Film-Tech Forum ARCHIVE: Dolby vs DTS....Some food for thought......

my profile | my password | search | faq & rules | forum home

»	Film-Tech Forum ARCHIVE » Operations » Film Handlers' Forum » Dolby vs DTS....Some food for thought...... (Page 1)

This topic comprises 2 pages: 1 2

Author

Topic: Dolby vs DTS....Some food for thought......

Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 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 @ GTS

Greetings,

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.

Scott Norwood
Film God

Posts: 8146
From: Boston, MA. USA (1774.21 miles northeast of Dallas)
Registered: Jun 99

posted 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...)

Evans A Criswell
Phenomenal Film Handler

Posts: 1579
From: Huntsville, AL, USA
Registered: Mar 2000

posted 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

John Walsh
Film God

Posts: 2490
From: Connecticut, USA, Earth, Milky Way
Registered: Oct 1999

posted 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/

Joe Redifer
You need a beating today

Posts: 12859
From: Denver, Colorado
Registered: May 99

posted 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?

Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 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

Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 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

John Eickhof
Jedi Master Film Handler

Posts: 588
From: Wendell, ID USA
Registered: Jan 2000

posted 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

Joe Redifer
You need a beating today

Posts: 12859
From: Denver, Colorado
Registered: May 99

posted 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.

Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 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

John Walsh
Film God

Posts: 2490
From: Connecticut, USA, Earth, Milky Way
Registered: Oct 1999

posted 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?

Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 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

Per Hauberg
Jedi Master Film Handler

Posts: 883
From: Malling, Denmark
Registered: Jul 2000

posted 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

Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 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

Per Hauberg
Jedi Master Film Handler

Posts: 883
From: Malling, Denmark
Registered: Jul 2000

posted 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.

All times are Central (GMT -6:00)

This topic comprises 2 pages: 1 2

Printer-friendly view of this topic

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.