diff options
Diffstat (limited to 'Documentation/DocBook/media/v4l/vidioc-enum-freq-bands.xml')
| -rw-r--r-- | Documentation/DocBook/media/v4l/vidioc-enum-freq-bands.xml | 179 |
1 files changed, 179 insertions, 0 deletions
diff --git a/Documentation/DocBook/media/v4l/vidioc-enum-freq-bands.xml b/Documentation/DocBook/media/v4l/vidioc-enum-freq-bands.xml new file mode 100644 index 00000000..6541ba01 --- /dev/null +++ b/Documentation/DocBook/media/v4l/vidioc-enum-freq-bands.xml @@ -0,0 +1,179 @@ +<refentry id="vidioc-enum-freq-bands"> + <refmeta> + <refentrytitle>ioctl VIDIOC_ENUM_FREQ_BANDS</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_ENUM_FREQ_BANDS</refname> + <refpurpose>Enumerate supported frequency bands</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_frequency_band +*<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_ENUM_FREQ_BANDS</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <note> + <title>Experimental</title> + <para>This is an <link linkend="experimental"> experimental </link> + interface and may change in the future.</para> + </note> + + <para>Enumerates the frequency bands that a tuner or modulator supports. +To do this applications initialize the <structfield>tuner</structfield>, +<structfield>type</structfield> and <structfield>index</structfield> fields, +and zero out the <structfield>reserved</structfield> array of a &v4l2-frequency-band; and +call the <constant>VIDIOC_ENUM_FREQ_BANDS</constant> ioctl with a pointer +to this structure.</para> + + <para>This ioctl is supported if the <constant>V4L2_TUNER_CAP_FREQ_BANDS</constant> capability + of the corresponding tuner/modulator is set.</para> + + <table pgwide="1" frame="none" id="v4l2-frequency-band"> + <title>struct <structname>v4l2_frequency_band</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>tuner</structfield></entry> + <entry>The tuner or modulator index number. This is the +same value as in the &v4l2-input; <structfield>tuner</structfield> +field and the &v4l2-tuner; <structfield>index</structfield> field, or +the &v4l2-output; <structfield>modulator</structfield> field and the +&v4l2-modulator; <structfield>index</structfield> field.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>type</structfield></entry> + <entry>The tuner type. This is the same value as in the +&v4l2-tuner; <structfield>type</structfield> field. The type must be set +to <constant>V4L2_TUNER_RADIO</constant> for <filename>/dev/radioX</filename> +device nodes, and to <constant>V4L2_TUNER_ANALOG_TV</constant> +for all others. Set this field to <constant>V4L2_TUNER_RADIO</constant> for +modulators (currently only radio modulators are supported). +See <xref linkend="v4l2-tuner-type" /></entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>index</structfield></entry> + <entry>Identifies the frequency band, set by the application.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>capability</structfield></entry> + <entry spanname="hspan">The tuner/modulator capability flags for +this frequency band, see <xref linkend="tuner-capability" />. The <constant>V4L2_TUNER_CAP_LOW</constant> +capability must be the same for all frequency bands of the selected tuner/modulator. +So either all bands have that capability set, or none of them have that capability.</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, for this frequency band.</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, for this frequency band.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>modulation</structfield></entry> + <entry spanname="hspan">The supported modulation systems of this frequency band. + See <xref linkend="band-modulation" />. Note that currently only one + modulation system per frequency band is supported. More work will need to + be done if multiple modulation systems are possible. Contact the + linux-media mailing list (&v4l-ml;) if you need that functionality.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[9]</entry> + <entry>Reserved for future extensions. Applications and drivers + must set the array to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + + <table pgwide="1" frame="none" id="band-modulation"> + <title>Band Modulation Systems</title> + <tgroup cols="3"> + &cs-def; + <tbody valign="top"> + <row> + <entry><constant>V4L2_BAND_MODULATION_VSB</constant></entry> + <entry>0x02</entry> + <entry>Vestigial Sideband modulation, used for analog TV.</entry> + </row> + <row> + <entry><constant>V4L2_BAND_MODULATION_FM</constant></entry> + <entry>0x04</entry> + <entry>Frequency Modulation, commonly used for analog radio.</entry> + </row> + <row> + <entry><constant>V4L2_BAND_MODULATION_AM</constant></entry> + <entry>0x08</entry> + <entry>Amplitude Modulation, commonly used for analog radio.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The <structfield>tuner</structfield> or <structfield>index</structfield> +is out of bounds or the <structfield>type</structfield> field is wrong.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> |