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D-Series Formats

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Zak Ray
D-Series Formats
on Aug 8, 2009 at 9:38:41 pm

So I was looking at the Cow's Tape Formats spreadsheet:
http://magazine.creativecow.net/article/tape-formats-bit-depths-data-rates-...

And I'm a bit confused about the sampling ratio specs. Did D2 really have an alpha channel, as 4:2:2:4 would imply? And was D3 really black and white, as 4:0:0 would seem to say?

Thanks-- my experience with these older formats is limited at best.

Zak


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maurice jansen
Re: D-Series Formats
on Aug 9, 2009 at 9:39:17 am

hi zak

D3 is a composite record format. not a component i guess that's why they made it 4:0:0
there is only 1channel to sample.
i guess it's better to call is 4Fsc if it's a composite format.
i never worked with D2 but when i google it it seems that it's a Composite format too so i don't
understand where the 4:2:2:4 is coming from.
can somebody explain ?????

greet
Maurice



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Bob Zelin
Re: D-Series Formats
on Aug 9, 2009 at 2:19:23 pm

D2 was parallel digital signals. The D2 machine is how AJA got started, because their first products were digital parallel to serial, and serial to parallel converters. As people started to purchase SD-SDI video switchers, this is how you got a D2 machine into a SD-SDI switcher. There were early digital switchers with all parallel digital inputs (25 pin connectors) that had all these huge multipin cables going in and out of it from the VTR's. what a mess.

This was also the days of AVID AVR75 and AVID AVR77 (the early "broadcast quality" non linear editing formats of the day).
In NY, we would take the output of an AVID AVR77 ABVB board (the composite video output) and go into the composite analog video input of a Sony D2 VTR, and deliver this to HBO in NY as a "digital master". A digital house in NY was 2 or 3 Sony or Ampex 1" VTRs, playing back thru an analog composite switcher, going into the composite video input of a Sony D2 VTR - THAT was a digital master.
Boy the bulls#$% back then was the same bull@#$% that exists today in our industry.

"I need a Sony SRW-5500 master" - when it comes from a DVCProHD 720p master tape, and simply cross converted. Nonsense back then, and nonsense now. All, just to play the game, and make a living.

Bob Zelin




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Tom Matthies
Re: D-Series Formats
on Aug 10, 2009 at 9:03:36 pm

Actually, Bob, the D2 format was considered to be "Composite Digital". A composite analog signal was digitized, turning it into a data stream and recorded onto the tape. Kind of like feeding an analog composite signal into a frame sync and then recording the resulting digital information onto a tape. The parallel digital thing was utilized to allow digital transfer in and out of the machine. I don't believe that component SDI digital had been invented yet. Or at least it wasn't in wide use. D1 was about the only component digital option at that time. Using the parallel digital signal through a digital switcher like an Abekas A-82 would allow "lossless" (yea, right) digital compositing when fed back into a D2 machine. I saw a demo where 100 generations of green screen compositing was done using pre-read on a D2 machine. At that time, it was like watching magic. Now we all take things line that for granted. We're so spoiled...
Tom

Life moves pretty fast. If you don't stop and look around once in a while, you could miss it.--Ferris Bueller


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maurice jansen
Re: D-Series Formats
on Aug 10, 2009 at 9:23:09 pm

the funny thing is that generation issue's are coming back big time with
all the reencodes with different codec's ;-) these day's.
i guess all of us had to use H264 or MPEG stuff from the web and hated the end result.
these things are coming back.

greet
Maurice


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Jeff Markgraf
Re: D-Series Formats
on Aug 24, 2009 at 10:51:31 pm

If I recall correctly, D2 decks could be fitted with serial digital I/O. Special order. Not sure that it was "SDI" as we know it today.

Tom, I actually worked in a bay like you describe: Abekas switcher with 2 integrated DDRs, 2 channels of A53-D DVE...even an A72 CG. And the D/ESAM digital audio board. Boy, what a room! Everything run by the Accom Axial 20/20, complete with the source video right in the EDL display.

Never has it as good before or since. I felt as if I could do anything in that bay. Avid -- who needs a stinkin' Avid?!

Wait - am I that old?


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Paul Harrington
Re: D-Series Formats
on Aug 25, 2009 at 5:05:04 am

D3 was composite I use to operate a ACE 200 suite with VPR 3 1 inch and used the D3s as pre read decks for multi layer graphics passes with ADO. Lining up vision a chroma level via anologe VDA's will be somthing I won't miss. We had D5s the heads would only last 300 to 500 hours. The drop-outs had the uncanny ability to know when you were passed layer 10 or more of pre reads, I'm sure.


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