VIDIOC_QUERY_DV_PRESET — Sense the DV preset received by the current input
int ioctl( | int fd, |
| int request, | |
struct v4l2_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
struct v4l2_dv_preset type. Once the hardware detects a preset, that preset is
returned in the preset field of struct 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.