DVD

Digital Versatile Disk (Digital Video Disk): A new video format for storing full length motion picture images on a 5” (120mm) compact disc (CD) using MPEG-2 compression for “better than VHS” quality.

DVD a high density development of the Compact Disk. It is the same size as a CD but stores from 4.38 GB (seven times CD capacity) on a single sided, single layer disk. DVDs can also be double sided or duel layer – storing even more data.

The capacities commonly available at present:

Future versions will have capacities rising from the current 4.38 GB to 15 GB with blue laser technology in the medium term, in the longer term 50 GB is a target achievable with advanced modulation schemes.

DVD-Video

This combines the DVD optical disk with MPEG-2 video compression, has multi-channel audio, subtitles and copy protection capability for recording video on a CD-sized disk.

To maximise quality and playing time DVD-Video uses variable bit rate (VBR) MPEG-2 coding where the bit rate varies with the demands of the material. Typically a 525/60 TV format, 24fps movie would use an average bit rate of 3.5 Mb/s, but for sections with a great deal of movement it would peak at 8 or 9 Mb/s. Only 24 fps are coded onto the disk, the 3:2 pulldown conversion to 30 fps being performed in the player. This allows a 120 minute 24 fps movie to fit on a DVD-5.

RSDL

For continuous playback of long movies, dual layer DVD-9 disks can employ a reverse spiral so the second layer starts where the first ends. This transition is supported by all DVD-Video players.

16:9 Widescreen

DVD-Video is the first domestic format natively to support anamorphic 16:9 video.

Multi-channel Audio

DVD-Video supports PCM, MPEG and Dolby Digital.

Region Coding

Disks can be region coded so as only to play in a particular region (as defined in the player), a set of regions or be ‘code-free’. A region coded disk can only play on a player that is allowed by the coding.