VidNumerator

This is a tiny library that uses syscalls to efficiently determine which /dev/videoN devices are webcams and which are the additional metadata control handles. The list of strings returned are the full filepaths to valid devices.

Important

In order for this library to work properly, the executing user must have either root or video group privileges

Technical Details

The library works by:

1. Scanning /dev for files matching the pattern video*
2. Calling the VIDIOC_QUERYCAP ioctl for each candidate
3. Reading the effective capability bits from deviceCaps when V4L2_CAP_DEVICE_CAPS is set, otherwise falling back to capabilities
4. Keeping only devices that advertise both V4L2_CAP_VIDEO_CAPTURE and V4L2_CAP_STREAMING

That filtering excludes metadata-only handles and other non-capture nodes that still show up as /dev/videoN.

Usage

devices, err := vidnumerator.EnumeratedVideoDevices()
if err != nil {
    // likely permission or ioctl failure
    log.Fatal(err)
}

for _, device := range devices {
    fmt.Println(device)
}

Implementation Notes

• Uses direct syscalls via golang.org/x/sys/unix
• Implements custom ioctl constants for V4L2 device querying
• Uses capability bit checks instead of matching one exact integer value, so drivers with additional flags still work correctly