A videodisc has one of two formats: CAV or CLV.
CAV (constant angular velocity) is the interactive format of videodiscs, which allows freeze frame and slow motion. The CAV videodisc can be addressed by chapter or by frame. A CAV videodisc can contain up to 30 minutes of video on each side of the disc. One disc holds up to 54,000 frames.
With a CAV format videodisc, the angular velocity of the disc is always the same (1800 RPM), no matter what track is being read, which is similar to the way a phonograph record is played.
CLV (constant linear velocity) is the format for extended-play videodiscs. The CLV videodisc can be addressed by chapter or by time. A CLV videodisc can contain up to 60 minutes of video on each side of the disc.
With a CLV format videodisc, the linear velocity of the disc is constant under the laser head; the disc spins slower when the outside tracks are read.
Note: The number of chapters on CAV and CLV discs varies, depending on the manufacturer of the disc.