Ensuring Compatibility Between Next-Generation
High-Definition Disc Players and Your A/V System

Dolby TrueHD and Dolby Digital Plus in A/V Receivers

Eventually, A/V receivers will have direct access to Dolby^® Digital Plus or Dolby TrueHD bitstreams. We are working with the IEC and HDMI organizations to update data protocols to enable future versions of these high-bandwidth interfaces to carry these bitstreams.

To decode these bitstreams, the A/V decoder will need to support the updated data protocols, as well as incorporate these new decoding algorithms. In addition, it will be necessary to select HD discs in which the content maker has permitted the core 5.1 or 7.1 audio bitstreams to bypass the player’s mixing process and be sent directly to the digital outputs of the player. We expect that certain HD discs will permit this, but they may represent a minority of titles. In the end, the sound quality will be essentially the same as that of audio decoded within the player as PCM signals and transported through a current-generation HDMI connection to the A/V receiver.

With six or eight channels of 24-bit/96 kHz audio to handle from these new HD formats, the post-processing DSP requirements for an A/V receiver more than double. Rather than devoting the considerable DSP resources to decoding the core audio signals within the A/V processor itself, it may be more fruitful to use the A/V processor’s DSP resources to perform high-resolution post-processing such as bass management, room or speaker equalization, Dolby Pro Logic^® IIx decoding, or other types of digital signal processing.

Figure 5 Connection via Next-Generation HDMI

As a result of the quality and capabilities that the new digital interfaces provide, hardware manufacturers can offer more highly optimized system designs that attain the ultimate in performance while providing the greatest flexibility and efficiency for the consumer.

Dolby, Pro Logic, and the double-D symbol are registered trademarks of Dolby Laboratories. FireWire is a registered trademark of Apple Computer, Inc. HDMI is a trademark of HDMI Licensing LLC. © 2005 Dolby Laboratories, Inc. All rights reserved. S05/16661