ioctl VIDIOC_QUERY_DV_PRESET &manvol; VIDIOC_QUERY_DV_PRESET Sense the DV preset received by the current input int ioctl int fd int request struct v4l2_dv_preset *argp fd &fd; request VIDIOC_QUERY_DV_PRESET argp The hardware may be able to detect the current DV preset automatically, similar to sensing the video standard. To do so, applications call VIDIOC_QUERY_DV_PRESET with a pointer to a &v4l2-dv-preset; type. Once the hardware detects a preset, that preset is returned in the preset field of &v4l2-dv-preset;. If the preset could not be detected because there was no signal, or the signal was unreliable, or the signal did not map to a supported preset, then the value V4L2_DV_INVALID is returned. &return-value;