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Digital
Video
The
FCC is moving US televsion to a digital
transmission format. This change is supposed to
start in late 1998 with stations in major markets,
and expand so that by 2002 every station will be
broadcasting a DTV signal and by 2006 stations will
relinquish there analog spectrum. It remains to be
seen whether this will happen on schedule; it's
already the middle of 1998 and different parties
involved (televsion stations, cable companies and
computer manufacturers to name just a few) have not
yet completely agreed on a standard.
There
are currently 18 different "DTV" formats, with
different resolutions, frame rates and scan
formats. There are three resolution formats; 704 x
480, 1280 x 720 and 1920 x 1080. Note:
HDTV
is defined as 1280 x 720 or 1920 x 1080.
The
current favorites for adoption are:
- 480P
(704 x 480 progressive scan) favored by cable
companies because of it's lower
bandwidth
- 720P
(1280 x 720 progressive scan) favored by
computer manufacturers
- 1080I
(1920 x 1080 interlaced) highest resolution, but
with a lower frame rate. [Favored by some
television stations?]
International
Data Corporation predicts mass market
acceptance of Digital TV is years away,
despite 42 U.S. TV stations transmitting the first
digital broadcasts on November 1 '98. Consumer
confusion, incomplete infrastructure, hardware
costs, and technical questions will prevent Digital
TV - particularly High Definition Television (HDTV)
- from growing as quickly as many have predicted,
according to a comprehensive Digital TV study
conducted by IDC.
IDC
forecasts that the installed base of HDTV sets and
compatible converter boxes will expand to over 13
million units by the end of 2002, then explode to
138 million units by the end of 2007. In the near
term, a large installed base of analog TVs, concern
over supported digital formats, and near term set
costs will keep true HDTV set volumes low. However,
lower cost Standard Definition TV (SDTV) sets and
set top converter boxes will provide users with
more affordable options. While not displaying HDTV
in all its glory, these lower cost alternatives
will enable users to receive digital signals and in
most cases yield improvements over analog.
The
report, Review & Forecast of the U.S. Digital
Television Market 1997 - 2002, includes analysis of
Digital Cable Television, HDTV, Digital Broadcast
Satellite, C-Band, Satellite Master Antenna
Television (SMATV), and Wireless Cable. It is
available for purchase by contacting Janis Dempsey
at 508-935-4145 or at jdempsey@idc.com.
<www.idc.com>
And
while HDTV television transmission tests
have just begun, the consumer electronics
industry and the cable television
industry have only just reached an agreement on
a standard for connections between digital
set-top boxes and digital television receivers.
Based on the IEEE-1394 specification ( "firewire")
the two industries say they must still work to
ensure that copyrighted material sent over this
digital link is protected, in recognition of the
concerns of the Motion Picture Association of
America (MPAA).
Because
of these delays, consumer electronics manufacturers
may not produce 1394-enabled digital television
receivers with content protection technology for
retail distribution until November 1999.
The
specification is available as CEMA document EIA-775
and OpenCable document OCI-C1, both of which will
now undergo the formal acceptance process required
by standards setting organizations.
<www.ncta.com>
Harris
Corporation says that, along with Lucent
Digital Video, have completed the broadcast
industry's first tests of how high definition
television (HDTV) receivers accept over-the-air
signals generated by a digital television (DTV)
encoding system. The device tested was...the Harris
FlexiCoder. The press release didn't
actually say what the results were -- we can only
assume they were a success
Earlier
this year, Harris and Lucent formed a strategic
partnership to bring FlexiCoder, a MPEG-2 encoding
system, to market. FlexiCoder has already been
delivered to more than half of all U.S. television
stations currently offering locally encoded
service.
To
date, HDTV receivers from Mutsubishi, Panasonic,
Philips, Samsung, Sharp, Thomson and Zenith have
passed interoperability tests with the Harris
FlexiCoder. Receivers from additional manufacturers
are currently being tested or scheduled for
testing.
Lucent
won a Emmy Award in 1997 for its pioneering work in
DTV as a member of the HDTV Grand Alliance. The
company, which contributed to the original MPEG-2
specification, also built the world's first MPEG-2
and digital HDTV encoders.
<www.harris.com/communications>
A
"new" television transmission format that features
a 19 x 8 aspect ratio (i.e. a "wide screen"
television.) Was supposed to offer much better
image quality than the existing digital formats.
HDTV, when it first was proposed some time ago was
really an idea with several different transmission
methods and formats. There were competing proposals
for an analog transmission format for HDTV which
were disqualified as investigations
progressed.
The
industry seems to be using the term
DTV
(Digital
Television)
as a superset name for a new digital transmission
format, with HDTV being tagged on to indicate high
resolution transmission formats. Everything will be
clear...someday.
The
Digital Versatile Disc (sometimes referred to as
the Digital Video Disc) is the successor to the
CD-ROM. Discs are the same physical size as CD-ROM
discs, but with the following
differences:
- Much
more information can be recorded on the disc
(4.7 GB instead of 640MB)
- A
disc can be dual layered. The second layer on a
disc can hold 3.8 GB. To switch from one layer
to another takes a fraction of a second or to
for current players, so when used in DVD-Video
the transition is usually placed at a point in
the movie where there is a transition that goes
to black so that the switch doesn't impact
playback of the movie.
- A
disc can be double sided (contain data on both
sides.) But you have to flip the disc to play
the other side.
- The
transfer rate of DVD players is a maximum of 9.8
Megabits per second [future players could be
faster?]
Because
of the dual-layer, double-sided nature of the
media, a DVD can have information stored in a
number of ways:
- 4.7
GB single layer single sided disc.
- 8.5
GB dual layer, single sided disc.
- 9.4
GB single layer, but double sided
disc.
- 17
GB dual layer, double sided disc.
At
9.8 Megabytes per second, approximately an hour of
video will fit on a 4.7 Gigabyte disc.
Note
that while DVD players can play CD discs, CD
players cannot read DVD discs.
A
separate page covers DVD authoring and disc writing
questions: <"DVD
Authoring">
Trying
to decipher the DVD drive options? I spent the last
couple of hours trying to figure out what was what.
From what I can understand, this is the current
status of DVD.
DVD-ROM:
These are the DVD drives that you can get for your
computer (technically, the home video players are
DVD-Video I guess.) These players can read the data
on DVD discs. You may or may not be able to play a
DVD-Video disc; to do that you'll need an MPEG2
decompressor to decompress the video stored on the
disc.
DVD-R:
These units are the closest to the DVD format, the
Pioneer DVR-S101 costs $16,000 but writes discs
that can be read by a standard DVD-ROM drive;
though you can't write a dual layer disc, only a
single layer, so the amount of data is limited to
3.95 GB on a side. I don't know what software
supports this on the PC (probably CD writing
software) For the Macintosh, Sonic Solutions ($$$$)
supports this drive, as does Toast DVD.
DVD-RAM:
is a rewriteable format that holds up to 5.2 GB on
a double sided disk (in a cartridge.) Why is this
mechanism called DVD when it isn't compatible with
the DVD-Video or DVD-ROM drives? Well, the drive
can read DVD media, and they muddy the waters by
saying it's to do with the fact that DVD is related
to drive performance rather than the actual
physical recording...
There
are a number of vendors for both Macintosh and PC.
I recently tried to get one of these mechanisms for
a PC system, but we weren't able to get a hold of
one due to shortages...
DVD-RW:
Just to confuse things even further, I believe that
there are two DVD-RW formats that are being
developed by two different groups. As far as I know
neither of these are actually available
yet.
The
DVD Forum has decided to develop
DVD-RW (DVD-ReWritable) as one of the
DVD-family format for Authoring use:
- DVD-RW
is the sequential rewritable disc system using
similar plastic injection substrate as DVD-R.
- This
system adopts a phase-change alloy material in
the recording layer of the disc to realize a
Rewritable characteristic.
- This
physical format has similar parameters as DVD-R
specifications, therefore DVD-R and DVD-RW discs
can be written or read by the same drive in the
future. Also, DVD-RW disc can be played-back on
the DVD-Video players and DVD-ROM drives with
small modification.
The
main application of this format is:
- Authoring
tool for content development (Content
Development of the DVD-Video/ROM).
- Others
applications, such as the archival.
The
specifications of DVD-RW physical format will be
examined by WG-6 of DVD-Forum.
DVD-RW
should not be confused with DVD-RAM which writes to
a cartridge based disc which is not compatable with
DVD-Video and -ROM drives.
<www.dvdforum.org>
Product
Info
E4
sells the CoolDVD Mac DVD Playback card, an
MPEG2/DVD card that enables Macs with DVD-ROM
drives to play DVD-Video (the current DVD-ROM drive
Apple ships with G3 Macs cannot be used to playback
DVD-Video.)
DVD-Multiplay
is a DVD format created by Multimedia 2000
that appears to be similar in concept to the CD-ROM
hybrid format in that it allows the creation of a
DVD that contains two types of data; both regular
video footage (that can be played by a DVD video
player) and interactive programming that will play
on a DVD-ROM player.
<www.news.com's
article "Another
DVD Scheme Emerges">
<www.m-2k.com>
VersaDisc
is a free Interactive Magazine on DVD disc
which will start monthly publication in June. Each
issue can be played in both DVD-ROM drives and DVD
Video Players, and according to their promotional
materials will contain a full length feature movie,
film previews, music videos, computer games,
children's activities, magazine and newspaper
editorials and articles, and software programs and
media products related to home, work and health
issues.
<www.dvd4u.com>
CNET
reports that Hitachi plans to market a
digital camcorder that uses DVD-RAM
instead of videotape by the end of next
year. This
might be an interesting development -- assuming you
could pop the discs out and read them on a DVD-RAM
drive connected to your computer it would make
editing video even easier. I assume that this
device uses the DV compression codec (or similar)
and doesn't use MPEG2 which is the format
used in DVD-Video discs.
<www.news.com
news report "Camcorder
adding DVD-RAM">
To
distinguish the DVD disc format itself from the DVD
discs that contain video material, some companies
use the term DVD-Video to indicate a disc that
contains video content (i.e. movies from
Hollywood.) The video content is compressed using
MPEG-2 to a specific file format defined for video
use, then placed on a DVD disc.
last
updated: 11/25/98
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