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Author Topic: Dolby Digital--Error Number Increase Cause Bill Enos Film God Posts: 2081 From: Richmond, Virginia, USA Registered: Apr 2000 posted 09-17-2007 12:20 PM                     What causes the error number on the processor to go up? We're playing a print of Sicko that is running at an unchanging 2. Examined in hand the DD track looks no better to the eye than prints that run at 5 or 6, definitely not unscuffed or undamaged, there are prints that look very good and run high numbers. ?????  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 09-17-2007 01:23 PM                     Everything causes the number to go up...it basically represents how hard the processor is having to work to recover all of the information. If the print has too much azimuth error or the corners are not easily found...you name it.  |  IP: Logged Monte L Fullmer Film God Posts: 8367 From: Nampa, Idaho, USA Registered: Nov 2004 posted 09-17-2007 01:24 PM                     I call it a lab thingey. On trailer paks, it's interesting that each trailer can issue a different error number. Then, when the feature begins, it ususally locks into a certain number.  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 09-17-2007 02:05 PM                     The causes of Dolby Digital error rates increasing as you play the print are from dirt and scratches on the Dolby track itself. While scratches and scuffing are pretty obvious causes, few people seem to realize that the data blocks in between the perforations are extremely tiny, such that a given sized tiny speck of dirt in the picture area that most people wouldn't find distracting from the movie will block a chunk of the Dolby Digital data if that same tiny piece of dirt is in between the perforations. Wet clean your prints regularly and make sure you don't have anything causing scratching/scuffing in between the perforations and the error rates will actually go DOWN. (This is assuming you do this as "preventive" measures and not "emergency recovery" measures, for by that point there isn't always a happy ending.)  |  IP: Logged Frank Dubrois Jedi Master Film Handler Posts: 896 From: Cleveland, OH Registered: Mar 2005 posted 09-17-2007 03:23 PM                    We have a brand new Cat 701 reader and the error rates are fairly consistant at 4-5. Granted, this is in a smaller house and gets the prints that are about 1 week from leaving. We clean our prints everday with a film cleaner and filmguard. Shouldn't we get much lower error rates?  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 09-17-2007 03:38 PM                        Remember there is nothing to be gained by a "low number" as long as nothing is faulting. The only other thought is that you have a better chance if your alignment "is in the center of normal." That way some variation in the printing of the film can be accepted. 4-5 on a penthouse reader is OK. I have seen lower on Kelmar basement readers on Century projectors, including "0" on a direct drive model. I have not seen an increase of the numer with time. In other words, wear does not seem to be a factor. If it starts at 3-4, it will stay there for the run, even 4-5 months later. Louis  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 09-17-2007 05:30 PM                     Louis, on Century projectors, yes. On others, not so much. As far as the cat701 reader, those have always been the shitty ones that Dolby made. Any of the other models will track better.  |  IP: Logged Tim Reed Better Projection Pays Posts: 5246 From: Northampton, PA Registered: Sep 1999 posted 09-17-2007 06:09 PM                       Believe it or not, I have gotten zeroes after aligning two houses at GC's flagship theatre in MA... on Cinemeccanica V-5 basement readers! Sure surprised me. Staff said they'd never before seen zero on any of them.  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 09-17-2007 07:55 PM                       The V5 and V8 readers are among the best in this regard if you live through the clunky adjustments. The reason is the large diameter drum is very good on vertical movement or jitter. It is not so good on lateral movement, but the SR.D hardware/software is not so fussy about this. I've seen error rates down to low 1's and 2's with either penthouse or Basement readers. There was a period of time where the 650 software gave optimistic low error readings so we need to factor in when we saw these numbers. A really good tech with a well running projector can get great results from basement readers, but these are the exception rather than the rule as a lot of cinemas get zero attention until something breaks.  |  IP: Logged Tim Reed Better Projection Pays Posts: 5246 From: Northampton, PA Registered: Sep 1999 posted 09-17-2007 08:17 PM                       FWIW, these were DA-20s and CP-65s.  |  IP: Logged Joe Redifer You need a beating today Posts: 12859 From: Denver, Colorado Registered: May 99 posted 09-17-2007 08:35 PM                        quote: Louis Bornwasser Remember there is nothing to be gained by a "low number" as long as nothing is faulting. True, but I noticed that sometimes when the number changes to F that it does not switch back to analog, most likely because the F happens very quickly and goes away. However you can definitely hear it in the auditorium when the Dolby Digital is F'ing. It sounds like small clicks and weird audio gaps/interruptions. We had many Kelmar basement readers and they would F all the time, even if the numbers were 3 or lower. We'd see readings similar to 2-F-2-F-5-4-4-1-F-0-4, etc all in that order as the print played in the span of maybe 30 seconds in any given auditorium on any given print and it would never switch back to SR. Sometimes it would even F-dot. F'ing Dolby Digital.  |  IP: Logged Bastiaan Fleerkate Film Handler Posts: 85 From: Linschoten, Utrecht, The Netherlands Registered: Jun 2006 posted 09-23-2007 09:45 PM                        We had a cat. 700 penthouse reader and a DA-20 with a CP-65 and we had some prints that would run 0's but there were also prints that were F'ing all the time, so that we had to switch to SR manually (turning the reader off) because the processor was switching from digital to analog and then back to digital multiple times a minute... the sound in the auditorium would 'skip' when the change to digital happened, but was always in sync... Is it true the new red-light readers are performing better and generating lower error numbers? Or has it all to do with the type of Dolby Digital Processor you've got...  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 09-23-2007 11:30 PM                     The red light readers are inherently inferior...even for digital sound scanning. A Cat 700 should out-track a Cat 701 or Cat 702. Furthermore, the Cat 700 has a user changable "EPT" lamp...the current LED readers require some skill in the LED replacement and an O'Scope for proper alignment. Note the BACP reader has a much more user friendly LED/head assy user changeout without test equipment. Steve  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 09-24-2007 09:53 AM                        I've "saved back" a cat 700 that I use in critical rentals for just the reason Steve mentioned. Louis  |  IP: Logged Patrick de Groot Expert Film Handler Posts: 161 From: Sprang-Capelle, Netherlands Registered: Apr 2001 posted 09-24-2007 11:24 AM                     When you ittermittently see the F go check if it's the reader or the movie. It is annoying to hear bleeps and clicks all the way through the movie. The processor never converts to analog in this case because the F is short. It just plays corrupted digital audio data.  |  IP: Logged

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