7.41. ioctl VIDIOC_G_STD, VIDIOC_S_STD, VIDIOC_SUBDEV_G_STD, VIDIOC_SUBDEV_S_STD

7.41.1. 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

7.41.2. Synopsis

int ioctl(int fd, VIDIOC_G_STD, v4l2_std_id *argp)
int ioctl(int fd, VIDIOC_S_STD, const v4l2_std_id *argp)
int ioctl(int fd, VIDIOC_SUBDEV_G_STD, v4l2_std_id *argp)
int ioctl(int fd, VIDIOC_SUBDEV_S_STD, const v4l2_std_id *argp)

7.41.3. Arguments

fd

File descriptor returned by open().

argp

Pointer to v4l2_std_id.

7.41.4. 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 v4l2_std_id type as argument. VIDIOC_G_STD can return a single flag or a set of flags as in struct v4l2_standard field id. The flags must be unambiguous such that they appear in only one enumerated 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 ioctl 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.

7.41.5. 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 Generic Error Codes chapter.

EINVAL

The VIDIOC_S_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.