DVD Demystified

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■ Entry points (chapters, programs, and cells) must start at a GOP
header and must be at least 0.4 seconds apart.
■ Corollary: An I frame is not necessarily a GOP header. To create an
entry point, you must force a GOP header, not just an I frame.
■ Subpictures cannot cross an entry point (chapters, programs, or cell).
■ GPRMs are reset to zero on title search or stop.
■ Cell commands are executed after the cell is presented.
■ If you want to play continuously from chapter to chapter, do not put a
next program command at the end of the program, since the player will
interrupt playback to execute the command. There is no need to add
any commands, since playback will automatically go to the next
chapter.
■ Never assume that anyone, even the client, knows what the DLT
contains. After authoring and writing to a DLT, fill out the replicator’s
project sheet personally to avoid inaccuracies.
■ Any amount of QC on a replicated check disc is worth more than the
cost of paying for a disc run that failed for the simplest problem.
DVD-ROM Production
Many details of producing a DVD for computers are covered in Chapter 11.
This section goes over a few of the basics. Also see the testing section earlier
in this chapter.
File Systems and Filenames
Chapter 12
DVD-ROM discs are specified to use the UDF bridge format, which includes
ISO 9660 and Micro UDF, but a DVD can be formatted with any file system:
full UDF, ISO 9660 only, Windows NTFS, Apple HFS, and so on. ISO 9660
Level 1 limits filenames to 8 characters plus a 3-character extension. Directory
names are limited to 8 characters with no extension. ISO 9660 Level 3
limits filenames to 30 characters (not counting the period between filename
and extension), although it’s possible to store up to 221 characters as the
file identifier. Directory names are limited to 31 characters, but 221 are possible.
UDF supports filenames of up to 255 characters using the Unicode
character set, which supports characters from almost every language. How-