VIDIOC_G_STD, VIDIOC_S_STD — Query or select the video standard of the current input
int ioctl( | int | fd, |
| int | request, | |
| v4l2_std_id * | argp); |
int ioctl( | int | fd, |
| int | request, | |
| const v4l2_std_id * | argp); |
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 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.