R9 refers to a DVD recording format that, as of 2011, represents state-of-the-art dual layering that increases a DVD's capacity for storage. Manufacturers that can work in R9, at the writing of this article, include Yamaha, Dell, Verbatim, Sony and Philips, among others.
What Is Dual Layering?
DVD+R9 and DVD-R9 are also known as DVD+R DL and DVD-R DL; the "DL" stands for "dual layering." This means that a single-sided disc has two different layers where recording is possible. The primary benefit of the second layer is a dramatic increase in capacity. Whereas the typical DVD-R or DVD+R has a limit of around two hours of storage time, the R9 format typically appears on discs that have four hours or so of time.
Plus or Minus?
DVD+R9 and DVD-R9 both have dual layering and both have the same storage capacity. The only difference between the plus and minus signs lies in the physical format. Different electronics manufacturers support different physical formats, based on licensing agreements -- similar to the VHS/Betamax war from back in the day but without the compatibility issues. Whereas VHS and Betamax cassettes required separate machine formats, depending on the manufacturer, you can usually play both types of discs in the same player.
Worth the Money?
If you want to make DVD+R9 or DVD-R9 movies, the primary difference between this format and earlier formats has to do with capacity. If you really need a disc that can play for four hours or that can hold 8,000 pictures in full colors, or 800,000 documents, then an R9 burner is for you. If not, you may just want to add speed to your existing burner system. If you're going to spend the money, increased speed may be more useful than increased capacity.
If you're going to play DVD+R9 or DVD-R9 discs in your player or disc drive, you need to have compatibility with dual-layer discs. Fortunately, incompatibility results from a design flaw that drive manufacturers will generally remedy for free. You can find contact information for your manufacturer on the published materials that came with your player, or you can go to the manufacturer's website and find contact information for the customer service department and order a new player.
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