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Author Topic: DTS & SRD reliability
Patrick de Groot
Expert Film Handler

Posts: 161
From: Sprang-Capelle, Netherlands
Registered: Apr 2001


 - posted 06-19-2001 11:38 AM      Profile for Patrick de Groot   Email Patrick de Groot   Send New Private Message       Edit/Delete Post 
We're thinking about using one of these system in our theater. I've got some questions about there reliability:

-From how much damage to the digital soundtrack can SRD decover? (how many meters)
-Same for the timecode strip of DTS
-When there is a reading error: will these systems try to read again after an amount of time from the timecode/digital soundtrack or will they just stay stucked at the analog soundtrack?

Say if you have to cut out one or two meters of film due to some "accident", will there be problems when reading digital sound with DTS and SRD?


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Adam Martin
I'm not even gonna point out the irony.

Posts: 3686
From: Dallas, TX
Registered: Nov 2000


 - posted 06-19-2001 01:19 PM      Profile for Adam Martin   Author's Homepage   Email Adam Martin       Edit/Delete Post 
SRD will default to analog after just a few sprockets of damaged data (heavy scratches or opaque splicing tape on the SRD data in the perf area).

DTS has a timecode buffer of about 4-5 seconds before it has to revert to analog due to damaged timecode.

Both systems will continue to try to read digital info after they default to analog and will switch back to digital playback automatically (if the automation controls are set up correctly) as soon as they see adequate digital info.

Regarding several meters of films being spliced out, both SRD and DTS will jump forward in time as required to accommodate the missing film. The worst would be defaulting to analog for a moment if the splice is not done well.

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Antonio Marcheselli
Phenomenal Film Handler

Posts: 1260
From: Florence, Italy
Registered: Mar 2000


 - posted 06-19-2001 02:28 PM      Profile for Antonio Marcheselli   Author's Homepage   Email Antonio Marcheselli   Send New Private Message       Edit/Delete Post 
Patrick,

Let's say that your equipment is well tuned up and your print is ok (regarding digital data and/or timecode).

In this case both systems are IMHO very reliable. In case of problem (a damaged print) DTS manages very well a lot of splices and scratches.

Let's suppose that you have a lot of splices due to an accident: DTS drops to analog after 4/5 seconds of bad timecode, but also one second of good timecode can "reset" the counter. So have a DTS player dropping to analog would rather indicate a problem on the timecode's print or to equipment. I cannot imagine a so damaged print that DTS cannot read properly. I have a piece of "TITANIC" in my booth. At splices image is HORRIBLE, full of scratches. DTS has absolutely no problem reding timecode. Dolby Digital probably will drop in analog at splices but tries continuously to revert in digital. After many drop-out it will stay in analog until it will have a couple of seconds of good datas.

However in normal situation both DD and DTS are very reliable. If your projector is ok and it does not scratch the print DD will never drop. DTS will "resist" also with many injuries to the movie!

I would check another side of the questions: what system sounds better? In this case, my choice will be surely DTS.

Bye
Antonio

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Randy Stankey
Film God

Posts: 6539
From: Erie, Pennsylvania
Registered: Jun 99


 - posted 06-19-2001 10:26 PM      Profile for Randy Stankey   Email Randy Stankey   Send New Private Message       Edit/Delete Post 
I had a theatre manager that just didn't like DTS for some reason. (Jazz Singer phobia, I guess.)

I had several arguements about this subject when she wanted me to run a print in SDDS instead of DTS. (The projector had both.) I would usually just acquiesce but switch it to DTS later on when the coast was clear.

I was able to change her mind one day when a print got totally TRASHED because some butt head misthreaded the projector and "spiked" (roped) the hell out of it. The analog soundtrack was useless. I told her that it would play in DTS. My arguement was that a full 80% of the timecode can be obliterated but the sound will still play.

As mentioned above, there's a five second buffer before the machine defaults back to analog but it only takes one second of good code to reset the "timer". As long as the thing can get one second's worth of code out of every five it will be OK. (Hence, the 80% statistic.)

I convinced her to move the print from the analog only house that it was in to one that had DTS. I told her that if we moved it and it didn't work, we didn't have anything to lose but if it did work we were still in business. (A no-lose proposition.)
She helped me move it, all the while saying, "This won't work... You are making me move this heavy print for nothing... If it doesn't work, I'll be pissed off at you!"

Of course it DID work and I had another DTS convert!

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Rick Long
Jedi Master Film Handler

Posts: 759
From: Toronto, Ontario, Canada
Registered: Nov 1999


 - posted 06-19-2001 11:43 PM      Profile for Rick Long   Email Rick Long   Send New Private Message       Edit/Delete Post 
Interesting.

At a theatre I was working at recently, both SDDS heads had "Do not use" signs on them. Took the scope and brought the leds up to level. Test looped the heads with a discarded trailer. - worked fine. Placed these into service for the first show that day.

A night or two before the film was dragged along a bar (roller support) and was emulsion scratched terribly. Having no spare print, they decided to use the print anyway scratched or not. At the last moment, that print was changed to the booth in which I had an SDDS head installed. By the end of the first encoded trailer, I shut the thing off as it was defaulting too many times.

I reasoned that SDDS couldnt read a track with that many scratches, (no spare Cat.701's available for SRD), but DTS, using a much simpler code (time-code only, no sound) might have a chance.

Hooked it up this morning - works fine.


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Antonio Marcheselli
Phenomenal Film Handler

Posts: 1260
From: Florence, Italy
Registered: Mar 2000


 - posted 06-20-2001 08:27 AM      Profile for Antonio Marcheselli   Author's Homepage   Email Antonio Marcheselli   Send New Private Message       Edit/Delete Post 
Randy,

Great! However I've noted that if player cannot read clearly at least few seconds at time, probably sound will start become crazy...
I remember when I had my old timecode readers: I had a DTS encoded film but with no disk. I had a (Karen, don't read) copy of "Anna and the king" disks. I put the DTS trailer before the movie and the disk A of Anna and the King in the player. My old readers didn't read timecode properly (were 8 years old) so the green led on the readers was almost off..

The trailer sounded properly in the auditorium but after that the player started to play the 20thFox fanfare... Unfortunately the film was distributed by Columbia...

Patrick, this is just a case, my old readers were in terrible conditions. As I told you if your equipment is in good shape you will never have these kind of problems. I tried again to put a different disk in the player with my new readers and after the trailer the unit dropped in Dolby.

Bye
Antonio

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Patrick de Groot
Expert Film Handler

Posts: 161
From: Sprang-Capelle, Netherlands
Registered: Apr 2001


 - posted 06-20-2001 09:03 AM      Profile for Patrick de Groot   Email Patrick de Groot   Send New Private Message       Edit/Delete Post 
Thanks for the info!

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Brad Miller
Administrator

Posts: 17775
From: Plano, TX (36.2 miles NW of Rockwall)
Registered: May 99


 - posted 06-20-2001 12:22 PM      Profile for Brad Miller   Author's Homepage   Email Brad Miller       Edit/Delete Post 
Antonio, in the US, "Anna and the King" was distributed by Fox. Sounds like you had US discs.

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99


 - posted 06-20-2001 01:42 PM      Profile for Mark Gulbrandsen   Email Mark Gulbrandsen   Send New Private Message       Edit/Delete Post 
Antonio said in a previous post...."I would check another side of the questions: what system sounds better? In this case, my choice will be surely DTS".

Its very difficult to tell which system you are listening to unless you have a playback system of extremely high caliber. I have heard the three different systems on in a large mix facility in L.A. and they were hard to tell apart there.........
Mark @ GTS


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Randy Stankey
Film God

Posts: 6539
From: Erie, Pennsylvania
Registered: Jun 99


 - posted 06-20-2001 03:28 PM      Profile for Randy Stankey   Email Randy Stankey   Send New Private Message       Edit/Delete Post 
Yes, you must be able to get a few seconds of "clean" time code to get the player started. I suppose you have to get the buffer loaded up enough.

I know that 80% figure is kind of pushing it. If you don't get one full second of clean code before the buffer runs out, you will have problems. You don't know where that one second will pop up. If the good sections of code are spaced too far apart, the player won't work right.

Even for DTS there is such a thing as "too far gone". It's just that, for DTS, "too far" is a lot "farther gone" than the other formats.

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Rick Long
Jedi Master Film Handler

Posts: 759
From: Toronto, Ontario, Canada
Registered: Nov 1999


 - posted 06-20-2001 06:14 PM      Profile for Rick Long   Email Rick Long   Send New Private Message       Edit/Delete Post 
Mark is right about being very difficult to determine which digital system is being used. It is a little easier, however to determine that it is digital rather than optical, I think.

More than once, while passing through an auditorium, I was led to think "Damn, I did a fine A-chain there" and then realized it was digital.

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Rory Burke
Expert Film Handler

Posts: 181
From: Burbank, CA, USA
Registered: Jun 2000


 - posted 06-21-2001 02:15 AM      Profile for Rory Burke   Email Rory Burke   Send New Private Message       Edit/Delete Post 
Well im happy that at least you are contemplating SRD vs DTS and that the concept of SDDS is now gone!! As far as reliability.....so long as print quality is to be maintained youll have no problems with Dolby Digital. This robust format is currently the workhorse of the industry and i am proud to admit it works!!! Way to go dolby!!! The guys and gals < hi Karen > at DTS have also come out with a very solid product. The only problem or pet pieve on DTS is the fact that those darn drive go out like "PEZ!" other than that is is also a very reliable digital format...in some ways easier to install...blah blah blah. and technically since they have the best compression ratio 4:1 its sounds the best! IMHO....this is yet to be demonstrated and proved...... My sure fire pick would be to go dolby, install it, and forget it!!!! Rory

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Brad Miller
Administrator

Posts: 17775
From: Plano, TX (36.2 miles NW of Rockwall)
Registered: May 99


 - posted 06-21-2001 02:46 AM      Profile for Brad Miller   Author's Homepage   Email Brad Miller       Edit/Delete Post 
Patrick,

Do you regularly receive dts discs with your prints? I've heard a lot of horror stories outside of the US about not being able to get discs. Make sure you evaluate that into your equation.

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Antonio Marcheselli
Phenomenal Film Handler

Posts: 1260
From: Florence, Italy
Registered: Mar 2000


 - posted 06-21-2001 04:40 AM      Profile for Antonio Marcheselli   Author's Homepage   Email Antonio Marcheselli   Send New Private Message       Edit/Delete Post 
Brad, In italy Anna and the King was distributed by Fox too. I was trying "Girls Interrupted" movie with "Anna and the king" disks: The player started with Fox logo above the Columbia logo...

Mark,

After 2 years of job, I simply realize if a movie is in DTS or DD... At least in my theater: it has few acoustic problem so DTS's HF sometimes put in trouble my theater...

Bye
Antonio

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Demetris Thoupis
Phenomenal Film Handler

Posts: 1240
From: Aradippou, Larnaca, Cyprus
Registered: Apr 2001


 - posted 06-21-2001 04:09 PM      Profile for Demetris Thoupis   Email Demetris Thoupis   Send New Private Message       Edit/Delete Post 
Well,
It depends. With SRD you are most probably sure that you will have a DIGITAL Sound with the film since the actual digital coding is on the film and not on the CD. The bad thing with SRD is that if there is oil on the print or many scratches or many splices, it will show fault and it will pulse to Analog. Splices are a huge problem for SRD since whole chanks,boom,creak sounds are heard through the theater's speakers.
Now moving to DTS. It is probably more reliable as a Digital system if the print is quite damaged. DTS reader will read timecode no matter what. It will then send signal to the DTS Playback unit and pick the soundtrack from the CD. This is the advantage/disadvantage of DTS. You might never receive the discs or even worse, the discs you receive might be scratched or damaged and therefore not being able to playback in DTS format.
Choosing between the two for quality, I would choose DTS since it is clearer and the "crystality" of the sound is much better than SRD. DTS SOUNDS Better. That's the way things is. And amazingly it is the easiest from all Digital systems to be installed. A proof that DTS is much better is the DVD's. Why do they make so much fuzz when a DVD carries DTS soundtrack additional rather than Dolby Digital Only?
Think about it.
Ciao all
Demetris Thoupis

"FOR STRENGTH AND HONOUR"

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