Media Replication - DVD Replication

Understanding DVD's and its terms...

Although a DVD looks like a CD it has many important differences. A DVD is actually two half discs bonded together. In its present configuration, a DVD may contain data on one or both sides of the disc. A DVD is the first optical disc to feature two data layers that are read from the same side of the disc. DVD's also exhibit a dual-layer feature in which a disc may contain data on from one to four layers. This gives a DVD up to twenty-five times the capacity of a CD. Additionally, a DVD's data read rate is almost nine times as fast as a CD-ROM. Yet, all consumer DVD players can read and play a CD.

On the technical side, a DVD-9 features two data layers (Layer 0 and Layer 1) which are read from the same side of the disc. The second, or top disc layer (Layer 1) may be read in one of two fashions:
Parallel Track Path (PTP) which is the same as the normal data layer. The player's head skips back to the inner radius to read Layer 1
Opposite Track Path (OTP) in which Layer 1 is read in the opposite direction to the first data layer, Layer 0.

Most DVD-9 movie discs are authored as OTP such that the DVD-Video play jumps layers at the outer disc radius to provide for a continuous play. OTP may also be referred to as Reverse Spiral Dual Layer.

As more and more product is being produced in the DVD format, DVD-9 is proving to be many producers' first choice for some simple reasons:

It looks like a CD or a DVD-5 but contains 8.5 GB of data
It permits bit rates to be raised for a significantly higher video quality
It allows the majority of movies to have a widescreen and a 4:3 version on the same disc
The disc can have up to a five color picture as a disc label
It is not necessary to turn the disc over
The consumer will always place the disc in the recorder with the proper side up (based on the picture disc label)
The producer has the option to include extra languages, subtitles, DTS, special features, trailers for new feature, without having to sacrifice content time, for the four hours of high quality DVD-Video will accommodate practically any movie.

Storage Capacity of DVD -

DVD-5 - 4.7 GB (1 side, 1 layer – playback time 133 minutes)
DVD-9 - 8.5 GB (1 side, 2 layers – playback time 241 minutes)