Talk:D-2 (video)

Digital composite video
How does this work? Is it digital sampling of the monochrome picture and the PAL/NTSC/whatever colour subcarrier? --Zilog Jones (talk) 22:11, 30 May 2009 (UTC)
 * yes, that's right. It's basically an analog signal such as you might get from a VHS tape machine -- only a lot nicer See Composite_video. Should we explain this more clearly for the reader? XyKyWyKy (talk) 22:09, 15 September 2013 (UTC)


 * Zilog: Please understand that when you're dealing with composite video you can regard the entire thing as one (very complicated) signal to be recorded, played back, etc... as long as you have the bandwidth. Yes, there is a color subcarrier in there (about 3.58 MHz for NTSC) but the luma information extends higher in bandwidth than that (to about 4.2 MHz). So the ADC in a system like this doesn't have to deal with the color subcarrier as anything separate. Note that the old Ampex two inch quad analog machines did the same thing, recording and playing back composite video directly. Jeh (talk) 23:07, 15 September 2013 (UTC)

coming to this late.... first, bringing VHS into the story as an example of composite video is very misleading; VHS & several other cassette-based videotape formats use colour-under recording, which separates & transposes the colour subcarrier, as distinct from sampling & recording it directly as D2 did....


 * OR alert** I'd like to find literature that tells this story properly, to support what I remember from the time-

.... but the article has bigger issues than that- it doesn't explain properly why the recording of composite video was a good solution, or a technical priority for ampex, as distinct from decoding the input to components (Y, R-Y, B-Y like betacam, or D1) & then re-encoding them to composite (NTSC or PAL) at the output. yes, the format was initially developed to replace spot-players based on 2" quad (ampex' own ACR-25, for example), but there was already sony's betacart filling this role, along with cart machines from other manufacturers, & based on component formats. so why did ampex push ahead with a digital composite format? there was a demand for 'digital quality' before the technology was mature enough to record component signals onto small-format stock, i.e. 1/2" cassettes with (initially) a suitable housing for a robotic cart machine like sony's betacart & LMS, or ampex' own ACR technology. later, the larger cassettes & studio/edit recorders were available too, but the cart version came first. there was pressure from ad agencies, via the broadcasters, for a less costly & labour-intensive spot player than the aging ACR-25. the betacart was in its early (pre-SP) variant, & picture quality wasn't what we saw from beta-SP & digibeta a few years later. beta tapes also degraded rapidly, & in the context of tv commercials this is a bad thing. sony field engineers recommended that the life of a beta cassette was around 400-500 airings. the evaporated-metal stock used in D2 was a lot more robust. anecdotally, then, ampex produced the format to address this issue ahead of the development of component digital formats, such as panasonic's D3, sony's digibeta & so on. ampex may have had plans to develop their own small-format digital compnent format but were likely deterred by the rapid uptake of D3 & then digibeta; they had lost ground by this time, & got into badge-engineering the sony machines.

again, I wish I could cite something to support all this recollection, & then improve the article. I'll see what I can dredge up.

duncanrmi (talk) 16:19, 17 July 2019 (UTC)

Notes on revisions of Sep 14-15 2013
XyKyWyKy aka raffriff42 (talk) 08:03, 16 September 2013 (UTC)
 * Entire article seems to be based on http://www.encyclopediapro.com/mw/D-2 (or is that vice-versa? Maybe that article borrowed from an early version of this article)
 * 2nd paragraph: "airchains, television studios, post-production and linear editing" REMOVED: is this list needed? Seems to disturb flow of the sentence.
 * Models: reformatted by grouping model series on a single line
 * "gallery" REMOVED: only one image, which duplicated image from info box
 * "See also D5 HD" REMOVED: this has nothing to do with composite digital

D-2 or D2
The article is inconsistent as to whether there is a hyphen. Incoming links are also inconsistent. Similar issue for D-1 (Sony}. Anyone know what's right? ~Kvng (talk) 01:16, 16 July 2018 (UTC)