Pre Mastering is the preparing of DLT Tapes or DDP Images for submission to a Replication Facility for mass replication of DVD's.
When this process was invented several years ago, it was thought that only Hollywood studios would be able to produce DVD's, and the state-of-the-art medium for exchanging large amounts of data was DLT (Digital Linear Tape). These tapes are read in by a program at the replicator, most often Eclipse but there are other systems. Replicators invested millions in equipment and software to be able to produce a "Glass Master", from which many copies can be "Mastered".
To protect their investment, the Hollywood studios came up with copy protection schemes, CSS (Content Scrambling System) and Macrovision (causes degradation of video streams copied directly by a VCR). Today these schemes are easily defeated by software and hardware freely available on the internet, but they are still widely used. Also a region scheme was adopted so that DVD's produced for one region would not play in another. (The world is divided up into six regions plus Airline/Ships).
DVDAfterEdit Mastering Edition offers Pre Mastering to DLT Tape and DDP Images on hard drive. It also will read tapes or images Pre Mastered by other software, and convert them to a disk folder for further editing. Usually, these tapes and images are only "tagged" for encryption, and the encryption is applied during the mastering process. We do not own the CSS keys, nor do we use decrypting software, so we cannot read tapes where the CSS encryption was applied directly. Luckily this is probably a very rare case, such tapes are not in general circulation as far as we know.
Some DVD Authoring Applications, such as DVD Studio Pro, do not pre master directly from a Video_TS folder, but always refer to their inputs (assets) when building a DLT or image. This prevents using their Pre Mastering after DVDAfterEdit has made changes, since the changes would be overwritten by the original data. Other Authoring Application separate the building and Pre Mastering phases such that their Pre Mastering can work from a modified folder, and therefore can coexist with DVDAfterEdit, giving you a choice of which system to use for Pre Mastering.
DVDAfterEdit Mastering Edition has been engineered for and tested with a wide variety of Authoring Applications. It gives you visual feedback on choosing the layer break, showing you multiple blue arrows for each of the possible layer breaks at each level of the hierarchical Program Chain display, and red arrows for the path to the currently chosen break. (A break is chosen at the cell level, but a current cell may be split in order to provide a new cell for the break). The layer break is always marked non-seamless, which is a spec requirement that has often been ignored by other Pre Mastering systems, particularly DVD Studio Pro.
[inline:1=center,DVDAfterEdit Mastering Edition Screen]
In this screen dump, the chosen layer break is VTS 1 PGC 1 PG 4 Cell 4. It was chosen by the author because it is a transition from black, and so any delay caused by the player switching layers will likely not be noticed.
Dual-layer DVD recording devices are not a reliable medium for testing layer breaks for replication, if you use utilities such as Toast or Nero, since they do not give the user any control over where to place the layer break. DVD-R's, whether dual layer or not, are not suitable for direct submission for replication unless the replicator has the necessary software and procedures in place to produce a non-CSS, region all disc from such a submission. Many replicators have not updated their software or procedures for years.
Most replicators are capable of accepting DDP images as data on DVD-R, if they understand the necessary procedures. In this case, the DVD-R is being used as merely a data carrier or transporter. For dual-layers, each layer is written to a separate DVD-R.
To produce a DDP Image from DVDAfterEdit, choose "Tape Image" as the output, and build the tape layer(s) to a hard drive. Then using Toast 6, copy each layer folder to a DVD-R using the settings DVD-ROM (UDF) and Data (not Video) to get a disc that is readable by both PC's and Macs.