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.. -*- coding: utf-8; mode: rst -*-
.. _VIDIOC_OVERLAY:
********************
ioctl VIDIOC_OVERLAY
********************
Name
====
VIDIOC_OVERLAY - Start or stop video overlay
Synopsis
========
.. cpp:function:: int ioctl( int fd, int request, const int *argp )
Arguments
=========
``fd``
File descriptor returned by :ref:`open() <func-open>`.
``request``
VIDIOC_OVERLAY
``argp``
Description
===========
This ioctl is part of the :ref:`video overlay <overlay>` I/O method.
Applications call :ref:`VIDIOC_OVERLAY` 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.
Drivers do not support :ref:`VIDIOC_STREAMON` or
:ref:`VIDIOC_STREAMOFF <VIDIOC_STREAMON>` with
``V4L2_BUF_TYPE_VIDEO_OVERLAY``.
Return Value
============
On success 0 is returned, on error -1 and the ``errno`` variable is set
appropriately. The generic error codes are described at the
:ref:`Generic Error Codes <gen-errors>` chapter.
EINVAL
The overlay parameters have not been set up. See :ref:`overlay`
for the necessary steps.
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