When talking to people about DVD, it appears that strangely,
some myths seem to have manifested themselves in peoples
minds, both, DVD owners and non-owners. The following section
will shed some light on some of the most common myths about
DVD, countering them with factual explanations.
1. Not HDTV compatible.
Current DVD players are compatible with HDTVs in the same
way VCRs, camcorders, and laserdisc players are compatible.
2. Dolby Digital is 5.1 channels.
Dolby Digital (formerly called AC-3) carries from 1 to 5 channels
of compressed digital audio, with an optional ".1"
low-frequency effects (LFE) channel. The Dolby Digital track
does not have to include 5.1 channels. It may be mono or stereo,
and the stereo may or may not be Dolby Surround encoded (for
playback on a system with a Dolby Pro Logic decoder).
3. Audio is only 12 bits.
This myth was started by Widescreen Review magazine, which
attempted to equate jitter in DVD players to a reduced audio
resolution. DVD audio can be either 16, 20, or 24 bits. Jitter
does not reduce the number of bits. There are many kinds of
jitter. Jitter in the channel signal is accounted for in the
readout circuitry. Jitter in the digital audio output is related
to the audio circuitry and is independent of the DVD format.
It's true that jitter at different stages can reduce audio
quality, but comparing it to a 12-bit sample size is naive
and inaccurate. Numerous reviews indicate that most DVD players
sound as good or better than most CD transports.
4. Audio level too low.
In truth the audio level is too high on everything else. Movie
soundtracks are extremely dynamic, ranging from near silence
to intense explosions. In order to support an increased dynamic
range and hit peaks (near the 2V RMS limit) without distortion,
the average sound level must be lower. This is why the line
volume from DVD players is lower than from almost all other
5. 133 minutes per side.
This is a meaninglessly exact figure. A single-layer disc
can easily hold 150 minutes at the typical average video data
rate if there's only one audio track. Lowering the data rate
slightly can accommodate over three hours on a single layer.
Dual-layer discs can hold over four hours on one side.
6. Digital artifacts.
Almost all reports of "artifacts" on DVD turn out
on examination to have nothing to do with MPEG compression.
Artifacts come from many sources: film problems, bad video
transfer, improper TV settings, bad video connections, electrical
interference, player faults, disc read errors, etc. Some of
these can be corrected by adjusting the TV or cleaning the
disc. Most DVDs have very few visible compression artifacts.
If you think otherwise, you are misinterpreting what you see.
7. Players can't read dual-layer discs.
All DVD-Video players and all DVD-ROM drives play dual-layer
discs. Dual-sided discs must be flipped over by hand. (There
are no side-flipping DVD players.)