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- .. -*- coding: utf-8; mode: rst -*-
- .. _VIDIOC_G_INPUT:
- ************************************
- ioctl VIDIOC_G_INPUT, VIDIOC_S_INPUT
- ************************************
- Name
- ====
- VIDIOC_G_INPUT - VIDIOC_S_INPUT - Query or select the current video input
- Synopsis
- ========
- .. c:function:: int ioctl( int fd, VIDIOC_G_INPUT, int *argp )
- :name: VIDIOC_G_INPUT
- .. c:function:: int ioctl( int fd, VIDIOC_S_INPUT, int *argp )
- :name: VIDIOC_S_INPUT
- Arguments
- =========
- ``fd``
- File descriptor returned by :ref:`open() <func-open>`.
- ``argp``
- Description
- ===========
- To query the current video input applications call the
- :ref:`VIDIOC_G_INPUT <VIDIOC_G_INPUT>` ioctl with a pointer to an integer where the driver
- stores the number of the input, as in the struct
- :c:type:`v4l2_input` ``index`` field. This ioctl will fail
- only when there are no video inputs, returning ``EINVAL``.
- To select a video input applications store the number of the desired
- input in an integer and call the :ref:`VIDIOC_S_INPUT <VIDIOC_G_INPUT>` ioctl with a pointer
- to this integer. Side effects are possible. For example inputs may
- support different video standards, so the driver may implicitly switch
- the current standard. Because of these possible side effects
- applications must select an input before querying or negotiating any
- other parameters.
- Information about video inputs is available using the
- :ref:`VIDIOC_ENUMINPUT` ioctl.
- 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 number of the video input is out of bounds.
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