High Def Audio FAQ - High-Def Digest Forums
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Old 02-26-2007, 06:10 PM
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Default High Def Audio FAQ

There have been a lot of questions lately about HD audio... mainly the new codecs, and what equipment is needed to play them. This is a list of the new codecs, and what is required to hear each.

Dolby Digital-Plus:
Dolby ®Digital Plus is the next-generation audio technology for all high-definition programming and media. It combines the efficiency to meet future broadcast demands with the power and flexibility to realize the full audio potential of the upcoming high-definition experience. Built on Dolby Digital, the multichannel audio standard for DVD and HD broadcasts worldwide, Dolby Digital Plus was designed for the delivery formats of the future, but remains fully compatible with all current A/V receivers. With Dolby Digital Plus, you get even higher quality audio, more channels, and greater flexibility. Amaze your ears.

  • Multichannel sound with discrete channel output.
  • Channel and program extensions can carry multichannel audio programs of up to 7.1 channels* and support multiple programs in a single encoded bitstream.
  • Outputs a 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.
  • Accurately reproduces what the director and producer intended.
  • nteractive mixing and streaming capability in advanced systems.
  • Supported by HDMI™, the new single-cable digital connection for high-definition audio and video.

  • Can deliver 7.1 channels and beyond* of enhanced-quality audio at up to 6 Mbps.
  • Allows multiple languages to be carried in a single bitstream.
  • Offers audio professionals new creative power and freedom.
  • Compatible with the millions of home entertainment systems equipped with Dolby Digital.
  • No latency or loss of quality in the conversion process.
  • Maintains high quality at more efficient broadcast bit rates (200 kbps for 5.1-channel audio).
  • Selected by the Advanced Television Systems Committee (ATSC) as the standard for future broadcast applications; named as an option by the Digital Video Broadcasting (DVB) Project for satellite and cable TV.
  • Selected as the mandatory audio format for HD DVD and as an optional audio format for the Blu-ray Disc.

Dolby Digital TrueHD:
Dolby® TrueHD is Dolby’s next-generation lossless technology developed for high-definition disc-based media. Dolby TrueHD delivers tantalizing sound that is bit-for-bit identical to the studio master, unlocking the true high-definition entertainment experience on next-generation discs. When coupled with high-definition video, Dolby TrueHD offers an unprecedented home theater experience that lets you enjoy sound as stunning as the high-definition picture.

  • 100 percent lossless coding technology.
  • Up to 18 Mbps bit rate.
  • Supports up to eight full-range channels of 24-bit/96 kHz audio.*
  • Supported by High-Definition Media Interface (HDMI™), the new single-cable digital connection for audio and video.
  • Supports extensive metadata including dialogue normalization and dynamic range control.
*Dolby TrueHD can support more than eight audio channels. HD DVD and Blu-ray Disc standards currently limit their maximum number of audio channels to eight.

  • Delivers enthralling studio-master-quality sound that unlocks the true high-definition entertainment experience on next-generation discs.
  • Offers more discrete channels than ever before for impeccable surround sound.
  • Compatible with the A/V receivers and home-theaters-in-a-box (HTIBs) of today and tomorrow.
  • Dialogue normalization maintains the same volume level when you change to other Dolby Digital and Dolby TrueHD programming.
  • Dynamic range control (Night mode) enables you to customize audio playback to reduce peak volume levels (no loud surprises) while experiencing all the details in the soundtrack, enabling late-night viewing of high-energy surround sound without disturbing others.
  • Selected as the mandatory format for HD DVD and as an optional format for Blu-ray Disc.

Additional information about Dolby Digital in HD

DTS-HD High Resolution Audio can deliver up to 7.1 channels of sound that is virtually indistinguishable from the original. DTS-HD High Resolution Audio delivers audio at high constant bit rates superior to standard DVDs---6.0 Mbps on Blu-ray discs and 3.0 Mbps on HD-DVD to produce outstanding sound quality. It is capable of delivering up to 7.1 channels at 96k sampling frequency/24 bit depth resolution. It allows content creators to deliver rich, high definition audio on movies where disc space may not allow for DTS-HD Master Audio.

DTS-HD Master Audio:
DTS-HD Master Audio is capable of delivering audio that is a bit-for-bit identical to the studio master. DTS-HD Master Audio delivers audio at super high variable bit rates -24.5 mega-bits per second (Mbps) on Blu-ray discs and 18.0 Mbps on HD-DVD - that are significantly higher than standard DVDs . This bit stream is so "fast" and the transfer rate is so "high" that it can deliver the Holy Grail of audio: 7.1 audio channels at 96k sampling frequency/24 bit depths that are identical to the original. With DTS-HD Master Audio, you will be able to experience movies and music, exactly as the artist intended: clear, pure, and uncompromised.


Uncompressed LPCM:
Uncompressed PCM 5.1: Found on a large number of Blu-Ray discs but not supported on HD-DVD, uncompressed PCM 5.1 is simply that: an uncompressed version of the film’s standard 5.1 to 7.1 soundtrack. This is exactly what the name says, uncompressed, raw audio.

What do I need to experience HD audio?
There are two ways to receive HD Audio, HDMI and 5.1 or higher analog audio connection.

HDMI will pass up to 7.1 channels of /HD audio fed from HD DVD or Blu-ray disc. There are two advantages to using HDMI: first, it is a digital connection, so the digital data is kept in digital form, and it uses a single cable.

Analog audio (5.1 or higher) will allow the player to feed the audio stream to an equiped receiver as PCM audio data.

Note: The player or receiver must have the codec built into it for proper decoding. There are currently NO receivers that will decode the DD or DTS HD audio streams, but they should be hitting the market by late summer.
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