Meridian on DualDisc
DualDiscs combine CD content on one side with a DVD on the other, making them slightly thicker than ordinary optical discs. Many DualDiscs have DVD-Audio content in one or more of the layers on the DVD side. DVD-A uses Meridian Lossless Packing (MLP) compression technology to squeeze as much data as possible onto the discs without compromising playback quality.
Several manufacturers have issued warnings that the hybrid discs may not play in their equipment or could cause problems with load/eject mechanisms. Such warnings aren't necessarily based on actual complaints from users, but are intended to relieve the manufacturers from responsibility for malfunctions caused by non-standard discs.
In mid-December, the Huntingdon, UK–based company issued a statement intended to clarify the issue for Meridian owners and potential owners. Meridian gear should exhibit no problems playing DVD content from DualDiscs, according to the statement. "The DVD side of a DualDisc is 100% consistent with the DVD specification and will play in all Meridian's past and present DVD-Video and DVD-Audio players," Meridian asserts.
The picture for DualDisc CD playback is not nearly as clear. "DualDisc market tests showed that a small percentage of CD players, and especially DVD players, were unable to play the CD-compatible side reliably," Meridian states. "This layer is not compliant with the Red Book CD specification because it is thinner than a normal CD (typically 0.9mm rather than 1.1mm) . . . primarily to keep the overall disc thickness below 1.5mm so as to minimize potential issues with slot-loading and caddy-based multi-disc players." (So far, Meridian has encountered no problems with another two-sided disc called DVD-Plus or OneDisc.)
Because the CD layer on DualDiscs diverges from the Red Book standard, Meridian says that it can't "guarantee that the CD-compatible side will play without audible errors in all players." Should errors result, no harm will occur to Meridian players, the manufacturer believes. All Meridian DVD players (models 586, 596, 598, 800, G98, and G91) will play the DVD content of DualDiscs "perfectly," and Meridian recommends to owners of such gear that they "should use this side of the disc."
Meridian has found that its DVD players "do not always play the CD-compatible side because the player optics are not designed for such thin CD layers." The company has no intention of modifying its DVD players to accommodate DualDisc CD playback because the machines' optics are "highly optimized for playability of Red Book CD and DVD." In lab tests, Meridian's CD-only players (models MCD and Pro-MCD; all 200 Series players; all 600 Series players; 500, 506, 507, 508, and G07) exhibited no problems playing DualDisc CD. However, the company's ROM-based CD players (588 and G08) could have difficulty with DualDiscs. Meridian offers "an inexpensive modification" that should enable these models to play DualDisc "perfectly with absolutely no change in the quality for regular CD." The modifications can be done only at Meridian authorized service centers. The mod program begins early in 2005. Contact the company's customer support for more information.