.. Permission is granted to copy, distribute and/or modify this
.. document under the terms of the GNU Free Documentation License,
.. Version 1.1 or any later version published by the Free Software
.. Foundation, with no Invariant Sections, no Front-Cover Texts
.. and no Back-Cover Texts. A copy of the license is included at
.. Documentation/userspace-api/media/fdl-appendix.rst.
..
.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections

.. _VIDIOC_G_STD:

**************************************************************************
ioctl VIDIOC_G_STD, VIDIOC_S_STD, VIDIOC_SUBDEV_G_STD, VIDIOC_SUBDEV_S_STD
**************************************************************************

Name
====

VIDIOC_G_STD - VIDIOC_S_STD - VIDIOC_SUBDEV_G_STD - VIDIOC_SUBDEV_S_STD - Query or select the video standard of the current input


Synopsis
========

.. c:function:: int ioctl( int fd, VIDIOC_G_STD, v4l2_std_id *argp )
    :name: VIDIOC_G_STD

.. c:function:: int ioctl( int fd, VIDIOC_S_STD, const v4l2_std_id *argp )
    :name: VIDIOC_S_STD

.. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_G_STD, v4l2_std_id *argp )
    :name: VIDIOC_SUBDEV_G_STD

.. c:function:: int ioctl( int fd, VIDIOC_SUBDEV_S_STD, const v4l2_std_id *argp )
    :name: VIDIOC_SUBDEV_S_STD


Arguments
=========

``fd``
    File descriptor returned by :ref:`open() <func-open>`.

``argp``
    Pointer to :c:type:`v4l2_std_id`.


Description
===========

To query and select the current video standard applications use the
:ref:`VIDIOC_G_STD <VIDIOC_G_STD>` and :ref:`VIDIOC_S_STD <VIDIOC_G_STD>` ioctls which take a pointer to a
:ref:`v4l2_std_id <v4l2-std-id>` type as argument. :ref:`VIDIOC_G_STD <VIDIOC_G_STD>`
can return a single flag or a set of flags as in struct
:c:type:`v4l2_standard` field ``id``. The flags must be
unambiguous such that they appear in only one enumerated
struct :c:type:`v4l2_standard` structure.

:ref:`VIDIOC_S_STD <VIDIOC_G_STD>` accepts one or more flags, being a write-only ioctl it
does not return the actual new standard as :ref:`VIDIOC_G_STD <VIDIOC_G_STD>` does. When
no flags are given or the current input does not support the requested
standard the driver returns an ``EINVAL`` error code. When the standard set
is ambiguous drivers may return ``EINVAL`` or choose any of the requested
standards. If the current input or output does not support standard
video timings (e.g. if :ref:`VIDIOC_ENUMINPUT`
does not set the ``V4L2_IN_CAP_STD`` flag), then ``ENODATA`` error code is
returned.

Calling ``VIDIOC_SUBDEV_S_STD`` on a subdev device node that has been registered
in read-only mode is not allowed. An error is returned and the errno variable is
set to ``-EPERM``.

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 :ref:`VIDIOC_S_STD <VIDIOC_G_STD>` parameter was unsuitable.

ENODATA
    Standard video timings are not supported for this input or output.

EPERM
    ``VIDIOC_SUBDEV_S_STD`` has been called on a read-only subdevice.
