Path: utzoo!attcan!uunet!zephyr.ens.tek.com!videovax!bobe
From: bobe@videovax.tv.tek.com (Bob Elkind)
Newsgroups: comp.graphics
Subject: Re: Looking for details of Sony D2 format...
Keywords: Sony D2, digital video.
Message-ID: <5908@videovax.tv.tek.com>
Date: 17 Jul 90 14:41:01 GMT
References: <3714@altos86.Altos.COM> <2751@dftsrv.gsfc.nasa.gov> <15201@thorin.cs.unc.edu>
Reply-To: bobe@videovax.tv.tek.com (Bob Elkind)
Organization: Tektronix TV Measurement Systems, Beaverton OR
Lines: 42

The previous articles explaining D1 and D2 formats were pretty good, this
article contains some corrections and amplifications:

D1 and D2 are both 10-bit video standards.  They had originally been 8-bit, but
the Society of Motion Picture and Television Engineers (aka SMPTE) has fixed
that.  Much of the professional equipment out there supporting D1 and D2 are
10-bit boxes (frame synchronizers, signal generators, switchers, etc.). Tape
recorders are 8-bit devices (I believe) in general.  8-bit video is represented
in 10-bit D1 and D2 formats by setting the two LSBs to zero.

D1 comes in two flavours: NTSC and PAL.  Both flavours are indeed component
video sampled at 13.5 MHz for Luminance (the information to which human eyes
are most sensitive) and 6.75 MHz for the two Color-difference channels.  NTSC
flavour of D1 is still 262.5 lines per video frame, two frames per field,
59.94 Hz video frame rate.  PAL flavour D1 is 312.5 lines per frame, two frames
per field, 50 Hz video frame rate.  So you see, D1 is still quite different
between the NTSC and PAL standards.

D2 is also in NTSC and PAL flavours.  D2 is basically digitized baseband
(composite) video sampled at 4 times the colour sub-carrier frequency
(appr 3.58 and 4.43 Mhz for NTSC and PAL, respectively), or 14.3818 and
17.8 Mhz respectively. Baseband composite video is pretty much what comes out
of the RCA video connector on the rear panel of your VCR.

Both D2 bandwidths are much lower than the 27Mhz D1 data bandwidth (13.5 MHz
+ 6.75 Mhz + 6.75 Mhz), and therefore the tape storage costs are lower for the
composite standards.  This is a significant operating cost factor!

By the way, D1 format is also called 4:2:2 by many manufacturers, particularly
Sony.  Serial transmission formats for D1 and D2 are being formalized at this
time by a SMPTE committee.  The data format is basically the same as the basic
non-serial D1 and D2 formats, but some extra information is inserted at every
horizontal line, provisions for conveying audio information in the same signal
have been made, and provisions for miscellaneous (auxiliary) data have also
made.  Serial video is still 10-bit data,and since it is bit-serial the
transmission bandwidths are 10x that of non-serial (or parallel) D1 and D2.
This is not you basic RS-232 serial interface.

I hope this exposition has been somewhat useful.  There's a lot of interesting
folklore, politics, and humor in the developmental history of video standards;
and there is much more of the same going on right now (anyone tracking HDTV
developments out there knows what I mean).