An abbreviation for Opposite Track Path, which is a technique for data organization on dual-layer DVD discs. With movies that have long playing times or very high picture quality, the storage capacity of one information layer on a DVD might not be sufficient so dual layer DVD’s are used. In many cases, such as with long movies, the need for seamless continuation of the playback from one layer to the other is important. The method used for this is usually Opposite Track Path (OTP) method, as opposed to PTP (Parallel Track Path).
With OTP the first information layer starts with a Lead-in area at the inner radius of the disc and ends at the outer radius. The second information layer starts at the outer radius and ends with a Lead-out area at the inner radius of the disc. Reading of the data stored on the disc will start at the inner radius of the first information layer and proceeds until the Middle Area of this layer (found at the outer radius) is reached. Then a switch-over to the Middle Area (found at the outer radius) in the second information layer is made, in order to continue reading of the data from the outer radius up to Lead-out area at the inner radius of the second information layer.