A Guide to Multi-Channel Dolby Sound

Dolby High Definition Audio

The lineup of Dolby Sound Systems include two new high definition audio formats that have been designed specifically to match the picture quality in high definition video content, but not only...

Dolby Digital High Definition Audio

Our discussion continues by taking a look at two of the latest Dolby Digital multi-channel audio formats - Dolby TrueHD and Dolby Digital Plus. 

Both Dolby TrueHD and Dolby Digital Plus fall under the category of high definition sound, or 'high resolution audio' as it is referred to under the DTS lineup.

These Dolby sound formats offer greatly improved sound quality by increasing both the bit rate from a maximum of 640 Kilobits per second to several Megabits per second, and also by increasing the number of full-range audio channels.

Dolby®TrueHD delivers true high-definition sound, while providing up to 7.1 channels of lossless audio that is bit-for-bit identical to the studio master. This may be considered as Dolby's version of its DTS counterpart, namely DTS-HD Master Audio.

This Dolby sound format has been developed for high-definition disc-based media such as HD DVD and Blu-ray Disc players, to deliver audio that matches the stunning high definition pictures created by these devices.

Dolby^® TrueHD has been selected as a mandatory format for HD DVD and as an optional format for Blu-ray Disc.

It is also fully backward compatible with A/V receivers and HTIB (home-theaters-in-a-box) solutions supporting multi-channel Dolby Digital surround sound.

Dolby TrueHD sound format features:

• 100 percent lossless coding technology.

• Up to 18 Mbps bit rate.

• Supports more than eight full-range channels of 24-bit/96 kHz audio, though current HD DVD and Blu-ray Disc standards limit maximum number of audio channels to eight.

• Fully supported by HDMI™.

• Supports extensive metadata including dialogue normalization and dynamic range control.

Dolby Digital Plus is considered as the next-generation audio format that delivers 'better-than-DVD' sound in high-definition packaged media because it requires less compression and provides up to 7.1 channels of audio. This Dolby sound format provides a somewhat similar sound quality to that achievable by DTS-HD High Resolution Audio format.

Dolby Digital Plus provide more than just a higher bit rate and increased number of full range audio channels; it also provides new coding efficiencies for future broadcasting and streaming of multi-channel audio. It is designed to complement all high-definition programming and media. Built on Dolby Digital, Dolby Digital Plus is fully compatible with all current A/V receivers.

Dolby Digital Plus features:

• Supports more than eight full-range channels of 24-bit/96 kHz audio, though current HD DVD and Blu-ray Disc standards limit maximum number of audio channels to eight.

• It also supports multiple programs in a single encoded bitstream.

• Outputs a standard Dolby Digital bitstream for playback on existing Dolby Digital systems.

• Supports data rates as high as 6 Mbps.

• Bit rate performance of at least 3 Mbps on HD DVD and up to 1.7 Mbps on Blu-ray Disc.

• Fully supported by HDMI^™.

• Also selected as a mandatory audio format for HD DVD and as an optional audio format for the Blu-ray Disc.

More on Dolby Sound Formats will follow soon.	Last updated on: 20th Dec. 2006
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