7.18. ioctl VIDIOC_ENUMINPUT

7.18.1. Name

VIDIOC_ENUMINPUT - Enumerate video inputs

7.18.2. Synopsis

int ioctl(int fd, VIDIOC_ENUMINPUT, struct v4l2_input *argp)

7.18.3. Arguments

fd
File descriptor returned by open().
argp
Pointer to struct v4l2_input.

7.18.4. Description

To query the attributes of a video input applications initialize the index field of struct v4l2_input and call the ioctl VIDIOC_ENUMINPUT 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.

v4l2_input
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 Any non-tuner video input, for example Composite Video, S-Video, HDMI, camera sensor. The naming as _TYPE_CAMERA is historical, today we would have called it _TYPE_VIDEO.
V4L2_INPUT_TYPE_TOUCH 3 This input is a touch device for capturing raw touch data.
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.
V4L2_IN_ST_NO_V_LOCK 0x00000400 No vertical sync lock.
V4L2_IN_ST_NO_STD_LOCK 0x00000800 No standard format lock in case of auto-detection format by the component.
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.

7.18.5. 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.