Science Fair Project Encyclopedia
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 bandwith, and static heads would require extremely high tape speeds. Video tape is used both invideo 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.
Professional and broadcast use
The first practical professional videotape machines were the Quad machines introduced by Ampex in the United States in 1956. Quad employed a helical scan system on a two-inch (5 cm) tape. The BBC experimented with a high-speed linear videotape system called VERA but this was ultimately unsuccessful, 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, 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 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. 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" C-format videotape. It introduced features such as shuttling and still framing.
The first video cassettes
Then, in 1969, Sony introduced the first widespread video cassette (prior formats had used open reels), the 3/4" 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" component video Betacam family (introduced in 1982), which, in its digital variants, is still among the market leaders. Panasonic had some limited success with ist MII system, but never could compare to Betacam in terms of market share.
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.
The introduction of HDTV production neccesitated 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.
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 due 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.
In camcorders, however, the field was more diverse, with the first formats to gain popularity being the 8mm video format (later replaced by Hi8 and its DV hybrid relative Digital8) and VHS-C (compact) tape. Now, MiniDV is the leading media for camcorder use. However, consumer MiniDV VCRs did not really catch on. Sony tried to introduce a new camcorder tape with MicroMV, but consumer interest has been low. For high definition, the most promising system seems to be the new MiniDV-based HDV.
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