ioctl VIDIOC_QUERYSTD &manvol; VIDIOC_QUERYSTD Sense the video standard received by the current input int ioctl int fd int request v4l2_std_id *argp fd &fd; request VIDIOC_QUERYSTD argp The hardware may be able to detect the current video standard automatically. To do so, applications call VIDIOC_QUERYSTD with a pointer to a &v4l2-std-id; type. The driver stores here a set of candidates, this can be a single flag or a set of supported standards if for example the hardware can only distinguish between 50 and 60 Hz systems. If no signal was detected, then the driver will return V4L2_STD_UNKNOWN. When detection is not possible or fails, the set must contain all standards supported by the current video input or output. &return-value; ENODATA Standard video timings are not supported for this input or output.