Flirting With Mermaids


Digital Video

DTV (Digital Television)

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


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.


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.


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.


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.
<'s article "Another DVD Scheme Emerges">

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.

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.
< 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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