a id="v4l2-mpeg-audio-emphasis"></a><code class="constant">V4L2_CID_MPEG_AUDIO_EMPHASIS</code> </td><td valign="top">enum v4l2_mpeg_audio_emphasis</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Audio Emphasis.
Possible values are:</td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top"><table width="100%" border="0"><colgroup><col /><col /></colgroup><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_EMPHASIS_NONE</code> </td><td valign="top">None</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_EMPHASIS_50_DIV_15_uS</code> </td><td valign="top">50/15 microsecond emphasis</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_EMPHASIS_CCITT_J17</code> </td><td valign="top">CCITT J.17</td></tr></tbody></table></td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><a id="v4l2-mpeg-audio-crc"></a><code class="constant">V4L2_CID_MPEG_AUDIO_CRC</code> </td><td valign="top">enum v4l2_mpeg_audio_crc</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">CRC method. Possible
values are:</td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top"><table width="100%" border="0"><colgroup><col /><col /></colgroup><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_CRC_NONE</code> </td><td valign="top">None</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_AUDIO_CRC_CRC16</code> </td><td valign="top">16 bit parity check</td></tr></tbody></table></td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_MPEG_AUDIO_MUTE</code> </td><td valign="top">boolean</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Mutes the audio when
capturing. This is not done by muting audio hardware, which can still
produce a slight hiss, but in the encoder itself, guaranteeing a fixed
and reproducable audio bitstream. 0 = unmuted, 1 = muted.</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><a id="v4l2-mpeg-video-encoding"></a><code class="constant">V4L2_CID_MPEG_VIDEO_ENCODING</code> </td><td valign="top">enum v4l2_mpeg_video_encoding</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">MPEG Video encoding
method. Possible values are:</td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top"><table width="100%" border="0"><colgroup><col /><col /></colgroup><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_MPEG_VIDEO_ENCODING_MPEG_1</code> </td><td valign="top">MPEG-1 Video encoding</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_VIDEO_ENCODING_MPEG_2</code> </td><td valign="top">MPEG-2 Video encoding</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_VIDEO_ENCODING_MPEG_4_AVC</code> </td><td valign="top">MPEG-4 AVC (H.264) Video encoding</td></tr></tbody></table></td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><a id="v4l2-mpeg-video-aspect"></a><code class="constant">V4L2_CID_MPEG_VIDEO_ASPECT</code> </td><td valign="top">enum v4l2_mpeg_video_aspect</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Video aspect.
Possible values are:</td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top"><table width="100%" border="0"><colgroup><col /><col /></colgroup><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_MPEG_VIDEO_ASPECT_1x1</code> </td><td class="auto-generated"> </td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_VIDEO_ASPECT_4x3</code> </td><td class="auto-generated"> </td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_VIDEO_ASPECT_16x9</code> </td><td class="auto-generated"> </td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_VIDEO_ASPECT_221x100</code> </td><td class="auto-generated"> </td></tr></tbody></table></td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_MPEG_VIDEO_B_FRAMES</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Number of B-Frames
(default 2)</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_MPEG_VIDEO_GOP_SIZE</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">GOP size (default
12)</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_MPEG_VIDEO_GOP_CLOSURE</code> </td><td valign="top">boolean</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">GOP closure (default
1)</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_MPEG_VIDEO_PULLDOWN</code> </td><td valign="top">boolean</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Enable 3:2 pulldown
(default 0)</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><a id="v4l2-mpeg-video-bitrate-mode"></a><code class="constant">V4L2_CID_MPEG_VIDEO_BITRATE_MODE</code> </td><td valign="top">enum v4l2_mpeg_video_bitrate_mode</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Video bitrate mode.
Possible values are:</td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top"><table width="100%" border="0"><colgroup><col /><col /></colgroup><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_MPEG_VIDEO_BITRATE_MODE_VBR</code> </td><td valign="top">Variable bitrate</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_VIDEO_BITRATE_MODE_CBR</code> </td><td valign="top">Constant bitrate</td></tr></tbody></table></td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_MPEG_VIDEO_BITRATE</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Video bitrate in bits
per second.</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_MPEG_VIDEO_BITRATE_PEAK</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Peak video bitrate in
bits per second. Must be larger or equal to the average video bitrate.
It is ignored if the video bitrate mode is set to constant
bitrate.</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_MPEG_VIDEO_TEMPORAL_DECIMATION</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">For every captured
frame, skip this many subsequent frames (default 0).</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_MPEG_VIDEO_MUTE</code> </td><td valign="top">boolean</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">"Mutes" the video to a
fixed color when capturing. This is useful for testing, to produce a
fixed video bitstream. 0 = unmuted, 1 = muted.</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_MPEG_VIDEO_MUTE_YUV</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Sets the "mute" color
of the video. The supplied 32-bit integer is interpreted as follows (bit
0 = least significant bit):</td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top"><table width="100%" border="0"><colgroup><col /><col /></colgroup><tbody valign="top"><tr><td valign="top">Bit 0:7</td><td valign="top">V chrominance information</td></tr><tr><td valign="top">Bit 8:15</td><td valign="top">U chrominance information</td></tr><tr><td valign="top">Bit 16:23</td><td valign="top">Y luminance information</td></tr><tr><td valign="top">Bit 24:31</td><td valign="top">Must be zero.</td></tr></tbody></table></td></tr></tbody></table></div></div><br class="table-break" /></div><div class="section" title="CX2341x MPEG Controls"><div class="titlepage"><div><div><h4 class="title"><a id="id2583138"></a>CX2341x MPEG Controls</h4></div></div></div><p>The following MPEG class controls deal with MPEG
encoding settings that are specific to the Conexant CX23415 and
CX23416 MPEG encoding chips.</p><div class="table"><a id="cx2341x-control-id"></a><p class="title"><b>Table 1.3. CX2341x Control IDs</b></p><div class="table-contents"><table summary="CX2341x Control IDs" width="100%" border="0"><colgroup><col /><col /><col /><col /></colgroup><thead><tr><th colspan="2" align="left">ID</th><th align="left">Type</th><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><th colspan="3" align="left">Description</th></tr></thead><tbody valign="top"><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><a id="v4l2-mpeg-cx2341x-video-spatial-filter-mode"></a><code class="constant">V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE</code> </td><td valign="top">enum v4l2_mpeg_cx2341x_video_spatial_filter_mode</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Sets the Spatial
Filter mode (default <code class="constant">MANUAL</code>). Possible values
are:</td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top"><table width="100%" border="0"><colgroup><col /><col /></colgroup><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_MANUAL</code> </td><td valign="top">Choose the filter manually</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_AUTO</code> </td><td valign="top">Choose the filter automatically</td></tr></tbody></table></td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER</code> </td><td valign="top">integer (0-15)</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">The setting for the
Spatial Filter. 0 = off, 15 = maximum. (Default is 0.)</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><a id="luma-spatial-filter-type"></a><code class="constant">V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE</code> </td><td valign="top">enum v4l2_mpeg_cx2341x_video_luma_spatial_filter_type</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Select the algorithm
to use for the Luma Spatial Filter (default
<code class="constant">1D_HOR</code>). Possible values:</td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top"><table width="100%" border="0"><colgroup><col /><col /></colgroup><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_OFF</code> </td><td valign="top">No filter</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_HOR</code> </td><td valign="top">One-dimensional horizontal</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_VERT</code> </td><td valign="top">One-dimensional vertical</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_HV_SEPARABLE</code> </td><td valign="top">Two-dimensional separable</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_SYM_NON_SEPARABLE</code> </td><td valign="top">Two-dimensional symmetrical
non-separable</td></tr></tbody></table></td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><a id="chroma-spatial-filter-type"></a><code class="constant">V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE</code> </td><td valign="top">enum v4l2_mpeg_cx2341x_video_chroma_spatial_filter_type</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Select the algorithm
for the Chroma Spatial Filter (default <code class="constant">1D_HOR</code>).
Possible values are:</td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top"><table width="100%" border="0"><colgroup><col /><col /></colgroup><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_OFF</code> </td><td valign="top">No filter</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_1D_HOR</code> </td><td valign="top">One-dimensional horizontal</td></tr></tbody></table></td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><a id="v4l2-mpeg-cx2341x-video-temporal-filter-mode"></a><code class="constant">V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE</code> </td><td valign="top">enum v4l2_mpeg_cx2341x_video_temporal_filter_mode</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Sets the Temporal
Filter mode (default <code class="constant">MANUAL</code>). Possible values
are:</td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top"><table width="100%" border="0"><colgroup><col /><col /></colgroup><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_MANUAL</code> </td><td valign="top">Choose the filter manually</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_AUTO</code> </td><td valign="top">Choose the filter automatically</td></tr></tbody></table></td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER</code> </td><td valign="top">integer (0-31)</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">The setting for the
Temporal Filter. 0 = off, 31 = maximum. (Default is 8 for full-scale
capturing and 0 for scaled capturing.)</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><a id="v4l2-mpeg-cx2341x-video-median-filter-type"></a><code class="constant">V4L2_CID_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE</code> </td><td valign="top">enum v4l2_mpeg_cx2341x_video_median_filter_type</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Median Filter Type
(default <code class="constant">OFF</code>). Possible values are:</td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top"><table width="100%" border="0"><colgroup><col /><col /></colgroup><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_OFF</code> </td><td valign="top">No filter</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR</code> </td><td valign="top">Horizontal filter</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_VERT</code> </td><td valign="top">Vertical filter</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR_VERT</code> </td><td valign="top">Horizontal and vertical filter</td></tr><tr><td valign="top"><code class="constant">V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_DIAG</code> </td><td valign="top">Diagonal filter</td></tr></tbody></table></td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_BOTTOM</code> </td><td valign="top">integer (0-255)</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Threshold above which
the luminance median filter is enabled (default 0)</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_TOP</code> </td><td valign="top">integer (0-255)</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Threshold below which
the luminance median filter is enabled (default 255)</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_BOTTOM</code> </td><td valign="top">integer (0-255)</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Threshold above which
the chroma median filter is enabled (default 0)</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_TOP</code> </td><td valign="top">integer (0-255)</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Threshold below which
the chroma median filter is enabled (default 255)</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_MPEG_CX2341X_STREAM_INSERT_NAV_PACKETS</code> </td><td valign="top">boolean</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">The CX2341X MPEG encoder
can insert one empty MPEG-2 PES packet into the stream between every
four video frames. The packet size is 2048 bytes, including the
packet_start_code_prefix and stream_id fields. The stream_id is 0xBF
(private stream 2). The payload consists of 0x00 bytes, to be filled
in by the application. 0 = do not insert, 1 = insert packets.</td></tr></tbody></table></div></div><br class="table-break" /></div></div><div class="section" title="Camera Control Reference"><div class="titlepage"><div><div><h3 class="title"><a id="camera-controls"></a>Camera Control Reference</h3></div></div></div><p>The Camera class includes controls for mechanical (or
equivalent digital) features of a device such as controllable lenses
or sensors.</p><div class="table"><a id="camera-control-id"></a><p class="title"><b>Table 1.4. Camera Control IDs</b></p><div class="table-contents"><table summary="Camera Control IDs" width="100%" border="0"><colgroup><col /><col /><col /><col /></colgroup><thead><tr><th colspan="2" align="left">ID</th><th align="left">Type</th><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><th colspan="3" align="left">Description</th></tr></thead><tbody valign="top"><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_CAMERA_CLASS</code> </td><td valign="top">class</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">The Camera class
descriptor. Calling <a class="link" href="re57.html" title="ioctl VIDIOC_QUERYCTRL, VIDIOC_QUERYMENU"><code class="constant">VIDIOC_QUERYCTRL</code></a> for this control will return a
description of this control class.</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><a id="v4l2-exposure-auto-type"></a><code class="constant">V4L2_CID_EXPOSURE_AUTO</code> </td><td valign="top">enum v4l2_exposure_auto_type</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Enables automatic
adjustments of the exposure time and/or iris aperture. The effect of
manual changes of the exposure time or iris aperture while these
features are enabled is undefined, drivers should ignore such
requests. Possible values are:</td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top"><table width="100%" border="0"><colgroup><col /><col /></colgroup><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_EXPOSURE_AUTO</code> </td><td valign="top">Automatic exposure time, automatic iris
aperture.</td></tr><tr><td valign="top"><code class="constant">V4L2_EXPOSURE_MANUAL</code> </td><td valign="top">Manual exposure time, manual iris.</td></tr><tr><td valign="top"><code class="constant">V4L2_EXPOSURE_SHUTTER_PRIORITY</code> </td><td valign="top">Manual exposure time, auto iris.</td></tr><tr><td valign="top"><code class="constant">V4L2_EXPOSURE_APERTURE_PRIORITY</code> </td><td valign="top">Auto exposure time, manual iris.</td></tr></tbody></table></td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_EXPOSURE_ABSOLUTE</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Determines the exposure
time of the camera sensor. The exposure time is limited by the frame
interval. Drivers should interpret the values as 100 µs units,
where the value 1 stands for 1/10000th of a second, 10000 for 1 second
and 100000 for 10 seconds.</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_EXPOSURE_AUTO_PRIORITY</code> </td><td valign="top">boolean</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">When
<code class="constant">V4L2_CID_EXPOSURE_AUTO</code> is set to
<code class="constant">AUTO</code> or <code class="constant">APERTURE_PRIORITY</code>,
this control determines if the device may dynamically vary the frame
rate. By default this feature is disabled (0) and the frame rate must
remain constant.</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_PAN_RELATIVE</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">This control turns the
camera horizontally by the specified amount. The unit is undefined. A
positive value moves the camera to the right (clockwise when viewed
from above), a negative value to the left. A value of zero does not
cause motion. This is a write-only control.</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_TILT_RELATIVE</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">This control turns the
camera vertically by the specified amount. The unit is undefined. A
positive value moves the camera up, a negative value down. A value of
zero does not cause motion. This is a write-only control.</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_PAN_RESET</code> </td><td valign="top">button</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">When this control is set,
the camera moves horizontally to the default position.</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_TILT_RESET</code> </td><td valign="top">button</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">When this control is set,
the camera moves vertically to the default position.</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_PAN_ABSOLUTE</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">This control
turns the camera horizontally to the specified position. Positive
values move the camera to the right (clockwise when viewed from above),
negative values to the left. Drivers should interpret the values as arc
seconds, with valid values between -180 * 3600 and +180 * 3600
inclusive.</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_TILT_ABSOLUTE</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">This control
turns the camera vertically to the specified position. Positive values
move the camera up, negative values down. Drivers should interpret the
values as arc seconds, with valid values between -180 * 3600 and +180
* 3600 inclusive.</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_FOCUS_ABSOLUTE</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">This control sets the
focal point of the camera to the specified position. The unit is
undefined. Positive values set the focus closer to the camera,
negative values towards infinity.</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_FOCUS_RELATIVE</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">This control moves the
focal point of the camera by the specified amount. The unit is
undefined. Positive values move the focus closer to the camera,
negative values towards infinity. This is a write-only control.</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_FOCUS_AUTO</code> </td><td valign="top">boolean</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Enables automatic focus
adjustments. The effect of manual focus adjustments while this feature
is enabled is undefined, drivers should ignore such requests.</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_ZOOM_ABSOLUTE</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Specify the objective lens
focal length as an absolute value. The zoom unit is driver-specific and its
value should be a positive integer.</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_ZOOM_RELATIVE</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Specify the objective lens
focal length relatively to the current value. Positive values move the zoom
lens group towards the telephoto direction, negative values towards the
wide-angle direction. The zoom unit is driver-specific. This is a write-only control.</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_ZOOM_CONTINUOUS</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Move the objective lens group
at the specified speed until it reaches physical device limits or until an
explicit request to stop the movement. A positive value moves the zoom lens
group towards the telephoto direction. A value of zero stops the zoom lens
group movement. A negative value moves the zoom lens group towards the
wide-angle direction. The zoom speed unit is driver-specific.</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_PRIVACY</code> </td><td valign="top">boolean</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Prevent video from being acquired
by the camera. When this control is set to <code class="constant">TRUE</code> (1), no
image can be captured by the camera. Common means to enforce privacy are
mechanical obturation of the sensor and firmware image processing, but the
device is not restricted to these methods. Devices that implement the privacy
control must support read access and may support write access.</td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_BAND_STOP_FILTER</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Switch the band-stop filter of a
camera sensor on or off, or specify its strength. Such band-stop filters can
be used, for example, to filter out the fluorescent light component.</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr></tbody></table></div></div><br class="table-break" /></div><div class="section" title="FM Transmitter Control Reference"><div class="titlepage"><div><div><h3 class="title"><a id="fm-tx-controls"></a>FM Transmitter Control Reference</h3></div></div></div><p>The FM Transmitter (FM_TX) class includes controls for common features of
FM transmissions capable devices. Currently this class includes parameters for audio
compression, pilot tone generation, audio deviation limiter, RDS transmission and
tuning power features.</p><div class="table"><a id="fm-tx-control-id"></a><p class="title"><b>Table 1.5. FM_TX Control IDs</b></p><div class="table-contents"><table summary="FM_TX Control IDs" width="100%" border="0"><colgroup><col /><col /><col /><col /></colgroup><thead><tr><th colspan="2" align="left">ID</th><th align="left">Type</th><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><th colspan="3" align="left">Description</th></tr></thead><tbody valign="top"><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_FM_TX_CLASS</code> </td><td valign="top">class</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">The FM_TX class
descriptor. Calling <a class="link" href="re57.html" title="ioctl VIDIOC_QUERYCTRL, VIDIOC_QUERYMENU"><code class="constant">VIDIOC_QUERYCTRL</code></a> for this control will return a
description of this control class.</td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_RDS_TX_DEVIATION</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Configures RDS signal frequency deviation level in Hz.
The range and step are driver-specific.</td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_RDS_TX_PI</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Sets the RDS Programme Identification field
for transmission.</td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_RDS_TX_PTY</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Sets the RDS Programme Type field for transmission.
This encodes up to 31 pre-defined programme types.</td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_RDS_TX_PS_NAME</code> </td><td valign="top">string</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Sets the Programme Service name (PS_NAME) for transmission.
It is intended for static display on a receiver. It is the primary aid to listeners in programme service
identification and selection. In Annex E of <a class="xref" href="bi01.html#en50067" title="Specification of the radio data system (RDS) for VHF/FM sound broadcasting in the frequency range from 87,5 to 108,0 MHz">[<abbr class="abbrev">EN 50067</abbr>]</a>, the RDS specification,
there is a full description of the correct character encoding for Programme Service name strings.
Also from RDS specification, PS is usually a single eight character text. However, it is also possible
to find receivers which can scroll strings sized as 8 x N characters. So, this control must be configured
with steps of 8 characters. The result is it must always contain a string with size multiple of 8.</td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_RDS_TX_RADIO_TEXT</code> </td><td valign="top">string</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Sets the Radio Text info for transmission. It is a textual description of
what is being broadcasted. RDS Radio Text can be applied when broadcaster wishes to transmit longer PS names,
programme-related information or any other text. In these cases, RadioText should be used in addition to
<code class="constant">V4L2_CID_RDS_TX_PS_NAME</code>. The encoding for Radio Text strings is also fully described
in Annex E of <a class="xref" href="bi01.html#en50067" title="Specification of the radio data system (RDS) for VHF/FM sound broadcasting in the frequency range from 87,5 to 108,0 MHz">[<abbr class="abbrev">EN 50067</abbr>]</a>. The length of Radio Text strings depends on which RDS Block is being
used to transmit it, either 32 (2A block) or 64 (2B block). However, it is also possible
to find receivers which can scroll strings sized as 32 x N or 64 x N characters. So, this control must be configured
with steps of 32 or 64 characters. The result is it must always contain a string with size multiple of 32 or 64. </td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_AUDIO_LIMITER_ENABLED</code> </td><td valign="top">boolean</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Enables or disables the audio deviation limiter feature.
The limiter is useful when trying to maximize the audio volume, minimize receiver-generated
distortion and prevent overmodulation.
</td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_AUDIO_LIMITER_RELEASE_TIME</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Sets the audio deviation limiter feature release time.
Unit is in useconds. Step and range are driver-specific.</td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_AUDIO_LIMITER_DEVIATION</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Configures audio frequency deviation level in Hz.
The range and step are driver-specific.</td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_AUDIO_COMPRESSION_ENABLED</code> </td><td valign="top">boolean</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Enables or disables the audio compression feature.
This feature amplifies signals below the threshold by a fixed gain and compresses audio
signals above the threshold by the ratio of Threshold/(Gain + Threshold).</td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_AUDIO_COMPRESSION_GAIN</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Sets the gain for audio compression feature. It is
a dB value. The range and step are driver-specific.</td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_AUDIO_COMPRESSION_THRESHOLD</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Sets the threshold level for audio compression freature.
It is a dB value. The range and step are driver-specific.</td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_AUDIO_COMPRESSION_ATTACK_TIME</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Sets the attack time for audio compression feature.
It is a useconds value. The range and step are driver-specific.</td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_AUDIO_COMPRESSION_RELEASE_TIME</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Sets the release time for audio compression feature.
It is a useconds value. The range and step are driver-specific.</td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_PILOT_TONE_ENABLED</code> </td><td valign="top">boolean</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Enables or disables the pilot tone generation feature.</td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_PILOT_TONE_DEVIATION</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Configures pilot tone frequency deviation level. Unit is
in Hz. The range and step are driver-specific.</td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_PILOT_TONE_FREQUENCY</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Configures pilot tone frequency value. Unit is
in Hz. The range and step are driver-specific.</td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_TUNE_PREEMPHASIS</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top"><a id="v4l2-preemphasis"></a>Configures the pre-emphasis value for broadcasting.
A pre-emphasis filter is applied to the broadcast to accentuate the high audio frequencies.
Depending on the region, a time constant of either 50 or 75 useconds is used. The enum v4l2_preemphasis
defines possible values for pre-emphasis. Here they are:</td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top"><table width="100%" border="0"><colgroup><col /><col /></colgroup><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_PREEMPHASIS_DISABLED</code> </td><td valign="top">No pre-emphasis is applied.</td></tr><tr><td valign="top"><code class="constant">V4L2_PREEMPHASIS_50_uS</code> </td><td valign="top">A pre-emphasis of 50 uS is used.</td></tr><tr><td valign="top"><code class="constant">V4L2_PREEMPHASIS_75_uS</code> </td><td valign="top">A pre-emphasis of 75 uS is used.</td></tr></tbody></table></td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_TUNE_POWER_LEVEL</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">Sets the output power level for signal transmission.
Unit is in dBuV. Range and step are driver-specific.</td></tr><tr><td colspan="2" valign="top"><code class="constant">V4L2_CID_TUNE_ANTENNA_CAPACITOR</code> </td><td valign="top">integer</td><td class="auto-generated"> </td></tr><tr><td class="auto-generated"> </td><td colspan="3" valign="top">This selects the value of antenna tuning capacitor
manually or automatically if set to zero. Unit, range and step are driver-specific.</td></tr><tr><td valign="top"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td><td class="auto-generated"> </td></tr></tbody></table></div></div><br class="table-break" /><p>For more details about RDS specification, refer to
<a class="xref" href="bi01.html#en50067" title="Specification of the radio data system (RDS) for VHF/FM sound broadcasting in the frequency range from 87,5 to 108,0 MHz">[<abbr class="abbrev">EN 50067</abbr>]</a> document, from CENELEC.</p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ch01s08.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch01.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ch01s10.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">User Controls </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Data Formats</td></tr></table></div></body></html>
