V4L2 - Video for Linux Version 2

Devices
Video4Linux provides the following sets of device files. These live on the character device formerly known as "/dev/bttv". /dev/bttv should be a symlink to /dev/video0 for most people.
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Device Name Minor Range Function
-- --- --- --- --- ----- -------------
/dev/video 0-63 Video Capture Interface
/dev/radio 64-127 AM/FM Radio Devices
/dev/vtx 192-223 Teletext Interface Chips
/dev/vbi 224-239 Raw VBI Data (Intercast/teletext)
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Video4Linux programs open and scan the devices to find what they are looking for. Capability queries define what each interface supports.