vidioc-g-std.rst (2710B)
1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later 2.. c:namespace:: V4L 3 4.. _VIDIOC_G_STD: 5 6************************************************************************** 7ioctl VIDIOC_G_STD, VIDIOC_S_STD, VIDIOC_SUBDEV_G_STD, VIDIOC_SUBDEV_S_STD 8************************************************************************** 9 10Name 11==== 12 13VIDIOC_G_STD - VIDIOC_S_STD - VIDIOC_SUBDEV_G_STD - VIDIOC_SUBDEV_S_STD - Query or select the video standard of the current input 14 15Synopsis 16======== 17 18.. c:macro:: VIDIOC_G_STD 19 20``int ioctl(int fd, VIDIOC_G_STD, v4l2_std_id *argp)`` 21 22.. c:macro:: VIDIOC_S_STD 23 24``int ioctl(int fd, VIDIOC_S_STD, const v4l2_std_id *argp)`` 25 26.. c:macro:: VIDIOC_SUBDEV_G_STD 27 28``int ioctl(int fd, VIDIOC_SUBDEV_G_STD, v4l2_std_id *argp)`` 29 30.. c:macro:: VIDIOC_SUBDEV_S_STD 31 32``int ioctl(int fd, VIDIOC_SUBDEV_S_STD, const v4l2_std_id *argp)`` 33 34Arguments 35========= 36 37``fd`` 38 File descriptor returned by :c:func:`open()`. 39 40``argp`` 41 Pointer to :c:type:`v4l2_std_id`. 42 43Description 44=========== 45 46To query and select the current video standard applications use the 47:ref:`VIDIOC_G_STD <VIDIOC_G_STD>` and :ref:`VIDIOC_S_STD <VIDIOC_G_STD>` ioctls which take a pointer to a 48:ref:`v4l2_std_id <v4l2-std-id>` type as argument. :ref:`VIDIOC_G_STD <VIDIOC_G_STD>` 49can return a single flag or a set of flags as in struct 50:c:type:`v4l2_standard` field ``id``. The flags must be 51unambiguous such that they appear in only one enumerated 52struct :c:type:`v4l2_standard` structure. 53 54:ref:`VIDIOC_S_STD <VIDIOC_G_STD>` accepts one or more flags, being a write-only ioctl it 55does not return the actual new standard as :ref:`VIDIOC_G_STD <VIDIOC_G_STD>` does. When 56no flags are given or the current input does not support the requested 57standard the driver returns an ``EINVAL`` error code. When the standard set 58is ambiguous drivers may return ``EINVAL`` or choose any of the requested 59standards. If the current input or output does not support standard 60video timings (e.g. if :ref:`VIDIOC_ENUMINPUT` 61does not set the ``V4L2_IN_CAP_STD`` flag), then ``ENODATA`` error code is 62returned. 63 64Calling ``VIDIOC_SUBDEV_S_STD`` on a subdev device node that has been registered 65in read-only mode is not allowed. An error is returned and the errno variable is 66set to ``-EPERM``. 67 68Return Value 69============ 70 71On success 0 is returned, on error -1 and the ``errno`` variable is set 72appropriately. The generic error codes are described at the 73:ref:`Generic Error Codes <gen-errors>` chapter. 74 75EINVAL 76 The :ref:`VIDIOC_S_STD <VIDIOC_G_STD>` parameter was unsuitable. 77 78ENODATA 79 Standard video timings are not supported for this input or output. 80 81EPERM 82 ``VIDIOC_SUBDEV_S_STD`` has been called on a read-only subdevice.