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DCT

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This article is about the Ampex DCT video tape format. For other uses, see DCT (disambiguation).
Ampex DCT Logo
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Ampex DCT Logo

DCT (Digital Component Technology) is a fully proprietary format launched by Ampex in 1992. According to Ampex, the main advantage of DCT over other digital formats is high tolerance for data errors, in the order of one uncorrected error per hour.


Contents

Ampex DCT history

In 1992, Ampex introduces its DCT® products, the first digital component post-production system using digital image compression technology to produce unsurpassed quality images. The system includes the finest videotape recorder ever made, the DCT 1700d.

Later, Ampex high-performance computer mass data storage systems able to store half the contents of the Library of Congress in 21 square feet of floor space.


Ampex DCT description

Ampex DCT-700d digital component VTR
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Ampex DCT-700d digital component VTR

Ampex DCT was the first VTR format to employ digital video compression to reduce recorded bit rate. The 2:1 compression is completely transparent. Although a path-breaking product, DCT has not enjoyed the great popularity that digital Betacam has enjoyed, probably because Ampex marched to the beat of it's own drummer on this product. Still, there are numerous well known facilities that have adopted DCT as their high-end component production standard. Sadly, this will probably be the last VTR that Ampex will ever produce.

The units can switch between 525/60 and 625/50 operation, and allow a maximum recording time of more than three hours. These qualities give the DCT format a central role in Ampex' electronic film mastering scheme.

Ampex DCT technical specifications

Video

  • Track length: 150.78 mm Track width: 1.54 mils Track angle: 6.1296 deg.
  • Guard band width: 0 Headwheel diameter: 2.95 in Speed: 5400 RPM NTSC
  • Head-to-tape writing speed: 1078 in/sec. (NTSC) 6000 RPM PAL
  • Head azimuth offset angle (one head):
  • No. of segments: 3 No. of lines/segment: 87.5
  • Control track width: .5 mm
  • Recorded waveform: Square wave
  • Video modulation or Component luminance channel
  • Sync tip frequency:
  • Blanking frequency:
  • Peak white frequency:
  • Color carrier frequency:
  • Component color channel
  • Chroma encoding:
  • Sync tip frequency:
  • Center frequency:
  • Negative peak frequency:
  • Positive peak frequency:
  • Digital only
  • Sampling rate: CCIR 601 4:2:2 w/2:1 digital compression
  • No. of bits: 10
  • Data encoding system:
  • Data rate:
  • Audio segment location: Center

Audio

  • No. of longitudnal channels: 1
  • Track width: .7 mm
  • No. of AFM channels: N/A
  • Carrier frequencies:
  • No. of digital channels:
  • Sampling rate:
  • No. of bits:

Time code

A seperate longitudnal track, like most digital formats.


Ampex DCT tape

  • Tape width: 19 mm
  • Tape speed(s): 5.18 ips NTSC, 5.77 ips
  • Tape thickness: .55 mils Playing time(s): 34/94/208 min PAL
  • Cassette dimensions: same as D1 and D2 (NTSC)
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