Many people have been curious about dual layer DVD products and how reliable they are. With so much information out there and new technology being created every day, it can get quite confusing whether or not to invest in this a dual layer DVD player.
The basic answer to the question what is dual layer DVD is that this type of recording allows DVD-R and DVD+R discs to store a lot more data. We are talking about close to 8.5 gigs per disc, whereas a single later disc can only store up to 4.7 gigs. As you can see, we’re talking about a significant upgrade in the amount of data that can be stored on a dual layer recording.
How the dual layer disc works is much different that the regular DVD that we have been accustomed to. The dual layer has a second physical layer inside the disc. The DVD drive with the capability to read these discs shines a laser through the initial transparent later. However, in some DVD players viewers have noticed a pause up to several seconds. This caused many people to wonder if dual layer discs were defective. The end result was the studios had to stick a warning label on all packaging explaining that there may be a pausing effect.
Since technology has greatly improved the newer dual layer DVD players do have some backward compatibility with some DVD-ROM drives and DVD players. Most of the DVD recorders on the market today do support the dual layer technology, and since they have been on the market for some time now, the price is comparable to regular DVD players. Although the blank media for the dual layer DVD is still more expensive. Also you will find recording speeds much slower on dual layer media than that of the single layer.
Dual layer orientation has two modes, PTP which stands for parallel track path and OTP which stands for opposite track path. The PTP method which is used primarily with DVD-ROM, both of the layers will begin recording at the ID which is the inside diameter, with the lead in and end at the OD which called the outside diameter and that is the lead out.
Each sectors runs in sequence that goes from the first layer to the very end of the first layer, then begins at the second layer where it stops at the end of the second layer. When it is in OTP mode, the second layer reads from the outer part of the disk.
When using DVD video, a different type of technique is utilized. It is always recorded in OTP mode, but the video data reads from the start of the first layer then moves towards the end of the first layer. After that it switches to second layer where it reads the data. However, the video data begins from the same location where the first layer ended right before the second layer begins. The reason it does it this way is to give the system time to catch up to the second layer, giving it the shortest time to pause during the layer changes.
In order to fully understand all of the capabilities of dual layer DVD and was just talked about, it is important that you look at a chart for further explanation. A good chart on the subject matter will be able to give you visual picture of how the the dual layer DVD switches from the first layer to the second while also trying to minimize the pause effect.
Dual layer DVD can be very confusing to some people, but with new technology it does take some time for everyone to catch up with what’s going on. In the future most of it will be cleared as more advanced DVD technology hits the market. Until then, learn all you can about dual layer DVD technology.