When talking to people about DVD, it appears that strangely, some myths seem to have manifested themselves in people’s minds, both, DVD owners and non-owners. The following section by Jim "The Frog" Taylor is trying to shed 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. In order to take take advantage of the digital nature and progressive scan of HDTV, new DVD players will be required. These players will make current discs look even better on HDTVs, but won't provide full HDTV resolution. Eventually a new "HD-DVD" format will appear, based on blue lasers. The new format will require new discs and new players, but the players will play old DVD discs and CDs.

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 sources.

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.)

8.  DVD is a worldwide standard.
In addition to regional codes that can be used to prevent playback in different areas, DVD uses different formats for NTSC or PAL playback. Almost no US players can play PAL DVDs. Most European players can play both PAL and NTSC TVs, but only on a 60-Hz-capable PAL TV or a multistandard TV. Most DVD-equipped computers can play both NTSC and PAL discs.

9.  Competing DVD from Sony.
Sony has made three announcements: 1) they're working on high-density DVD; 2) they're proposing the DSD audio storage format for DVD-Audio and they'll support it on their own if it's not accepted for DVD-Audio; and 3) they're developing a different version of erasable DVD called DVD+RW. These somehow morphed together into a rumor that Sony will release a competitor to DVD. There's no truth to this rumor. Many of the DVD Forum companies are working on new "HDVD" formats that are expected to be unified the same way DVD was and that won't be available until 2002 at the very earliest. Sony and Philips say their DVD+RW will be compatible with DVD-ROM and DVD-R and is intended only for use with computers.

“DVD Myths” is re-printed with the friendly permission by Jim "The Frog" Taylor. Please visit Jim’s Website “DVD Demystified” where you can also find other helpful and educational pieces of information.

 [Last updated 99-07-09]

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