This is topic Dolby vs DTS....Some food for thought...... in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.
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Posted by Mark Gulbrandsen (Member # 72) on 02-20-2001, 05:03 PM:
I found this note on the Association Of Moving Image Archivists noteboard and thought it was quite interesting so I decided to post it here. Its interesting that they didn't even consider SDDS at all in this comparison.
Mark @ GTSGreetings,
As we increasingly encounter digital sound records for motion pictures, the
academic question as to which of the two fares better when compared by an
audience when two paired sound samples are played back in succession, with
each half of the pair recorded by identical or different systems. This
question is answered in a report from Guy Walker BSc and Shui-I-Shih PhD, in
a paper entitled: "Dolby v DTS-The academic viewpoint", pp. 35-30, in Cinema
Technology (ISSN 0995-2251), published by the British Kinematograph Sound
and Television Society (BKSTS) . Their website is: www.bksts.com. What is
significant about the results is that although the differences were almost
imperceptible, the listeners indicated that Dolby Digital data-reduced audio
sounded better than data-lossless DTS! Yet the amount of the originally
recorded sound data of Dolby Digital that is used, only amounts to 20%,
meaning a compression ratio of 5:1, yet it sounded better than uncompressed
DTS.
This is also the subject of discussion in the video community where
presentation quality is optimized for an optimum viewing quality that may be
surprisingly good for compressed images, such as when comparing 35mm cinema
projection using film vs digital cinema projected from data reduced DVD
media.
PS. The corresponding author's contact details are: guy.walker@brunel.ac.uk
or Tel: +44 (0)1784 431341, Ext. 244.
Posted by Scott Norwood (Member # 30) on 02-20-2001, 05:23 PM:
Since when is DTS uncompressed?
(Personally, I'd argue that neither format is really appropriate for archival use and that 35mm magfilm and optical-track negatives are more likely to be playable in 50-100 years than proprietary compressed digital formats...)
Posted by Evans A Criswell (Member # 381) on 02-20-2001, 05:49 PM:
I agree, Scott. If digital audio is used for archival, I think plain old simple uncompressed samples are the best way to go. All you have to do to read them is read them in succession, knowing the sample size, number of channels, and sample rate.Think about archival this way:
Suppose an archaeologist from the future found some of our sound or picture recordings and had no idea how our technology worked, the pure analog forms, such as vinyl records and film prints would be the easiest to read and figure out, obviously. Anything in digital form would need to be as simple and straightforward as possible to decode to have any hope of recovering it without any algorithm documentation.
Evans A Criswell
Posted by John Walsh (Member # 168) on 02-20-2001, 06:38 PM:
But with magnetic media, there is the possiblity of it being erased, or distorted with stray magnetic fields. Sound is recorded pretty "hot" on printmasters and 70mm; I would think after many years there also might be print-through.Scott's idea of optical tracks is probably the best for archival purposes.
Don't forget to visit: http://www.deadmedia.org/
Posted by Joe Redifer (Member # 3) on 02-20-2001, 07:00 PM:
Using the term "lossless" implies that DTS is compressed, but it does not loose anything from the original after decompression, similar to the way GIF images use lossless compression. They are exact to the original, pixel for pixel, just as long as you use 256 colors or less. Not true with JPEG. It is NEVER pixel for pixel perfect. And DTS is the same way. Like SDDS and Dolby Digital, it is a lossy format.Where do these guys get their info?
Posted by Gordon McLeod (Member # 33) on 02-20-2001, 07:21 PM:
I read the complete article and they did some very interesting tests with a reasonably large sample group.
I too find the results odd
Posted by Mark Gulbrandsen (Member # 72) on 02-20-2001, 08:34 PM:
Other than Gord you all got the wrong point. The actual note was about the sound differences between Dolby VS DTS. Not the archival storage of digital tracks. Go to BKSTS and read the whole article.
Mark @ GTS
Posted by John Eickhof (Member # 323) on 02-20-2001, 10:22 PM:
It's interesting! Mark, About three years ago,I did several side by side tests with both blind audiences and SMPTE Sacramento chapter members w/ families at the Colfax Theatre in Colfax, Cal. We demo'ed
all three digital formats (permanently installed) through the same B chain, with the following results every time:
The audience chose DTS as the most dynamic and clear sounding, Dolby was next, with the plain USL analog third and SDDS 8 channel FOURTH!!! (Lonnie Jennings of Dolby was there and did his own B chain adjustments, as I was also and the audience was subjected to the same reel of film four times without knowing the sound format! Basically the audience liked the DTS first! Only once out of three of these sessions did SDDS beat out the Analog USL! Verrrrrry interrrresting!!!------------------
John Eickhof President, Chief Slave
Northwest Theatre Equipment Co., Inc.
P.O.Box 258
Wendell, ID. 83355-0258
208-536-5489
email: jeickhof@nteequip.com
Posted by Joe Redifer (Member # 3) on 02-21-2001, 12:00 AM:
Please explain to me how I got the wrong point. They used the term "lossless" and I explained that DTS was in fact not lossless. I didn't mention anything about archiving sound. 
Posted by Mark Gulbrandsen (Member # 72) on 02-21-2001, 07:03 AM:
Hello Joe, Whaddya know........I just got back from the show!
The real point was the fact that the tests revealed that SRD was the prefered sounding system over DTS. The statement that DTS is losless is certainly misleading but that isn't really a factor for the tests. The sound difference was the real point of the article. Ya need to read the whole article in BKSTS. I copied the note directly form the bulliten board as a whole and didn;t edit it at all.
Mark @ GTS
Added 10:AM
I e-mailed the guy that posetd the message and let him know that DTS has 4 to 1 compression ratio(as per stated in the 6D manual that I have). Apparently he was unaware of that and thanked me for the clairification. The main point though was the difference in perceved sound between the two systems.
Mark
Posted by John Walsh (Member # 168) on 02-21-2001, 10:37 AM:
Where is this article? I couldn't find it on the BKSTS site.I don't know exactly how to state this question, but... You know how kids like to turn up the bass because they think it's cool? Does SR-D 'color' the sound such that it might sound better to your ear, but is not being reproduced (techinally) correctly? Were the two systems set up correctly and fairly, to provide an accurate A-B comparison?
Posted by Mark Gulbrandsen (Member # 72) on 02-21-2001, 11:19 AM:
Actually I have had the same experience as they. I have never been able to detect any major differences between the two. I have done this on all types of sound systems, HPS, THX, large JBL systems and thats why I always stuck with SRD when it comes to selling product. It IS a bit more expensive but far more practical, and far more reliable. And with proper film treatment there is not a wear factor in the track involved.
The article was there a while ago, but you may have to go to your library and look for the particuluar copy that it was in. If you subscribe to IMage Technology you can go into their site and pull up the paper.
Mark
Posted by Per Hauberg (Member # 529) on 02-21-2001, 04:50 PM:
I would always claim DTS being more dynamic than SRD...
Mark says> SRD more reliable<
Doesn't that very much depend on how far down the distribution alley You are..?
To many drop-outs on SRD, when You're not on first-run, but become 2-3 months old prints as 4th or 5th theatre, i think.
Normally no such problems on DTS. --That is:
Right now Cast Away is making my hair grey:
First 3 days in screen #1 DTS ok. On 4th day all blinking - system never on. On 5th day print moved to Screen #2, running perfect, and two even older prints (Chicken and Parents) coming to screen #1 ok too....
Ready to panic !BTW: May i hear from Your experience, please:
Some of You guys have been discussing SRD penthouse versus basement readers, and i think the vote majoriry goes for basement readers being less good. -Does that go for all makes ?
My screen 1 is two Norelco (DP70)s with DTS and cat 700 / 701. Screen 2 is Vicoria 9 with DTS, and i'm now considering SRD for this one also. What would You say about the Cinemec basement reader - Should i wait for that nice day, when boxoffice allows Miss Victoria to be replaced with an FP30 from Kinoton or what..?
Per
Posted by Mark Gulbrandsen (Member # 72) on 02-21-2001, 04:59 PM:
Per,
You need to Film-Guard those old 2nd run prints. It cleans them up amazingly well. I can't speak for prints that have really bad abrasion between the perfs though. It is still possible that Filmguard would clean em up and make em run more reliably.When I speak of reliability I am referring to the equipment. DTS has not been at all reliable for me till lately. I have rebuilt a number of units twice due to bad drives and needing software upgrades.
I have had quite a number of theaters that play 2nd run movies and they have little or no trouble with SRD but thye all use Flmguard. Is there no distributer in Denmark yet?
Mark @ GTS
Posted by Per Hauberg (Member # 529) on 02-21-2001, 05:09 PM:
Mark:No, still no one dared taking in the wonder brew. -And Yes: while the first DTS now runs on its 7th year without other problems than the above mentioned, my newer one - the 3 disc model went dead in 13 months because of its ability to suck dust. -My booth is not that filty!! - New drives - and fine running again (but for how long..?)
I've seen the fine offer for trying out the Film Guard - but how much for the cleaning device ?
/ p.
Posted by Mark Gulbrandsen (Member # 72) on 02-21-2001, 05:19 PM:
Per,
If you pay the shipping I'll send you a quart of Filmguard to try out. Keep in mind though that if you don;t haev a KElmar type film cleaner you'll hvae to apply it by hand. This is a bit difficult to do. Let me know what you think. Personally, I'd get two more DP-70's and send the Cinemec on its way. If you do put digital on the Cinemec then use a Cat 701. When you do send the machine to projector heaven you will still have the intact digital system you can install on the new machine.
We are developing an SRD reader to retrofit onto the DP70 sound reproducer. The main problem is that you have to go to a sound drum in which the film overhangs the edge so you can scan between the perfs. This gets away from the non-contact type of drum which this reproducer is so famous for. We are trying to work this out so we can use the non-contact type but it only leaves a bit more than a millimeter to support the edge of the film. It does work ok and has low error rates but we're concerned about supporting an edge this small. Cinemec also does it this way...with a 1mm edge for the film.
Mark @ GTS
Posted by Per Hauberg (Member # 529) on 02-21-2001, 05:26 PM:
Mark -Thanks in plenty - Now sales offer cant be any better, i think. -The Kelmar cleaner - is that the one in the Film Guard photos ?
Will it go for the DP without trouble ?
/p.
Posted by Per Hauberg (Member # 529) on 02-21-2001, 05:31 PM:
Wish, I had a scanner. -Then You could see the main reason for not getting DPs for screen 2. -My 250+ pound are almost down on knees to get round the Victoria (without column, -hung onto build-in wooden console.
Otherwise - great idea - especially saying goodbye to the Shakeamec.
-And then: Used DP's never available - over here, at least... -for some reason 
/ p.
Posted by Mark Gulbrandsen (Member # 72) on 02-21-2001, 05:33 PM:
It should work on the DP-70 although I have never installed one. Kelmar lists a 70mm projector bracket P/N 7508330 and a 35mm to 70mm adaptor bracket which is P/N 7508315, however they do not specify what 70mm machine it is for. I can find out tommrrow though. The other option is to run the film through a Kelmar cleaner on the rewind bench. We have one customer that does that. They once got in a print of Top Gun that was terrible and practically unusable but after 3 or 4 passes through the Kelmar with Filmguard on the rewind bench the print actually looked decent sans the emulsion scratches. That is what sold me on FilmGuard. Do you have a Kelmar cleaner?
Mark @ GTS
Posted by Per Hauberg (Member # 529) on 02-21-2001, 05:39 PM:
Never tryed other than Kodak PTR cleaner - with absolutely no succes !
As someone once put it here: Particles tranferred from one place on print to another. Demounted after almost ruining a brand new Toy Story (I) print several years ago.../p.
Posted by Karen Hultgren (Member # 395) on 02-21-2001, 05:52 PM:
I believe the article is concerning DTS for CDs and DVDs. It's not about DTS discs for motion pictures on film.Karen at DTS
Posted by Karen Hultgren (Member # 395) on 02-21-2001, 06:04 PM:
For clairification, the codec used for DTS on CDs and DVDS is NOT the same as used on DTS discs for motion pictures on film. The compression rate for the "home" codec is 3:1, the compression rate for the "cinema" codec is 4:1.It seems to me the article is confusing more people than informing anyone. It should have been made more clear that they were comparing home product and not professional cinema (movie theater) product.
This whole "who sounds better" debate of DTS vs DD for DVDs/Cds/laser discs has been going on for years. It's not my area of expertise (home applications), so I leave it to the "other" side of DTS to handle.
Karen at DTS
Posted by Karen Hultgren (Member # 395) on 02-21-2001, 06:05 PM:
One last time....The reason they did not consider SDDS is that there is no SDDS for home systems.
Karen at DTS
Posted by Jeffry L. Johnson (Member # 453) on 02-23-2001, 01:47 PM:
The tests took place at a university theater with both Dolby SR*D and DTS equipment. The testers evaluated motion picture film sequences. It was not a home theater or CD/DVD evaluation.
Posted by Stefan Scholz (Member # 147) on 02-23-2001, 02:33 PM:
I readthrough thearticle, when the magazine was in the mail, about two month ago. It deliveres some interesting points for discussion, and reveals a subjective test with an audiénce in a´given theatrical environment, whivch not considered the best, or reference site. Within this the results were archieved, bút I have not read through it, that people have preferred DD to DTS in general. It is worth reading through everything before continuing the discussion.
Posted by Ari Nordström (Member # 288) on 02-23-2001, 02:35 PM:
Well, with all due respect to those concerned, I much prefer SRD to DTS. It sounds better (IMHO, of course), and it's available without having to call the ditribution company for discs. If they have them.At the Göteborg Film Festival three weeks ago, I screened 66 35mm prints (and one 70mm print) from all over the world. Of these, about half had SRD tracks. Exactly _one_ print came with DTD discs even though about nine or ten had the time code track. Thankfully, most, if not all, of them had an SRD track, too. Please note that these prints were shipped directly to us from various film festivals, labs, or special screenings. Also note that most of our screenings were the first European or Swedish screenings of the films in question. We had a few world premieres as well.
So what became of those DTS discs? Is it our responsibility to see to it that the film is actually delivered with the digital sound track?
I rest my case.
Posted by Mark Gulbrandsen (Member # 72) on 02-23-2001, 05:10 PM:
Hi Karen,
It was indeed a Motion Picture sequence evaluation. It has been a while since I read the original article myself. Yes, He mistakenly said that DTS was lossless implying that there was no comperssion, bu this is not the case. I e-mailed him and let him know about that and I did gt a reply fomr him that he was not aware about the system used in DTS. Compresssion aside though it was a simple sequence evaluation. I think you may have picked up some of the stuff mentioned about video compression for Digital Cinema / TV that he mentioned in the posting and assumed that it was home video they were talking about.
Best,
Mark @ GTS
Posted by Per Hauberg (Member # 529) on 02-24-2001, 05:49 PM:
Ari tells about missing DTS discs.
It has and sure always will be a problem, because to few employees at the distribution offices appreciate the added quality, but only gives thoughts to their extra work, delivering not only film print but discs.
Often, some danish bookers have given us the message, when complaining, that if a cinema has installed both DTS and SRD, they see no reason, sending us the discs - we can run digital whatsoever...! (It goes better now than 5 years ago, though !)
Luckily, Karen and her collegues in DTS' former Brussels office and nowaday their English department, don't shy the trouble, but has been helping me several times with discs coming across the sea, so that the best possible presentation can be done. -Just as their patience was far beoynd what you could expect about all my questions during a period some years ago with very poor dealer/service possibilities local in Denmark.
That was great service to a small custumer, and the #1 reason, i ever considered to go digital on my humble 39 seat screen 2.
Thanks again !Per
P.S.: Only DTS disappointment: trailer discs not available i Denmark, except a single go back at the start of DTS....
P.P.S.: About that photo of Yours, Ari - Are You keeping birds in the booth in Göteborg ? -Can't help thinking back on Hrundi v. Bakshi and his "birdy-num-num"...
Posted by Ari Nordström (Member # 288) on 02-25-2001, 01:06 PM:
Well, Per, about that photo...No, it isn't a booth pic. It was taken in Vancouver, of all places, three years ago, and it's one of the few decent pics I could think of when Brad came up with this portrait thing. I'm as handsome as ever, of course, but people keep failing miserably when pointing their cameras at me.
Posted by Heyward Garner (Member # 722) on 02-26-2001, 12:10 AM:
Ahhhhh...
This debate is like taking both Coke and Pepsi into an uncivilized culture and asking them which one is better?
The "average" (by that I mean 99% of moviegoing patrons) CAN NOT distinguish a difference, nor even know what unit is running in what auditorium... Just so long as it's digital.
I must say, that I think of myself as having a rather keen ear. I played piano for several years, have been playing guitar for two years now, and have worked various a/v tech jobs aside from running my booth. I have noticed that DTS dialouge (high end) noise seems more crisp. Dolby managed to sneak in their old-school "noise-reduction" into SRD, which muffles the higher end frequencies so as to rid the sound of that famous hiss. DTS does not do so, making things like dialouge or a symphony orchestra sound really *REALLY* good. However, the special effects I have to give props to Dolby. Everything other than the center channel sounds GREAT. Extranneous noises such as a car blowing up shake the seats, instead of a crisp clean fire burning like DTS would produce. Nothing wrong with either, I like both. Those are the main differences I've noted...
Also, DTS is compressed if I am not sadly mistaken. It's just not compressed nearly as much as dolby, because DTS has more room for the data, plain and simple. Dolby has a good idea though, fitting everything onto the film. Less to mess with. That's all they were trying to accomplish. In doing so they sacrificed *some* quality, but nothing a consumer would ever be able to tell. We are supposed to know and detect the difference, that's our job. Not theirs... =)