[deliverable/linux.git] / Documentation / DocBook / media / v4l / vidioc-g-tuner.xml

<refentry id="vidioc-g-tuner">
  <refmeta>
    <refentrytitle>ioctl VIDIOC_G_TUNER, VIDIOC_S_TUNER</refentrytitle>
    &manvol;
  </refmeta>

  <refnamediv>
    <refname>VIDIOC_G_TUNER</refname>
    <refname>VIDIOC_S_TUNER</refname>
    <refpurpose>Get or set tuner attributes</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <funcsynopsis>
      <funcprototype>
	<funcdef>int <function>ioctl</function></funcdef>
	<paramdef>int <parameter>fd</parameter></paramdef>
	<paramdef>int <parameter>request</parameter></paramdef>
	<paramdef>struct v4l2_tuner
*<parameter>argp</parameter></paramdef>
      </funcprototype>
    </funcsynopsis>
    <funcsynopsis>
      <funcprototype>
	<funcdef>int <function>ioctl</function></funcdef>
	<paramdef>int <parameter>fd</parameter></paramdef>
	<paramdef>int <parameter>request</parameter></paramdef>
	<paramdef>const struct v4l2_tuner
*<parameter>argp</parameter></paramdef>
      </funcprototype>
    </funcsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Arguments</title>

    <variablelist>
      <varlistentry>
	<term><parameter>fd</parameter></term>
	<listitem>
	  <para>&fd;</para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term><parameter>request</parameter></term>
	<listitem>
	  <para>VIDIOC_G_TUNER, VIDIOC_S_TUNER</para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term><parameter>argp</parameter></term>
	<listitem>
	  <para></para>
	</listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Description</title>

    <para>To query the attributes of a tuner applications initialize the
<structfield>index</structfield> field and zero out the
<structfield>reserved</structfield> array of a &v4l2-tuner; and call the
<constant>VIDIOC_G_TUNER</constant> ioctl with a pointer to this
structure. Drivers fill the rest of the structure or return an
&EINVAL; when the index is out of bounds. To enumerate all tuners
applications shall begin at index zero, incrementing by one until the
driver returns <errorcode>EINVAL</errorcode>.</para>

    <para>Tuners have two writable properties, the audio mode and
the radio frequency. To change the audio mode, applications initialize
the <structfield>index</structfield>,
<structfield>audmode</structfield> and
<structfield>reserved</structfield> fields and call the
<constant>VIDIOC_S_TUNER</constant> ioctl. This will
<emphasis>not</emphasis> change the current tuner, which is determined
by the current video input. Drivers may choose a different audio mode
if the requested mode is invalid or unsupported. Since this is a
<!-- FIXME -->write-only ioctl, it does not return the actually
selected audio mode.</para>

    <para>To change the radio frequency the &VIDIOC-S-FREQUENCY; ioctl
is available.</para>

    <table pgwide="1" frame="none" id="v4l2-tuner">
      <title>struct <structname>v4l2_tuner</structname></title>
      <tgroup cols="3">
	<colspec colname="c1" colwidth="1*" />
	<colspec colname="c2" colwidth="1*" />
	<colspec colname="c3" colwidth="1*" />
	<colspec colname="c4" colwidth="1*" />
	<spanspec spanname="hspan" namest="c3" nameend="c4" />
	<tbody valign="top">
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>index</structfield></entry>
	    <entry spanname="hspan">Identifies the tuner, set by the
application.</entry>
	  </row>
	  <row>
	    <entry>__u8</entry>
	    <entry><structfield>name</structfield>[32]</entry>
	    <entry spanname="hspan"><para>Name of the tuner, a
NUL-terminated ASCII string. This information is intended for the
user.<!-- FIXME Video inputs already have a name, the purpose of this
field is not quite clear.--></para></entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>type</structfield></entry>
	    <entry spanname="hspan">Type of the tuner, see <xref
		linkend="v4l2-tuner-type" />.</entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>capability</structfield></entry>
	    <entry spanname="hspan"><para>Tuner capability flags, see
<xref linkend="tuner-capability" />. Audio flags indicate the ability
to decode audio subprograms. They will <emphasis>not</emphasis>
change, for example with the current video standard.</para><para>When
the structure refers to a radio tuner only the
<constant>V4L2_TUNER_CAP_LOW</constant>,
<constant>V4L2_TUNER_CAP_STEREO</constant> and
<constant>V4L2_TUNER_CAP_RDS</constant> flags can be set.</para></entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>rangelow</structfield></entry>
	    <entry spanname="hspan">The lowest tunable frequency in
units of 62.5 kHz, or if the <structfield>capability</structfield>
flag <constant>V4L2_TUNER_CAP_LOW</constant> is set, in units of 62.5
Hz.</entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>rangehigh</structfield></entry>
	    <entry spanname="hspan">The highest tunable frequency in
units of 62.5 kHz, or if the <structfield>capability</structfield>
flag <constant>V4L2_TUNER_CAP_LOW</constant> is set, in units of 62.5
Hz.</entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>rxsubchans</structfield></entry>
	    <entry spanname="hspan"><para>Some tuners or audio
decoders can determine the received audio subprograms by analyzing
audio carriers, pilot tones or other indicators. To pass this
information drivers set flags defined in <xref
		  linkend="tuner-rxsubchans" /> in this field. For
example:</para></entry>
	  </row>
	  <row>
	    <entry></entry>
	    <entry></entry>
	    <entry><constant>V4L2_TUNER_SUB_MONO</constant></entry>
	    <entry>receiving mono audio</entry>
	  </row>
	  <row>
	    <entry></entry>
	    <entry></entry>
	    <entry><constant>STEREO | SAP</constant></entry>
	    <entry>receiving stereo audio and a secondary audio
program</entry>
	  </row>
	  <row>
	    <entry></entry>
	    <entry></entry>
	    <entry><constant>MONO | STEREO</constant></entry>
	    <entry>receiving mono or stereo audio, the hardware cannot
distinguish</entry>
	  </row>
	  <row>
	    <entry></entry>
	    <entry></entry>
	    <entry><constant>LANG1 | LANG2</constant></entry>
	    <entry>receiving bilingual audio</entry>
	  </row>
	  <row>
	    <entry></entry>
	    <entry></entry>
	    <entry><constant>MONO | STEREO | LANG1 | LANG2</constant></entry>
	    <entry>receiving mono, stereo or bilingual
audio</entry>
	  </row>
	  <row>
	    <entry></entry>
	    <entry></entry>
	    <entry spanname="hspan"><para>When the
<constant>V4L2_TUNER_CAP_STEREO</constant>,
<constant>_LANG1</constant>, <constant>_LANG2</constant> or
<constant>_SAP</constant> flag is cleared in the
<structfield>capability</structfield> field, the corresponding
<constant>V4L2_TUNER_SUB_</constant> flag must not be set
here.</para><para>This field is valid only if this is the tuner of the
current video input, or when the structure refers to a radio
tuner.</para></entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>audmode</structfield></entry>
	    <entry spanname="hspan"><para>The selected audio mode, see
<xref linkend="tuner-audmode" /> for valid values. The audio mode does
not affect audio subprogram detection, and like a <link
linkend="control">control</link> it does not automatically change
unless the requested mode is invalid or unsupported. See <xref
		  linkend="tuner-matrix" /> for possible results when
the selected and received audio programs do not
match.</para><para>Currently this is the only field of struct
<structname>v4l2_tuner</structname> applications can
change.</para></entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>signal</structfield></entry>
	    <entry spanname="hspan">The signal strength if known, ranging
from 0 to 65535. Higher values indicate a better signal.</entry>
	  </row>
	  <row>
	    <entry>__s32</entry>
	    <entry><structfield>afc</structfield></entry>
	    <entry spanname="hspan">Automatic frequency control: When the
<structfield>afc</structfield> value is negative, the frequency is too
low, when positive too high.<!-- FIXME need example what to do when it never
settles at zero, &ie; range is what? --></entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>reserved</structfield>[4]</entry>
	    <entry spanname="hspan">Reserved for future extensions. Drivers and
applications must set the array to zero.</entry>
	  </row>
	</tbody>
      </tgroup>
    </table>

    <table pgwide="1" frame="none" id="v4l2-tuner-type">
      <title>enum v4l2_tuner_type</title>
      <tgroup cols="3">
	&cs-def;
	<tbody valign="top">
	  <row>
	    <entry><constant>V4L2_TUNER_RADIO</constant></entry>
	    <entry>1</entry>
	    <entry></entry>
	  </row>
	  <row>
	    <entry><constant>V4L2_TUNER_ANALOG_TV</constant></entry>
	    <entry>2</entry>
	    <entry></entry>
	  </row>
	</tbody>
      </tgroup>
    </table>

    <table pgwide="1" frame="none" id="tuner-capability">
      <title>Tuner and Modulator Capability Flags</title>
      <tgroup cols="3">
	&cs-def;
	<tbody valign="top">
	  <row>
	    <entry><constant>V4L2_TUNER_CAP_LOW</constant></entry>
	    <entry>0x0001</entry>
	    <entry>When set, tuning frequencies are expressed in units of
62.5&nbsp;Hz, otherwise in units of 62.5&nbsp;kHz.</entry>
	  </row>
	  <row>
	    <entry><constant>V4L2_TUNER_CAP_NORM</constant></entry>
	    <entry>0x0002</entry>
	    <entry>This is a multi-standard tuner; the video standard
can or must be switched. (B/G PAL tuners for example are typically not
      considered multi-standard because the video standard is automatically
      determined from the frequency band.) The set of supported video
      standards is available from the &v4l2-input; pointing to this tuner,
      see the description of ioctl &VIDIOC-ENUMINPUT; for details. Only
      <constant>V4L2_TUNER_ANALOG_TV</constant> tuners can have this capability.</entry>
	  </row>
	  <row>
	<entry><constant>V4L2_TUNER_CAP_STEREO</constant></entry>
	<entry>0x0010</entry>
	<entry>Stereo audio reception is supported.</entry>
	  </row>
	  <row>
	    <entry><constant>V4L2_TUNER_CAP_LANG1</constant></entry>
	    <entry>0x0040</entry>
	    <entry>Reception of the primary language of a bilingual
audio program is supported. Bilingual audio is a feature of
two-channel systems, transmitting the primary language monaural on the
main audio carrier and a secondary language monaural on a second
carrier. Only
      <constant>V4L2_TUNER_ANALOG_TV</constant> tuners can have this capability.</entry>
	  </row>
	  <row>
	    <entry><constant>V4L2_TUNER_CAP_LANG2</constant></entry>
	    <entry>0x0020</entry>
	    <entry>Reception of the secondary language of a bilingual
audio program is supported. Only
      <constant>V4L2_TUNER_ANALOG_TV</constant> tuners can have this capability.</entry>
	  </row>
	  <row>
	    <entry><constant>V4L2_TUNER_CAP_SAP</constant></entry>
	    <entry>0x0020</entry>
	    <entry><para>Reception of a secondary audio program is
supported. This is a feature of the BTSC system which accompanies the
NTSC video standard. Two audio carriers are available for mono or
stereo transmissions of a primary language, and an independent third
carrier for a monaural secondary language. Only
      <constant>V4L2_TUNER_ANALOG_TV</constant> tuners can have this capability.</para><para>Note the
<constant>V4L2_TUNER_CAP_LANG2</constant> and
<constant>V4L2_TUNER_CAP_SAP</constant> flags are synonyms.
<constant>V4L2_TUNER_CAP_SAP</constant> applies when the tuner
supports the <constant>V4L2_STD_NTSC_M</constant> video
standard.</para><!-- FIXME what if PAL+NTSC and Bi but not SAP? --></entry>
	  </row>
	  <row>
	<entry><constant>V4L2_TUNER_CAP_RDS</constant></entry>
	<entry>0x0080</entry>
	<entry>RDS capture is supported. This capability is only valid for
radio tuners.</entry>
	  </row>
	  <row>
	<entry><constant>V4L2_TUNER_CAP_RDS_BLOCK_IO</constant></entry>
	<entry>0x0100</entry>
	<entry>The RDS data is passed as unparsed RDS blocks.</entry>
	  </row>
	  <row>
	<entry><constant>V4L2_TUNER_CAP_RDS_CONTROLS</constant></entry>
	<entry>0x0200</entry>
	<entry>The RDS data is parsed by the hardware and set via controls.</entry>
	  </row>
	</tbody>
      </tgroup>
    </table>

    <table pgwide="1" frame="none" id="tuner-rxsubchans">
      <title>Tuner Audio Reception Flags</title>
      <tgroup cols="3">
	&cs-def;
	<tbody valign="top">
	  <row>
	    <entry><constant>V4L2_TUNER_SUB_MONO</constant></entry>
	    <entry>0x0001</entry>
	    <entry>The tuner receives a mono audio signal.</entry>
	  </row>
	  <row>
	    <entry><constant>V4L2_TUNER_SUB_STEREO</constant></entry>
	    <entry>0x0002</entry>
	    <entry>The tuner receives a stereo audio signal.</entry>
	  </row>
	  <row>
	    <entry><constant>V4L2_TUNER_SUB_LANG1</constant></entry>
	    <entry>0x0008</entry>
	    <entry>The tuner receives the primary language of a
bilingual audio signal. Drivers must clear this flag when the current
video standard is <constant>V4L2_STD_NTSC_M</constant>.</entry>
	  </row>
	  <row>
	    <entry><constant>V4L2_TUNER_SUB_LANG2</constant></entry>
	    <entry>0x0004</entry>
	    <entry>The tuner receives the secondary language of a
bilingual audio signal (or a second audio program).</entry>
	  </row>
	  <row>
	    <entry><constant>V4L2_TUNER_SUB_SAP</constant></entry>
	    <entry>0x0004</entry>
	    <entry>The tuner receives a Second Audio Program. Note the
<constant>V4L2_TUNER_SUB_LANG2</constant> and
<constant>V4L2_TUNER_SUB_SAP</constant> flags are synonyms. The
<constant>V4L2_TUNER_SUB_SAP</constant> flag applies when the
current video standard is <constant>V4L2_STD_NTSC_M</constant>.</entry>
	  </row>
	  <row>
	    <entry><constant>V4L2_TUNER_SUB_RDS</constant></entry>
	    <entry>0x0010</entry>
	    <entry>The tuner receives an RDS channel.</entry>
	  </row>
	</tbody>
      </tgroup>
    </table>

    <table pgwide="1" frame="none" id="tuner-audmode">
      <title>Tuner Audio Modes</title>
      <tgroup cols="3">
	&cs-def;
	<tbody valign="top">
	  <row>
	    <entry><constant>V4L2_TUNER_MODE_MONO</constant></entry>
	    <entry>0</entry>
	    <entry>Play mono audio. When the tuner receives a stereo
signal this a down-mix of the left and right channel. When the tuner
receives a bilingual or SAP signal this mode selects the primary
language.</entry>
	  </row>
	  <row>
	    <entry><constant>V4L2_TUNER_MODE_STEREO</constant></entry>
	    <entry>1</entry>
	    <entry><para>Play stereo audio. When the tuner receives
bilingual audio it may play different languages on the left and right
channel or the primary language is played on both channels.</para><para>Playing
different languages in this mode is
deprecated. New drivers should do this only in
<constant>MODE_LANG1_LANG2</constant>.</para><para>When the tuner
receives no stereo signal or does not support stereo reception the
driver shall fall back to <constant>MODE_MONO</constant>.</para></entry>
	  </row>
	  <row>
	    <entry><constant>V4L2_TUNER_MODE_LANG1</constant></entry>
	    <entry>3</entry>
	    <entry>Play the primary language, mono or stereo. Only
<constant>V4L2_TUNER_ANALOG_TV</constant> tuners support this
mode.</entry>
	  </row>
	  <row>
	    <entry><constant>V4L2_TUNER_MODE_LANG2</constant></entry>
	    <entry>2</entry>
	    <entry>Play the secondary language, mono. When the tuner
receives no bilingual audio or SAP, or their reception is not
supported the driver shall fall back to mono or stereo mode. Only
<constant>V4L2_TUNER_ANALOG_TV</constant> tuners support this
mode.</entry>
	  </row>
	  <row>
	    <entry><constant>V4L2_TUNER_MODE_SAP</constant></entry>
	    <entry>2</entry>
	    <entry>Play the Second Audio Program. When the tuner
receives no bilingual audio or SAP, or their reception is not
supported the driver shall fall back to mono or stereo mode. Only
<constant>V4L2_TUNER_ANALOG_TV</constant> tuners support this mode.
Note the <constant>V4L2_TUNER_MODE_LANG2</constant> and
<constant>V4L2_TUNER_MODE_SAP</constant> are synonyms.</entry>
	  </row>
	  <row>
	    <entry><constant>V4L2_TUNER_MODE_LANG1_LANG2</constant></entry>
	    <entry>4</entry>
	    <entry>Play the primary language on the left channel, the
secondary language on the right channel. When the tuner receives no
bilingual audio or SAP, it shall fall back to
<constant>MODE_LANG1</constant> or <constant>MODE_MONO</constant>.
Only <constant>V4L2_TUNER_ANALOG_TV</constant> tuners support this
mode.</entry>
	  </row>
	</tbody>
      </tgroup>
    </table>

    <table pgwide="1" frame="all" id="tuner-matrix">
      <title>Tuner Audio Matrix</title>
      <tgroup cols="6" align="center">
	<colspec align="left" />
	<colspec colname="c2" colwidth="1*" />
	<colspec colwidth="1*" />
	<colspec colwidth="1*" />
	<colspec colnum="6" colname="c6" colwidth="1*" />
	<spanspec namest="c2" nameend="c6" spanname="hspan" align="center" />
	<thead>
	  <row>
	    <entry></entry>
	    <entry spanname="hspan">Selected
<constant>V4L2_TUNER_MODE_</constant></entry>
	  </row>
	  <row>
	    <entry>Received <constant>V4L2_TUNER_SUB_</constant></entry>
	    <entry><constant>MONO</constant></entry>
	    <entry><constant>STEREO</constant></entry>
	    <entry><constant>LANG1</constant></entry>
	    <entry><constant>LANG2 = SAP</constant></entry>
	    <entry><constant>LANG1_LANG2</constant><footnote><para>This
mode has been added in Linux 2.6.17 and may not be supported by older
drivers.</para></footnote></entry>
	  </row>
	</thead>
	<tbody valign="top">
	  <row>
	    <entry><constant>MONO</constant></entry>
	    <entry>Mono</entry>
	    <entry>Mono/Mono</entry>
	    <entry>Mono</entry>
	    <entry>Mono</entry>
	    <entry>Mono/Mono</entry>
	  </row>
	  <row>
	    <entry><constant>MONO | SAP</constant></entry>
	    <entry>Mono</entry>
	    <entry>Mono/Mono</entry>
	    <entry>Mono</entry>
	    <entry>SAP</entry>
	    <entry>Mono/SAP (preferred) or Mono/Mono</entry>
	  </row>
	  <row>
	    <entry><constant>STEREO</constant></entry>
	    <entry>L+R</entry>
	    <entry>L/R</entry>
	    <entry>Stereo L/R (preferred) or Mono L+R</entry>
	    <entry>Stereo L/R (preferred) or Mono L+R</entry>
	    <entry>L/R (preferred) or L+R/L+R</entry>
	  </row>
	  <row>
	    <entry><constant>STEREO | SAP</constant></entry>
	    <entry>L+R</entry>
	    <entry>L/R</entry>
	    <entry>Stereo L/R (preferred) or Mono L+R</entry>
	    <entry>SAP</entry>
	    <entry>L+R/SAP (preferred) or L/R or L+R/L+R</entry>
	  </row>
	  <row>
	    <entry><constant>LANG1 | LANG2</constant></entry>
	    <entry>Language&nbsp;1</entry>
	    <entry>Lang1/Lang2 (deprecated<footnote><para>Playback of
both languages in <constant>MODE_STEREO</constant> is deprecated. In
the future drivers should produce only the primary language in this
mode. Applications should request
<constant>MODE_LANG1_LANG2</constant> to record both languages or a
stereo signal.</para></footnote>) or
Lang1/Lang1</entry>
	    <entry>Language&nbsp;1</entry>
	    <entry>Language&nbsp;2</entry>
	    <entry>Lang1/Lang2 (preferred) or Lang1/Lang1</entry>
	  </row>
	</tbody>
      </tgroup>
    </table>
  </refsect1>

  <refsect1>
    &return-value;

    <variablelist>
      <varlistentry>
	<term><errorcode>EINVAL</errorcode></term>
	<listitem>
	  <para>The &v4l2-tuner; <structfield>index</structfield> is
out of bounds.</para>
	</listitem>
      </varlistentry>
    </variablelist>
  </refsect1>
</refentry>
Commit	Line	Data
8e080c2e MCC	1	<refentry id="vidioc-g-tuner">
	2	<refmeta>
	3	<refentrytitle>ioctl VIDIOC_G_TUNER, VIDIOC_S_TUNER</refentrytitle>
	4	&manvol;
	5	</refmeta>
	6
	7	<refnamediv>
	8	<refname>VIDIOC_G_TUNER</refname>
	9	<refname>VIDIOC_S_TUNER</refname>
	10	<refpurpose>Get or set tuner attributes</refpurpose>
	11	</refnamediv>
	12
	13	<refsynopsisdiv>
	14	<funcsynopsis>
	15	<funcprototype>
	16	<funcdef>int <function>ioctl</function></funcdef>
	17	<paramdef>int <parameter>fd</parameter></paramdef>
	18	<paramdef>int <parameter>request</parameter></paramdef>
	19	<paramdef>struct v4l2_tuner
	20	*<parameter>argp</parameter></paramdef>
	21	</funcprototype>
	22	</funcsynopsis>
	23	<funcsynopsis>
	24	<funcprototype>
	25	<funcdef>int <function>ioctl</function></funcdef>
	26	<paramdef>int <parameter>fd</parameter></paramdef>
	27	<paramdef>int <parameter>request</parameter></paramdef>
	28	<paramdef>const struct v4l2_tuner
	29	*<parameter>argp</parameter></paramdef>
	30	</funcprototype>
	31	</funcsynopsis>
	32	</refsynopsisdiv>
	33
	34	<refsect1>
	35	<title>Arguments</title>
	36
	37	<variablelist>
	38	<varlistentry>
	39	<term><parameter>fd</parameter></term>
	40	<listitem>
	41	<para>&fd;</para>
	42	</listitem>
	43	</varlistentry>
	44	<varlistentry>
	45	<term><parameter>request</parameter></term>
	46	<listitem>
	47	<para>VIDIOC_G_TUNER, VIDIOC_S_TUNER</para>
	48	</listitem>
	49	</varlistentry>
	50	<varlistentry>
	51	<term><parameter>argp</parameter></term>
	52	<listitem>
	53	<para></para>
	54	</listitem>
	55	</varlistentry>
	56	</variablelist>
	57	</refsect1>
	58
	59	<refsect1>
	60	<title>Description</title>
	61
	62	<para>To query the attributes of a tuner applications initialize the
	63	<structfield>index</structfield> field and zero out the
	64	<structfield>reserved</structfield> array of a &v4l2-tuner; and call the
65	<constant>VIDIOC_G_TUNER</constant> ioctl with a pointer to this
66	structure. Drivers fill the rest of the structure or return an
67	&EINVAL; when the index is out of bounds. To enumerate all tuners
68	applications shall begin at index zero, incrementing by one until the
69	driver returns <errorcode>EINVAL</errorcode>.</para>
70
71	<para>Tuners have two writable properties, the audio mode and
72	the radio frequency. To change the audio mode, applications initialize
73	the <structfield>index</structfield>,
74	<structfield>audmode</structfield> and
75	<structfield>reserved</structfield> fields and call the
76	<constant>VIDIOC_S_TUNER</constant> ioctl. This will
77	<emphasis>not</emphasis> change the current tuner, which is determined
78	by the current video input. Drivers may choose a different audio mode
79	if the requested mode is invalid or unsupported. Since this is a
80	<!-- FIXME -->write-only ioctl, it does not return the actually
81	selected audio mode.</para>
82
83	<para>To change the radio frequency the &VIDIOC-S-FREQUENCY; ioctl
84	is available.</para>
85
86	<table pgwide="1" frame="none" id="v4l2-tuner">
87	<title>struct <structname>v4l2_tuner</structname></title>
88	<tgroup cols="3">
89	<colspec colname="c1" colwidth="1*" />
90	<colspec colname="c2" colwidth="1*" />
91	<colspec colname="c3" colwidth="1*" />
92	<colspec colname="c4" colwidth="1*" />
93	<spanspec spanname="hspan" namest="c3" nameend="c4" />
94	<tbody valign="top">
95	<row>
96	<entry>__u32</entry>
97	<entry><structfield>index</structfield></entry>
98	<entry spanname="hspan">Identifies the tuner, set by the
99	application.</entry>
100	</row>
101	<row>
102	<entry>__u8</entry>
103	<entry><structfield>name</structfield>[32]</entry>
104	<entry spanname="hspan"><para>Name of the tuner, a
105	NUL-terminated ASCII string. This information is intended for the
106	user.<!-- FIXME Video inputs already have a name, the purpose of this
107	field is not quite clear.--></para></entry>
108	</row>
109	<row>
6016af82	110	<entry>__u32</entry>
8e080c2e MCC	111	<entry><structfield>type</structfield></entry>
	112	<entry spanname="hspan">Type of the tuner, see <xref
	113	linkend="v4l2-tuner-type" />.</entry>
	114	</row>
	115	<row>
	116	<entry>__u32</entry>
	117	<entry><structfield>capability</structfield></entry>
	118	<entry spanname="hspan"><para>Tuner capability flags, see
	119	<xref linkend="tuner-capability" />. Audio flags indicate the ability
	120	to decode audio subprograms. They will <emphasis>not</emphasis>
	121	change, for example with the current video standard.</para><para>When
	122	the structure refers to a radio tuner only the
	123	<constant>V4L2_TUNER_CAP_LOW</constant>,
	124	<constant>V4L2_TUNER_CAP_STEREO</constant> and
	125	<constant>V4L2_TUNER_CAP_RDS</constant> flags can be set.</para></entry>
	126	</row>
	127	<row>
	128	<entry>__u32</entry>
	129	<entry><structfield>rangelow</structfield></entry>
	130	<entry spanname="hspan">The lowest tunable frequency in
	131	units of 62.5 kHz, or if the <structfield>capability</structfield>
	132	flag <constant>V4L2_TUNER_CAP_LOW</constant> is set, in units of 62.5
	133	Hz.</entry>
	134	</row>
	135	<row>
	136	<entry>__u32</entry>
	137	<entry><structfield>rangehigh</structfield></entry>
	138	<entry spanname="hspan">The highest tunable frequency in
	139	units of 62.5 kHz, or if the <structfield>capability</structfield>
	140	flag <constant>V4L2_TUNER_CAP_LOW</constant> is set, in units of 62.5
	141	Hz.</entry>
	142	</row>
	143	<row>
	144	<entry>__u32</entry>
	145	<entry><structfield>rxsubchans</structfield></entry>
	146	<entry spanname="hspan"><para>Some tuners or audio
	147	decoders can determine the received audio subprograms by analyzing
	148	audio carriers, pilot tones or other indicators. To pass this
	149	information drivers set flags defined in <xref
	150	linkend="tuner-rxsubchans" /> in this field. For
	151	example:</para></entry>
	152	</row>
	153	<row>
	154	<entry></entry>
	155	<entry></entry>
	156	<entry><constant>V4L2_TUNER_SUB_MONO</constant></entry>
	157	<entry>receiving mono audio</entry>
	158	</row>
	159	<row>
	160	<entry></entry>
	161	<entry></entry>
	162	<entry><constant>STEREO \| SAP</constant></entry>
	163	<entry>receiving stereo audio and a secondary audio
	164	program</entry>
	165	</row>
	166	<row>
	167	<entry></entry>
	168	<entry></entry>
	169	<entry><constant>MONO \| STEREO</constant></entry>
	170	<entry>receiving mono or stereo audio, the hardware cannot
	171	distinguish</entry>
	172	</row>
	173	<row>
	174	<entry></entry>
175	<entry></entry>
176	<entry><constant>LANG1 \| LANG2</constant></entry>
177	<entry>receiving bilingual audio</entry>
178	</row>
179	<row>
180	<entry></entry>
181	<entry></entry>
182	<entry><constant>MONO \| STEREO \| LANG1 \| LANG2</constant></entry>
183	<entry>receiving mono, stereo or bilingual
184	audio</entry>
185	</row>
186	<row>
187	<entry></entry>
188	<entry></entry>
189	<entry spanname="hspan"><para>When the
190	<constant>V4L2_TUNER_CAP_STEREO</constant>,
191	<constant>_LANG1</constant>, <constant>_LANG2</constant> or
192	<constant>_SAP</constant> flag is cleared in the
193	<structfield>capability</structfield> field, the corresponding
194	<constant>V4L2_TUNER_SUB_</constant> flag must not be set
195	here.</para><para>This field is valid only if this is the tuner of the
196	current video input, or when the structure refers to a radio
197	tuner.</para></entry>
198	</row>
199	<row>
200	<entry>__u32</entry>
201	<entry><structfield>audmode</structfield></entry>
202	<entry spanname="hspan"><para>The selected audio mode, see
203	<xref linkend="tuner-audmode" /> for valid values. The audio mode does
204	not affect audio subprogram detection, and like a <link
205	linkend="control">control</link> it does not automatically change
206	unless the requested mode is invalid or unsupported. See <xref
207	linkend="tuner-matrix" /> for possible results when
208	the selected and received audio programs do not
209	match.</para><para>Currently this is the only field of struct
210	<structname>v4l2_tuner</structname> applications can
211	change.</para></entry>
212	</row>
213	<row>
214	<entry>__u32</entry>
215	<entry><structfield>signal</structfield></entry>
216	<entry spanname="hspan">The signal strength if known, ranging
217	from 0 to 65535. Higher values indicate a better signal.</entry>
218	</row>
219	<row>
220	<entry>__s32</entry>
221	<entry><structfield>afc</structfield></entry>
222	<entry spanname="hspan">Automatic frequency control: When the
223	<structfield>afc</structfield> value is negative, the frequency is too
224	low, when positive too high.<!-- FIXME need example what to do when it never
225	settles at zero, &ie; range is what? --></entry>
226	</row>
227	<row>
228	<entry>__u32</entry>
229	<entry><structfield>reserved</structfield>[4]</entry>
230	<entry spanname="hspan">Reserved for future extensions. Drivers and
231	applications must set the array to zero.</entry>
232	</row>
233	</tbody>
234	</tgroup>
235	</table>
236
237	<table pgwide="1" frame="none" id="v4l2-tuner-type">
238	<title>enum v4l2_tuner_type</title>
239	<tgroup cols="3">
240	&cs-def;
241	<tbody valign="top">
242	<row>
243	<entry><constant>V4L2_TUNER_RADIO</constant></entry>
244	<entry>1</entry>
245	<entry></entry>
246	</row>
247	<row>
248	<entry><constant>V4L2_TUNER_ANALOG_TV</constant></entry>
249	<entry>2</entry>
250	<entry></entry>
251	</row>
252	</tbody>
253	</tgroup>
254	</table>
255
256	<table pgwide="1" frame="none" id="tuner-capability">
257	<title>Tuner and Modulator Capability Flags</title>
258	<tgroup cols="3">
259	&cs-def;
260	<tbody valign="top">
261	<row>
262	<entry><constant>V4L2_TUNER_CAP_LOW</constant></entry>
263	<entry>0x0001</entry>
264	<entry>When set, tuning frequencies are expressed in units of
265	62.5 Hz, otherwise in units of 62.5 kHz.</entry>
266	</row>
267	<row>
268	<entry><constant>V4L2_TUNER_CAP_NORM</constant></entry>
269	<entry>0x0002</entry>
270	<entry>This is a multi-standard tuner; the video standard
271	can or must be switched. (B/G PAL tuners for example are typically not
272	considered multi-standard because the video standard is automatically
273	determined from the frequency band.) The set of supported video
274	standards is available from the &v4l2-input; pointing to this tuner,
275	see the description of ioctl &VIDIOC-ENUMINPUT; for details. Only
276	<constant>V4L2_TUNER_ANALOG_TV</constant> tuners can have this capability.</entry>
277	</row>
278	<row>
279	<entry><constant>V4L2_TUNER_CAP_STEREO</constant></entry>
280	<entry>0x0010</entry>
281	<entry>Stereo audio reception is supported.</entry>
282	</row>
283	<row>
284	<entry><constant>V4L2_TUNER_CAP_LANG1</constant></entry>
285	<entry>0x0040</entry>
286	<entry>Reception of the primary language of a bilingual
287	audio program is supported. Bilingual audio is a feature of
288	two-channel systems, transmitting the primary language monaural on the
289	main audio carrier and a secondary language monaural on a second
290	carrier. Only
291	<constant>V4L2_TUNER_ANALOG_TV</constant> tuners can have this capability.</entry>
292	</row>
293	<row>
294	<entry><constant>V4L2_TUNER_CAP_LANG2</constant></entry>
295	<entry>0x0020</entry>
296	<entry>Reception of the secondary language of a bilingual
297	audio program is supported. Only
298	<constant>V4L2_TUNER_ANALOG_TV</constant> tuners can have this capability.</entry>
299	</row>
300	<row>
301	<entry><constant>V4L2_TUNER_CAP_SAP</constant></entry>
302	<entry>0x0020</entry>
303	<entry><para>Reception of a secondary audio program is
304	supported. This is a feature of the BTSC system which accompanies the
305	NTSC video standard. Two audio carriers are available for mono or
306	stereo transmissions of a primary language, and an independent third
307	carrier for a monaural secondary language. Only
308	<constant>V4L2_TUNER_ANALOG_TV</constant> tuners can have this capability.</para><para>Note the
309	<constant>V4L2_TUNER_CAP_LANG2</constant> and
310	<constant>V4L2_TUNER_CAP_SAP</constant> flags are synonyms.
311	<constant>V4L2_TUNER_CAP_SAP</constant> applies when the tuner
312	supports the <constant>V4L2_STD_NTSC_M</constant> video
313	standard.</para><!-- FIXME what if PAL+NTSC and Bi but not SAP? --></entry>
314	</row>
315	<row>
316	<entry><constant>V4L2_TUNER_CAP_RDS</constant></entry>
317	<entry>0x0080</entry>
318	<entry>RDS capture is supported. This capability is only valid for
319	radio tuners.</entry>
320	</row>
146d35b0 HV	321	<row>
	322	<entry><constant>V4L2_TUNER_CAP_RDS_BLOCK_IO</constant></entry>
	323	<entry>0x0100</entry>
	324	<entry>The RDS data is passed as unparsed RDS blocks.</entry>
	325	</row>
	326	<row>
	327	<entry><constant>V4L2_TUNER_CAP_RDS_CONTROLS</constant></entry>
	328	<entry>0x0200</entry>
	329	<entry>The RDS data is parsed by the hardware and set via controls.</entry>
	330	</row>
8e080c2e MCC	331	</tbody>
	332	</tgroup>
	333	</table>
	334
	335	<table pgwide="1" frame="none" id="tuner-rxsubchans">
	336	<title>Tuner Audio Reception Flags</title>
	337	<tgroup cols="3">
	338	&cs-def;
	339	<tbody valign="top">
	340	<row>
	341	<entry><constant>V4L2_TUNER_SUB_MONO</constant></entry>
	342	<entry>0x0001</entry>
	343	<entry>The tuner receives a mono audio signal.</entry>
	344	</row>
	345	<row>
	346	<entry><constant>V4L2_TUNER_SUB_STEREO</constant></entry>
	347	<entry>0x0002</entry>
	348	<entry>The tuner receives a stereo audio signal.</entry>
	349	</row>
	350	<row>
	351	<entry><constant>V4L2_TUNER_SUB_LANG1</constant></entry>
	352	<entry>0x0008</entry>
	353	<entry>The tuner receives the primary language of a
	354	bilingual audio signal. Drivers must clear this flag when the current
	355	video standard is <constant>V4L2_STD_NTSC_M</constant>.</entry>
	356	</row>
	357	<row>
	358	<entry><constant>V4L2_TUNER_SUB_LANG2</constant></entry>
	359	<entry>0x0004</entry>
	360	<entry>The tuner receives the secondary language of a
	361	bilingual audio signal (or a second audio program).</entry>
	362	</row>
	363	<row>
	364	<entry><constant>V4L2_TUNER_SUB_SAP</constant></entry>
	365	<entry>0x0004</entry>
	366	<entry>The tuner receives a Second Audio Program. Note the
	367	<constant>V4L2_TUNER_SUB_LANG2</constant> and
	368	<constant>V4L2_TUNER_SUB_SAP</constant> flags are synonyms. The
	369	<constant>V4L2_TUNER_SUB_SAP</constant> flag applies when the
	370	current video standard is <constant>V4L2_STD_NTSC_M</constant>.</entry>
	371	</row>
	372	<row>
	373	<entry><constant>V4L2_TUNER_SUB_RDS</constant></entry>
	374	<entry>0x0010</entry>
	375	<entry>The tuner receives an RDS channel.</entry>
	376	</row>
	377	</tbody>
	378	</tgroup>
	379	</table>
	380
	381	<table pgwide="1" frame="none" id="tuner-audmode">
	382	<title>Tuner Audio Modes</title>
	383	<tgroup cols="3">
	384	&cs-def;
	385	<tbody valign="top">
	386	<row>
	387	<entry><constant>V4L2_TUNER_MODE_MONO</constant></entry>
	388	<entry>0</entry>
	389	<entry>Play mono audio. When the tuner receives a stereo
	390	signal this a down-mix of the left and right channel. When the tuner
	391	receives a bilingual or SAP signal this mode selects the primary
	392	language.</entry>
	393	</row>
	394	<row>
395	<entry><constant>V4L2_TUNER_MODE_STEREO</constant></entry>
396	<entry>1</entry>
397	<entry><para>Play stereo audio. When the tuner receives
398	bilingual audio it may play different languages on the left and right
399	channel or the primary language is played on both channels.</para><para>Playing
400	different languages in this mode is
401	deprecated. New drivers should do this only in
402	<constant>MODE_LANG1_LANG2</constant>.</para><para>When the tuner
403	receives no stereo signal or does not support stereo reception the
404	driver shall fall back to <constant>MODE_MONO</constant>.</para></entry>
405	</row>
406	<row>
407	<entry><constant>V4L2_TUNER_MODE_LANG1</constant></entry>
408	<entry>3</entry>
409	<entry>Play the primary language, mono or stereo. Only
410	<constant>V4L2_TUNER_ANALOG_TV</constant> tuners support this
411	mode.</entry>
412	</row>
413	<row>
414	<entry><constant>V4L2_TUNER_MODE_LANG2</constant></entry>
415	<entry>2</entry>
416	<entry>Play the secondary language, mono. When the tuner
417	receives no bilingual audio or SAP, or their reception is not
418	supported the driver shall fall back to mono or stereo mode. Only
419	<constant>V4L2_TUNER_ANALOG_TV</constant> tuners support this
420	mode.</entry>
421	</row>
422	<row>
423	<entry><constant>V4L2_TUNER_MODE_SAP</constant></entry>
424	<entry>2</entry>
425	<entry>Play the Second Audio Program. When the tuner
426	receives no bilingual audio or SAP, or their reception is not
427	supported the driver shall fall back to mono or stereo mode. Only
428	<constant>V4L2_TUNER_ANALOG_TV</constant> tuners support this mode.
429	Note the <constant>V4L2_TUNER_MODE_LANG2</constant> and
430	<constant>V4L2_TUNER_MODE_SAP</constant> are synonyms.</entry>
431	</row>
432	<row>
433	<entry><constant>V4L2_TUNER_MODE_LANG1_LANG2</constant></entry>
434	<entry>4</entry>
435	<entry>Play the primary language on the left channel, the
436	secondary language on the right channel. When the tuner receives no
437	bilingual audio or SAP, it shall fall back to
438	<constant>MODE_LANG1</constant> or <constant>MODE_MONO</constant>.
439	Only <constant>V4L2_TUNER_ANALOG_TV</constant> tuners support this
440	mode.</entry>
441	</row>
442	</tbody>
443	</tgroup>
444	</table>
445
446	<table pgwide="1" frame="all" id="tuner-matrix">
447	<title>Tuner Audio Matrix</title>
448	<tgroup cols="6" align="center">
449	<colspec align="left" />
450	<colspec colname="c2" colwidth="1*" />
451	<colspec colwidth="1*" />
452	<colspec colwidth="1*" />
453	<colspec colnum="6" colname="c6" colwidth="1*" />
454	<spanspec namest="c2" nameend="c6" spanname="hspan" align="center" />
455	<thead>
456	<row>
457	<entry></entry>
458	<entry spanname="hspan">Selected
459	<constant>V4L2_TUNER_MODE_</constant></entry>
460	</row>
461	<row>
462	<entry>Received <constant>V4L2_TUNER_SUB_</constant></entry>
463	<entry><constant>MONO</constant></entry>
464	<entry><constant>STEREO</constant></entry>
465	<entry><constant>LANG1</constant></entry>
466	<entry><constant>LANG2 = SAP</constant></entry>
467	<entry><constant>LANG1_LANG2</constant><footnote><para>This
468	mode has been added in Linux 2.6.17 and may not be supported by older
469	drivers.</para></footnote></entry>
470	</row>
471	</thead>
472	<tbody valign="top">
473	<row>
474	<entry><constant>MONO</constant></entry>
475	<entry>Mono</entry>
476	<entry>Mono/Mono</entry>
477	<entry>Mono</entry>
478	<entry>Mono</entry>
479	<entry>Mono/Mono</entry>
480	</row>
481	<row>
482	<entry><constant>MONO \| SAP</constant></entry>
483	<entry>Mono</entry>
484	<entry>Mono/Mono</entry>
485	<entry>Mono</entry>
486	<entry>SAP</entry>
487	<entry>Mono/SAP (preferred) or Mono/Mono</entry>
488	</row>
489	<row>
490	<entry><constant>STEREO</constant></entry>
491	<entry>L+R</entry>
492	<entry>L/R</entry>
493	<entry>Stereo L/R (preferred) or Mono L+R</entry>
494	<entry>Stereo L/R (preferred) or Mono L+R</entry>
495	<entry>L/R (preferred) or L+R/L+R</entry>
496	</row>
497	<row>
498	<entry><constant>STEREO \| SAP</constant></entry>
499	<entry>L+R</entry>
500	<entry>L/R</entry>
501	<entry>Stereo L/R (preferred) or Mono L+R</entry>
502	<entry>SAP</entry>
503	<entry>L+R/SAP (preferred) or L/R or L+R/L+R</entry>
504	</row>
505	<row>
506	<entry><constant>LANG1 \| LANG2</constant></entry>
507	<entry>Language 1</entry>
508	<entry>Lang1/Lang2 (deprecated<footnote><para>Playback of
509	both languages in <constant>MODE_STEREO</constant> is deprecated. In
510	the future drivers should produce only the primary language in this
511	mode. Applications should request
512	<constant>MODE_LANG1_LANG2</constant> to record both languages or a
513	stereo signal.</para></footnote>) or
514	Lang1/Lang1</entry>
515	<entry>Language 1</entry>
516	<entry>Language 2</entry>
517	<entry>Lang1/Lang2 (preferred) or Lang1/Lang1</entry>
518	</row>
519	</tbody>
520	</tgroup>
521	</table>
522	</refsect1>
523
524	<refsect1>
525	&return-value;
526
527	<variablelist>
528	<varlistentry>
529	<term><errorcode>EINVAL</errorcode></term>
530	<listitem>
531	<para>The &v4l2-tuner; <structfield>index</structfield> is
532	out of bounds.</para>
533	</listitem>
534	</varlistentry>
535	</variablelist>
536	</refsect1>
537	</refentry>