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6.2.1.1 DVD (Digital Versatile Disk) (Next-Generation CD)




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This article is from the storage FAQ part1, by Rodney D. Van Meter with numerous contributions by others.

6.2.1.1 DVD (Digital Versatile Disk) (Next-Generation CD)

    Digital Versatile Disk (DVD), the new standard, is a two-layer
single or double-sided CD, 8.5 or 17 GB, or double-sided single-layer
CD, 9.4 GB. Transfer rate is 11 Mbits/sec (1.4 MB/s).
http://www.ima.org/forums/imf/dvd/faq.html contains a quick overview.
First versions will be read only, later will come WORM, then
rewritable.

First products are slated to be available by the end of 1996.

There were two new standards in the works, digital video disk (DVD)
and high-density compact disk (HDCD).  DVD was proposed by 8 major
consumer electronics giants (including Toshiba, with Time-Warner on
board) and would have featured a double sided disk capable of storing
5GB of data per side.  HDCD, backed by Philips and Sony, would have
held 3.7GB data, with the potential to double them up to hold 7.4GB by
using a two-layer technology.

VHS/Beta wars all over again, along with issues such as backwards
compatability to existing CDs, were avoided, thankfully. In December
of 1995, everybody agreed on the new DVD format.

See the article by Alan Bell in the July 1996 Scientific American.

(John Wiest (john.wiest@24stex.com), gold@sri.com (Michael Gold) and
others, 95/04/20, rdv, 96/7/1)

My (rdv) notes from the Goddard mass storage conference, 1996:

Mike Wingart, Sony, talked about DVD.

Their data rate is 11.08 Mbps, though video formats are generally used 
in a slower mode than that.  Two sizes, 8 cm and 12 cm.

size	single layer,	double layer,
	single side	double side
8cm	1.4 GB		5.2 GB
12cm	4.7 GB		17 GB

track pitch is 0.74 mm, compared to 1.6 for CD (I wrote mm, but I'm
sure that's microns).

Starts at the inner hub and moves out as it reads the first layer,
when it switches to the second it reverses direction.

They are working for backward compatibility, but the CD-recordable
format uses a dye polymer that's wavelength sensitive; CD-R is 750 nm, 
but they are using 650 nm laser.

Movie is only 4.8 Mbps (he didn't explain the discrepancy, but I
presume they just don't use the extra bw). Video is 3.5 Mbps, the rest 
is audio (5.1 channels, 3 languages, 4 subtitles).

They run 130 to 472 minutes of video on 12 cm disks.

Using ISO 13346, the volume & file standard for write once and RW
non-sequential media.

Using ISO 9660, the CD-ROM FS std, needs some modification to work?

DVD-ROM spec 1.0 released Sept. 6th, 1996; others coming soon.

Rewritable 2.6 GB single layer requires cartridge to protect disk.
Cyclability of rewritable media is still an issue.
    

 

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