7.19.1. Name

VIDIOC_ENUMOUTPUT - Enumerate video outputs

7.19.2. Synopsis

int ioctl(int fd, VIDIOC_ENUMOUTPUT, struct v4l2_output *argp)

7.19.3. Arguments

File descriptor returned by open().
Pointer to struct v4l2_output.

7.19.4. Description

To query the attributes of a video outputs applications initialize the index field of struct v4l2_output and call the ioctl VIDIOC_ENUMOUTPUT 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 outputs applications shall begin at index zero, incrementing by one until the driver returns EINVAL.

struct v4l2_output
__u32 index Identifies the output, set by the application.
__u8 name[32] Name of the video output, a NUL-terminated ASCII string, for example: “Vout”. This information is intended for the user, preferably the connector label on the device itself.
__u32 type Type of the output, see Output Type.
__u32 audioset

Drivers can enumerate up to 32 video and audio outputs. This field shows which audio outputs were selectable as the current output if this was the currently selected video output. It is a bit mask. The LSB corresponds to audio output 0, the MSB to output 31. Any number of bits can be set, or none.

When the driver does not enumerate audio outputs no bits must be set. Applications shall not interpret this as lack of audio support. Drivers may automatically select audio outputs without enumerating them.

For details on audio outputs and how to select the current output see Audio Inputs and Outputs.

__u32 modulator Output devices can have zero or more RF modulators. When the type is V4L2_OUTPUT_TYPE_MODULATOR this is an RF connector and this field identifies the modulator. It corresponds to struct v4l2_modulator field index. For details on modulators see Tuners and Modulators.
v4l2_std_id std Every video output 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 capabilities This field provides capabilities for the output. See Output capabilities for flags.
__u32 reserved[3] Reserved for future extensions. Drivers must set the array to zero.
Output Type
V4L2_OUTPUT_TYPE_MODULATOR 1 This output is an analog TV modulator.
V4L2_OUTPUT_TYPE_ANALOG 2 Any non-modulator video output, for example Composite Video, S-Video, HDMI. The naming as _TYPE_ANALOG is historical, today we would have called it _TYPE_VIDEO.
V4L2_OUTPUT_TYPE_ANALOGVGAOVERLAY 3 The video output will be copied to a video overlay.
Output capabilities
V4L2_OUT_CAP_DV_TIMINGS 0x00000002 This output supports setting video timings by using VIDIOC_S_DV_TIMINGS.
V4L2_OUT_CAP_STD 0x00000004 This output supports setting the TV standard by using VIDIOC_S_STD.
V4L2_OUT_CAP_NATIVE_SIZE 0x00000008 This output supports setting the native size using the V4L2_SEL_TGT_NATIVE_SIZE selection target, see Common selection definitions.

7.19.5. 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.

The struct v4l2_output index is out of bounds.