Recording technology of a 1-inch Hi-Vision digital VTR

A 1-inch high-vision digital VTR made by Sony

Fig.1 A 1-inch high-vision digital VTR made by Sony

A 1-inch high-vision digital VTR made by Hitachi

Fig.2 A 1-inch high-vision digital VTR made by Hitachi

The world’s first digital VTR (SMPTE D-1) for standard television (SDTV) was commercialized in 1986. As regards digital VTR for high-definition television (HDTV or “Hi-Vision” TV), which has five times the information capasity of SDTV, both Hitachi and Sony had been developing prototypes for trail production since 1984. It was in 1988 that both companies launched the world’s first digital VTR commercially, meeting the unified specification following NHK’s “guidelines regarding Hi-Vision digital VTR” released in October 1987. With this VTR, a video signal with studio-standard data rate of 1.2 Gb/s (effective video data rate of 944 Mb/s) for the 1125/60 Hi-Vision system is recorded in uncompressed form and played back. This VTR took a leading role in digitization of Hi-Vision program production and was utilized as a signal source for equipment development. Moreover, it made a good showing when used for broadcasting the Seoul Olympics in 1988.

For enabling one-hour recording of uncompressed high-vision digital signal on tapes on 11.75-inch-diameter reels, a thin metal tape based on 1-inch open-reel-type VTR (which was at the core VTR used for SDTV broadcasts at that time) was introduced. Moreover, advanced technology for magnetic-tape recording, such as ratating a large-scale scanner (134.6-mm diameter) at high speed (i.e., 7200 rpm) and recording the video for one field segment on 16 tracks by a group of four heads, was fully utilized. The track width with a length of 400 mm was 37 μm. In the case of “insert editing”, difficult conditions, like substituting the video for one field segment and maintaining recording and playback interchangeability between different VTRs (for inclusion, editing, and broadcasting), were satisfied and, in terms of mechatronics as well, this VTR was the best available.

To achieve the first ever slow motion of Hi-Vision broadcasts, error-correction functions and frame memory (which are the essence of digital recording and playback) were utilized. As a result, in the case of sports broadcasts, like the Olympics in particular, this digital VTR demonstrated its superiority as a powerful method for program production.

In 1996, a HDTV digital VTR (D-5 HD) using video signal compression for half-inch cassette tape was commercialized in time for the Atlanta Olympics. As a key device for program production of high qualityHi-Visionvideo, this VTR made a significant contribution to the spread of Hi-Vision broadcasting by broadcasting satellites.



Publications

[1] Thorpe et al、HDTV Digital VTR、1988、SMPTE J. , pp.738-747

Related Researches

Category

Broadcasting
(Information Storage)

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