7.41. ioctl VIDIOC_G_STD, VIDIOC_S_STD¶
7.41.1. Name¶
VIDIOC_G_STD - VIDIOC_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)¶
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.
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.