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Codec Divx Xtech: How to Encode and Decode High-Quality Video



On the consumer level, DTS is the oft-used shorthand for the DTS Coherent Acoustics (DCA) codec, transportable through S/PDIF and part of the LaserDisc, DVD, and Blu-ray specifications. This system is the consumer version of the DTS standard, using a similar codec without needing separate DTS CD-ROM media. As with standard CD players, DVD and Blu-ray Disc players cannot decode audio from DTS audio CDs.




Codec Divx Xtech



In the consumer market, AC-3 and DTS are close in terms of audio performance. When the DTS audio track is encoded at its highest legal bitrate (1509.75 kbit/s), technical experts rank DTS as perceptually transparent for most audio program material (i.e., indistinguishable to the uncoded source in a double blind test).[citation needed] Dolby claims its competing AC-3 codec achieves similar transparency at its highest coded bitrate (640 kbit/s). However, in program material available to home consumers (DVD, broadcast, and subscription digital TV), neither AC-3 nor DTS typically run at their highest allowed bitrate. DVD and broadcast (ATSC) HDTV cap AC-3 bitrate at 448 kbit/s. But even at that rate, consumer audio gear already enjoys better audio performance than theatrical (35 mm movie) installations, in which AC-3 is limited to 320kbps. When DTS audio was introduced to the DVD specification, a few studios authored DTS tracks on some DVDs at the full bitrate (1509.75 kbit/s). Most later DVD titles that offered DTS tracks were encoded at 754.5 kbit/s (about half the rate of 1536kbit/s). At this reduced rate, DTS no longer retains audio transparency. This was done to make room for more audio tracks and content to reduce costs of spreading extra material on multiple discs.


AC-3 and DTS are sometimes judged by their encoded bitrates.[citation needed] Dolby Digital 5.1 can compress the same data to less, taking up minimal space. Conversely, DTS proponents claim that the extra bits give higher fidelity and more dynamic range, providing a richer and more lifelike sound. But no conclusion can be drawn from their respective bitrates, as each codec relies on different coding tools and syntax to compress audio.


In addition to the standard 5.1-channel DTS Surround codec, the company has several other technologies in its product range designed to compete with similar systems from Dolby Labs. Those which conceptually extend DTS (to add more channels and/or more accurate sound reproduction) are implemented as extensions to a core DTS Coherent Acoustics data stream.[18] The core stream is compatible with DTS decoders which do not support the extension(s); the extension(s) provide the additional data required to implement the additional functionality.


DTS-ES Matrix provides 5.1 discrete channels, with a matrixed center-surround audio channel. DTS processors that are compatible with the ES codec look for and recognize "flags" built into the audio coding and "unfold" the rear-center sound from data that would otherwise be sent to rear surround speakers. DTS decoders which do not understand ES process the sound as if it were standard 5.1 and the matrixed audio for the center surround channel is output equally from the two surround speakers (very much as a sound intended to be in the center of the sound field in a stereo recording is played equally by the left and right speakers). This is notated as DTS-ES 5.1.


In contrast, Dolby's competing EX codec, which also boasts a center rear channel, can only handle matrixed data and does not support a discrete sixth channel; it is most directly comparable to DTS-ES Matrix. 2ff7e9595c


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