SMPTE D-2 Video Format
SMPTE D-2 Format Information:
Videotape Format: SMPTE D-2 Composite Digital
In use: 1988 - Present (in limited venues today)
Recording mode: Composite digital video, helical scan. 4 channels of AES/EBU PCM format audio, sampled at 48 kHz. Time code channel.
Tape width: 19mm (3/4") cassette.
Features: The first uncompressed composite digital VTR. First with pre-read capability.
Existing machine longevity: A few are maintained for remastering purposes, although the CBS and ABC TV networks apparently still accept programming delivered on this format.
Videotape longevity: Unknown.
Prior usage: Enabled the first widespread direct replacement for analog VTR’s such as one-inch C. Also gave the opportunity for lossless “clones” or dubs from one tape to another, in digital form.
Notes on the SMPTE D-2... The D-2 format really was a dream come true for many in the production and post-production world. For decades, the thought of dropping down a generation or two for editing, graphic, or titling operations meant a carefully thought out strategy to minimize generation loss (increased audio/video noise, dropouts, etc.). In a D-2 edit bay, with a D-2 (composite digital) switcher i.e. GVG 3000, virtually identical multiple generational editing was available for the first time (unless you already had the “pure” component digital D-1 gear). The ability to “pre-read” was a huge plus. A one inch VTR could be directly replaced by a D-2 VTR as a big first step, even if the switcher was an earlier generation analog devise i.e. GVG-300. Although first generation D-2’s had some issues (they were later resolved in other production models), being able to record digital video and 4 tracks of audio was a huge gain. Hence, D-2 was utilized heavily in major post houses, but may have not been justifiable in smaller venues (others were satisfied with analog Betacam SP and one inch type C). It was only a few years later, in the 1990’s, that Digital Betacam came along and pretty much ended D-2’s somewhat short lifespan.
The difference between component digital (D-1) and composite digital (D-2 and D-3), was that the input to these formats was an encoded NTSC signal, sampled at 4fsc, as opposed to a discreet component signal consisting of RGB (uncomposited NTSC) video. Both were workable formats, but D-1 was superior as all video processing was in the raw, component form. For example, a chroma key could be manipulated much easier in D-1 with discreet RGB. In D-2, even though it was a high quality signal, the composite digital stream had to be decoded into RGB for processing, which in itself was a somewhat bandwidth limited video element, due to prior NTSC encoding.
D-2 is in less use for production/post production now. But tapes still exist in archives, along with D-1 and D-3, etc.