A Quick Guide to DVD Recording Media

This article is now very, very, out of date, but is included here for historical information purposes.

The DVD boasts substantially higher density recording when compared with previous types of optical discs. The width of the grooves and size of the pits formed on the disc substrate are considerably narrower and smaller. Moreover the thickness of the DVD substrate, at 0.6mm, is half that of the 1.2mm used for CDs. For the DVD to realise its high recording density, it uses a red laser with a shorter wavelength than that of CD-R. Compared with CD-R and CD-RW, with their wavelength recording of 780nm, the DVDs wavelength is shorter, from 635 to 650nm. When the next generation DVD, with a 15GB capacity or greater is realised in the near future, it will make use of a blue laser with an even shorter wavelength (in the 400nm range).

‘The DVD Forum’ sets the standards for DVD technologies and has endorsed 3 different recordable DVD formats; DVD-RAM, DVD-R & DVD-RW.

- Panasonic, Toshiba and Hitachi are backing DVD-RAM.

- Pioneer is the corporate force behind DVD-R and its rewritable extension, DVD-RW.

- A fourth format, DVD+RW, is backed by Philips, Sony, HP, Ricoh and Yamaha, but has not yet been approved by the Forum.

The three different flavours of recordable DVD trying to become the digital home video format of the future are DVD-RAM, DVD-RW and DVD+RW

Each has approximately the same recording time using Mpeg compression - between two hours at DVD quality and five hours at VHS quality – and can all be re-recorded up to 100,000 times.

However, they are not interchangeable, so the chances are only one will survive as a domestic format. Just which one that will be is still wide open.

The main roadblock to arriving at a single DVD recordable format has been DVD-Video/DVD ROM cross-platform compatibility.

What is the difference between DVD-ROM, DVD-Video, DVD-RAM, DVD-R, DVD-RW and DVD+RW?

DVD-ROM is a play-only optical disc similar to today’s CD-ROM. The DVD-ROM has a much higher storage capacity (4.7Gbytes per side).

DVD-Video is a play-only disc that will hold a full length feature film. The DVD-Video will hold 135 minutes of high quality video and will add extra’s like multi-language support, subtitles and even interactivity. The DVD-Video quality is higher than laser discs and VHS. DVD-Video titles can be played in DVD players and computers with DVD-ROM players and MPEG2 decoder boards.

DVD-RAM is a rewritable version of DVD. Panasonic launched DVD-RAM to the PC market over two years ago but the lack of domestic DVD-RAM video machines has meant that its first mover advantage has been lost. The recordable disc is held within a caddy - this protects the media from dust contamination but means the discs will not work with existing DVD players. It uses a phase-change recording principle. TDK has developed a new type of phase change recording material called AVIST (Advanced & Versatile Information Storage Technology). It is expected that major DVD-ROM drive manufacturers will soon release DVD-RAM readable DVD-ROM drives, which have a standard tray loader.

DVD-R is a write-once recordable version of DVD. It uses an improved cyanine dye, similar to the material used in CD-R. DVD-R can be used for both DVD-ROM and DVD-Video applications.

DVD-RW: Pioneer’s DVD-RW format is a naked disc that has been developed from CD-RW technology using a phase changing dye between disc layers. Thanks to AVIST, TDK has already completed development work on a phase-change layer that is ideal for the DVD-RW format. Although current DVD players will not replay DVD-RW discs, next generation players may well do as the format has the backing of the DVD Forum in Japan. The first domestic recordable DVD players to market (early this year) are likely to be DVD-RW.

DVD+RW: Developed by Sony, Philips and Hewlett-Packard, DVD+RW is another naked disc format but has the advantage of being more compatible with existing DVD drives. DVD+RW promises full backward compatibility with existing DVD-ROM drives and DVD-Video players. However, the DVD Forum does not sanction this format as yet – this will delay compatible players coming to market, but both Sony and Philips are active members of the Forum.

What is the difference between Type I, Type II and Type III DVD-RAM?

Basically, Type II DVD-RAM has a hinged slot on the cartridge to allow removal of the disc inside – Type I does not (the disc is housed in a sealed cartridge).

Therefore Type II has the advantage of being able to use the media in jukeboxes type applications (nb. Disc cannot then be put back in caddy).

The more recent version, Type III, is a bare disc that is placed in an ‘open cartridge’ for recording.

DVD MEDIA LINE-UP:

DVD-RAM 2.6GB – Single-sided Type II
DVD-RAM 5.2GB – Double-sided Type I
DVD-RAM 4.7GB – Single-sided Type II
DVD-RW 4.7GB
DVD-R 3.95GB
DVD-R47S (General purpose)
DVD-R47SV20 (Authoring)

DVD-R47S is 100% compatible with Pioneer’s DVR-301 and Panasonic’s SW-9501 recorders. Both recorders are compatible with the DVD-R for GENERAL USE V1.0 spec.

DVD-R47SV20 can only be used on the Pioneer DVR-201s. Fully compatible with the DVD-R for AUTHORING v2.0 standard. Target customers for this item are professional authoring houses, document archival systems, DVD replicators etc.

Both media types are NOT interchangeable.

(DVD-R395 will work in the Pioneer DVR-S201)

re-listed: Sep.2015 Record House, Emsworth, Hampshire address