Everything you want to know about in...: What does Dolby and DTS mean to me?

When cinema was invented, there was no sound it was only picture and later on after years of experimentation sound track was introduced which gave life to movies. Thus, the first step in sound technology started from a monaural (single or mono channe) to upto 22.2 Channel setups until now.

Before giving you an answer of what is Dolby or DTS, let me describe how these technologies evolved and how much both have grown as of today.

Dolby Laboratories was founded in 1965 by Ray Dolby and initially started in Britain. Later on, Ray Dolby moved his company to United States in 1976 and started researching and made a Type A prototype Dolby Noise Reduction (DNR, you can see in your old Tape decks) which suppress the tape noise generated while playing and marketed his technology to all tape recording companies under his trade mark Dolby. Many companies started implementing Dolby's technology. Later in 1975, Dolby introduced Dolby Stereo which gave a wider dimension to monaural track by adding one more track to it. Thus evolved the Stereo sound which we are still using currently as a standard format in our CD, MP3, Ipod, TVs etc.

2 Channel Stereo setup

Stereo gave more impact to a movie from a monaural sound giving a wider spectrum from a 2 channel track. The audio track is recorded in 2 channels separately and one can distinguish the 2 channels as different musical instruments sound distinctly from 2 channels. Movies were more life like when sound travelled from left to right and vice versa creating a wider spectrum to listening.

Later in 1976, Dolby Surround was introduced giving more life to 2 channel enhancing the spaciousness of both the channels. The first movie in Dolby Surround was released was "A Star is Born". Dolby introduced a compression technology which captured the surround effects to be mixed with 2 channels and when played giving more spaciousness to the sound with the introduction of a centre channel. Thus, there were 3 channels Left, Centre and Right where each channel recorded separately to capture the distinct sounds during the movie or music.

5.1 Surround Sound speaker setup

In 1992, the first movie "Batman Returns" was recorded in Dolby Digital where the technology now called as Dolby AC3 5.1. In Dolby Digital technology, the sound track contains 6 separate channels for Front Left, Front Centre, Front Right, Surround Left, Surround Right and LFE (Low Frequency Level denotes the ".1" in "5.1") providing true surround sound enveloping around the listener when viewing movie. This was not introduced to the consumer market as the technology required specialised hardware to decode the sound track which was expensive for a home user. Hence, Dolby Digital was available in commercial theatre to showcase movies in true surround sound.

During 1993, Digital Theatre Systems (shortly called as DTS Inc.) was founded in California. DTS started their research in 1991 was trying to implement a much more better compression technology that can supersede Dolby Digital. One of the initial investors is film director Stephen Spielberg who later released his movie "Jurassic Park" in 1993 with DTS Surround Sound technology.

7.1 Channel Surround Sound speaker setup

Dolby started introducing technology in personal computers, softwares, headphones, mobiles, making the competition tougher for DTS. During 2005, an additional of 2 more channels were introduced to create more indepth surround field for immersive surround sound as 7.1 Channel surround sound started to be popular slowly. In a 7.1 surround sound, 2 additional surround back left & right channels are added to the existing 5.1 channel thus creating a more indepth surround field as seen in the figure on the right. So, I am now sure you would have understood what Dolby & DTS. In ahat as a layman's understanding Dolby and DTS. In a layman's language both are two different companies researching sound technology. For eg, like the case of Coke and Pepsi war which is still going strong in the market. Lets now don't debate which whether Dolby or DTS won the war rather than seeing the technical difference between both these technologies and how they are used commonly in various home entertainment appliances, media etc.

Difference between Dolby and DTS sound technologies...

Before answering this question, I should explain you how a typical film sound track appears as you see in figure on the right. As you have noticed, there is one more sound technology called SDDS (Sony Dynamic Digital Sound by Sony Corpn.) which is only available for professional use in selected theatres, so lets not discuss about it. Coming to the figure, you can notice how soundtrack is being laid in a commercial movie film. Dolby sound track between the perforated holes and DTS on a separate track on right side and ordinary stereo (analog) in parallel to the DTS soundtrack. One has to keep in mind the practical wear & tear of the movie film when played over again and again. As you see in the figure, DTS sound track consists of timecodes whereas Dolby has soundtrack encoded between the perforated holes. Lets see how both soundtrack performs, in a Dolby soundtrack over a period of time due to wear & tear of the movie film played so many time it starts to form scratches over the film and thus affecting the sound quality in Dolby giving ticks, clicks, breaks during playtime. The sound quality wouldn't be the same as the first show as we see the same movie after 50 days. Whereas, in DTS the soundtrack is in the form timecodes which contains digital information in '0s' & '1s' which is then sent to a special optical converter where these digital information is made to sync with a separate DTS audio track in a compact disc (CD) matching the '0s' & '1s' from the movie film timecodes and thus reproducing the sound during playtime. Here, since the soundtrack is available as timecodes, even though there are scratches or any information is missing the optical sync converter simply skips at the same matching with the DTS sound available in the separate CD thereby giving quality sound without any breaks, clicks or ticks even played after 100 days.

The fiilm technology was earlier used only in a commercial theatre projectors, but gone are the days where a movie theatre uses film to play movies. Technology enhancements gave boon to digital age to bring the best picture and sound quality for an immersive experience. Digital projectors phases out the old film/analogue projectors out of the market thereby bringing movies in the form of digital format like in harddisk, BluRay media. Both Dolby and DTS store their movie soundtrack in digital format along with the digital movie and played from a harddisk. Now, competition has become tougher for both the players since the digital format has become a common platform.

Soundtrack into BITS...

Sound has to be recorded in digital format and so the role of BITS come into play. Well, BITS indicate the quality of the compression taken place from the original sound recorded in the studio. If an original sound has to be directly transferred to digital format in a movie without any compression, then one has to need more and more of storage space to hold the orginal studio master recording to reproduce the sound in a movie theatre. This is practically going to be an expensive solution, so thats the reason companies like Dolby/DTS are using their own patented algorithms to compress the original master audio to a compressed form without losing on the quality.

You would have noticed MP3 songs are smaller in size but at the same time reproduces CD quality sound which is less noticeable. For eg. If I were to store CD quality music in a 700MB CD, it can hold only max upto 16 tracks. Whereas, if I were to compress the CD to MP3 format and then store in the same 700MB CD with upto 150 songs.

Similarly, Dolby & DTS compresses the studio master sound to hold onto a much affordable storage size without compromising on the audio quality. Now, here comes the role of BITS which are talking about. As you are aware in a MP3 format the maximum BIT we can achieve as equivalent to CD quality is 320KBps. Likewise, there are BITS involved in Dolby & DTS technologies as seen in the below comparison table.

The above table clearly shows better bitrates for DTS over Dolby, theoritically this gives us the feeling of DTS winning the game. But, the role of the compression technology comes in to play when delivering the compressed sound quality, so as Dolby claims that they use a special algorithm to compress the master audio to without compromising on the sound quality. There is no denying that both Dolby & DTS formats new high definition audio bitrates sounds superior to their respective entry level variants.

Now, DTS like Dolby have become popular in home entertainment systems, DVD, BluRay and in movie theatres just like Dolby. Most of available DVD, BluRay movies disc features either of these technology and it is the people who choose upon personal hearing preference.

Test Bench: As far as I am concerned, there is subtle sound quality difference between Dolby and DTS. For testing purpose, I played the DVD movie "Dinosaurs" which contained both Dolby Digital 5.1 (448 KBps) and DTS surround 5.1 (1.536 MBps) audio tracks. I played the scene where a giant bird trying to hold the dinosaurs egg while flying to her nest and dropping in the midst, where the egg falls into the forest and hits the trees, leaves and finally landing softly on the bushes. Here I bookmarked this scene in my DVD player from A to B and played it using the Dolby & DTS audio tracks. I notices in Dolby, that the voice channel gets more wider and rest of the left, right, surround reproducing perfectly with balanced bass through the LFE '".1". Whereas in DTS, in the same scene the centre channel is not getting wider but producing the same effect produced in Dolby, but rather getting more wider in surround channels and front left/right and adding heaviness in bass to the LFE ".1". Frankly, I loved both the sound quality and would further say that if I have a movie with both Dolby & DTS sound tracks then based on the movie genre I would like to switch between the two formats. Like, say If I am watching a war/action movie like "Saving Private Ryan" or "Transformers" etc then I would probable switch to DTS, wherein for drama, comedy type I prefer Dolby. I also noticed that Dolby is more musical/balanced and DTS for that heavy impact scenes. But, my testing went all wrong when I listened to both high resolution audio formats of Dolby TrueHD & DTS Master Audio. I can hardly find any difference between the two high resolution formats and I personally say that we needn't worry whether it is Dolby or DTS but just listen to whatever the DVD/BluRay disc contains. Because, the brain behind these technologies have really worked hard to get the surround sound experience at par quality no matter if it Dolby or DTS - Both wins!

I will have a separate article about how to setup/configure 5.1/7.1 surround speakers using the correct equipments required to reproduce the desired theatre experience. Meanwhile, you can have a look at the common logos seen in your DVD/Bluray players, Audio/Video Receiver, CD/DVD/BluRay disc which get certification for using the respective brands.