Dolby TrueHD, from Dolby Laboratories, is an advanced lossless multi-channel audio codec, intended primarily for high-definition home-entertainment equipment, such as HD DVD and Blu-ray Disc. Lossless data compression is a class of Data compression Algorithms that allows the exact original data to be reconstructed from the compressed data not insert the publicly disclosed HD DVD key into this article for the time being In this application, Dolby TrueHD competes with DTS-HD Master Audio, another lossless codec from Digital Theater System. DTS-HD Master Audio is a lossless audio Codec created by Digital Theater System. DTS (also known as Digital Theater Systems) owned by DTS Inc ( is a multi-channel digital Surround sound format used for both commercial/theatrical
Dolby TrueHD uses Meridian Lossless Packing (MLP) as its mathematical basis for compressing audio samples. Meridian Lossless Packing, also known as Packed PCM (PPCM is a proprietary Lossless compression technique for compressing PCM audio data developed by Meridian MLP was used on the earlier DVD-Audio format, but details of TrueHD and DVD-Audio differ substantially. DVD-Audio (commonly abbreviated as DVD-A) is a digital format for delivering very High-fidelity audio content on a DVD. A Dolby TrueHD bitstream can carry up to 14 discrete sound channels. Sample-depths up to 24 bits/sample and audio sample-rates up to 192 kHz are supported. The hertz (symbol Hz) is a measure of Frequency, informally defined as the number of events occurring per Second. Like the more common legacy codec Dolby Digital, TrueHD bitstreams carry program metadata. Dolby Digital is the marketing name for a series of lossy audio compression technologies developed by Dolby A bitstream or bit stream is a Time series of Bits A Bytestream is a series of Bytes typically of 8 bits each and can be Metadata is separate from the coding format and compressed audio samples, but stores relevant information about the audio waveform. Metadata ( meta data, or sometimes metainformation) is "data about data" of any sort in any media For example, dialog normalization and Dynamic range compression are controlled by metadata embedded in the TrueHD bitstream. Audio normalization is the process of increasing (or decreasing the Amplitude of an Audio signal Dynamic range compression, also called DRC (often seen in DVD player settings or simply compression, is a process that reduces the Dynamic range of
TrueHD and high-definition optical disc
In the HD DVD format, TrueHD is a mandatory codec – all HD DVD players must support the extraction and decoding of a 2-channel (stereo) waveform from a TrueHD bitstream, although all HD DVD players currently support 5. 1 decoding. HD DVD allows the sole (primary) audiotrack of a movie to be encoded in TrueHD, with no (other) secondary audiotracks present. In Blu-ray Disc, TrueHD is an optional codec, meaning that TrueHD may only be present on a disc which already contains a sountrack encoded in one of the mandatory formats, such as Dolby Digital, DTS or PCM. Dolby Digital is the marketing name for a series of lossy audio compression technologies developed by Dolby DTS (also known as Digital Theater Systems) owned by DTS Inc ( is a multi-channel digital Surround sound format used for both commercial/theatrical The primary Dolby Digital audiotrack ensures all Blu-ray players, including those incapable of processing TrueHD, can access a playable audiotrack.
For both HD DVD and Blu-ray, TrueHD's capabilities are the same: the program may carry up to 8 discrete audio channels, at a sample depth & rate of 24-bit/96 kHz (Blu-Ray Disc format specification allows also for encoding up to 6 channels at 192 kHz). The maximum (disc) encoded bitrate is 18 Mbit/s, although movie-titles (thus far) have remained below 5 Mbit/s. All TrueHD players are capable of downmixing the decoded TrueHD audiotrack to an arbitrary number of channels more suitable for player output. Downmixing is a general term used for manipulating Audio where a number of distinct audio channels are mixed together to produce a lower number of channels For example, all TrueHD-capable players can create a 2-channel (stereo-compatible) downmix from a 6-channel source audiotrack. Stereophonic sound, commonly called stereo, is the reproduction of Sound, using two or more independent audio channels through a Symmetrical
Connecting a TrueHD source to a TrueHD receiver requires a digital-link capable of transporting either the encoded bitstream (up to 18 Mbit/s), or the unpacked linear-PCM audio (>35 Mbit/s). HDMI 1. 1 (and higher) can transport multichannel PCM-audio, and therefore can transport an unpacked TrueHD audiotrack. An HDMI 1. The High-Definition Multimedia Interface ( HDMI) is a compact audio/video connector interface for transmitting uncompressed digital streams 3 (or higher) link is required to transport TrueHD in raw bitstream form. [1] TOSLINK (and SPDIF) cannot carry TrueHD without transcoding, due to limitations of the specification. TOSLINK or Optical Cable is a standardized Optical fiber connection system S/PDIF specifies a Data Link Layer protocol and choice of Physical Layer specifications for carrying Digital audio See also Lossy data conversion Transcoding is the direct digital-to-digital conversion of one encoding to another
HDMI-equipped players can internally decode TrueHD to LPCM, and output the LPCM over an HDMI 1. Linear pulse code modulation ( LPCM) is a method of encoding audio information digitally 1 (or higher) interface; all HD DVD players and the PlayStation 3 currently support this. [2] If a player cannot internally decode TrueHD, it can transport the bitstream over HDMI 1. 3 to a receiver capable of decoding it; this feature is now supported on Toshiba HD-A35 HD DVD player, as well as the Samsung 1400 BD player with a firmware upgrade. HD DVD players can also transcode the TrueHD bitstream into a different legacy format (such as Dolby Digital or DTS), providing a high-quality approximation of TrueHD audio over a legacy TOSLINK cable for those that do not have HDMI.
The Phantom of the Opera, released April 18, 2006 on HD DVD, was the first movie to offer a TrueHD soundtrack. The Phantom of the Opera is a 2004 film adaptation of Andrew Lloyd Webber and Charles Hart 's 1986 stage musical, which is based Events 1025 - Bolesław Chrobry is crowned in Gniezno, becoming the first King of Poland. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. not insert the publicly disclosed HD DVD key into this article for the time being
References
- ^ HDMI Part 5 - Audio in HDMI Versions (2006-08-09). Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 48 BC - Caesar's civil war: Battle of Pharsalus - Julius Caesar decisively defeats Pompey at Pharsalus
- ^ HDMI FAQ at hdmi.org
External links
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