We Only Need One Rewritable DVD Standard

Posted on July 01, 1998

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We Only Need One Rewritable DVD Standard

By Jeff Saake

Every year, companies around the globe spend billions of dollars to find out what customers want and need. Often, if the answers don`t fit management`s pre-established concepts of the "right" answers, the research is discarded as meaningless and worthless. They follow their own path, certain that the multitudes are mistaken.

In the storage industry, the rewritable DVD standard, which was developed to provide a universal solution for audio, video, and data storage, offers an excellent example of this approach.

To ensure that the new storage technology would meet the needs of computer manufacturers and users, a computer industry alliance was formed in mid-1995 that included Apple, Compaq, Fujitsu, Gateway, HP, IBM, Intel, Kodak, Microsoft, NEC, and Packard Bell. The alliance wanted a technology that would be backward compatible with existing CDs, would support write-once and rewritable solutions at the outset, would be both scalable and extensible, and would provide high performance for video, audio, and data applications.

Based on their input and the requirements of the motion picture industry`s Hollywood Digital Video Disc Advisory Group, a single rewritable DVD standard--DVD-RAM--was developed. It was hammered out by the DVD Forum`s technical working group, which included representatives from every manufacturer, and was approved by the Hollywood DVD Advisory Group and the DVD Forum, which now has more than 160 members. It was tested, proven, and approved by more than 20 PC and media manufacturers from around the world. And it was approved by JIS and ECMA. ISO approval is imminent.

Developing a Standard

Development of the standard began with every manufacturer in the DVD Forum submitting its recommendations for review. The field was narrowed to two proposed formats: MMCD and SD. Ultimately, a third solution was developed that incorporates the best features of both formats. Following extensive testing, the 10 original DVD Forum members (Hitachi, JVC, Matsushita, Mitsubishi, Philips, Pioneer, Sony, Thomson, Time Warner, and Toshiba) all agreed on the hybrid format as the DVD-RAM standard.

No single company "owns" DVD. The DVD Forum pooled all of the applicable patents for DVD-RAM and has assigned a third party to manage the distribution of royalties. It has been said that the royalty issue was the driving force behind the emergence of an alternative solution to the DVD-RAM standard.

Phase-Change Rewritable (PCR), also called DVD+RW, is based on closely-held proprietary technology that doesn`t include specifications for audio and video. It has been described as a short-term solution that doesn`t provide proof of expandability to higher capacities and doesn`t acknowledge the convergence that is occurring in the storage industry. It has also been described as a solution developed by some vendors` financial departments.

With a DVD-RAM drive connected to a PC, users have a single low-cost storage solution for reading CDs, performing system backups, and downloading large files to removable media. They can also use a DVD-RAM camcorder to shoot training films, sales presentations, and corporate profiles that can be edited on the DVD-RAM drive connected to their PC. Using the same disc, they can view the videos with a DVD-ROM player attached to a TV.

In meeting the requirements of both the Computer Alliance and Hollywood Digital Video Disc Advisory Group, the DVD Forum recognized that many businesses aren`t ready for audio and video applications. However, many of the technical advancements that enable these capabilities enhance the performance of DVD-RAM drives in data storage applications.

Without getting into the technical aspects of DVD-RAM and DVD+RW, tests show that DVD-RAM provides better data security, faster writing rates, easier format compatibility, and easier migration to higher capacities than DVD+RW.

DVD-RAM drives that are now available from Hitachi, Maxoptix, Panasonic, and Toshiba--and the drives of a number of others are scheduled to be announced--offer media interchangeability plus twice the transfer rate and four times the capacity of CD-R and CD-RW at a storage cost that rivals CD-R. 2.6GB single-sided media and 5.2GB double-sided removable media provide a million overwrites, which makes the low cost even more economical.

With a universal standard established that includes a growth path to the future, more than 30 of the industry`s most respected interface and software producers have announced the availability of DVD-RAM-compatible products or their intention to deliver products that support the standard. Content developers and solution developers are already using the standard.

Bare Discs vs. Protected

Other than a few megabytes of proposed additional storage capacity (which may be consumed with overhead), the strongest differentiating claim for the alternative proposal (DVD+RW) is that the media will "look and feel" like a CD because it will be a bare disc. But DVD-RAM drives do not require the media to be in a cartridge; it is simply recommended.

All storage media today (floppies, tape, MO media, and removable hard drives) have a protective case of one type or another to protect vital data. Even CDs are stored in cases when they are not in use. History has proven the wisdom of providing a protective case or cartridge when mission-critical data, which is often irreplaceable, is involved.

There are also other alternative being proposed as alternatives for rewritable DVD; however, none of these proposals provide forward and backward compatibility with CD and DVD-based products. Nor do they provide media interchangeability, except within their own family. Finally, none of the proposals provide the low drive and media costs that DVD-RAM provides, or the potential for even greater price reductions when all of the manufacturers (drive and media) are in full production.

The DVD Forum developed industry standards before products were announced and produced. More than 200 firms worldwide set aside their personal biases and agendas to work for the common good of consumers. With the assistance of content developers and providers, system manufacturers, and international standards organizations, the DVD Forum achieved the majority of its objectives in record time. Specifications for copyright protection and video encoding are under development.

In finalizing the format, the Forum sought to ensure expandability, economy, reliability, and unprecedented compatibility while satisfying, as much as possible, the desires of computer manufacturers and a wide range of users, as well as numerous media manufacturers and drive manufacturers.

The storage users told the industry what they wanted. Hundreds of organizations participated in the development and testing of a standard that meets these requirements.

Could all of these organizations be wrong? Can we afford another short-term storage solution that prolongs the royalties of an aging technology?

DVD-RAM: Key Features

1. Track format

- Wobbled land & groove format--High reliability

- ZCLV format--Large capacity and high access speed

- Single-spiral L/G--High accessibility

2. Addressing scheme

- Wobble-linked ID--High address reliability

3. Sector format

- ROM-compatible ECC block

- Divided into 16 sectors with header

- Common control data part among DVD family

4. Recording scheme

- Multipulse write strategy, applicable to various media

- Polarity randomization--high overwrite durability

Source: Panasonic/Matsushita

Jeff Saake is general manager at Panasonic Industrial Company in Milpitas, CA.

Originally published on .

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