Dolby TrueHD Offers Product Differentiation and Ultimate Audio Quality
With Dolby TrueHD’s 100 percent lossless audio coding technology, equipment manufacturers and content producers can now stand out from the competition by delivering studio-quality surround sound that is identical to the original recording.
For playback through a home theater system, Dolby TrueHD is transported via HDMI® (High Definition Multimedia Interface) version 1.3 or later, a single-cable digital connection for audio and video. Dolby TrueHD content may also be introduced to a playback system via Ethernet or USB connections.
The power of metadata
The powerful Dolby metadata parameters give content creators comprehensive control over how their artistry will be heard in the home.
Dialogue normalization (dialnorm) maintains consistent volume levels when switching between Dolby TrueHD and Dolby Digital or Dolby Digital Plus programming.
Dynamic range control enables reduced peak volume levels without impacting overall sound quality. It’s ideal for late-night viewing.
Downmixing allows the content creator to enable stereo playback from the original multichannel source or to provide an independent stereo “artist’s mix” that is incorporated into the Dolby TrueHD bitstream.
Three presentations, one bitstream
A single Dolby TrueHD stream can contain up to three separate mixes (presentations): a 7.1-channel surround mix, a 5.1-channel surround mix, and a two-channel “artist’s” stereo mix. This gives content creators the ability to tailor each mix for optimum listening on any playback system.
Advanced 96k upsampling
Movie soundtracks and TV shows are often recorded using a 48 kHz (48k) sampling frequency. The brickwall filters required for 48k analog-to-digital (A-to-D) conversion in the recording process introduce artifacts called preringing, heard as an unnatural hardness or edginess.
To deliver clearer, more natural playback sound from this content, Dolby TrueHD encoding now includes a proven 96 kHz (96k) upsampling process developed by Meridian Audio. It significantly improves the sound from a Blu-ray Disc in any channel configuration.
The process applies higher sample rates and increased playback quality through an advanced apodizing filter that masks undesirable digital artifacts in 48k material. The upsampling takes place before Dolby TrueHD encoding.
By applying the upsampling in software, Dolby TrueHD creates content that’s compatible with all Blu-ray™ players and all A/V receivers with 96k digital-to-analog converters (DACs). It does not add any computing burden in playback. Although the upsampling increases file size and data rates, the optional Dolby Mapping (noise-shaping) feature, specifically designed for Dolby TrueHD, minimizes or eliminates these increases.
Content producers can employ the upsampling feature at their discretion. The process is designed to improve 48k audio files and is not needed for native 96k material.
Ready for the future
Dolby TrueHD can deliver up to 16 channels of pristine audio, so it is ready for any future HD streamed formats. On Blu-ray Disc today, it delivers up to eight full-range channels of 24-bit/96 kHz audio and supports up to 24-bit/192 kHz for stereo and 5.1 content.