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Discussion in 'Archived Threads 2001-2004' started by Sheldon, Mar 11, 2002.
Can anyone explain it in somewhat simple terms?
Theere are DVD-9 discs also known as dual-layer discs. DVDs with two layers on them. The layer change occurs when the laser in a DVD player reaches the end of one layer and refocuses or moves the second layer.
When a film is spread over two layers of one side of a disc, the layer change is basically just the point at which your player switches from reading one layer to the next. This usually results in a very slight pause during playback. How noticable it is varies depending on the DVD and the hardware you are using for playback.
I don't know if you were looking for a more technical response. That's about the best I can do.
Many DVDs have two separate layers on the same side. Different information is stored on each layer. There is a special variety of disc known as "RSDL" in which the two layers are intended to be played continuousy. The laser pickup in your player reads the first layer, starting at the center of the disc and tracking out to the edge. Then the pickup pauses, the laser refocuses to the second layer, and the pickup tracks back from the outer edge to the center.
Depending on the player and on where this change occurs in the course of the movie or program you're watching, you may see a short pause. That's what people generally mean when they refer to the "layer change".
Not all dual-layer discs are RSDL. Sometimes the two layers are used to store distinct and separate materials (e.g., a widescreen version of a film on one layer and a P&S on the other).
It is the death of most Apex DVD players! ;-)