A Guide to Multi-Channel Surround Sound
DTS Surround Sound Formats

DTS Surround Sound formats represent the second most popular lineup of sound formats available today. Many audiophiles feel that DTS deliver better sound.

In this guide to DTS sound, we look at the different surround formats from DTS Digital Surround, up to the latest DTS-HD audio designed to complement the picture quality of Blu ray and HD DVD.

Introducing 'Digital Theater Systems'

DTS, or 'Digital Theater Systems' - constitute a full lineup of multi-channel surround sound formats for use in both commercial applications, as well as in the home.

Like Dolby Digital, DTS started as a moviehouse application in around 1991 through its DTS Digital Surround sound format - a 5.1 multi-channel surround sound format that is more commonly referred to as simply 'DTS'.

The first theatrical release using DTS surround sound came in 1993 with Jurassic Park - a year after Dolby Digital debut with Batman Returns

It has since then started to steadily invade the home; the first home video release came in 1997 on laser disc - again with Jurassic Park.

DTS Digital Surround has now become the second most popular audio format in use today - despite fierce competition from Dolby Digital in both theatrical and home applications, as well as from SDDS (Sony Dynamic Digital Sound) in theatrical applications.

Further more, even though DTS is not compulsory on DVD releases, a large number of titles have so far been released for home entertainment on DVD-video with a DTS surround sound track as an alternative to the mandatory Dolby Digital soundtrack.

Today, the family of DTS surround sound formats includes a variety of newer versions ranging from DTS-ES, a 6.1/7.1 competitor to Dolby Digital EX, DTS Neo:6, a six-channel competitor to Dolby matrixed Pro Logic format, DTS 94/26, a lossy yet high-resolution format used in some DVD-Audio releases, DTS-HD Master Audio, DTS competitor to Dolby TrueHD, used as an optional surround sound format on HD-DVD and Blu-ray discs, and DTS Virtual, designed to provide a surround sound experience on a two-channel audio playback setup.

Most of today's home theater receivers and HTIB solutions incorporate DTS decoders capable of decoding a variety of DTS sound formats in addition to the more popular Dolby Digital (AC-3), Dolby Digital EX, and Dolby Pro Logic formats.

DTS Surround Sound Formats - Index

DTS Audio Formats for Playback

• DTS Digital surround

• DTS Neo:6

• DTS ES (Extended Surround)

• DTS Digital Out

• DTS Interactive

• DTS Virtual

DTS High-definition Audio Formats

• DTS 96/24

• DTS-HD Master Audio

• DTS-HD High Resolution Audio

• DTS Encore

DTS Audio formats for Playback

DIGITAL SURROUND

DTS Digital Surround™ is the most popular DTS surround sound format in use today and the second most popular 5.1 surround sound format after Dolby Digital.

As already indicated under our introduction, this DTS sound format is available both as a 5.1-channel surround sound in movie theater applications as well an optional soundtrack on some DVD-Video movies for home theater viewing. 

Many audiophiles and home theater enthusiasts alike argue that DTS - due to its higher raw-bit rate and lower compression - is capable of delivering better sound than Dolby Digital. But is it really so?  In reality, this has turned out to be a rather hotly debated issue. At the same time, one has to keep in mind that raw bit-rate and compression levels alone cannot be taken as a direct measure of sound quality. But more on this topic appears in our article: Dolby vs DTS Sound.

At present, the number of DVD-Video titles with a DTS surround sound track is still on the lower side compared to Dolby Digital. Yet, it is expected that we will see more and more DTS-encoded DVDs even though unlike Dolby Digital - which is a mandatory format for DVD-video, DTS is optional; further more it is not used by HDTV or digital satellite broadcasting.

DTS Neo:6 provides up to six full-band channels of matrix decoding from stereo matrix content; it is available on all DTS-ES equipped receivers, and is fully compatible with all two-channel (stereo) content mastered on CD, VHS, DVD, etc.

It is the DTS equivalent to Dolby Pro Logic II and Pro logic IIx matrix sound decoders, and is fully compatible with all stereo sources. Neo:6 can be used to generate a seamless 5.1, 6.1 or 7.1 surround soundstage - depending on the audio playback setup. Note however that in the case of a 7.1 setup, the 2 rear surround channels would actually play in mono.

While it is a fact that matrix content in general cannot produce the same precise localized soundstage as that generated by discrete multi-channel surround, yet Neo:6 technology can do a remarkable job towards delivering a natural surround soundfield with relatively precise localization.

DTS Neo:6 also supports a music mode that expands stereo non-matrix recordings into the five or six-channel surround sound. It yields a relatively soft-focused overall sound while still maintaining the integrity of the original stereo content.

DTS ES (Extended Surround) is the extended version of the DTS Digital Surround, and Dolby Digital EX counterpart. It provides a 6.1 DTS surround sound format over either a 6.1 or a 7.1 audio playback setup, and is fully backward compatible with DTS 5.1 digital surround.

This DTS surround sound format includes two variants, DTS-ES Matrix and DTS-ES Discrete 6.1, depending on how the sound was originally mastered and stored.

DTS-ES Matrix provides 5.1 discrete channels plus an extra sixth back surround audio channel that is matrixed over the two rear surround channels; for this purpose, DTS-ES Matrix is also noted as DT-ES 5.1.

DTS surround sound processors that are compatible with the ES codec look for and recognize 'flags' built into the audio coding and 'un-fold' the rear-center sound from data that would otherwise be sent to rear surround speakers. This extended DTS surround sound format happens to be more popular than the discrete version.

DTS-ES Discrete provides 6.1 discrete channels, with a discretely recorded back surround channel. This means that the audio data for this extra 6th channel is stored separately from the audio content for the other channels. This DTS surround sound format is also at times referred to as DTS-ES 6.1. Note that when this format is played over a 7.1 set-up, the two back surround channels would play in mono.

Devices carrying the DTS-ES logo handle both DTS 6.1 Matrix and DTS 6.1 Discrete decoding, while still offering DTS 5.1 capabilities.

In contrast, Dolby's competing Dolby Digital EX codec, which also boasts a center back surround channel, can only handle matrixed data and does not support a discrete 6th channel.

It should be remarked that when it comes to the consumer implementation of ES DTS Surround Sound:

• The center back surround channel is always matrixed into the Left Surround (LS) and Right Surround (RS) channels.

• A discrete center surround channel can optionally be encoded.

• A DTS-ES 6.1 Discrete decoder will play the discrete center surround channel and will subtract the discrete center surround channel from the matrixed LS and RS channels.

• Any DTS-ES track, discrete or not, is fully compatible with 6.1-matrix decoders because the matrixed tracks are always present.

• Any ES DTS surround sound track is also fully compatible with 5.1 decoders because the center back surround channel information is matrixed into the LS and RS channels and will be heard in and between the LS and RS speakers.

DVDs with DTS-ES encoded sound remains scarce - irrespective of whether this is discrete or matrixed - with matrix content being more common.

Digital Out

DTS Digital Out is not some DTS surround sound format in itself; rather, the DTS Digital Out logo indicates that the unit reads and passes the DTS raw bit stream via the device's digital output to a device equipped with a DTS decoder.

This is a necessary feature for playback of a DTS soundtrack through a DTS-capable decoding receiver or preamplifier equipped with digital inputs.

INTERACTIVE

DTS Interactive is a DTS surround sound encoder that is capable of converting a stereo or multi-channel audio signal to a DTS Digital Surround format bitstream - on the fly - for transport and playback through a home theater system.

This yields for more realistic surround sound effects during interactive video game-play.

This is somewhat equivalent to Dolby Digital Live, which is found on PC and console-based video game applications; the main difference is that DTS Interactive is mainly intended for use during multi-channel interactive playback for PlayStation®2 games when connected to a DTS-equipped AV receiver.

VIRTUAL

DTS Virtual down-converts 5.1 or 6.1-channel DTS surround sound to stereo while still providing a realistic simulation (hence the term 'virtual'), of surround sound for playback over two-channel equipment such as headphones.

DTS Virtual is DTS's equivalent to Dolby virtual surround sound technology. It makes use of advanced virtual surround algorithms to manipulate audio signals with sonic spatial cues by applying varying delays and phase-shifts between the different channels. The whole process is based on extensive room-modeling technologies to reproduce the sonic spectrum and dynamics of a properly placed 5.1 multi-speaker system in a typical room environment.

More on DTS Surround Sound will follow soon.	Last updated on: 19th Jan. 2007
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