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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>ioctl VIDIOC_G_MODULATOR, VIDIOC_S_MODULATOR</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="index.html" title="LINUX MEDIA INFRASTRUCTURE API"><link rel="up" href="user-func.html" title="Appendix A. Function Reference"><link rel="prev" href="vidioc-g-jpegcomp.html" title="ioctl VIDIOC_G_JPEGCOMP, VIDIOC_S_JPEGCOMP"><link rel="next" href="vidioc-g-output.html" title="ioctl VIDIOC_G_OUTPUT, VIDIOC_S_OUTPUT"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">ioctl VIDIOC_G_MODULATOR, VIDIOC_S_MODULATOR</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="vidioc-g-jpegcomp.html">Prev</a> </td><th width="60%" align="center">Appendix A. Function Reference</th><td width="20%" align="right"> <a accesskey="n" href="vidioc-g-output.html">Next</a></td></tr></table><hr></div><div class="refentry"><a name="vidioc-g-modulator"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>VIDIOC_G_MODULATOR, VIDIOC_S_MODULATOR — Get or set modulator attributes</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">ioctl</b>(</code></td><td>int <var class="pdparam">fd</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">request</var>, </td></tr><tr><td> </td><td>struct v4l2_modulator
*<var class="pdparam">argp</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div><div class="funcsynopsis"><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">ioctl</b>(</code></td><td>int <var class="pdparam">fd</var>, </td></tr><tr><td> </td><td>int <var class="pdparam">request</var>, </td></tr><tr><td> </td><td>const struct v4l2_modulator
*<var class="pdparam">argp</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="id-1.4.11.36.4"></a><h2>Arguments</h2><div class="variablelist"><dl class="variablelist"><dt><span class="term"><em class="parameter"><code>fd</code></em></span></dt><dd><p>File descriptor returned by <a class="link" href="func-open.html" title="V4L2 open()"><code class="function">open()</code></a>.</p></dd><dt><span class="term"><em class="parameter"><code>request</code></em></span></dt><dd><p>VIDIOC_G_MODULATOR, VIDIOC_S_MODULATOR</p></dd><dt><span class="term"><em class="parameter"><code>argp</code></em></span></dt><dd><p></p></dd></dl></div></div><div class="refsect1"><a name="id-1.4.11.36.5"></a><h2>Description</h2><p>To query the attributes of a modulator applications initialize
the <em class="structfield"><code>index</code></em> field and zero out the
<em class="structfield"><code>reserved</code></em> array of a struct <a class="link" href="vidioc-g-modulator.html#v4l2-modulator" title="Table A.76. struct v4l2_modulator">v4l2_modulator</a> and
call the <code class="constant">VIDIOC_G_MODULATOR</code> ioctl with a pointer
to this structure. Drivers fill the rest of the structure or return an
<span class="errorcode">EINVAL</span> error code when the index is out of bounds. To enumerate all modulators
applications shall begin at index zero, incrementing by one until the
driver returns <span class="errorcode">EINVAL</span>.</p><p>Modulators have two writable properties, an audio
modulation set and the radio frequency. To change the modulated audio
subprograms, applications initialize the <em class="structfield"><code>index
</code></em> and <em class="structfield"><code>txsubchans</code></em> fields and the
<em class="structfield"><code>reserved</code></em> array and call the
<code class="constant">VIDIOC_S_MODULATOR</code> ioctl. Drivers may choose a
different audio modulation if the request cannot be satisfied. However
this is a write-only ioctl, it does not return the actual audio
modulation selected.</p><p><a class="link" href="sdr.html" title="Software Defined Radio Interface (SDR)">SDR</a> specific modulator types are
<code class="constant">V4L2_TUNER_SDR</code> and <code class="constant">V4L2_TUNER_RF</code>.
For SDR devices <em class="structfield"><code>txsubchans</code></em> field must be
initialized to zero.
The term 'modulator' means SDR transmitter in this context.</p><p>To change the radio frequency the <a class="link" href="vidioc-g-frequency.html" title="ioctl VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY"><code class="constant">VIDIOC_S_FREQUENCY</code></a> ioctl
is available.</p><div class="table"><a name="v4l2-modulator"></a><p class="title"><b>Table A.76. struct <span class="structname">v4l2_modulator</span></b></p><div class="table-contents"><table summary="struct v4l2_modulator" width="100%" border="0"><colgroup><col class="c1"><col class="c2"><col class="c3"></colgroup><tbody valign="top"><tr><td valign="top">__u32</td><td valign="top"><em class="structfield"><code>index</code></em></td><td valign="top">Identifies the modulator, set by the
application.</td></tr><tr><td valign="top">__u8</td><td valign="top"><em class="structfield"><code>name</code></em>[32]</td><td valign="top">Name of the modulator, a NUL-terminated ASCII
string. This information is intended for the user.</td></tr><tr><td valign="top">__u32</td><td valign="top"><em class="structfield"><code>capability</code></em></td><td valign="top">Modulator capability flags. No flags are defined
for this field, the tuner flags in struct <a class="link" href="vidioc-g-tuner.html#v4l2-tuner" title="Table A.87. struct v4l2_tuner">v4l2_tuner</a>
are used accordingly. The audio flags indicate the ability
to encode audio subprograms. They will <span class="emphasis"><em>not</em></span>
change for example with the current video standard.</td></tr><tr><td valign="top">__u32</td><td valign="top"><em class="structfield"><code>rangelow</code></em></td><td valign="top">The lowest tunable frequency in units of 62.5
KHz, or if the <em class="structfield"><code>capability</code></em> flag
<code class="constant">V4L2_TUNER_CAP_LOW</code> is set, in units of 62.5
Hz, or if the <em class="structfield"><code>capability</code></em> flag
<code class="constant">V4L2_TUNER_CAP_1HZ</code> is set, in units of 1 Hz.</td></tr><tr><td valign="top">__u32</td><td valign="top"><em class="structfield"><code>rangehigh</code></em></td><td valign="top">The highest tunable frequency in units of 62.5
KHz, or if the <em class="structfield"><code>capability</code></em> flag
<code class="constant">V4L2_TUNER_CAP_LOW</code> is set, in units of 62.5
Hz, or if the <em class="structfield"><code>capability</code></em> flag
<code class="constant">V4L2_TUNER_CAP_1HZ</code> is set, in units of 1 Hz.</td></tr><tr><td valign="top">__u32</td><td valign="top"><em class="structfield"><code>txsubchans</code></em></td><td valign="top">With this field applications can determine how
audio sub-carriers shall be modulated. It contains a set of flags as
defined in <a class="xref" href="vidioc-g-modulator.html#modulator-txsubchans" title="Table A.77. Modulator Audio Transmission Flags">Table A.77, “Modulator Audio Transmission Flags”</a>. Note the tuner
<em class="structfield"><code>rxsubchans</code></em> flags are reused, but the
semantics are different. Video output devices are assumed to have an
analog or PCM audio input with 1-3 channels. The
<em class="structfield"><code>txsubchans</code></em> flags select one or more
channels for modulation, together with some audio subprogram
indicator, for example a stereo pilot tone.</td></tr><tr><td valign="top">__u32</td><td valign="top"><em class="structfield"><code>type</code></em></td><td colspan="3" valign="top">Type of the modulator, see <a class="xref" href="vidioc-g-tuner.html#v4l2-tuner-type" title="Table A.88. enum v4l2_tuner_type">Table A.88, “enum v4l2_tuner_type”</a>.</td></tr><tr><td valign="top">__u32</td><td valign="top"><em class="structfield"><code>reserved</code></em>[3]</td><td valign="top">Reserved for future extensions. Drivers and
applications must set the array to zero.</td></tr></tbody></table></div></div><br class="table-break"><div class="table"><a name="modulator-txsubchans"></a><p class="title"><b>Table A.77. Modulator Audio Transmission Flags</b></p><div class="table-contents"><table summary="Modulator Audio Transmission Flags" width="100%" border="0"><colgroup><col class="c1"><col class="c2"><col class="c3"></colgroup><tbody valign="top"><tr><td valign="top"><code class="constant">V4L2_TUNER_SUB_MONO</code></td><td valign="top">0x0001</td><td valign="top">Modulate channel 1 as mono audio, when the input
has more channels, a down-mix of channel 1 and 2. This flag does not
combine with <code class="constant">V4L2_TUNER_SUB_STEREO</code> or
<code class="constant">V4L2_TUNER_SUB_LANG1</code>.</td></tr><tr><td valign="top"><code class="constant">V4L2_TUNER_SUB_STEREO</code></td><td valign="top">0x0002</td><td valign="top">Modulate channel 1 and 2 as left and right
channel of a stereo audio signal. When the input has only one channel
or two channels and <code class="constant">V4L2_TUNER_SUB_SAP</code> is also
set, channel 1 is encoded as left and right channel. This flag does
not combine with <code class="constant">V4L2_TUNER_SUB_MONO</code> or
<code class="constant">V4L2_TUNER_SUB_LANG1</code>. When the driver does not
support stereo audio it shall fall back to mono.</td></tr><tr><td valign="top"><code class="constant">V4L2_TUNER_SUB_LANG1</code></td><td valign="top">0x0008</td><td valign="top">Modulate channel 1 and 2 as primary and secondary
language of a bilingual audio signal. When the input has only one
channel it is used for both languages. It is not possible to encode
the primary or secondary language only. This flag does not combine
with <code class="constant">V4L2_TUNER_SUB_MONO</code>,
<code class="constant">V4L2_TUNER_SUB_STEREO</code> or
<code class="constant">V4L2_TUNER_SUB_SAP</code>. If the hardware does not
support the respective audio matrix, or the current video standard
does not permit bilingual audio the
<code class="constant">VIDIOC_S_MODULATOR</code> ioctl shall return an <span class="errorcode">EINVAL</span> error code
and the driver shall fall back to mono or stereo mode.</td></tr><tr><td valign="top"><code class="constant">V4L2_TUNER_SUB_LANG2</code></td><td valign="top">0x0004</td><td valign="top">Same effect as
<code class="constant">V4L2_TUNER_SUB_SAP</code>.</td></tr><tr><td valign="top"><code class="constant">V4L2_TUNER_SUB_SAP</code></td><td valign="top">0x0004</td><td valign="top">When combined with <code class="constant">V4L2_TUNER_SUB_MONO
</code> the first channel is encoded as mono audio, the last
channel as Second Audio Program. When the input has only one channel
it is used for both audio tracks. When the input has three channels
the mono track is a down-mix of channel 1 and 2. When combined with
<code class="constant">V4L2_TUNER_SUB_STEREO</code> channel 1 and 2 are
encoded as left and right stereo audio, channel 3 as Second Audio
Program. When the input has only two channels, the first is encoded as
left and right channel and the second as SAP. When the input has only
one channel it is used for all audio tracks. It is not possible to
encode a Second Audio Program only. This flag must combine with
<code class="constant">V4L2_TUNER_SUB_MONO</code> or
<code class="constant">V4L2_TUNER_SUB_STEREO</code>. If the hardware does not
support the respective audio matrix, or the current video standard
does not permit SAP the <code class="constant">VIDIOC_S_MODULATOR</code> ioctl
shall return an <span class="errorcode">EINVAL</span> error code and driver shall fall back to mono or stereo
mode.</td></tr><tr><td valign="top"><code class="constant">V4L2_TUNER_SUB_RDS</code></td><td valign="top">0x0010</td><td valign="top">Enable the RDS encoder for a radio FM transmitter.</td></tr></tbody></table></div></div><br class="table-break"></div><div class="refsect1"><a name="id-1.4.11.36.6"></a><h2>Return Value</h2><p>On success <span class="returnvalue">0</span> is returned, on error <span class="returnvalue">-1</span> and the <code class="varname">errno</code> variable is set appropriately. The generic error codes are described at the <a class="link" href="gen_errors.html#gen-errors" title="Table 17.1. Generic error codes">Generic Error Codes</a> chapter.</p><div class="variablelist"><dl class="variablelist"><dt><span class="term"><span class="errorcode">EINVAL</span></span></dt><dd><p>The struct <a class="link" href="vidioc-g-modulator.html#v4l2-modulator" title="Table A.76. struct v4l2_modulator">v4l2_modulator</a>
<em class="structfield"><code>index</code></em> is out of bounds.</p></dd></dl></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="vidioc-g-jpegcomp.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="user-func.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="vidioc-g-output.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">ioctl VIDIOC_G_JPEGCOMP, VIDIOC_S_JPEGCOMP </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> ioctl VIDIOC_G_OUTPUT, VIDIOC_S_OUTPUT</td></tr></table></div></body></html>