Introduction to DVD+R Double Layer Medias
General Information
Understanding the Newest Rewritable Technology
For several years, DVD movie buffs have appreciated the benefits of pre-recorded (pressed) dual-layer DVD media . Dual-layer DVD media enables movies of up to 4 hours (240 minutes) in length to be played without disc-swapping, and provides nearly twice the room on each disc for bonus features. However, until the development of double layer rewritable DVD drives and media in 2004, PC users could read, but could not create, dual-layer discs . In this article, you learn how double layer DVD rewritable drives work, how to enable older single-layer DVD drives to read double layer media , and which vendors produce double layer DVD drives and DVD media .
The first (and so far, only) double layer rewritable standard comes from the DVD+RW Alliance: DVD+R DL , although all drives capable of writing the DVD+R DL format will also be able to write the future DVD-R DL format when it is eventually released. Sony was the first to introduce a dual-layer drive (the DRU-700A) in March 2004, however many manufacturers including BenQ, LiteON, Philips, Pioneer, NEC, and others have since followed suit.
MediaTek is the world's largest supplier of optical drive chipsets, and supplies the chipsets driving most of the DVD burners on the market, including double layer models . Other companies including NEC, Philips, Sanyo and TDK also provide chipsets for double layer drives .
It is interesting to note that the DL in DVD+R DL actually stands for Double Layer and not Dual-Layer , however the terms are often interchanged, and some media is advertised using both terms. The DVD+RW Alliance uses the Double Layer terminology to help prevent confusion with the fact that most DVD burners are also capable of reading and writing Dual Format (+ and -) media. Since the term Dual-Layer was originally used with pressed DVD-9 discs, it seems that many are maintaining the use of that terminology for pressed DVD-9 discs, while reserving the Double Layer designation for writable or rewritable discs . In the end, the only important thing to note is that for all intents and purposes the terms are identical, and are often used interchangeably.
How Dual-Layer DVD Media Works
Dual-layer DVD-Video media has been used for several years by the DVD movie industry. Dual-layer DVDs have a thin substrate layer between the first and second layers of DVD data. Single-sided dual-layer DVD-Video mediais known as DVD-9 . Note that DVD+R DL is also referred to as DVD+R9. It has a capacity of 8.5GB (slightly less than twice the 4.7GB capacity of standard DVD-5 media). It's also possible to have double-sided dual-layer DVD-Video media , known as DVD-18 ; some movie vendors use this technology to place widescreen (letterbox) and fullscreen (4:3 TV format) versions of a film on a single DVD . The user inserts the media into the DVD player or drive with the widescreen side up to view the film in its original format. By inserting the media with the fullscreen side up, the film can be viewed in its modified TV format. Almost all DVD set-top boxes and DVD-ROM drives except for possibly some very old models can read DVD-9 and DVD-18 media. Inside the drive, a single laser is refocused when switching between layers, accounting for a slight delay when moving from the top to the bottom layer.
How Double Layer DVD Rewritable Drives Work
DVD+R DL discs use a single refocusable laser to write both layers. The top layer (Layer 0; L0) is written first. The metal reflector used by L0 is semi-transparent, enabling the refocused laser to write to the second layer (Layer 1; L1). Because the L0 layer absorbs some of the laser's energy, only about half the laser power reaches the L1 layer.
Comparing Write Performance of Double Layer and Single-Layer DVD+R Media
Although mainstream single-layer DVD rewritable drives have now reached 12X to 16X DVD+R write speeds, DVD+R DL media speeds are far behind at only 2.4X to 4X. At the 2.4X speed, it takes about 45 minutes to fill an 8.5GB double layer disc , compared to about 25 minutes at the 4X speed. By comparison, it takes about only 6 minutes to burn a 4.7GB single-layer disc at 16X speed. Since only a few of the double layer drives incorporate 4X as well as 2.4X write strategies, I recommend you check for 4X capability before purchasing. 4X capable drives will support second-generation 4X DVD+R DL media when it becomes available.
Compatibility Issues with Existing DVD Drives
Although early compatibility tests suggest that double layer media can be read successfully by most DVD set-top players, compatibility issues are a much bigger concern with DVD drives in PCs. If you want to use a double layer DVD+R drive to create backups for use in other systems with DVD rewritable or DVD-ROM drives , it's important to check with the maker of your existing drives to determine if they can read double layer DVD+R media . The best general recommendation is to insure that all of your existing drives are upgraded to the latest internal firmware revision since most of the time, firmware upgrades will correct any issues with reading DVD+R DL discs .
Conclusion
Although double layer rewritable DVD drives are generally more expensive than their single-layer siblings, their additional capacity and ability to write to single-layer media at the highest possible speeds makes them a useful alternative if you need more than 4.7GB per DVD disc .
Introduction to DVD+R Double Layer (DL)
Imagine being able to record 4 hours instead of 2 hours of the highest quality DVD video on a disc. Or to store 8.5 gigabytes, equaling about 12 fully recorded CD-Rs , instead of 4.7 gigabytes, on a single sided DVD .
All this is possible, here and now, with the advent of DVD+R Double Layer recording technology. Based on the proven double layer technology that has been used in DVD-Video for many years, DVD+R DL almost doubles the recording capacity when compared to traditional DVD recording media. And because the disc is single sided, there’s no need to flip it over halfway through playback or recording.
But the best thing is, you can play a DVD+R DL disc in your current DVD-Video player , DVD games console, or DVD-ROM equipped PC. Double layer playback has been part of the DVD format since the beginning, so most existing DVD playback equipment has no problem playing the new high capacity DVD+R DL discs !
The only thing you need to store these huge quantities of data or long video recording times is a DVD+R DL capable DVD rewriter and the new sophisticated DVD+R DL media . Currently, more than a dozen manufacturers already offer DVD+R DL capable drives . And these drives are backward compatible, they let you record DVD+RW and single layer DVD+R media .
Check out the Frequently Asked Questions for more information.
DVD+R Double Layer (DL) - FAQ
Do I need new equipment to play a recorded DVD+R DL disc?
No. Completely in line with the philosophy of the DVD+RW Alliance, the new DVD+R DL discs can be played on existing equipment. This is because double layer playability has been part of the DVD-Video/DVD-ROM standard since the beginning. DVD+R DL compatibility is about equal to that of current single layer DVD+R .
What products support DVD+R DL?
To record on a DVD+R DL disc , you need a DVD+R DL capable writer. Refer to the DVD+R DL Products listing for an overview of these new writers.
Do I need different media to record a DVD+R DL disc?
Yes. To take advantage of the double layer recording capabilities of the new DVD+R DL writers , you need the highly advanced DVD+R DL media . This media consists of two recordable layers, instead of just one (as with traditional recordable DVD discs ). Note that you can still record single layer DVD+R discs and DVD+RW discs on those new DVD+R DL drives . The release of DVD+R DL media has been announced by all major blank media manufacturers, including Philips, Verbatim,Optodisc, Ricoh, CMC Mr. Data, Maxell, Infodisc and Ritek.
Do I need new software to write a DVD+R DL disc?
To write a DVD+R DL disc , your CD/DVD recording software needs to support DVD+R DL . Almost all software vendors have announced support for DVD+R DL in their upcoming versions, and most of them offer upgrades for their existing products to include DVD+R DL writing support. Among the companies that have already announced DVD+R DL support are Ahead Nero, Sonic, Ulead, InterVideo, Roxio and Gear.
What is the capacity of a DVD+R DL disc?
A DVD+R DL disc hold 8.5 gigabytes of data. This is fully equal to the amount of data on a pre-recorded double layer DVD-Video disc , sometimes referred to as DVD9 . A single layer DVD holds 4.7 gigabytes. As the track distance on both layers of any double layer DVD is about 10% wider, the total capacity of both layers equals 8.5 GB.
How much video does a DVD+R DL disc hold?
As with DVD+RW and single layer DVD+R , the amount of video one discs holds depends on the quality setting that was chosen during recording. When recorded in the highest possible DVD-Video quality, a DVD+R DL disc holds about 4 hours of video. When video is recorded at VHS quality level, recording time increases to up to 16 hours per disc.
Do I need to flip the DVD+R DL disc over to get access to its full capacity?
No. Contrary to other recordable DVD proposals, where you need to manually turn the disc over halfway through recording or playback, a DVD+R DL disc nearly doubles the capacity on a single recording side. The entire disc’s contents can be accessed without the need to take the disc out to turn it over. Furthermore, a single sided disc allows for easy identification on the label side.
Will single layer DVD+R continue to be available?
Yes. Because single layer DVD+R media holds up to 4.7 gigabytes of data (equaling about 6 CD-Rs), this technology still provides very high storage capacities suitable for a wide range of applications. Furthermore, the new DVD+R DL writers will still be able to record to single layer DVD+R as well as DVD+RW media .
