7.13. ioctl VIDIOC_ENUM_DV_TIMINGS, VIDIOC_SUBDEV_ENUM_DV_TIMINGS

7.13.1. Name

VIDIOC_ENUM_DV_TIMINGS - VIDIOC_SUBDEV_ENUM_DV_TIMINGS - Enumerate supported Digital Video timings

7.13.2. Synopsis

int ioctl(int fd, VIDIOC_ENUM_DV_TIMINGS, struct v4l2_enum_dv_timings *argp)

int ioctl(int fd, VIDIOC_SUBDEV_ENUM_DV_TIMINGS, struct v4l2_enum_dv_timings *argp)

7.13.3. Arguments

fd

File descriptor returned by open().

argp

Pointer to struct v4l2_enum_dv_timings.

7.13.4. Description

While some DV receivers or transmitters support a wide range of timings, others support only a limited number of timings. With this ioctl applications can enumerate a list of known supported timings. Call ioctl VIDIOC_DV_TIMINGS_CAP, VIDIOC_SUBDEV_DV_TIMINGS_CAP to check if it also supports other standards or even custom timings that are not in this list.

To query the available timings, applications initialize the index field, set the pad field to 0, zero the reserved array of struct v4l2_enum_dv_timings and call the VIDIOC_ENUM_DV_TIMINGS ioctl on a video node with a pointer to this structure. Drivers fill the rest of the structure or return an EINVAL error code when the index is out of bounds. To enumerate all supported DV timings, applications shall begin at index zero, incrementing by one until the driver returns EINVAL.

注釈

Drivers may enumerate a different set of DV timings after switching the video input or output.

When implemented by the driver DV timings of subdevices can be queried by calling the VIDIOC_SUBDEV_ENUM_DV_TIMINGS ioctl directly on a subdevice node. The DV timings are specific to inputs (for DV receivers) or outputs (for DV transmitters), applications must specify the desired pad number in the struct v4l2_enum_dv_timings pad field. Attempts to enumerate timings on a pad that doesn't support them will return an EINVAL error code.

v4l2_enum_dv_timings

struct v4l2_enum_dv_timings

__u32	index	Number of the DV timings, set by the application.
__u32	pad	Pad number as reported by the media controller API. This field is only used when operating on a subdevice node. When operating on a video node applications must set this field to zero.
__u32	reserved[2]	Reserved for future extensions. Drivers and applications must set the array to zero.
struct v4l2_dv_timings	timings	The timings.

7.13.5. 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 struct v4l2_enum_dv_timings index is out of bounds or the pad number is invalid.

ENODATA

Digital video presets are not supported for this input or output.