Creative Sound Blaster Audigy 2 ZS User Manual page 62

The physical disc medium can be:
• DVD-ROM: read only, used for commercial content, manufactured by a
commercial press
• DVD+R/RW: R=Recordable once, RW = ReWritable
• DVD-R/RW: R=Recordable once, RW = ReWritable
• DVD-RAM: random access rewritable
The disc may have one or two sides, and one or two layers of data per side. The
number of sides and layers determines the disc capacity:
• DVD-5: single sided, single layer, 4.7 GB
• DVD-9: single sided, double layer, 8.5 GB
• DVD-10: double sided, single layer on both sides, 9.4 GB
• DVD-18: double sided, double layer on both sides, 17.1 GB
The DVD Forum, an industry consortium of over 220 companies, has created the
official DVD-R(W) standards. Additionally, another group was founded, the
DVD+RW Alliance, who created the competing DVD+R(W) standard. The "+"
(plus) and "-" (dash) are two similar technical standards that are partially
compatible; the media are similarly priced. Most DVD readers (DVD-ROM drives in
PCs and in consumer DVD players) currently on the market read/write both
formats, although compatibility issues exist between specific readers, writers and
media.
The speed of a DVD drive is given in multiples of 1350 Kbps, which means that a
drive with speed 16x allows a data transfer rate of 16 x 1350 = 21600 Kbps
(approx 21 Mbps).
The operation of writing an image to a DVD disc is called creating a session. The
session may be closed, thereby finalizing the disc and allowing it to be played on a
DVD player; otherwise a session may be left open for further writing operations.
Once a recordable disc (DVD-R, DVD+R) has been closed, it cannot be reopened.
Rewriteable discs can be reopened.
DVD-Video
Commercial DVD movies are encoded using MPEG2 video and audio of varying
formats. Typical data rates for DVD movies range from 3-9.5 Mbps.
Technology Glossary A-13