Technical information

through this layer to extract data from the bottom layer. Such a disc has, in
single-sided format, a capacity of 8.5GB, rather then the 4.7GB of a single layer
DVD.
DVD Digital Versatile Disc or Digital Video Disc. In the former usage, it is the
12cm optical disc capable of holding masses of data for computer use, video, still
pictures or audio.
DVD Audio Digital Versatile Disc - Audio. This is the form of DVD which primarily
holds DVD Audio material, all of which resides in a folder on the disc called
'AUDIO_TS'. The material may be either PCM or, more commonly, MLP encoded.
The DVD Audio material can only be played on a DVD Audio player. DVD Audio
discs almost always also hold a repeat of the material in DVD Video format so that
they can be used in DVD Video players as well. Typically, though, the audio in this
section is recorded in a lower standard of PCM, Dolby Digital or DTS.
DVD-RAM A rewritable (i.e. recorded material can be erased or over-written)
recordable DVD. This format is supported by the DVD Forum. It should noted
that DVD-RAM has very limited compatibility with standard DVD players (although
recent Panasonic models support it), because it uses significantly different
technology to the other types of recordable DVDs. In particular, it offers true
random access writing to identified sections of the disc, which has allowed
Panasonic DVD recorders to implement a 'time-slip' feature (continuous recording,
and the ability to rewind and watch recorded material, even while recording
continues). It is also said to support a higher order of magnitude of re-write
cycles than either DVD-RW or DVD+RW.
DVD recorder A consumer electronics device which uses one or more of several
different types of recordable DVD media as storage for video and audio material.
A replacement for the VCR, offering significant improvements in picture quality,
plus the usual DVD playback conveniences of fast access, chapter breaks and the
like. Most quality DVD recorders are multi-format now, capable of recording to
four different kinds of media. Most support only single layer recordable DVDs and
thus offer a capacity of 4.7GB, however some are appearing with support for dual
layer discs. DVD recorders permit different recording times, with longer times
trading off for poorer quality. Very good quality recordings of two hours duration
are achievable with a 4.7GB disc, while some offer six or more eight at low
quality. Some premium DVD recorders incorporate a computer-style hard disk
drive upon which recordings can be made, then edited, before being dubbed (at
high speed) to a blank disc.
DVD-RW A rewritable (i.e. recorded material can be erased or over-written)
recordable DVD.