83 lines
2.6 KiB
ReStructuredText
83 lines
2.6 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_STD:
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**************************************************************************
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ioctl VIDIOC_G_STD, VIDIOC_S_STD, VIDIOC_SUBDEV_G_STD, VIDIOC_SUBDEV_S_STD
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**************************************************************************
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Name
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====
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VIDIOC_G_STD - VIDIOC_S_STD - VIDIOC_SUBDEV_G_STD - VIDIOC_SUBDEV_S_STD - Query or select the video standard of the current input
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Synopsis
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========
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.. c:macro:: VIDIOC_G_STD
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``int ioctl(int fd, VIDIOC_G_STD, v4l2_std_id *argp)``
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.. c:macro:: VIDIOC_S_STD
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``int ioctl(int fd, VIDIOC_S_STD, const v4l2_std_id *argp)``
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.. c:macro:: VIDIOC_SUBDEV_G_STD
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``int ioctl(int fd, VIDIOC_SUBDEV_G_STD, v4l2_std_id *argp)``
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.. c:macro:: VIDIOC_SUBDEV_S_STD
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``int ioctl(int fd, VIDIOC_SUBDEV_S_STD, const v4l2_std_id *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 to :c:type:`v4l2_std_id`.
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Description
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===========
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To query and select the current video standard applications use the
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:ref:`VIDIOC_G_STD <VIDIOC_G_STD>` and :ref:`VIDIOC_S_STD <VIDIOC_G_STD>` ioctls which take a pointer to a
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:ref:`v4l2_std_id <v4l2-std-id>` type as argument. :ref:`VIDIOC_G_STD <VIDIOC_G_STD>`
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can return a single flag or a set of flags as in struct
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:c:type:`v4l2_standard` field ``id``. The flags must be
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unambiguous such that they appear in only one enumerated
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struct :c:type:`v4l2_standard` structure.
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:ref:`VIDIOC_S_STD <VIDIOC_G_STD>` accepts one or more flags, being a write-only ioctl it
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does not return the actual new standard as :ref:`VIDIOC_G_STD <VIDIOC_G_STD>` does. When
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no flags are given or the current input does not support the requested
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standard the driver returns an ``EINVAL`` error code. When the standard set
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is ambiguous drivers may return ``EINVAL`` or choose any of the requested
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standards. If the current input or output does not support standard
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video timings (e.g. if :ref:`VIDIOC_ENUMINPUT`
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does not set the ``V4L2_IN_CAP_STD`` flag), then ``ENODATA`` error code is
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returned.
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Calling ``VIDIOC_SUBDEV_S_STD`` on a subdev device node that has been registered
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in read-only mode is not allowed. An error is returned and the errno variable is
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set to ``-EPERM``.
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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 :ref:`VIDIOC_S_STD <VIDIOC_G_STD>` parameter was unsuitable.
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ENODATA
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Standard video timings are not supported for this input or output.
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EPERM
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``VIDIOC_SUBDEV_S_STD`` has been called on a read-only subdevice.
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