Video devices are peripherals added to a computer to allow it to work with video. A video capture card provides a way to input video to the computer from conventional sources such as a camera, a VCR, or a TV cable or antenna. A video output card allows video to be output from the computer to a monitor. It is also possible to get video output cards that output video via a cable that can be connected directly to a television, allowing video to be played from a computer and watched on a television.

All information stored on a computer is stored in digital form as a sequence of numbers. When video is received from a source outside the computer, such as a VCR, it is usually in analog format and must be converted into digital form that can be stored in the computer...