7.58. ioctl VIDIOC_SUBDEV_G_CROP, VIDIOC_SUBDEV_S_CROP¶
VIDIOC_SUBDEV_G_CROP - VIDIOC_SUBDEV_S_CROP - Get or set the crop rectangle on a subdev pad
int ioctl(int fd, VIDIOC_SUBDEV_G_CROP, struct v4l2_subdev_crop *argp)
int ioctl(int fd, VIDIOC_SUBDEV_S_CROP, const struct v4l2_subdev_crop *argp)
File descriptor returned by
Pointer to struct
To retrieve the current crop rectangle applications set the
field of a struct
v4l2_subdev_crop to the
desired pad number as reported by the media API and the
V4L2_SUBDEV_FORMAT_ACTIVE. They then call the
VIDIOC_SUBDEV_G_CROP ioctl with a pointer to this structure. The
driver fills the members of the
rect field or returns
code if the input arguments are invalid, or if cropping is not supported
on the given pad.
To change the current crop rectangle applications set both the
which fields and all members of the
rect field. They then
VIDIOC_SUBDEV_S_CROP ioctl with a pointer to this
structure. The driver verifies the requested crop rectangle, adjusts it
based on the hardware capabilities and configures the device. Upon
return the struct
contains the current format as would be returned by a
Applications can query the device capabilities by setting the
V4L2_SUBDEV_FORMAT_TRY. When set, ‘try’ crop rectangles are not
applied to the device by the driver, but are mangled exactly as active
crop rectangles and stored in the sub-device file handle. Two
applications querying the same sub-device would thus not interact with
If the subdev device node has been registered in read-only mode, calls to
VIDIOC_SUBDEV_S_CROP are only valid if the
which field is set to
V4L2_SUBDEV_FORMAT_TRY, otherwise an error is returned and the errno
variable is set to
Drivers must not return an error solely because the requested crop rectangle doesn’t match the device capabilities. They must instead modify the rectangle to match what the hardware can provide. The modified format should be as close as possible to the original request.
Pad number as reported by the media framework.
Crop rectangle to get or set, from enum v4l2_subdev_format_whence.
Crop rectangle boundaries, in pixels.
Reserved for future extensions. Applications and drivers must set the array to zero.
7.58.5. 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.
The crop rectangle can’t be changed because the pad is currently busy. This can be caused, for instance, by an active video stream on the pad. The ioctl must not be retried without performing another action to fix the problem first. Only returned by
padreferences a non-existing pad, the
whichfield references a non-existing format, or cropping is not supported on the given subdev pad.
VIDIOC_SUBDEV_S_CROPioctl has been called on a read-only subdevice and the
whichfield is set to