doc/spec/r12816.htm

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>ioctl VIDIOC_OVERLAY</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN12820"
></A
><H2
>Name</H2
>VIDIOC_OVERLAY&nbsp;--&nbsp;Start or stop video overlay</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN12823"
></A
><H2
>Synopsis</H2
><DIV
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><P
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><A
NAME="AEN12824"
></A
><P
><CODE
><CODE
CLASS="FUNCDEF"
>int ioctl</CODE
>(int fd, int request, const int *argp);</CODE
></P
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN12834"
></A
><H2
>Arguments</H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><CODE
CLASS="PARAMETER"
>fd</CODE
></DT
><DD
><P
>File descriptor returned by <A
HREF="r14090.htm"
><CODE
CLASS="FUNCTION"
>open()</CODE
></A
>.</P
></DD
><DT
><CODE
CLASS="PARAMETER"
>request</CODE
></DT
><DD
><P
>VIDIOC_OVERLAY</P
></DD
><DT
><CODE
CLASS="PARAMETER"
>argp</CODE
></DT
><DD
><P
></P
></DD
></DL
></DIV
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><DIV
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><A
NAME="AEN12854"
></A
><H2
>Description</H2
><P
>This ioctl is part of the <A
HREF="x6570.htm"
>video
    overlay</A
> I/O method. Applications call
    <CODE
CLASS="CONSTANT"
>VIDIOC_OVERLAY</CODE
> 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.</P
><P
>Drivers do not support <A
HREF="r13817.htm"
><CODE
CLASS="CONSTANT"
>VIDIOC_STREAMON</CODE
></A
> or
<A
HREF="r13817.htm"
><CODE
CLASS="CONSTANT"
>VIDIOC_STREAMOFF</CODE
></A
> with <CODE
CLASS="CONSTANT"
>V4L2_BUF_TYPE_VIDEO_OVERLAY</CODE
>.</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN12865"
></A
><H2
>Return Value</H2
><P
>On success <SPAN
CLASS="RETURNVALUE"
>0</SPAN
> is returned, on error <SPAN
CLASS="RETURNVALUE"
>-1</SPAN
> and the <CODE
CLASS="VARNAME"
>errno</CODE
> variable is set appropriately:</P
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><SPAN
CLASS="ERRORCODE"
>EINVAL</SPAN
></DT
><DD
><P
>Video overlay is not supported, or the
parameters have not been set up. See <A
HREF="x6570.htm"
>Section 4.2</A
> for the necessary steps.</P
></DD
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