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Only two or three years ago, nobody would have expected that the storage capacity of 4.7GB on standard DVDs wouldn't be sufficient -- even for users at home. But with video and high-resolution still photography moving from analogue to digital, the number of applications demanding higher capacities has grown. Double Layer DVD (DVD+R DL ) will enable you to record 4 hours of DVD-quality video or 16 hours of VHS-quality video, without the need to turn over the disc. You'll be able to archive up to 8.5GB of computer files on a single disc, which almost doubles the storage capacity compared with the 4.7GB for the single-layer DVD+R discs currently available. And you don't need to flip the disc to achieve full capacity.
Is it Double Layer or Dual Layer?
The Double Layer disc is referred to by several names in the industry. Initially the Alliance (made up of Philips, Sony, Dell, HP, Yamaha, Mitsubishi Chemical-Verbatim, Ricoh, and Thomson) referred to the disc as the Dual Layer disc. Drive manufacturers began to market their Dual Layer drives, which were quickly confused with the drives capable of reading and writing Dual Format (+ and -) media. The Alliance quickly converted to calling the media Double Layer and some of the drive manufacturers followed suit with their drive nomenclature. However, you will still find the Double Layer and Dual Layer nomenclature interchanged.
Regardless of what it is called, one fact remains constant -- it is the highest capacity DVD media available and nearly doubles the storage capacity of a DVD recordable disc from 4.7GB to 8.5GB (equivalent to twelve CD-Rs) on a single side. All this storage capacity and you don't even need to turn the disc over during recording. The double layer disc utilizes only one side for recording, which leaves the other side available for labeling the disc. So if you have drawers full of old VHS or 8mm tapes from your state-of-the art 1990's camcorder, get ready to down-size and burn some DVDs!
How is it made? What's it for?
The media is made up of two thin embedded organic dye films for data storage separated by a spacer layer, which is about 55 µm thick. Heating with a focused laser beam irreversibly modifies the physical and chemical structure of each layer such that the modified areas have different optical properties to those of their unmodified surroundings. This causes a variation in reflectivity as the disc rotates to provide a read-out signal as with commercially pressed read-only discs.
This increases the capacity of a single disc, allowing you to store:
- Four hours of DVD-quality MPEG-2 video* (HDTV Broadcast, Cable TV, Digital Satellite
Systems, etc.) - Up to 8 hours of MPEG-1 video
- 16 hours of VHS-quality video
- Over 120 hours of 128 kbps MP3 audio (approximately 200 songs)
You can also use the media to store important data files or back up a hard drive on your computer. The media is write-once and after being recorded is playable in most, but possibly not all, standard consumer DVD-Video players, DVD games consoles, or DVD-ROM equipped PCs. Of course, you will need a Double (Dual) Layer drive to actually burn the media.
A bit about Recorders & Drives
DVD recorders combine the capabilities of both DVD players and VCRs by allowing home users to record to discs instead of to tapes. DVD recordable drives are similar to the read-only DVD drives that come with many computers, with the exception that the recordable drive allows you to burn your own DVDs, back up your hard drive, or transfer large files from one computer to another.
Double Layer drives are just as fast with single-layer media as single-layer-only drives. In addition to burning Double Layer discs at 2.4X, the first generation of Double Layer drives burn single-layer DVD+R and DVD-R discs at 8X and DVD+RW and DVD-RW discs at 4X. Waiting for the Double Layer disc to record at 2.4X speed can seem like an hour -- well actually around 40 minutes to burn a standard 7GB movie - but is well worth the wait. Some drives (like the Pioneer DVR-108) allow burning at 4x speed, which takes about 27 minutes.
However, there is no guarantee that the media can be played back in your DVD player or DVD-ROM computer drive. So, what can be done about that?
Burning Software, How To, & Settings
Several companies have made software available that is capable of double layer media recording. Some of the companies who have already announced support for the Double Layer media are Ahead Nero, Sonic, Ulead, InterVideo, Roxio and Gear. Easy to follow instructions are a part of the burning software. Pop-up boxes will guide the user through the process and are fairly intuitive. Deciding whether to select Data, Audio, or Movies & Pictures depends on what you want to copy to the disc.
To copy your 8mm or VHS home movies and allow editing you will need to first transfer the movie to your hard drive. Once you have copied the movies to your hard drive, the software allows you to edit and then burn your DVD. Using the convenient drop-down boxes you can search your hard drive to find the folder you stored the movie file in and select it by clicking on it. Next you will be prompted to select the drive you are using to burn the disc. Again, the drop-down box allows the search to be easy. Selecting the drive and clicking on the "OK" button starts the actual process of burning the movie file to the disc. Some drives will have a slight delay before the burning process begins while others will start instantaneously. Actual recording speed may hover at or slightly below 2.4X. You may notice during this process that the software displays the disc format as DVD-9, DVD-ROM, or DVD+R DL. This format is determined by the "Book Type" setting before recording and can enhance playback compatibility. This setting is commonly referred to as the "bit setting", and should be set to DVD-ROM rather than DVD+R DL to ensure the optimum compatibility with the widest range of DVD players. Until the drive manufacturers offer bit setting support for their drives the incompatibility with DVD players will be an issue.