D-3 is an

uncompressed In information theory, data compression, source coding, or bit-rate reduction is the process of encoding information using fewer bits than the original representation. Any particular compression is either lossy or lossless. Lossless compression ...

composite

digital video Digital video is an electronic representation of moving visual images (video) in the form of encoded digital data. This is in contrast to analog video, which represents moving visual images in the form of analog signals. Digital video comprises ...

format invented at

NHK , also known by its Romanization of Japanese, romanized initialism NHK, is a Japanese public broadcasting, public broadcaster. It is a statutory corporation funded by viewers' payments of a television licence, television license fee. NHK ope ...

and introduced commercially by

Panasonic is a Japanese multinational electronics manufacturer, headquartered in Kadoma, Osaka, Kadoma, Japan. It was founded in 1918 as in Fukushima-ku, Osaka, Fukushima by Kōnosuke Matsushita. The company was incorporated in 1935 and renamed and c ...

. It was launched in 1991 to compete with

Ampex Ampex Data Systems Corporation is an American electronics company founded in 1944 by Alexander M. Poniatoff as a spin-off of Dalmo-Victor. The name ''AMPEX'' is an acronym, created by its founder, which stands for Alexander M. Poniatoff Excell ...

's D-2.

Overview

D-3 uses half-inch

metal particle tape Audio compact cassettes use magnetic tape of three major types which differ in fundamental magnetic properties, the level of bias applied during recording, and the optimal time constant of replay equalization. Specifications of each type were se ...

at 83.88 mm/s (compare to D-2's 19 mm and 131.7 mm/s). Like D-2, the

composite video Composite video, also known as CVBS (composite video baseband signal or color, video, blanking and sync), is an analog video format that combines image information—such as brightness (luminance), color (chrominance), and synchronization, int ...

signal is sampled at four times the color subcarrier frequency, with eight bits per sample. Four channels of 48 kHz 16–20 bit PCM audio, and other ancillary data, are inserted during the

vertical blanking interval In a raster scan display, the vertical blanking interval (VBI), also known as the vertical interval or VBLANK, is the time between the end of the final visible line of a frame or field and the beginning of the first visible line of the next fra ...

. The aggregate net (error corrected) bitrate of the format is 143 Mbit/s, and because the codec is lossless, it has been used in data applications.

Camcorder A camcorder is a self-contained portable electronic device with video and recording as its primary function. It is typically equipped with an articulating screen mounted on the left side, a belt to facilitate holding on the right side, hot-sw ...

s were available which used this format, and are to date the only digital tape camcorders to use a lossless encoding scheme. The D-5 digital component video format, introduced in 1993 by Panasonic, uses the D-3 transport and tape running at roughly double D-3 speed. The D-3 transport in turn is derived from the MII transport. D-3/D-5 tapes come in small (161 mm × 96 mm × 25 mm), medium (212 mm × 124 mm × 25 mm), and large (296 mm × 167 mm × 25 mm) cassettes, with format-specific recognition holes. Maximum D-3 runtimes (in the Fujifilm lineup) are 50, 126, and 248 minutes. The D-3 format is now regarded as obsolete. In the early 1990s the

BBC The British Broadcasting Corporation (BBC) is a British public service broadcaster headquartered at Broadcasting House in London, England. Originally established in 1922 as the British Broadcasting Company, it evolved into its current sta ...

embarked on a massive project to copy its older video tapes onto D-3 for archival, but the D-3 cassettes themselves have become obsolete and are being transferred to modern digital video standards. There is doubt over whether the surviving D-3 machines will last long enough to play the 340,000 tapes which the corporation holds.

References

External links

Technical Glossary of Common Audiovisual Terms: D3

International Association of Broadcasting Manufacturers Technical Reference on Video Tape Recording Formats, January 2000
{{Video storage formats Video storage Audiovisual introductions in 1991 Television terminology Videocassette formats Composite video formats