U-matic is an analogue recording videocassette format first shown by Sony in prototype in October 1969, and introduced to the market in September 1971. It was among the first video formats to contain the videotape inside a cassette, as opposed to the various reel-to-reel or open-reel formats of the time. Unlike most other cassette-based tape formats, the supply and take-up reels in the cassette turn in opposite directions during playback, fast-forward, and rewind: one reel would run clockwise while the other would run counter-clockwise. A locking mechanism integral to each cassette case secures the tape hubs during transportation to keep the tape wound tightly on the hubs. Once the cassette is taken off the case, the hubs are free to spin. A spring-loaded tape cover door protects the tape from damage; when the cassette is inserted into the VCR, the door is released and is opened, enabling the VCR mechanism to spool the tape around the spinning video drum. Accidental recording is prevented by the absence of a red plastic button fitted to a hole on the bottom surface of the tape; removal of the button disabled recording.
For synchronisation to broadcast or post-production editing house genlock systems, U-Matic VCRs required a time base corrector (TBC). Some TBCs had a drop-out compensation (DOC) circuit which would hold lines of video in temporary digital memory to compensate for oxide drop-out or wrinkle flaws in the videotape, however the DOC circuits required several cables and expert calibration for use.
U-matic tapes were also used for easy transport of filmed scenes for dailies in the days before VHS, DVD, and portable hard drives. Several movies have surviving copies in this form. The first rough cut of Apocalypse Now, for example (the raw version of what became Apocalypse Now Redux), survived on three U-Matic cassettes.
Audio quality was compromised due the use of longitudinal audio tape heads in combination with slow tape speed. Sony eventually implemented Dolby noise reduction circuitry (using Dolby C) to improve audio fidelity.
The 2012 film No, set in 1980s Chile, used U-matic tape for filming.
U-matic was also used for the storage of digital audio data. Most digital audio recordings from the 1980s were recorded on U-matic tape via a Sony PCM-1600, -1610, or -1630 PCM adaptor. These devices accepted stereo analogue audio, digitised it, and generated "pseudo video" from the bits, storing 48 bits—three 16-bit samples—as bright and dark regions along each scan line. (On a monitor the "video" looked like vibrating checkerboard patterns.) This could be recorded on a U-matic recorder. This was the first system used for mastering audio compact discs in the early 1980s. The famous compact disc 44.1 kHz sampling rate was based on a best-fit calculation for NTSC and PAL's video's horizontal line period and rate and U-matic's luminance bandwidth. On playback the PCM adapter converted the light and dark regions back to bits. Glass masters for audio CDs were made via laser from the PCM-1600's digital output to a photoresist- or dye-polymer-coated disc. This method was common until the mid-1990s.
U-matic is no longer used as a mainstream television production format, but it has found lasting appeal as a cheap, well specified, and hard-wearing format. The format permitted many broadcast and non-broadcast institutions to produce television programming on an accessible budget, spawning programming distribution, classroom playback, etc. At its peak popularity, U-matic recording and playback equipment was manufactured by Sony, Panasonic, JVC and Sharp, with many spin-off product manufacturers, such as video edit controllers, time base correctors, video production furniture, playback monitors and carts, etc.
Many television facilities the world over still have a U-matic recorder for archive playback of material recorded in the 1980s. For example, the Library of Congress facility in Culpeper, Virginia holds thousands of titles on U-matic video as a means of providing access copies and proof for copyright deposit of old television broadcasts and films.
More than four decades after it was introduced, the format is still used for the menial tasks of the industry, being more highly specialised and suited to the needs of production staff than the domestic VHS, although as time passes it has been replaced at the bottom of the tree of tape-based production formats by Betacam and Betacam SP as these in turn are replaced by Digital Betacam and HDCAM.