8.18. ioctl VIDIOC_ENUMINPUT¶

8.18.1. Name¶

VIDIOC_ENUMINPUT - Enumerate video inputs

8.18.2. Synopsis¶

int ioctl(int fd, int request, struct v4l2_input *argp)¶

8.18.3. Arguments¶

fd: File descriptor returned by open().
request: VIDIOC_ENUMINPUT

argp

8.18.4. Description¶

To query the attributes of a video input applications initialize the index field of struct v4l2_input and call the ioctl VIDIOC_ENUMINPUT ioctl 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 inputs applications shall begin at index zero, incrementing by one until the driver returns EINVAL.

struct v4l2_input¶
__u32	`index`	Identifies the input, set by the application.
__u8	`name`[32]	Name of the video input, a NUL-terminated ASCII string, for example: “Vin (Composite 2)”. This information is intended for the user, preferably the connector label on the device itself.
__u32	`type`	Type of the input, see Input Types.
__u32	`audioset`	Drivers can enumerate up to 32 video and audio inputs. This field shows which audio inputs were selectable as audio source if this was the currently selected video input. It is a bit mask. The LSB corresponds to audio input 0, the MSB to input 31. Any number of bits can be set, or none. When the driver does not enumerate audio inputs no bits must be set. Applications shall not interpret this as lack of audio support. Some drivers automatically select audio sources and do not enumerate them since there is no choice anyway. For details on audio inputs and how to select the current input see Audio Inputs and Outputs.
__u32	`tuner`	Capture devices can have zero or more tuners (RF demodulators). When the `type` is set to `V4L2_INPUT_TYPE_TUNER` this is an RF connector and this field identifies the tuner. It corresponds to struct v4l2_tuner field `index`. For details on tuners see Tuners and Modulators.
v4l2_std_id	`std`	Every video input supports one or more different video standards. This field is a set of all supported standards. For details on video standards and how to switch see Video Standards.
__u32	`status`	This field provides status information about the input. See Input Status Flags for flags. With the exception of the sensor orientation bits `status` is only valid when this is the current input.
__u32	`capabilities`	This field provides capabilities for the input. See Input capabilities for flags.
__u32	`reserved`[3]	Reserved for future extensions. Drivers must set the array to zero.

Input Types¶
`V4L2_INPUT_TYPE_TUNER`	1	This input uses a tuner (RF demodulator).
`V4L2_INPUT_TYPE_CAMERA`	2	Analog baseband input, for example CVBS / Composite Video, S-Video, RGB.

Input Status Flags¶
General
`V4L2_IN_ST_NO_POWER`	0x00000001	Attached device is off.
`V4L2_IN_ST_NO_SIGNAL`	0x00000002
`V4L2_IN_ST_NO_COLOR`	0x00000004	The hardware supports color decoding, but does not detect color modulation in the signal.
Sensor Orientation
`V4L2_IN_ST_HFLIP`	0x00000010	The input is connected to a device that produces a signal that is flipped horizontally and does not correct this before passing the signal to userspace.
`V4L2_IN_ST_VFLIP`	0x00000020	The input is connected to a device that produces a signal that is flipped vertically and does not correct this before passing the signal to userspace. .. note:: A 180 degree rotation is the same as HFLIP \| VFLIP
Analog Video
`V4L2_IN_ST_NO_H_LOCK`	0x00000100	No horizontal sync lock.
`V4L2_IN_ST_COLOR_KILL`	0x00000200	A color killer circuit automatically disables color decoding when it detects no color modulation. When this flag is set the color killer is enabled and has shut off color decoding.
Digital Video
`V4L2_IN_ST_NO_SYNC`	0x00010000	No synchronization lock.
`V4L2_IN_ST_NO_EQU`	0x00020000	No equalizer lock.
`V4L2_IN_ST_NO_CARRIER`	0x00040000	Carrier recovery failed.
VCR and Set-Top Box
`V4L2_IN_ST_MACROVISION`	0x01000000	Macrovision is an analog copy prevention system mangling the video signal to confuse video recorders. When this flag is set Macrovision has been detected.
`V4L2_IN_ST_NO_ACCESS`	0x02000000	Conditional access denied.
`V4L2_IN_ST_VTR`	0x04000000	VTR time constant. [?]

Input capabilities¶
`V4L2_IN_CAP_DV_TIMINGS`	0x00000002	This input supports setting video timings by using VIDIOC_S_DV_TIMINGS.
`V4L2_IN_CAP_STD`	0x00000004	This input supports setting the TV standard by using VIDIOC_S_STD.
`V4L2_IN_CAP_NATIVE_SIZE`	0x00000008	This input supports setting the native size using the `V4L2_SEL_TGT_NATIVE_SIZE` selection target, see Common selection definitions.

8.18.5. 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_input index is out of bounds.