D-2 (video)

For other uses, see D2.

D2 (video)

Sony D2 VCR
Media type	Magnetic Tape
Encoding	NTSC, PAL
Read mechanism	Helical scan
Write mechanism	Helical scan
Standard	Interlaced video
Developed by	Sony
Usage	Video production

D-2 is a professional digital recording videocassette format created by Ampex and other manufacturers through a standards group of the Society of Motion Picture and Television Engineers (SMPTE) and introduced at the 1988 NAB (National Association of Broadcasters) (NAB) convention as a lower-cost alternative to the D-1 format. Like D-1, D-2 video is uncompressed; however, it saves bandwidth and other costs by sampling a fully encoded NTSC or PAL composite video signal, and storing it directly to magnetic tape, rather than sampling analog component video. This is known as digital composite.

Ampex conceived of D-2 as a more practical solution for TV broadcasters since it could be inserted into existing broadcast airchains, television studio and post-production linear editing facilities without extensive redesign or modifications. This was because, among other things, in addition to its lower purchase and operating costs this digital composite video tape transport accepted standard analog video inputs and outputs.

Four audio channels are available for editing as well as an analog cue channel. D-2 was the first digital recording video tape format to offer Sel-Sync "read before write" (an Ampex term) also known as "preread" on Sony tape recorders. Read before write allowed simultaneous playback and recording on the same VCR. For example a title could be super imposed over existing video already on the same video tape by playing the tape through a video switcher, adding the title, and recording the new composite image back onto the same location of the tape. This eliminated the need for an additional recorder and saved considerable time in linear editing. If the digital inputs and outputs are used with a digital composite switcher multigenerational performance is excellent. Hundreds of layers of video are possible without image quality loss using the digital inputs and outputs. If one were to edit using D2 VTRs with analog I/O then there is image loss due to repeated analog to digital conversions and the normal image defects contained in a studio's analog infrastructure. The first PreRead edit facility was Video-It, Inc in Culver City, California. Steven Fuiten was the first PreRead Editor to composite video using a full D2 digital system. Ampex D-2 tape transports are extremely fast. A high speed search at 60 times playback speed with a recognizable color picture allowed three hours of videotape to be searched through in approximately three minutes.

D-2 used 19 mm (¾ inch) metal particle tape loaded into three different sized videocassettes. PCM-encoded audio and timecode are also recorded on the tape. Although the D-2 videocassette appear similar in appearance to the D1 (Sony) format, they are not interchangeable.

D-2 had a relatively brief heyday. As of 2003, only a handful of broadcasters use the D-2 format, and even then only to access materials recorded when the format was more popular.

During its early stages, finished episodes of South Park were hastily recorded to D-2 to be sent to Comedy Central for airing in just a few days' time^[1].

Panasonic's competing composite digital format is known as D-3.

Models

• Sony
  • DVR-10
  • DVR-18
  • DVR-20
  • DVR-28
  • DVC 80 Library Management System - LMS
  • DVC 1000s Library Management System - LMS

• • • DCR-10 (sold by BTS)
    • DCR-18 (sold by BTS)
    • DCR-20 (sold by BTS)
    • DCR-28 (sold by BTS)

• Ampex
  • VPR-200
  • VRP-250
  • VPR-300

• Hitachi

• 

  Sony D2

See also

• D-5 HD

References

1. ^ [1]

• - All Mobile Video D2 Specs
• - Sony Digital Age
• - The history of television, 1942 to 2000 By Albert Abramson
• - Ampex Digital VTRs
• Ampex ACR-225
• Ampex history
• Ampex history