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+<refentry id="vidioc-enum-freq-bands">
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+ <refmeta>
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+ <refentrytitle>ioctl VIDIOC_ENUM_FREQ_BANDS</refentrytitle>
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+ &manvol;
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+ </refmeta>
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+
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+ <refnamediv>
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+ <refname>VIDIOC_ENUM_FREQ_BANDS</refname>
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+ <refpurpose>Enumerate supported frequency bands</refpurpose>
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+ </refnamediv>
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+
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+ <refsynopsisdiv>
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+ <funcsynopsis>
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+ <funcprototype>
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+ <funcdef>int <function>ioctl</function></funcdef>
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+ <paramdef>int <parameter>fd</parameter></paramdef>
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+ <paramdef>int <parameter>request</parameter></paramdef>
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+ <paramdef>struct v4l2_frequency_band
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+*<parameter>argp</parameter></paramdef>
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+ </funcprototype>
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+ </funcsynopsis>
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+ </refsynopsisdiv>
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+
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+ <refsect1>
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+ <title>Arguments</title>
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+
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+ <variablelist>
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+ <varlistentry>
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+ <term><parameter>fd</parameter></term>
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+ <listitem>
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+ <para>&fd;</para>
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+ </listitem>
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+ </varlistentry>
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+ <varlistentry>
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+ <term><parameter>request</parameter></term>
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+ <listitem>
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+ <para>VIDIOC_ENUM_FREQ_BANDS</para>
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+ </listitem>
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+ </varlistentry>
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+ <varlistentry>
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+ <term><parameter>argp</parameter></term>
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+ <listitem>
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+ <para></para>
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+ </listitem>
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+ </varlistentry>
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+ </variablelist>
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+ </refsect1>
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+
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+ <refsect1>
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+ <title>Description</title>
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+
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+ <note>
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+ <title>Experimental</title>
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+ <para>This is an <link linkend="experimental"> experimental </link>
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+ interface and may change in the future.</para>
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+ </note>
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+
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+ <para>Enumerates the frequency bands that a tuner or modulator supports.
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+To do this applications initialize the <structfield>tuner</structfield>,
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+<structfield>type</structfield> and <structfield>index</structfield> fields,
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+and zero out the <structfield>reserved</structfield> array of a &v4l2-frequency-band; and
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+call the <constant>VIDIOC_ENUM_FREQ_BANDS</constant> ioctl with a pointer
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+to this structure.</para>
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+
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+ <para>This ioctl is supported if the <constant>V4L2_TUNER_CAP_FREQ_BANDS</constant> capability
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+ of the corresponding tuner/modulator is set.</para>
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+
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+ <table pgwide="1" frame="none" id="v4l2-frequency-band">
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+ <title>struct <structname>v4l2_frequency_band</structname></title>
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+ <tgroup cols="3">
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+ &cs-str;
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+ <tbody valign="top">
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+ <row>
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+ <entry>__u32</entry>
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+ <entry><structfield>tuner</structfield></entry>
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+ <entry>The tuner or modulator index number. This is the
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+same value as in the &v4l2-input; <structfield>tuner</structfield>
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+field and the &v4l2-tuner; <structfield>index</structfield> field, or
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+the &v4l2-output; <structfield>modulator</structfield> field and the
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+&v4l2-modulator; <structfield>index</structfield> field.</entry>
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+ </row>
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+ <row>
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+ <entry>__u32</entry>
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+ <entry><structfield>type</structfield></entry>
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+ <entry>The tuner type. This is the same value as in the
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+&v4l2-tuner; <structfield>type</structfield> field. The type must be set
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+to <constant>V4L2_TUNER_RADIO</constant> for <filename>/dev/radioX</filename>
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+device nodes, and to <constant>V4L2_TUNER_ANALOG_TV</constant>
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+for all others. Set this field to <constant>V4L2_TUNER_RADIO</constant> for
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+modulators (currently only radio modulators are supported).
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+See <xref linkend="v4l2-tuner-type" /></entry>
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+ </row>
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+ <row>
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+ <entry>__u32</entry>
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+ <entry><structfield>index</structfield></entry>
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+ <entry>Identifies the frequency band, set by the application.</entry>
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+ </row>
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+ <row>
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+ <entry>__u32</entry>
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+ <entry><structfield>capability</structfield></entry>
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+ <entry spanname="hspan">The tuner/modulator capability flags for
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+this frequency band, see <xref linkend="tuner-capability" />. The <constant>V4L2_TUNER_CAP_LOW</constant>
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+capability must be the same for all frequency bands of the selected tuner/modulator.
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+So either all bands have that capability set, or none of them have that capability.</entry>
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+ </row>
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+ <row>
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+ <entry>__u32</entry>
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+ <entry><structfield>rangelow</structfield></entry>
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+ <entry spanname="hspan">The lowest tunable frequency in
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+units of 62.5 kHz, or if the <structfield>capability</structfield>
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+flag <constant>V4L2_TUNER_CAP_LOW</constant> is set, in units of 62.5
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+Hz, for this frequency band.</entry>
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+ </row>
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+ <row>
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+ <entry>__u32</entry>
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+ <entry><structfield>rangehigh</structfield></entry>
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+ <entry spanname="hspan">The highest tunable frequency in
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+units of 62.5 kHz, or if the <structfield>capability</structfield>
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+flag <constant>V4L2_TUNER_CAP_LOW</constant> is set, in units of 62.5
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+Hz, for this frequency band.</entry>
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+ </row>
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+ <row>
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+ <entry>__u32</entry>
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+ <entry><structfield>modulation</structfield></entry>
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+ <entry spanname="hspan">The supported modulation systems of this frequency band.
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+ See <xref linkend="band-modulation" />. Note that currently only one
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+ modulation system per frequency band is supported. More work will need to
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+ be done if multiple modulation systems are possible. Contact the
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+ linux-media mailing list (&v4l-ml;) if you need that functionality.</entry>
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+ </row>
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+ <row>
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+ <entry>__u32</entry>
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+ <entry><structfield>reserved</structfield>[9]</entry>
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+ <entry>Reserved for future extensions. Applications and drivers
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+ must set the array to zero.</entry>
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+ </row>
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+ </tbody>
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+ </tgroup>
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+ </table>
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+
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+ <table pgwide="1" frame="none" id="band-modulation">
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+ <title>Band Modulation Systems</title>
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+ <tgroup cols="3">
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+ &cs-def;
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+ <tbody valign="top">
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+ <row>
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+ <entry><constant>V4L2_BAND_MODULATION_VSB</constant></entry>
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+ <entry>0x02</entry>
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+ <entry>Vestigial Sideband modulation, used for analog TV.</entry>
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+ </row>
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+ <row>
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+ <entry><constant>V4L2_BAND_MODULATION_FM</constant></entry>
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+ <entry>0x04</entry>
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+ <entry>Frequency Modulation, commonly used for analog radio.</entry>
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+ </row>
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+ <row>
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+ <entry><constant>V4L2_BAND_MODULATION_AM</constant></entry>
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+ <entry>0x08</entry>
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+ <entry>Amplitude Modulation, commonly used for analog radio.</entry>
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+ </row>
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+ </tbody>
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+ </tgroup>
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+ </table>
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+ </refsect1>
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+
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+ <refsect1>
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+ &return-value;
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+
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+ <variablelist>
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+ <varlistentry>
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+ <term><errorcode>EINVAL</errorcode></term>
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+ <listitem>
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+ <para>The <structfield>tuner</structfield> or <structfield>index</structfield>
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+is out of bounds or the <structfield>type</structfield> field is wrong.</para>
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+ </listitem>
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+ </varlistentry>
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+ </variablelist>
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+ </refsect1>
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+</refentry>
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