A read-only optical disc that can store up to two hours of video data. Normally used to store a complete film (as a rival to the video cassette) or in an interactive system with text, video and still images. For interactive use, a videodisc can store 54,000 frames of information. If the videodisc contains a complete film, the data is recorded using a constant linear velocity format. If used to store interactive data, it is stored in a constant angular velocity format.