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.. -*- coding: utf-8; mode: rst -*-
.. _VIDIOC_G_STD:
********************************
ioctl VIDIOC_G_STD, VIDIOC_S_STD
********************************
Name
====
VIDIOC_G_STD - VIDIOC_S_STD - Query or select the video standard of the current input
Synopsis
========
.. cpp:function:: int ioctl( int fd, int request, v4l2_std_id *argp )
.. cpp: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
: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
:ref:`v4l2_standard <v4l2-standard>` field ``id``. The flags must be
unambiguous such that they appear in only one enumerated
:ref:`struct v4l2_standard <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.
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.
|
