Should I use Dual Layer DVD's?

There seems to be some confusion with regards to Dual Layer DVD discs. Lets clear up some of the misconceptions.

Firstly, some background.

DVD+/-R DL (DL stands for Double Layer) also called DVD+/-R9, employ two recordable dye layers, each capable of storing nearly the 4.7 GB capacity of a single-layer disc, almost doubling the total disc capacity to 8.55 GB (or 7.96 GiB). Discs can be read in many DVD devices (older units are less compatible) and can only be created using DVD+/-R DL drives. DL drives started appearing on the market during mid 2004, at prices comparable to those of existing single-layer drives. However, the price of DL media is many times that of single-layer media. The latest DL drives write double layer discs at a slower rate (up to 16) than current single-layer media (up to 20).

DVD-R DL has compatibility issues with legacy DVD-ROM drives known as pickup head overrun. To avoid this issue, the two layers of the disc need to be equally recorded. But this is a contradiction with the sequential nature of the DVD recording. Thus DVD Forum under Pioneer's lead developed a technology known as Layer Jump Recording (LJR), which incrementally record smaller sections of each layer to maintain compatibility with DVD-ROM drives.

Most DVD movies now days, ie. at your local video library, are replicated using a glass master onto discs which have the data layer physically molded into each disc. These movies are dual layer discs with a capacity of 8.55 GB. Have you ever noticed how half way through a long DVD movie there is a brief pause? The laser on your DVD player has reached the end of the first layer, then refocuses and moved onto the beginning of the second layer. This movement takes about a quarter of a second and doesn't detract from the viewing experience. But most burnable media, either DVD-R or DVD+R, is single layer with a capacity of only 4.7 GB. Why not just use dual layer?

Compatibility. Many older DVD players won't play burn't dual layer discs. Because of this, demand for dual layer discs isn't very high, and as we all know, price is determined by supply and demand. Dual layer disc, are double the capacity of a single layer disc, but around 4 times the cost. Dual layer discs are ideal thugh for computer backups where the drive you burn on is the drive you read through, and involves managing less discs.

Swimming through all the technical information, what does it mean? Well a dual layer disc costs about 4 times more than a single layer DVD and won't play on all DVD players.
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