Big Picture Big Sound

At the CEDIA show in Indianapolis this week, Dolby Laboratories announced and began demonstrations of its latest advancement in lossless audio technology, Dolby® TrueHD. Designed to take full advantage of the storage capabilities of the upcoming optical disc formats (Blu-ray Disc and HD-DVD), Dolby TrueHD will allow home theater viewers to experience audio performance that captures the highest-resolution studio masters currently available. It should also provide an audio signal that is up to snuff with the high definition video signals also available on the new media.

The company is demonstrating Dolby TrueHD along with Dolby Digital Plus at its CEDIA Expo exhibit booth (#538). These two Dolby technologies have been adopted for use in both the HD-DVD and Blu-ray Disc formats. Dolby TrueHD and Dolby Digital Plus technologies are mandatory audio codecs in the HD-DVD format as well as optional features in the Blu-ray Disc format. Standard Dolby Digital is mandatory in both formats.

"The high-definition disc formats being discussed today will provide viewers with new levels of image quality," said Craig Eggers, Dolby Senior Manager, Consumer Electronics Technology Marketing. "With Dolby TrueHD, those same viewers can experience multichannel surround sound that fully complements the detail and fidelity of the high-definition picture."

Dolby TrueHD builds upon the foundation of MLP Lossless™ technology by incorporating higher bit rates, additional channels, enhanced stereo mix support, and extensive metadata functionality, including dynamic range control and dialogue normalization. Enabling recordings that are bit-for-bit identical to studio masters, MLP Lossless was first introduced as part of the DVD-Audio standard, and has since become the leading multichannel lossless audio format.

In comparison to standard Dolby Digital and DTS encoding, which introduce some audio artifacts into the encoding/decoding process, lossless encoding systems like Dolby TrueHD use advanced algorithms to reconstruct the encoded signal bit perfect. In other words, the copy is identical to the original, so no audible artifacts should be present. In addition, Dolby TrueHD provides support for all of the new speaker locations designated by the Society of Motion Picture and Television Engineers (SMPTE) for digital cinema applications (RP 226).

"When coupled with high-definition video, Dolby TrueHD offers an exceptional home theater experience that enables you to enjoy sound as stunning as the picture," said Ed Schummer, Senior Vice President and General Manager of the Consumer Division, Dolby Laboratories. "When a playback system displays the Dolby TrueHD logo, viewers are assured they are hearing the highest-quality audio performance possible -- as if they are hearing the studio master itself."

We'll see about that. In theory, lossless encoding programs do allow for bit-perfect copies, while still saving storage space and bandwidth over traditional PCM-based digital recordings. But the DVD-Audio implementation introduced artifacts of its own in the form of analog copy protection "watermarks" that some audio purists claimed had a negative impact on the sound quality.

If the HD-DVD and Blu-ray discs implement copy protection in the digital domain, then there is no reason to suspect that analog watermarking will be an issue for these formats, and we should get a real treat for both our eyes and ears once HD-DVD and Blu-ray Disc content becomes available.