DVD burners at ceatec: inside looking out.
And so the story ends? Nope. Just when you thought life would settle down and you could focus on mastering your video software, the burner and media camps have set out to meet your insatiable appetite for capacity.
[FIGURE 1 OMITTED]
The great thing about going to CEATEC (a trade show held in Japan) is that you get to see all the newest and greatest fun techie toys. It took a lot of willpower to stay away from the do-everything cell phones that will be available in the Pacific Basin and Europe but we were on a mission: to focus on the future of DVD storage and video production.
The good news for readers is that within 12 months:
* The burner and media manufacturers will be able to double the capacity of the recordable DVD discs giving us 8.5GB of capacity on a single side (currently to get more than 4.7GB on a disc double-sided media was used)
* The new media will store four hours of DVD-quality video or 16 hours of VHS quality
* The discs can be played by the majority of the players in use today.
The bad news is:
* It will require new DVD burners
* We will still have two formats (+/-) to contend with
* Neither side seems willing to compromise
For the sake of space, we are going to divide the dual-layer discussion into two parts: burners and media.
After a lifespan of ten years, the CD-ROM finally got the facelift it required to take it into the next century when the standard for DVD was finally agreed on during 1996.
The movie companies immediately saw a big CD as a way of stimulating the video market, producing better quality sound and pictures on a disc that costs considerably less to produce than a VHS tape. Using MPEG-2 video compression (the same system that is used for digital TV, satellite and cable transmissions), it is quite possible to fit a full-length movie onto one side of a DVD disc. The picture quality is as good as live TV and the DVD-Video disc can carry multi-channel digital sound.
All writable DVD formats include a set of specifications that define a media's physical layer that enables the media to be read. The application layer specification deals with the content. Motion pictures are typically released on replicated ROM media (the physical layer) and authored using the DVD-Video format (the application layer).
The DVD-Video format is essentially a publishing format for one-time-only mastering. Today there are four flavors of DVD:
* DVD-5 is a single-sided single-layered disc with 4.7GB
* DVD-9 is a single-sided double-layered disc offering 8.5GB
* DVD-10 is a 9.4GB dual-sided single-layered disc
* DVD-18 will deliver 17GB on a dual-sided dual-layered disc
A single-sided (DVD-5) DVD-Video disc was designed to hold a typical feature-length movie, which averages 133 minutes. For a dual-layer disc (DVD-9) capacity increases to 240 minutes (see Figure1).
DVD's data layer is right in the middle so that the disc can be double-sided. As a result, the laser assembly of a DVD-ROM drive is more complex than the CD-ROM to enable it to read from both CD and DVD media. Early drives used a pair of lenses on a swivel but current designs use dual optical pickup lasers optimized for CD (780nm wavelength) and DVD (650 nm).
[FIGURE 2 OMITTED]
Some DVD movies have taken advantage of double-sided discs by putting a version formatted for a normal TV or monitor with a 4:3 aspect ratio on one side and a widescreen version formatted for 16:9 aspect ratio on the other. But most of today's DVD movies take advantage of the dual-layer, single-sided media, which until now was only produced by professional replicators/duplicators. Pits on both layers of the DVD-9 layers are 10% longer than on a DVD-5 or DVD-10 disc. Each layer is molded in one substrate, the two are joined using an optically transparent bonding layer and the replicators print the discs in the conventional way (see Figure 2).
There are two ways of writing the DVD data layers: parallel track path (PTP) and opposite track path (OTP). The refection film of the first layer is semi-transparent and the bonding agent is transparent, providing instant access from the first to the second layer. They provide seamless continuous playback from the two layers.
In PTP discs, both layers read from the inside of the disc to the outside, whereas in an OTP disc the outer layer reads from the inside to out and then back in for the inner layer. This allows the drive to read both layers almost continuously, with only a short break to refocus the pickup lens. This is especially useful for DVD movies, where long playtime without interruption is needed.
Both the DVD Forum and the +RW Alliance have maintained their approach to write-once and rewritable DVD is best for the consumer. With R media both formats provide optimum drive and player compatibility. For RW media there continues to be compatibility issues just as we experience with CD-RW discs. When Sony, LG, NEC, BenQ, LiteOn and others introduced +/- recorders, the issues became moot. You were free to focus on buying the media preferred or could make your buying decisions based on market economics--which brand name discs were least expensive when you went to the store.
Presently 4x DVD Burners (writing a 4.7GB disc in about 15 minutes) are available at almost fire sale prices. New 8x DVD Burners (writing 4.7GB discs in less than 9 minutes) are readily available and are already aggressively priced. Before the ink was dry on the 8x announcements or specifications had been finalized, burner manufacturers were already advising us that 12x burners (+/- that would write a disc in under 5 minutes) would be available very shortly.
But at CEATEC, the "preferred format discussion" continued as Pioneer demonstrated their DVD Forum compliant dual-layer DVD-R burner along with DVD-R9 media. To add balance to the discussion, Philips, with the assistance of MKM (Mitsubishi Kagaku Media)/Verbatim, demonstrated the +RW Alliance consumer solution.
[FIGURE 3 OMITTED]
Both claim the high ground in playback compatibility, which means they are probably very similar. The questions readers will have to wait to answer will be:
* If you wait a heartbeat will there be a +/- burner?
* Do you really need 4 hours of video on a single disc or are you buying the unit for the added back-up capacity first and video capacity second?
* Which units will be available first and at what cost?
* What will be the cost of the 8.5GB write-once media?
These questions weren't answered at CEATEC and you'll have a few months to read up on the matter and decide for yourself. To get you started, let's examine the burners that were announced (in the next issue of CTR, we will cover the media).
While it was an impressive technology demonstration, Pioneer was sketchy regarding the specifics surrounding the implementation of DVD-R9. Company officials noted that they would shortly submit a proposal to the DVD Forum for the higher capacity technology.
It appears as though DVD-R9 will continue to use a constant linear velocity (CLV) rotation technique to maximize the storage density on the disc surface. This results in a variable number of revolutions per minute (RPM) as disc writing/reading progresses from one end to the other. Recording begins at the inner radius and ends at the outer. The media will probably use track pitch of 0.74[micro]m.
The company says tests of their dual-layer recording technology delivers 9.34% jitter with 17.3% reflection rate on the first layer and 8.08% jitter with 19.5% reflection rate for the second layer. Since these results are very similar to those achieved with DVD-ROMs and DVD-Video discs playback with existing DVD players should be very good.
Shortly after the introduction of DVD+R, Philips began work on dual-layer DVD recording technology development, which is endorsed by members of the +RW Alliance (see Figure 3).
According to Philips, compatibility has been achieved by using controlled laser power and special reflector material in the media manufacturing which economically optimizes media reflectivity. In addition the prototype DVD burners utilize firmware controlled signal amplitude and tracking signals during the writing process. This is designed to ensure compatibility with DVD standards.
DVD+R9 technology has much in common with the rival DVD-R9 technology, using phase-change. With the DVD+R9 format, discs can be recorded in either CLV format for sequential video access or CAV format for random access. By using "Lossless linking" video can be written, stopped and continued without any linking loss. The company says their objective has been to deliver higher capacity storage solutions that will write media that has maximum compatibility with existing DVD players and drives.
The final specifications and format book for DVD+R9 seem to be much further along than that for the DVD Forum's DVD-R9 format. Philips, the first to produce DVD+R products, received specification and book approval by the +RW Alliance late last year. The company and other members of the Alliance expect to begin introducing hardware during the third quarter of this year.
The key to the success of either or both technologies will be the media technologies that will be implemented ... we'll look behind the scenes in this area in the next issue.
|Printer friendly Cite/link Email Feedback|
|Title Annotation:||Storage Networking; DVD Burners|
|Publication:||Computer Technology Review|
|Date:||Apr 1, 2004|
|Previous Article:||Tale of the tape: deciphering data storage for SMB backup.|
|Next Article:||Serial ATA: hits & misses.|