Video tape recorder

A video tape recorder (VTR) is a tape recorder designed to record video material on magnetic tape. The first practical video tape recorder, using transverse tape head scanning, was developed by Ampex Corporation in 1956. The early VTRs were reel to reel devices which recorded on individual reels of 2 inch (5.08 cm) wide magnetic tape. They were used in television studios, serving as a replacement for motion picture film stock and making recording for television applications cheaper and quicker. Beginning in 1963, videotape machines made instant replay during televised sporting events possible. Improved formats, in which the tape was contained inside a videocassette, were introduced around 1969; the machines which play them are called videocassette recorders. Agreement by Japanese manufacturers on a common standard recording format, so cassettes recorded on one manufacturer's machine would play on another's, made a consumer market possible, and the first consumer videocassette recorder was introduced by Sony in 1971.

The first efforts at video recording, using recorders similar to audio recorders with fixed heads, were unsuccessful. The problem was that a video signal has a much wider bandwidth than an audio signal (6 MHz vs 20 kHz), requiring extremely high tape speeds to record it. One of the first efforts was the Vision Electronic Recording Apparatus, a high speed multi-track machine developed by the BBC in 1952. This machine used a thin steel tape on a 21-inch (53.5 cm) reel traveling at over 200 inches (510 cm) per second. Despite 10 years of research and improvements, it was never widely used due to the immense length of tape required for each minute of recorded video. Many other fixed-head recording systems were tried but all required impractically high tape speed.

It became clear that practical video recording technology depended on finding some way of recording the wide-bandwidth video signal without the high tape speed required by linear-scan machines. The solution was the transverse-scan technology invented by Ampex around 1954, in which the recording heads are mounted on a spinning drum and record tracks in the transverse direction, across the tape. By recording on the full width of the tape rather than just a narrow track down the center, this technique achieved a much higher density of data per linear centimeter of tape, allowing a lower tape speed of 15 inches per sec. to be used. The Ampex VRX-1000 became the world's first commercially successful videotape recorder in 1956. It used the 2" Quadruplex format, using two-inch (5.1 cm) tape. Because of its US$50,000 price, the Ampex VRX-1000 could be afforded only by the television networks and the largest individual stations.

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