Film-Tech Forum ARCHIVE: Dolby Digital print issue

This is topic Dolby Digital print issue in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Antonio Marcheselli (Member # 373) on 11-21-2003, 09:17 PM:

I found on one of my matrix print that error rate was at 6.5 and I checked the print for damages. No physical damages but a brown area that was coming in and out from the perf area. I was able to take a picture of the issue (while projecting, I still have to understand how it was possible, since the camera is a cheap digital one!) and you can see the brown area that is disturbing the DD area.

I was just curious what can create a problem like this during print

Posted by Brad Miller (Member # 2) on 11-21-2003, 09:29 PM:

That's amazing your camera caught that during projection.

What does that reader normally track at? What do the other reels in that print track at? I'm betting that is not the cause of your problem, but I'm sure John Pytlak can explain where the marks come from in printing.

Posted by Antonio Marcheselli (Member # 373) on 11-21-2003, 09:41 PM:

Brad

I have to say that I didnt' had time to check the error rate of the other parts, I just know for sure that the sound is not reverting!

However, I'm sure that I have no problem with the reader. Usually all of my machines with good prints reach 1/1. with no problems. I'll check tomorrow what happen with the other reels.

Oh, Brad.
I forgot to say that the brown area reached the center of the DD data at the maximum "extension". It is cycling but continuous.

Bye
A

Posted by John Pytlak (Member # 331) on 11-21-2003, 10:06 PM:

Looks like a very low level of fogging, possibly from light, pressure from a sprocket tooth, or static discharge. From the photo, I would be surprised if it was causing the increased error rate.

Posted by Mark Hathaway (Member # 1044) on 11-21-2003, 10:10 PM:

Hello Antonio,

if you say there is no physical damage, then possibly the damage originates from the lab.

Victoria 5's are know to scratching the film around the perforations when dirt is allowed to build up in the keeper rollers, etc. Is the projector clean?

Posted by Daryl C. W. O'Shea (Member # 1303) on 11-21-2003, 10:49 PM:

I wouldn't be surprised at all if it was causing higher error rates. The right most complete block is awfully dark on the left side.

Posted by Antonio Marcheselli (Member # 373) on 11-22-2003, 07:45 AM:

Daryl,
Yes, and there was not the worst moment. As I said the dark part reach the center of the data.

John
Thanks. Why the brown marks couldn't increase the error rate? It is a darker area in the datas...
How can static create a problem like this?

Mark,
Of course it is clean... I clean it once a year. [Wink]

Bye
A

Posted by Michael Schaffer (Member # 1204) on 11-22-2003, 02:10 PM:

Does the camera even see that brown stuff?

Posted by Antonio Marcheselli (Member # 373) on 11-22-2003, 07:41 PM:

What camera, Dolby one or the camera I used for the photo?

Bye
A

Posted by John Pytlak (Member # 331) on 11-23-2003, 08:11 PM:

From the photos, the marks appear to be mostly in the yellow. If you have a red LED reader, it would not "see" the yellow dye. Even a white light reader would get most of its signal from the other layers.

In color print film, the yellow layer is the fastest, and most sensitive to "seeing" any static discharge.

Posted by Mark Gulbrandsen (Member # 72) on 11-23-2003, 08:23 PM:

I too noticed that same thing at a theatre just south of SLC. Same high error about 6 to 6. on the DA-20 with BACP reader and also never reverted and had basically the same type of marks at the sprockets and I just accorded that the lab slipped up on this one a bit. Since it never reverted and the theatre was going to be retiring the print in a DTS house for the remainder of the run at its complex I didn't think much of it. The machinery in this case was a DP-70.

Mark @ CLACO

Posted by John McConnel (Member # 2000) on 11-23-2003, 09:34 PM:

One reel of SEABISCUIT last summer came with a faulty Dolby Digital track. It was a lab problem, as one edge of the Dolby image block was blackened. We didn't have our system set to revert, so we caught it immediately. The replacement reel was fine and I cut samples from each reel to compare.

We also had problems on LEGALLY BLONDE 2, which we didn't open on the break. The previous theatre had run it off sprocket, and ruined the Dolby Digital track.

We spoiled one Dolby Digital track ourselves, on RADIO. The damage was caused by a defective roller on the upper feed sprocket pad roller assembly on a Cinemeccanica V-18. It put tiny scratches in the center of the Digital image block, and on the second showing, the system reverted. Soft emulsion may have also been a contributing factor, as trailers weren't damaged. Removing the defective roller has contributed to maintaining a lower error level on all succeeding prints. Error levels which had ranged up to 5 and 6 by the end of a run are now 3 to 4. I'm still looking for other causes of track degradation.

Posted by Dean Kollet (Member # 1789) on 11-25-2003, 08:50 AM:

maybe I am the only one...but doesn't anyone find that amazing how he got that shot (assuming that the projector was running). I have an expensieve digital camera, and that's a hard shot to take. Hell, that's a hard shot to take with a nice SLR camera...there is no indication of the film even moving...Nice Job Antonio, you may want to consider a profitable hobby :-)

Posted by Antonio Marcheselli (Member # 373) on 11-25-2003, 11:23 AM:

Dean

I was just Lucky... I made 10 shots, 9 of them was bad! [Smile]

However, thanks!
A

Posted by Steve Scott (Member # 630) on 12-03-2003, 10:26 AM:

Our print of Narc had four seconds of film, in the middle of a reel, that looked as if it had fallen out of the printer because all of the soundtracks skewed into the main image... I haven't seen anything that bad since, but I do get quite a few trailers (esp. Coke) that have the Dolby Digital data half shaded out (i.e. printed sprocket holes instead of data)

Posted by John Pytlak (Member # 331) on 12-03-2003, 10:39 AM:

quote:
...four seconds of film, in the middle of a reel, that looked as if it had fallen out of the printer because all of the soundtracks skewed into the main image...

Sounds like those defective prints jumped a sprocket during printing. Labs usually inspect the prints by high speed projection as they leaves the processing machine, but a very brief problem like that might be missed.