142 lines
4.6 KiB
XML
142 lines
4.6 KiB
XML
<refentry id="vidioc-enum-dv-timings">
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<refmeta>
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<refentrytitle>ioctl VIDIOC_ENUM_DV_TIMINGS, VIDIOC_SUBDEV_ENUM_DV_TIMINGS</refentrytitle>
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&manvol;
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</refmeta>
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<refnamediv>
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<refname>VIDIOC_ENUM_DV_TIMINGS</refname>
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<refname>VIDIOC_SUBDEV_ENUM_DV_TIMINGS</refname>
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<refpurpose>Enumerate supported Digital Video timings</refpurpose>
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</refnamediv>
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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_enum_dv_timings *<parameter>argp</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Arguments</title>
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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_DV_TIMINGS, VIDIOC_SUBDEV_ENUM_DV_TIMINGS</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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<refsect1>
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<title>Description</title>
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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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<para>While some DV receivers or transmitters support a wide range of timings, others
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support only a limited number of timings. With this ioctl applications can enumerate a list
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of known supported timings. Call &VIDIOC-DV-TIMINGS-CAP; to check if it also supports other
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standards or even custom timings that are not in this list.</para>
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<para>To query the available timings, applications initialize the
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<structfield>index</structfield> field and zero the reserved array of &v4l2-enum-dv-timings;
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and call the <constant>VIDIOC_ENUM_DV_TIMINGS</constant> ioctl on a video node with a
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pointer to this structure. Drivers fill the rest of the structure or return an
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&EINVAL; when the index is out of bounds. To enumerate all supported DV timings,
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applications shall begin at index zero, incrementing by one until the
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driver returns <errorcode>EINVAL</errorcode>. Note that drivers may enumerate a
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different set of DV timings after switching the video input or
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output.</para>
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<para>When implemented by the driver DV timings of subdevices can be queried
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by calling the <constant>VIDIOC_SUBDEV_ENUM_DV_TIMINGS</constant> ioctl directly
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on a subdevice node. The DV timings are specific to inputs (for DV receivers) or
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outputs (for DV transmitters), applications must specify the desired pad number
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in the &v4l2-enum-dv-timings; <structfield>pad</structfield> field. Attempts to
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enumerate timings on a pad that doesn't support them will return an &EINVAL;.</para>
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<table pgwide="1" frame="none" id="v4l2-enum-dv-timings">
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<title>struct <structname>v4l2_enum_dv_timings</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>index</structfield></entry>
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<entry>Number of the DV timings, set by the
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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>pad</structfield></entry>
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<entry>Pad number as reported by the media controller API. This field
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is only used when operating on a subdevice node. When operating on a
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video node applications must set this field to zero.</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>[2]</entry>
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<entry>Reserved for future extensions. Drivers and applications must
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set the array to zero.</entry>
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</row>
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<row>
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<entry>&v4l2-dv-timings;</entry>
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<entry><structfield>timings</structfield></entry>
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<entry>The timings.</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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<refsect1>
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&return-value;
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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 &v4l2-enum-dv-timings; <structfield>index</structfield>
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is out of bounds or the <structfield>pad</structfield> number is invalid.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><errorcode>ENODATA</errorcode></term>
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<listitem>
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<para>Digital video presets are not supported for this input or output.</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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<!--
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Local Variables:
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mode: sgml
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sgml-parent-document: "v4l2.sgml"
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indent-tabs-mode: nil
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End:
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-->
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