Physical spec evolution:
DVD functionality is officially specified by the DVD Forum, a partnership of media houses, manufacturers and industry experts. The specs of relevance include:
- DVD5 is 4.7Gb, single sided, single layer, common ROM, R and RW media
- DVD9 is 8.5Gb, single sided, double layer, used for DVD-V
- DVD10 is 9.4Gb, double sided, single layer, "flipable" media
- DVD18 is 17.1Gb, double sided, double layer, flipable, probably exists in proto.
Due to their laminated composition, DVD9-18 can't be burned in consumer DVDR or DVDRW drives. This capability is likely to exist in the future. The public wants to burn rental media and everybody's storage requirements keep going up and up.
DVD9 enjoys greater than 95% compatibility with conventional DVD drives, making it the clear choice for commercial production..
Soft specs:
For our interests, two adopted specifications were DVDROM and DVD-V. DVDROM extends the storage capability of CDROM. DVD-V was created to be a way to market movies and to replace the VHS format for post-release distribution via enhanced quality and functionality. Ask why each of the following are written in, the answer is either to sell movies or to sell hardware.
- 133 minutes of high quality MPEG-2 encoded video with multi-channel surround sound audio.
- The choice of widescreen, letter box and pan & scan video formats.
- Audio in up to 8 languages
- Subtitles for a further 32 languages
- Menus and program chains for user interactivity
- Content branching for multiple story lines
- Up to 9 camera angles
- Digital and analogue copy protection
- Parental control
The PAL/NTSC and regionalization issues are largely for movie marketing reasons as well. They allow some control over who can see what from which region at which time. While numerous workarounds exist for these restrictive features for the technically literate, for the mass market it achieves an admirable level of control over global product flow and audience exposure. If Free Media ever distributes product overseas it will confront this issue (easily handled in production).
The whole DVD+, DVD- conflict is sinking beneath "dual" hardware that can read and write both formats. Good news. The whole issue will resurface as these compete to release consumer multilayer DVDR and DVDRW products. Shucks.