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Videotape

Bottom view of VHS videotape cassette with magnetic tape exposed
Bottom view of VHS videotape cassette with magnetic tape exposed

Videotape is a means of recording television pictures and accompanying sound onto magnetic tape as opposed to movie film. In virtually all cases, a helical scan video head rotates against the moving tape, because video signals have a very high bandwidth, and static heads would require extremely high tape speeds. Video tape is used in both video tape recorders (VTRs or, more common, video cassette recorders (VCRs)) and video cameras. Tape is a linear method of storing information, and since nearly all video recordings made nowadays are digital, it is expected to gradually lose importance as non-linear/random access methods of storing digital video data are becoming more common.

History

Professional and broadcast use

Open reel

The first practical professional videotape machines were the Quadruplex machines introduced by Ampex in the United States in 1956. Quad employed a transverse (scanning the tape across its width) four-head system on a two-inch (5.08 cm) tape, and linear heads for the soundtrack. The BBC experimented with a high-speed linear videotape system called VERA, but this was ultimately unfeasible, it used 1/2 inch (1.27 cm) tape traveling at 200 inches (5.08 m) per second, and all subsequent videotape systems have used helical scan.

Although Quad became the industry standard for 20 years, it had drawbacks such as an inability to freeze pictures, no picture search, and in early machines, a tape could only reliably be played back using the same set of hand-made tape heads, which wore out very quickly. Despite these problems, Quad could produce excellent images. Unfortunately, very few early videotapes still exist. The high cost of early videotapes meant that most broadcasters erased and reused them, and (in the United States) regarded videotape as simply a better and more cost-effective means of time-delaying broadcasts than the previous kinescope technology, which recorded television pictures onto photographic film. It was the four time zones of the continental United States which had made the system very desirable in the first place. However, some early broadcast videotapes have survived, including The Edsel Show, broadcast live in 1957, and 1958's An Evening With Fred Astaire, the oldest color broadcast videotape known to exist.

The next format to gain widespread usage was the 1" (2.54 cm) C-format videotape from the end of the 1970s onwards. It introduced features such as shuttling and still framing, but the sound and picture reproduction attainable on the format were inferior to Quad.

The first video cassettes

Then, in 1969, Sony introduced the first widespread video cassette (prior formats had used open reels), the 3/4" (1.905 cm) composite U-matic system, which it later refined to Broadcast Video U-matic or BVU. Sony continued its hold on the professional market with its ever-expanding 1/2" (1.27 cm) component video Betacam family (introduced in 1982), which, in its digital variants, is still among the market leaders. Panasonic had some limited success with its MII system, but never could compare to Betacam in terms of market share.

Going digital

The next step was the digital revolution. Among the first digital video formats Sony's D1, which featured uncompressed digital component recording. Because D1 was extremely expensive, the composite D2 and D3 (by Sony and Panasonic, respectively) were introduced soon after. Ampex introduced the first compressed component recording with its Ampex DCT series in 1992. Panasonic trumped D1 with its D5 format, which was uncompressed as well, but much more affordable. JVC developed the S-VHS-based D9 format, which compresses video data in a way similar to DVCPRO.

For camcorders, Sony adapted the Betacam system with is Digital Betacam format, later following it up with the more low-cost Betacam SX and MPEG IMX formats, and the semiprofessional DV-based DVCAM system. Panasonic used its DV variant DVCPRO for all professional cameras, with the higher end format DVCPRO50 being a direct descendant.

High definition

The introduction of HDTV production necessitated a medium for storing high resolution video information. In 1997, Sony bumped its Betacam series up to HD with the HDCAM standard and its higher-end cousin HDCAM SR. Panasonic's competing format for cameras was based on DVCPRO and called DVCPRO HD. For VTR and archive use, Panasonic expanded the D5 specification to store compressed HD streams and called it D5 HD.

Consumer use

Home VCRs

The first domestic videocassette recorders were launched in the early 1970s, but it was not until the Japanese systems, Sony's Beta (1975) and JVC's VHS, were launched, that videotape moved into the mass market, resulting in what came to be known as the "format wars". VHS finally won, mainly owing to its longer recording time compared to Beta. VHS is still the leading consumer VCR format, since its follow-ups S-VHS and D-VHS never caught up on popularity. It has, however, lost the battle against the nonlinear and disc based DVD, and will probably become obsolete in the next few years.

Camcorders

In camcorders, however, the field was more diverse; early camcorders generally took full-sized VHS tapes, but the greatest popularity for some time shared by the 8mm video format (later replaced by Hi8 and its DV hybrid relative Digital8) and VHS-C (compact) tape. MiniDV is now the most popular format for consumer camcorders, providing near-broadcast quality video and sophisticated nonlinear editing capability on consumer equipment; however, though intended as a digital successor to VHS, MiniDV VCRs are not widely available outside professional circles. Sony tried to introduce a new camcorder tape with MicroMV, but consumer interest has been low due to the proprietary nature of the format and limited support for anything but low-end Windows video editors. For high definition, the most promising system seems to be the new MiniDV-based HDV, which uses MiniDV media to store a roughly broadcast-quality HDTV data stream.

There has been a trend, largely spearheaded by Hitachi, Panasonic, and Sony, to sell consumer camcorders based on DVD-family media, but professional users consider DVD camcorders too limited for anything but casual use and have remained with digital videotape or switched to solid-state or hard disk storage.


 

 

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