mirror of https://gitee.com/openkylin/linux.git
100 lines
2.8 KiB
XML
100 lines
2.8 KiB
XML
<refentry id="vidioc-g-std">
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<refmeta>
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<refentrytitle>ioctl VIDIOC_G_STD, VIDIOC_S_STD</refentrytitle>
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&manvol;
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</refmeta>
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<refnamediv>
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<refname>VIDIOC_G_STD</refname>
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<refname>VIDIOC_S_STD</refname>
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<refpurpose>Query or select the video standard of the current input</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>v4l2_std_id
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*<parameter>argp</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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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>const v4l2_std_id
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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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<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_G_STD, VIDIOC_S_STD</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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<para>To query and select the current video standard applications
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use the <constant>VIDIOC_G_STD</constant> and <constant>VIDIOC_S_STD</constant> ioctls which take a pointer to a
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&v4l2-std-id; type as argument. <constant>VIDIOC_G_STD</constant> can
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return a single flag or a set of flags as in &v4l2-standard; field
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<structfield>id</structfield>. The flags must be unambiguous such
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that they appear in only one enumerated <structname>v4l2_standard</structname> structure.</para>
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<para><constant>VIDIOC_S_STD</constant> accepts one or more
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flags, being a write-only ioctl it does not return the actual new standard as
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<constant>VIDIOC_G_STD</constant> does. When no flags are given or
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the current input does not support the requested standard the driver
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returns an &EINVAL;. When the standard set is ambiguous drivers may
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return <errorcode>EINVAL</errorcode> or choose any of the requested
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standards.</para>
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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>This ioctl is not supported, or the
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<constant>VIDIOC_S_STD</constant> parameter was unsuitable.</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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