Quadruplex

Quadruplex is a two-inch videotape format and home video introduced by Ampex in November 30, 1956 to December 30, 1989. It was the first practical videotape format and the first commercially successful format.
Due to its quality, it continued to be an industry standard until the 1980s, when newer and smaller videotape formats such as Type C superseded it.
== History ==
=== Before quadruplex ===
==== Time shifting using film ====
In the 1950s, within the West Coast of the United States, time-shifting using kinescope film was a rushed and perilous ordeal, because there were only three hours for the West Coast branches to receive video from programs from the East Coast live via microwave relay stations or coaxial cable circuits provided by AT&T at the time. 
By then, the stations recorded such to kinescope film, only for the film to be developed to air on the West Coast three hours later. This process of recording and developing meant that the kinescope was aired almost immediately after it came out of the developing equipment, even if was still warm from the film dryer, which was referred to as "hot kines". 
The networks used so much film for time-shifting that, by 1954, these networks used more raw film stock for kinescopes than all of the combined Hollywood film studios, spending $4,000 per hour. The networks were desperate to obtain a quicker, less expensive and more practical solution.
=== Development ===
==== Competition for development ====
Around the early 1950s, Ampex and several other companies such as the BCE and the RCA, were competing to release a videotape format. Both the BCE and the RCA had working prototypes of their recorders, but their downfall was due to these recorders using a stationery-head method of recording, much like audio tape recorders. This meant that the tape had to be recorded at high speeds (at 10 ft or 3 m per second) to accommodate sufficient bandwidth to reproduce an adequate video image (at least 2 to 3 MHz for a watchable image), requiring large amounts of tape on large reels.
Aside from prototypes from the aforementioned companies, the BBC developed a similar stationery-head VTR called VERA, developed in 1952. However, despite some on-air use, the VERA system would not be perfected until 1958 and the system was abandoned later on, after it also adopted quadruplex in the Lime Grove Studios that same year.
==== Prototypes ====
Ampex later started to develop a more practical videotape format with tape economy in mind, as well as providing a solution to the networks' West Coast delay woes. In 1952, Ampex developed a videotape recorder prototype, known as the Mark I, using two-inch tape. The company decided that the head would be made to move rapidly across the slow moving tape. 
Instead of using the stationery-head method, Mark I used arcuate scanning, consisting of a spinning disk with a face which contacted the tape, and as a result, an arc-shaped track was recorded across the tape width. However, Ampex later abandoned arcuate scanning in favor of the transverse scanning system, due to problems with the timebase stability of the reproduced video signal from the tape.
In the mid-1950s, the company made Mark II and Mark III; both of them used transverse scanning. Mark II used FM for recording video to tape, resulting in an improved, though noisy, video image, and the Mark III had improved signal processing and servo electronics, resulting in better video production.
==== Demonstrations ====
Although the Mark III worked well, its appearance was similar to a prototype, and not a finished product. The Mark IV was later built, and was first demonstrated publicly in The NARTB Show (now known as The NAB Show) in Chicago, Illinois on 14 April 1956.
The Mark III was later given some improvements, and was demonstrated in the Ampex headquarters in Redwood City, California that same day. These demonstrations were a success, and Ampex took $2 million in orders for the machines in 4 days.
=== Release and later use ===
==== First usage ====
CBS became the first network to use Quadruplex videotape, using it for West Coast-delayed versions of its programs in November 1956, and the NBC also followed suit in January 1957, when it used pre-recorded tape to broadcast to all NBC stations in all time zones.
==== Advancements ====
Videotape editing was first introduced in 1958. Prior to this, kinescope film was the only way to edit audio and video, through a copy in kinescope film.
As Quadruplex machines became more reliable, it had outside broadcast use. Due to the machine's large size, they required their own trucks and were incredibly labor intensive. The format was initially black-and-white, but Ampex later developed machines and tapes for color production.
In 1963, electronic ways of editing were introduced by Ampex. In 1966, attempts of video slow-motion took place for the World Cup, using a modified Ampex machine. The machine was installed in the BBC Television Centre in West London. 
It was relatively risky to do video slow-motion and there were many problems trying to get it right, but the BBC Sports department was said to have "taken the gamble".
==== Military use ====
Aside from broadcast use, the US Military used it in reconnaissance applications in vehicles and aircraft. This is due to the VR-3000 being self-contained and portable. Quadruplex was a definite advantage for signals intelligence applications, due to its ability to record a wide bandwidth of signals, even high-frequency signals.
=== Decline ===
Quadruplex was later supplanted by easier-to-use, more practical and lower-maintenance analog videotape formats such as Type C, U-matic and Betacam. Later on, television broadcasters changed to digital videotape formats such as DVCAM and Digital Betacam, before tapeless formats entered the market. These newer formats had helical scan, unlike Quadruplex.
Quadruplex machines continued to be use for transferring, but most Quadruplex tapes from the 1950s to the late-1960s have already been transferred into modern media some years ago, even the past decade.
== External links ==
Some of the links may not be reliable
* Quadruplex videotape - Wikipedia
* Quadruplex - Museum of Obsolete Media
* Videotape: Images With Impact - YouTube
*Two Inch Quadruplex Videotape. - YouTube
*BBC Editing Archive - YouTube