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