written by Mike Shea on 2 October 2000
This article will answer the following questions:
What you should learn from this article:
Among the most confusing elements of home theater, the subject of audio decoding methods stands the tallest. The market hype of the home theater industry will try to sell you on dozens of different "standards", but only a couple of them are really important when it comes to the quality of your home theater. If you are new to home theater and need an objective guide to the different audio formats, this article is for you.
There are basically three formats on the market right now that are of significance. Dolby Pro-Logic, Dolby Digital and DTS. You will find these logos on the front of many receivers and DVD players alike.
Dolby Pro-Logic. is probably the oldest of the true audio decoding schemes. Also known as Dolby Surround, this audio format takes a normal stereo signal and split it to include the center and surround channels. Because of the backward compatibility with original two channel sound, Dolby Pro-Logic is the most widely used but the least powerful of all the surround sound decoding methods. Originally receivers included this for a high price, but now every home theater receiver on the market includes Dolby Pro-Logic. For a more detailed look at this format, see the Dolby Pro Logic homepage from Dolby.
Dolby Digital 5.1 is a new format that has become more popular with the coming of DVD. This audio format offers any number of dedicated channels up to five main channels and one low frequency effect channel. Dolby Digital is the most popular current decoding method for DVDs and offers the following improvements on movie soundtracks:
If you are buying a new home theater receiver, make sure it includes Dolby Digital 5.1. For more information on purchasing home theater equipment, see the Home theater 101 guide, the Home theater for Cheap guide.
DTS is a competitor of Dolby Digital. It also offers a five channel plus low frequency effect channel, but it is not compatible with the Dolby Digital soundtrack. The marketing babble that comes out of DTS says that it uses a lower form of compression which gives you a better overall sound for your movies. I personally have not found this to be the case. Listening to both DTS and Dolby Digital versions of the film gave me little sense that one was better than the other. Dolby Digital or DTS can both sound excellent or shoddy depending on the quality of the soundtrack. Regardless, I certainly recommend getting DTS compatible equipment for both your DVD player and your receiver since the cost is minimal. Many DVDs now come with both Dolby Digital 5.1 soundtracks and DTS 5.1 soundtracks, letting you pick the version to listen to. One interesting side note, Dolby Digital includes a signal compression feature for late night viewing that DTS does not. This allows you to hear dialog and quiet scenes at their normal volume while louder scenes are suppressed.
No home theater trend is more misunderstood than THX. THX is a seal of approval for equipment and software, but not a particular decoding algorithm like Dolby Digital or DTS. There are detailed technical specifications applied to equipment or software in order for it to be THX certified. When you buy a THX certified piece of equipment, you are guarenteeing that this piece of equipment meets the THX standards. Here's an example of the specifications:
It is important to realize that there are many pieces of high quality equipment that do not meet THX standards. For example, the Skywalker ranch sound studio uses non-THX certified B&W 802 speakers to monitor THX certified recordings. THX certification is not something that one should require when purchasing equipment. Because of the high cost, I do not recommend the purchase of THX certified equipment.
Recently, Lucasfilm created a new lower standard for equipment known as THX-select and renamed the original standard to THX Ultra. The only difference between the two specs is the size of the room.
Recently, there has been two new formats, Dolby Digital EX, and DTS-ES. This decoding method first came to light with the theatrical release of Star Wars Episode 1. Immediately, the home theater industry spoke up about this format. Many home theater enthusiasts complained about the need to purchase new equipment while the industry started making "EX Compatible" equipment. DTS jumped on board with DTS-ES, a similar effort.
This decoding method works by taking the two rear channels of a Dolby Digital 5.1 soundtrack and run them through a Dolby Prologic-like decoder. This builds a third channel of sound from the two surround channels, which is sent to one or two amplifiers and speakers positioned behind the primary viewing position.
A few new receivers and decoders are hitting the market with Dolby Digital EX and DTS/ES decoding as well as some newer DVDs.My recommendation is to only include Dolby Digital EX as a required feature on receivers above $700. While it is still not a full requirement for a good home theater, more and more DVDs are including rear center channel information.
Within this plethora of acronyms, there are only a couple that are important when purchasing a home theater system. Dolby Digital 5.1 is the most important multi-channel decoding scheme used today for DVDs. Make sure whatever receiver you get has the ability to natively decode Dolby Digital 5.1. DTS is the second most used format, and it is cheap enough to purchase equipment with DTS compatibility that it is worth getting. DTS ES and Dolby Digital EX are becoming more popular but mainly for more expensive receivers. They are not required but if you can afford them, they may be worth getting.
From: Homersim ( odddooo3@yahoo.com ) on 14 December 2004
Subject: DD Vs. DTS
Hello, It has been my experience that Dolby Digital make me rather tired trying to hear all of the brilliant sounds on my DVDs. DTS seems to bring out these minute sounds and provides me with a true cinematic experience with robust low frequencies, and clarity unmatched by DD.
As for the DVD players that do not have 6-speaker output connections, yet claim to decode surround sound...
While it is true that these DVD players in question decode the surround sound, whichever coding method, they usually work best when connected to an external amplifier, via the coaxial digital output, that takes care of amplifing and distributing the signal. If you do not have an external amplifier as described, then I encourage you to visit this link for directions and insight to an analogous method of doing so.
http://www.amsky.com/~cirkuit/media/surround.html
I wish, to each of you, a happy holiday season, and may more movies be encoded in DTS!
HS
http://www.magnetix.com
From: Incopass ( dale_Edwards@comcast.net ) on 6 December 2004
Subject: DTS-vs-Dolby Digital 5.1
An excellent source DVD to determine which of the above sounds best is X-Men 2. I've listened to both and the DTS signal processed by my Yamaha DSP-A1 blew Dolby Digital 5.1 away.
From: Shadowclaire ( shadow_claire@hotmail.com ) on 30 September 2004
Subject: I dunno
I've done many dvd encodings over the years and I've
found that they do sound almost identical in 80% of movies there is a few where DTS souns better but it's just not worth the price of the hassle. plus even if it has TRUE 7.1 90% of studio movies have FAKE 6.1 and 5.1, so how does this help?. I have a 7.1 system with the DTS ES or what ever and on DTS hardly anything comes out of the rear center channels on movies like lord of the ring and pearl harbor, yet the other channels are just louder than DD exept the frnt center that one is much softer. Is gonna be a hard battle no matter what, everybody is diffrent, But I almost always encode my DVD's to DD primaly and DTS second, mainly because DD is easier to use and more supported. Always thanks for your time. :)
From: David Magda ( UseGoogleToFindMe@a.com ) on 29 September 2004
Subject: only two speakers for 5.1
Does anyone have any comments or suggestions on using a receiver that translates the 5.1 signal to only two speakers (with a sub-woofer perhaps)?
An example of this would be Dolby Virtual Speaker technology. There's even a paper published in IEEE's Spectrum magazine with the thesis that two speakers is better than many.
An example of a receiver that has it would be a Denon AVR-485S.
Any thoughts?
From: Gregory Palmer ( preatis@hotmail.com ) on 23 September 2004
Subject: TOTAL BS about DTS being EQUIL
This Artical provides some factual content but mostly opinionated content. Just becuase some persons are not audiofiles and have problems distingishing sound differences does not mean that there is not an actuall difference in sound. Fact is, DTS is Clearer, higher SNR, and is in EVERY WAY far better than DD. Digital Theater Sound is for more versitly in the amounts of "bit rate" that can be decoded than Dolby. And to answer the question, "why does DTS pay royalty fees to Dolby, for using the THX certification is because it is a merged company. And DTS does not pay royalties for the 6.1 but for the THX certification as EVERYONE (but Luca himself) is charged for this optimisation of leveled shound. THX doesn't make it sound better but just ensures that the Unit, Player and Speakers will play a certain range of sound equily. ""This is almost like Pepsi paying a royalty to Coca-Cola"" Not at all it is more like bud Light and bud ice, and if Coors whants to use the Bud Light Logo they are going to pay. You do not need to be THX certified to have DTS 6.1 Lucas was inspired to invent THX with his first movie THX1138. So he partnered with audio manufactures to inquire the level of difficulty to create dolby Surround and "from his specifications" dolby digital was born. Yes DTS stood on the shoulders of Dolby to create the DTS format but DTS has acheieved much more effective streamlined digital compression with less bit rate loss while decoding. DTS was the first (and still is) the only format that can carry 24 bit/96k, not to mention it is able to seperate the rear "6.1" speakers into 7.1. Dolby attempts to make the rear channels independent by simply panning the suround speakers from left to right also, In other words, you cannnot have the rear left speaker playing something independantly from the back right with DD. Dts allows TRUE 7.1 chanels each independantly controled and processesed while Dolby allows only 5.1+1 (delayed) time signature. If you are going to pay $700 for a DD EX reciever then get one that is also DTS ES compatable. Grab the Borne Idenity, Extended edition verson of LOTR the two towers and tell me which is better. Fact either fromat can be done inccorectly but they still have to setuo when the channels The butterly effect has both, DTS 6.1 Es and DD EX. Look at the repororts. DTS wins hands down.
From: Abe ( seeberg666@yahoo.com ) on 27 July 2004
Subject: I have a question about the necessity of a subwoofer.
I recently got a pair of KLH 9250B floorstanding tower speakers, and I understand they are advertised to go as low as 28Hz from www.klhaudio.com. The towers use a single 12" woofer in each inclosure, and I had the Bose Acoustimass 15 subwoofer. I know what you're thinking, "what the hell are you thinking?!" I got the Bose garbage for cheap and I'm selling it. So what I wonder is, is it necessary to add on a sub if my towers are already adequate music, sonic, and impact wise in a Dolby Digital/DTS 5.1 system, or should I add on an LFE amp upgrade to my towers? I've seen nice amps for as little as 90$, and that seems far more reasonable than getting a powered sub outright. Any advice?
From: Jim ( jeidalpha@att.net ) on 3 January 2004
Subject: dvd built in decoders
This is in response to an earlier post here regarding not being able to find a dvd player with a built in decoder.
My experience has taught me this: A lot of players say they are 5.1 or DTD "ready" and need to hooked up to a receiver with a decoder, but they acutally do have a built in decoder themselves. Why this is, I have no idea.
My mother just bought me a second dvd player for Christmas. The box has the digital logos on it, but no mention of decoders. The little advertisement tags on the model make no mention of the decoders and said 'ready'. I open it up and the instruction manual states clearly:
"Built in Decoders
This unit has Dolby Digital and DTS decoders so you can enjoy discs that display the indicated logo in stereo without connecting a separate decoder."
One great dvd player with decoders for only $80. It's the Panasonic DVD-S25.
From: mike ( mikegscot@yahoo.com ) on 3 January 2004
Subject: dvd movie compatibility
i have the following in my bedroom
1. pioneer dv 333 dvd player
2. toshiba flatscreen 20 inch tv
as i have no reciever so no reason for surround sound, can anyone explain why a lot of movies will not play properly ????
they appear to be recorded in 5.1,does this mean they can ONLY be watched on a full theater type system or am i missing something here ???
cant i watch any movie nowadays on just a tv and dvd player ????
spent hours trying to get it to work but to no avail.I get picture but the sound is all fuzzy and distorted.
Some movies have ability to change to 2 channel and they are fine but some appear not to.
any ideas ????
From: Sam ( dtsrulez@yahoo.com ) on 30 December 2003
Subject: dts- two thumbs up!
Unbeleivable....but its true. dts makes yr movie alive and real. U don't feel tired to play the same dvd again and again. I've tried dd & dts so many times but the credit goes to dts. Pearl Harbor is one of the good example, when the jap's plane re pounding the arizona.
From: Chris Swinney ( swin@fab-sas.co.uk ) on 20 December 2003
Subject: What's 7.1?
So what does 7.1 sound signify? Are there any other techologies coming up that should be known?
Chris
From: Chris Swinney ( swin@fab-sas.co.uk ) on 20 December 2003
Subject: Newbie to this and thanks. But a few questions abould audio from TV broadcasts.
I have spent many hours wondering around stores looking at Home Theatre systems and have been totally bemused by the different specification and I simply don't trust the majority of store staff to be able to give a logical, unbiased and accurate overview of the technologies involved. I think your article has given me at least an overview of these points - if being just a little biased! Not bade a top search query in Google!
I hope I can now look for more in depth coverage of home theatre before I actually go out and can make a slightly more informed purchasing decision. Maybe a little money may also help, but that’s another story!
Can I also ask a couple of rather simplistic questions to do with different audio from general TV viewing? I understand that the different audio sources are encoded onto a DVD, but what about TV broadcasts?
I’m guessing that normal analogue broadcast will only carry a stereo NICAM signal so I assume this could be split with Dolby Pro Logic with the right decoder? I would then assume that you would run the audio out from your TV into the receiver so this could be accomplished.
But what about a digital TV source such as satellite, cable or digital through an aerial (Sky, NTL/Telewest, and Freeview as I’m in the UK)? What type of audio signals do these broadcasts carry? Would you need a digital or optical SPDIFF connector from the digital TV box to the home theatre equipment?
What I would be looking for eventually is a system that is not only capable of giving good DVD movie production but also works well for general TV viewing.
If these questions have been answered in another location I would be grateful if you could point me in the right direction.
Many thanks for your article.
Chris
From: Mister ( mr@mister.com ) on 1 December 2003
Subject: @ Matt
Look on Ebay and try to find an older model DVD player with internal decoding. You wont find hardly any dvd players out now with decoders built in since all receivers come with them now.
From: Matt ( benzim@rpi.edu ) on 1 December 2003
Subject: DTS add-on?
Hi; Question for anyone.
I already have a reciever with Dolby 5.1 but without
DTS. Is it possible to get any sort of add-on hardware that will decode DTS?
Thanks
From: Cameron ( hahahahaha@guess.com ) on 21 November 2003
Subject: More experience
Well, I've viewed about half of the movies that I own that feature both soundtracks, and on those particular movies, DTS won out. Same reasons as I mentioned before. I think I'll be paying much more attention to which movies have DTS when I'm selecting movies now.
From: Rob ( Chandler ) on 19 November 2003
Subject: DTS or Dolby Digital
Well, after having read all comments I'm still undecided. After recently buying both the Lion King special Ed and Lord of the Rings: Two Towers (both with DTS and DD) I made a point of trying both soundtracks out.
On the Lion King, DTS was immensely superior: Louder; More clarity; you didn't need to crank up the volume (you did with DD), and the Centre speaker volume was perfect. With DD the whole soudetrack was just too quiet.
With The Two Towers, it is a different story. Once again DTS is louder and more significant, but the centre channel (i.e voices) was just too quiet, and the Bass was at a distortional level. To enable happy viewing I had to turn the bass to 25% and the centre up full. Even like this the voices were still a tad quiet. The Dobly track is good, but still not as good as the DTS - even after adjustment.
I'm in favour of DTS, but have a go at this and I would be interested to hear.
From: Cameron ( MonK555@hotmail.com ) on 17 November 2003
Subject: Hmm...
I'm glad I found this article. I'm listening to an audio DVD right now, and just figured out how to turn on the DTS decoder in my DVD player (that's what I get for not reading the manual!). I noticed a HUGE difference right away. The DTS sound is MUCH clearer, distinguished and separated. The LFE is much more powerful with less distortion, and the high end is sharper and more precise. Spaciality has improved tenfold, and I can hear all 6(5.1) channels clearly anywhere in my apartment. Now, of course I'm sure this has to do with the way it was mastered, and I haven't had occasion to watch a movie with DTS yet, but so far Dolby has been no competition. It was interesting to see that you said that DTS and Dolby Digital are really close, but that hasn't been my LIMITED experience. I'll post again after I've seen a few movies with both settings, but so far I'm really impressed with the DTS sound.
From: Guy ( nothing@nothing.com ) on 18 September 2003
Subject: DTS Rules Shea
I don't think Pearl Harbor is crap. DTS rocks the house, Dolby is left in the dust with its "superior" sound.
From: Az ( no@email.com ) on 28 August 2003
Subject: nice article
cheers dude this has been a helpful article.
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From: Tom ( catiwompis29@aol.com ) on 25 January 2005
Subject: 7.1 ?
Im buying a Pioneer 1041 7.1 receiver.....where do i hook up the extra 2 speakers...and is there any movies that r 7.1 yet?