Dolby Digital vs. DTS: A Guide to the Strengths of the Formats

With the advent of home theater, consumers are continually demand higher performance. As technology improves and becomes more competitive, increased performance is realized at lower cost to the consumer. The market floods with newer and newer technology, allowing consumers to be less easily impressed and more picky, sometimes loosing touch with what was involved in producing this marvel of technology that only a few years ago, would have been a nearly impossible feat. I remember the days when I used to hook up my 2 channel audio system to my mono VCR and thought life was good. Well, I must say since then, life has gotten a whole lot better in the realm of audio.

Birth of Dolby Digital and DTS

With the birth of Dolby Surround in movie theaters, it was only a matter of time before we the consumers would reap the benefits of this trickle down technology into the consumer A/V marketplace. However, this would soon not be enough for a society that thrives on the "bigger and better" mentality. We wanted more. Enter Dolby's newest creation, Dolby Digital (DD). For the first time, a fully discrete digital 5.1 channel surround format was created for both the theaters and home audio marketplace. When the consumer-electronics industry DVD Working Group (DVDWG) sought the best audio coding technology for the new format back in 1995, Dolby Labs jumped at the opportunity. Dolby argued that its name recognition, familiarity with the movie industry, and the choice of its system for audio coding in the new DTV standard made it a logical choice for DVD as well. The DVDWG agreed, and DD was selected as 1 of 2 required soundtracks, the other being PCM, on all DVD releases in the USA. The DVDWG also allowed for DTS and SDDS as optional soundtracks. A year after this occurrence, Digital Theater Systems (DTS) joined the soiree claiming its coding method sounded better due to higher bit rates and less compression. The DVDWG mandated that any DVD carrying a DTS soundtrack must also contain one of two of the previously mentioned required soundtracks.

What's the Bit Idea?

In order to minimize the limited space allocated on a DVD for audio soundtracks, DD and DTS utilize lossy data reduction algorithms, which reduce the number of bits needed to encode an audio signal. DD compresses a 5.1 channel surround track to 384 kbps to 448 kbps (DVD Standard limited, DD has the potential of up to 640 kbps) while DTS uses much higher bit rates up to 1.4 Mbps for CD's / LD's and 1.5 Mbps for DVD. A higher bit rate must imply DTS will be superior sounding right? In theory, the less compression used in the encoding process, the more realistic the sound will be, as it will better represent the original source. DD tends to boast that its encoding method is more efficient than DTS and thus does not require the extra bit rates. However, even if DD is slightly more efficient, it is still not 1.5 / .448 = 3.35 times more efficient.. However, both DD & DTS will boast data rates, efficiency, etc, but what actually translates to better sound is a very ambiguous matter as there are more factors involved here that goes beyond the scope of this article.

Pros and Cons of Dolby Digital / DTS

I have tabulated the pro's and con's of DD/DTS in the matrix below.

So What Did We Learn from This?

In my opinion there are very apparent sonic benefits of DTS over DD especially on audio systems which are refined enough to appreciate the differences. I really enjoy listening to many of the 5.1 DTS audio cd's currently available but wish they had a larger selection. Many of these DTS CD's /DVD-A discs produce excellent and eveloping multi channel surround. This is partly the reason why Dolby and Meridian introduced a new high resolution format know as DVD-Audio.

It has been interesting to observe the impact of DVD-Audio over the past year. Hardware vendors have begun offering a multitude of player options covering a wide range of consumer budgets. However, the Record Labels have been offering software to support this format at a snails pace with options that don't cover the majority of the consumer marketplace. According to mass market Electronic Chains such as Best Buy, It seams that DTS still holds quite an edge in this respect that it has become the most popular selling music surround format to date.

2007 Update: What's Next?

With the dawn of HD-DVD formats upon us (whether they succeed or not has yet to be seen) there is a new awakening of high resolution audio - though it seems to be tied to movie soundtracks at present. Dolby TrueHD and DTS-HD are lossless formats. When decoded they represent bit-for-bit copies of the studio recording. This renders the Dolby vs. DTS contest a draw - with consumers winning hands down. Lossless is where it's at and we seem to be getting there, albeit slowly and with much resistance from the RIAA.