Inside looking out observations from the dark side of the industry

Computer Technology Review, August, 2004

With all of the discussion surrounding double/dual-layer burners, we've been asked why we don't get more excited about the hardware that will deliver 8.5GB single-side writing capabilities.

Maybe we are a little negligent because the engineers at Philips, Pioneer and Matsushita have done a great job of proving the technology. But only a few firms (such as NEC, Toshiba and Matsushita) produce the laser diodes, which are bought by the true burner manufacturers that are then bought by the PC manufacturers and branded product producers. After they are all done, you can buy the new burner, produce your great DVDs and send copies to business associates, friends and family.

Compared to the present DVD /-R media you use, the new dual-layer discs are a beautiful work of art and technology. The media chemists and scientists deserve a tremendous amount of credit for developing the two dye layers and special UV adhesive that bond the two breath-thin resin layers. Moving those specifications onto the high-speed media production line demands a lot of quality production attention. During the early stages, only the name brand media manufacturers will have the equipment and talent necessary to ensure that you don't produce more coasters.

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Dual Standards, Dual Layer

Because neither side has yet to blink, there will still be two different versions of DVDR9 media ( /-). By the time you read this the DVD R9 media spec will be a matter of record. The DVD-R9 specs will still be making their way through committee and DVD Forum approval.

One format won't be better than the other (unless you ask someone deeply committed to one camp or the other). However, it is a lot easier for two companies to work on a common goal and have six others agree than have multiple camps reach agreement and then get the coliseum of interested parties to agree.

All Philips and MKM (Mitsubishi Kagaku Media)/Verbatim had to do was develop the hardware/media technologies, make certain it could be inexpensively and reliably produced and the RW Alliance was off to the races. Most of the rest of the members don't care which way the wind blows--as long as it blows.

On the other hand, Pioneer, Toshiba and Matsushita/Panasonic (two of the three don't play well together) had to hammer out their differences, go through a series of different working group studies, and get the 200 members of the DVD Forum to agree. Dictatorships just seem to reach consensus faster than democracies!

Despite the fact that there are differences (incompatibilities) between the two approaches, there are some similarities. Both have two thin substrates joined by specially designed UV bonding materials. When the laser is through writing to the first layer, it increases power slightly and begins writing to the second layer. When you are playing the dual-layer DVDR9 disc ( or -) you'll have to look hard to notice the switchover from one layer to the other.

The result is a full 8.5GB or 4 hours of DVD-quality (16 hours of VHS-quality) video. Some manufacturers may refer to the capacity of 4 hours of SP and 16 hours of EP, so be sure you understand the playback quality you want before you begin writing your write-once discs.

The other big similarity is that the DVD specification requires that players and drives read dual-layer discs. If you encounter one that will read "standard" /- discs but won't read DVD /-R9 media, it means the manufacturer had a design flaw, which they should correct at no charge.

DVD R9

Cross-section of a dual-layer DVD R disc The big hurdle was to keep the new write-once discs compatible with existing player standards. MKM was able to deliver compatibility by designing media that uses a thin layer silver-alloy as a reflector in the upper layer. This has produced reflectivity that complies with dual-layer DVD-ROM standards. In addition, the laser beam can pass through the first and reflective layers to write to the second layer. Voila! You can write and read to each layer.

Of course, all of that is an over simplification because they also had to develop unique dye materials and coating techniques, silver deposition and grooves that are stamped into the media to guide the write and read processes.

The DVD R9 format book has already been completed and approved by the Alliance. The organization also has more feature and performance plans they are working on that you'll be seeing over the next few years (speed increases and rewritable DVD).

DVD-R9

Dual-layer, single-sided DVD-R9 disc The -R or DVD Forum approach is similar for write-once DVD media. It also provides 8.5GB storage capacity. The reflection film on the first layer is semi-transparent. The bonding agent is totally transparent (as in dual-layer DVD video discs). You simply fill up the first layer and the (write or read) laser automatically moves to the second layer without missing a beat.

The pits on both layers are 10% longer than on your present DVD-R discs. Each layer is molded in one substrate and the substrates are joined with the optically transparent bonding layer. Even though you'll be able to write your data a number of different ways depending upon the application you are using, the two layers are treated as a single volume. That means you can expect to have to upgrade your software to take advantage of the new burners and media (true of both /-). This is because for video applications the software will take what is called the opposite track path (OTP) approach. The first layer starts at the ID (inner) area of the disc and the second layer starts where the first layer ends. This produces the seamless video storage and playback you expect with your movies.