Documentation/linux_tv/media/v4l/vidioc-g-std.rst

.. -*- coding: utf-8; mode: rst -*-

.. _vidioc-g-std:

********************************
ioctl VIDIOC_G_STD, VIDIOC_S_STD
********************************

*man VIDIOC_G_STD(2)*

VIDIOC_S_STD
Query or select the video standard of the current input


Synopsis
========

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

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

Arguments
=========

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

``request``
    VIDIOC_G_STD, VIDIOC_S_STD

``argp``


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

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

``VIDIOC_S_STD`` accepts one or more flags, being a write-only ioctl it
does not return the actual new standard as ``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 <vidioc-enuminput>`
does not set the ``V4L2_IN_CAP_STD`` flag), then ENODATA error code is
returned.


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 ``VIDIOC_S_STD`` parameter was unsuitable.

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


.. ------------------------------------------------------------------------------
.. This file was automatically converted from DocBook-XML with the dbxml
.. library (https://github.com/return42/sphkerneldoc). The origin XML comes
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..
.. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook
.. ------------------------------------------------------------------------------