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<refentry id="vidioc-overlay">
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<refentrytitle>ioctl VIDIOC_OVERLAY</refentrytitle>
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<refname>VIDIOC_OVERLAY</refname>
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<refpurpose>Start or stop video overlay</refpurpose>
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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 int *<parameter>argp</parameter></paramdef>
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<title>Arguments</title>
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<term><parameter>fd</parameter></term>
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<term><parameter>request</parameter></term>
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<para>VIDIOC_OVERLAY</para>
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<term><parameter>argp</parameter></term>
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<title>Description</title>
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<para>This ioctl is part of the <link linkend="overlay">video
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overlay</link> I/O method. Applications call
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<constant>VIDIOC_OVERLAY</constant> to start or stop the
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overlay. It takes a pointer to an integer which must be set to
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zero by the application to stop overlay, to one to start.</para>
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<para>Drivers do not support &VIDIOC-STREAMON; or
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&VIDIOC-STREAMOFF; with <constant>V4L2_BUF_TYPE_VIDEO_OVERLAY</constant>.</para>
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<term><errorcode>EINVAL</errorcode></term>
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<para>The overlay parameters have not been set up. See <xref
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linkend="overlay" /> for the necessary steps.</para>