64 lines
1.7 KiB
ReStructuredText
64 lines
1.7 KiB
ReStructuredText
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.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
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.. c:namespace:: V4L
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.. _VIDIOC_G_INPUT:
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************************************
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ioctl VIDIOC_G_INPUT, VIDIOC_S_INPUT
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************************************
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Name
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====
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VIDIOC_G_INPUT - VIDIOC_S_INPUT - Query or select the current video input
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Synopsis
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========
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.. c:macro:: VIDIOC_G_INPUT
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``int ioctl(int fd, VIDIOC_G_INPUT, int *argp)``
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.. c:macro:: VIDIOC_S_INPUT
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``int ioctl(int fd, VIDIOC_S_INPUT, int *argp)``
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Arguments
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=========
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``fd``
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File descriptor returned by :c:func:`open()`.
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``argp``
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Pointer an integer with input index.
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Description
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===========
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To query the current video input applications call the
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:ref:`VIDIOC_G_INPUT <VIDIOC_G_INPUT>` ioctl with a pointer to an integer where the driver
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stores the number of the input, as in the struct
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:c:type:`v4l2_input` ``index`` field. This ioctl will fail
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only when there are no video inputs, returning ``EINVAL``.
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To select a video input applications store the number of the desired
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input in an integer and call the :ref:`VIDIOC_S_INPUT <VIDIOC_G_INPUT>` ioctl with a pointer
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to this integer. Side effects are possible. For example inputs may
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support different video standards, so the driver may implicitly switch
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the current standard. Because of these possible side effects
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applications must select an input before querying or negotiating any
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other parameters.
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Information about video inputs is available using the
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:ref:`VIDIOC_ENUMINPUT` ioctl.
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Return Value
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============
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On success 0 is returned, on error -1 and the ``errno`` variable is set
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appropriately. The generic error codes are described at the
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:ref:`Generic Error Codes <gen-errors>` chapter.
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EINVAL
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The number of the video input is out of bounds.
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