By Jon Iverson

August 11, 1998 — Another crucial piece of the DVD-Audio puzzle fell into place recently when the WG-4 (Working Group 4) DVD-Audio Working Group approved the adoption of MLP (see previous articles 1, 2) as the lossless algorithm for DVD-Audio at its August 5th meeting in Tokyo. WG-4 will require official approval from its supervising organizations, the Technical Coordination Group and Steering Committee---considered a formality at this point.

MLP, which stands for Meridian Lossless Packing, is a digital audio coding technology developed by Bob Stuart, Peter Craven, and the late Michael Gerzon. Lossless compression is employed in the MLP scheme to save disc space and transmission bandwidth, in a manner similar to "zipping" and "unzipping" computer files.

Meridian's Bob Stuart has stated that MLP can be easily implemented and will not alter the decoded signal in any way. He emphasizes its "cascadable" quality, meaning that there is no "error accumulation" in multiple generations of copies. The process requires relatively little computing power: six channels of 24-bit/96kHz audio can be processed by an inexpensive DSP chip, he said, and will offer the added advantage of much longer playing times.

"I believe MLP will be welcomed by all of the music industry, because its high performance is already well-known and field-proven," stated WG-4 chairman Bike H. Suzuki. "MLP fully meets the requirement from the ISC (International Steering Committee, representing the RIAA, RIAJ, and IFPI) with a playing time of 74 or more minutes in all modes of DVD-Audio."

Mr. Suzuki also said that, "at the request of Meridian Audio, MEI (Matsushita Electric Industrial Co.), who has been a leader in the DVD Technology, is going to cooperate with Meridian to implement MLP into the Audio Specifications Ver. 1.0."

Mr. Suzuki said he hopes the v.1.0 specification will be released around the end of September. He noted that "lossless is the last issue before Ver. 1.0 is released. That's why I and other WG-4 members are very glad to settle the lossless issue. The WG-4 have responded to any new requirement from the ISC with the right technical solution."

One other contentious issue facing the WG-4 has been the recent announcements from Sony and others regarding Direct Stream Digital (DSD), a competing high-resolution audio format (see previous articles 1, 2). Mr. Suzuki comments that "there is no WG-4 move to approach DSD at the moment. But the WG-4 have repeatedly said that DVD-Audio Specifications reserve space for DSD as an optional audio coding [format]. I understand some people outside the WG-4 say that DVD-Audio and DSD should merge into one format." He added, "Yes, I think a format war should be avoided. However, as far as I am concerned, there is no breakthrough on the matter yet."

Further information about the DVD-Audio Specification and the upcoming DVD Conference (see previous article) can be found at the DVD Forum website.