linux/Documentation/DocBook/media/v4l/vidioc-overlay.xml

<refentry id="vidioc-overlay">
  <refmeta>
    <refentrytitle>ioctl VIDIOC_OVERLAY</refentrytitle>
    &manvol;
  </refmeta>

  <refnamediv>
    <refname>VIDIOC_OVERLAY</refname>
    <refpurpose>Start or stop video overlay</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <funcsynopsis>
      <funcprototype>
	<funcdef>int <function>ioctl</function></funcdef>
	<paramdef>int <parameter>fd</parameter></paramdef>
	<paramdef>int <parameter>request</parameter></paramdef>
	<paramdef>const int *<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_OVERLAY</para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term><parameter>argp</parameter></term>
	<listitem>
	  <para></para>
	</listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Description</title>

    <para>This ioctl is part of the <link linkend="overlay">video
    overlay</link> I/O method. Applications call
    <constant>VIDIOC_OVERLAY</constant> to start or stop the
    overlay. It takes a pointer to an integer which must be set to
    zero by the application to stop overlay, to one to start.</para>

    <para>Drivers do not support &VIDIOC-STREAMON; or
&VIDIOC-STREAMOFF; with <constant>V4L2_BUF_TYPE_VIDEO_OVERLAY</constant>.</para>
  </refsect1>

  <refsect1>
    &return-value;

    <variablelist>
      <varlistentry>
	<term><errorcode>EINVAL</errorcode></term>
	<listitem>
	  <para>The overlay parameters have not been set up. See <xref
linkend="overlay" /> for the necessary steps.</para>
	</listitem>
      </varlistentry>
    </variablelist>
  </refsect1>
</refentry>