FEEL THE NOISE: Dolby versus dts for DVD - Technology Information

Emedia Professional, July, 2000 by Michelle Manafy

HE SAID, SHE SAID

A popular urban legend surfaces in every discussion of the Dolby/dts rivalry. The story goes that when the dB levels of dts-encoded soundtracks are compared to those of the original studio masters, the dts versions (especially the subwoofer tracks) will be several dBs higher. For many, louder would be perceived as better. Though listeners might imagine that they are able to distinguish between clarity and volume, it isn't always that obvious. Peter Tribeman of Atlantic Technology provides an excellent analogy: "If you walked into a HiFi store back in the 70s, and a dealer could make a bit more by selling you one set of speakers over another, when the salesman put audio up on the switcher, they would punch the sound of the preferred speakers up a couple of dB. Those speakers invariably sounded better."

Dolby's DiCossimo argues that the dts crowd is pumping up the volume in just the same manner to curry listeners' favor. "dts' mastering is not true to original film masters," he says. "What they do is encode their own dts masters; we've found that there are level errors in terms of fidelity to the master." He goes on to say, "How could one not stick to the fidelity of the originals? These are made in the sound stations of Woody Allen, and Brian DiPalma--why would anyone want to take that work and change anything?"

In dts' defense, DelGrosso suggests that the impression of a manipulated master is simply a product of dts' superior compression algorithm when its results are compared with Dolby's. "Because of Dolby's continuous lobbying that their compression doesn't affect the sound, there are those who think that we must play with the master. Several years ago, Roger Dressler from Dolby found a laserdisc where the dts surrounds were three dBs hotter than Dolby's. We found that one of our post-houses was marking the surround levels incorrectly--surround levels are created differently for cinema and home at a 3dB difference--and we would have compensated if we'd known. We don't do the encoding anymore, so this should never be a problem again."

Whatever the origins or veracity of the rumor, the point may soon be moot. Recently, Spruce Technologies and dts partnered to provide a fully enabled solution for encoding and authoring DVD titles using the dts digital surround audio standard. DVD producers can now, for the first time, encode dts audio directly into their authoring projects at their own workstations rather than sending material to dts for encoding, which should prevent this sort of error (and rumor) from surfacing again.

This capability could make a big difference to authoring houses in terms of offering the dts choice to their clients at similar cost and turnaround times to Dolby Digital. Wolfgang Martens, head of technique premastering at Sonopress in Germany, calls dts audio "an important technology for advanced DVD production." He says, "The reliance on other facilities interrupts our production processes and adds expense to a project. We have been looking forward to having the ability to handle dts encoding, since this is a standard within the DVD specifications. In conjunction with our Spruce DVD Maestro systems, the new dts encoder makes this high-quality audio technology much more feasible for Sonopress and our customers."