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

» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » Dolby Digital WOW at reel change? (Page 3)

This topic comprises 7 pages: 1  2  3  4  5  6  7

Author Topic: Dolby Digital WOW at reel change? Max Biela Film Handler Posts: 89 From: Dortmund, Germany Registered: Sep 2003 posted 01-04-2006 11:27 AM                     Hi, I just put in a loop with music and it also happens on our CP 650. However, we don't have any problems with splices and cues. I will check the firmware version later. Max  |  IP: Logged Mark J. Marshall Film God Posts: 3188 From: New Castle, DE, USA Registered: Aug 2002 posted 01-04-2006 12:51 PM                    Thanks, Max. Do you use foil cues along the edges of the film, or something else?  |  IP: Logged Max Biela Film Handler Posts: 89 From: Dortmund, Germany Registered: Sep 2003 posted 01-04-2006 01:05 PM                     Yes, but those cues are very very thin (from CPI) and are on the back side on the film so they doesn't cover up any blocks. The two arms on the Cat 702 don't bounce from cues made with the CPI stuff. I will check the sound with a few different splices on the same loop tomorrow. Max  |  IP: Logged Robert Schultz Film Handler Posts: 28 From: Tehachapi, CA, USA Registered: Mar 2004 posted 01-04-2006 09:49 PM                        OK...I suspected outside forces and oscillation of some kind to be the culperate of the WOW so this is where I started looking first. I found the problem very quickly actually, and really it's quite simple. Brad put in his 2 cents and suspected the splices, but he had never seen the problem himself (neither had I). I can now say that I've seen a bad splice cause WOW when using a Cat. 701 reader. The culprit...a splicer that leaves hanging edges beyond the 35mm width of the film? Simple. All sound readers are subject to errors or reading problems at or around a splice, but in this case, my customer was using solid yellow splicing tape and had a splicer that was so gummed up that each splice was a bit different from the last. The inconsistency in splices (and the fact that they have 4 different splicers) made some splices go through just fine, while others would bounce the rollers on the Cat. 701 all over the place. Another factor to contend with is that the problem is not normally heard unless there is some steady tones to make the wow audible (like music). In a 'dialog only' scene it is much harder to hear the WOW problem. One problem I am still having is that once a large amount of bouncing starts it seems to take about 20 seconds for the reader to get back to a completely steady state. There should be some better dampening in this system, but the platter tension is so soft (almost non-existent) that it's letting the reader oscillate like a spring with no dampening to quickly stop the problem. The fix to this problem right now is to just simply make better splices. I was able to find a film at this theatre that had a great example of the type of splices that cause the problem. The picture below is a great example of what NOT TO DO! I have seen people adjust their splicers to leave just a small edge hanging so that it's easy to see the splices when breaking down prints (I am not a fan of this), but at this theatre, this was not the intention. No matter what, splicers should be adjusted to make as clean and smooth a splice as possible.  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 01-04-2006 10:03 PM                     There is an airpot adjustment inside the cat701 you can adjust to minimize that bouncing.  |  IP: Logged Richard Hamilton Phenomenal Film Handler Posts: 1341 From: Evansville, Indiana Registered: Jan 2000 posted 01-04-2006 10:44 PM                     quote: Robert Schultz The fix to this problem right now is to just simply make better splices. Really????? The real fix is to get rid of the person who made these splices in the first place!  |  IP: Logged Max Biela Film Handler Posts: 89 From: Dortmund, Germany Registered: Sep 2003 posted 01-05-2006 03:38 AM                     quote: Really????? The real fix is to get rid of the person who made these splices in the first place! Really? I know some places where simply isn't enough money for a new CIR U-blade or other parts. EDIT: Firmware version is 2.2.5.0 [ 01-05-2006, 07:27 AM: Message edited by: Max Biela ]  |  IP: Logged Mark J. Marshall Film God Posts: 3188 From: New Castle, DE, USA Registered: Aug 2002 posted 01-06-2006 08:08 AM                    Yeah, we have three crappy splicers (but not so bad that they make splices like THAT), but we won't replace them or get them refurbished for fear of managers losing their quarterly bonuses. Our firmware is also 2.2.5.0. I'm curious if the folks who have 650s that don't warble have the same version. Also, does anyone know what the latest firmware version is?  |  IP: Logged Christos Mitsakis Expert Film Handler Posts: 242 From: Ag.Paraskevi, ATHENS, GREECE Registered: Sep 1999 posted 01-06-2006 10:35 AM                     Current CP650 firmware is version 2.5.5.3. It aderesses only a problem of the volume indicator. Otherwise it is exactly the same as 2.5.5.0. Christos.  |  IP: Logged Demetris Thoupis Phenomenal Film Handler Posts: 1240 From: Aradippou, Larnaca, Cyprus Registered: Apr 2001 posted 01-07-2006 01:11 AM                     Always have a scissor at hand and trim the edjes of the splice as to have the same width as the film. D  |  IP: Logged Carl Martin Phenomenal Film Handler Posts: 1424 From: Oakland, CA, USA Registered: Feb 2002 posted 01-07-2006 02:25 AM                        i'm a little late getting around to posting this, but i just wanted to point out that on both our bacp reader and our cat. 700, there are blocks preventing the tension rollers from moving so far as to let film come into contact with that bar, so there's no chance of scratching. is the cat 702 different?  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 01-07-2006 07:39 AM                     Correction to the above post...the current CP650 firmware is 2.2.5.3. Dolby is still working on 2.3.x.x and is no where near a 2.5.x.x. Steve  |  IP: Logged Christos Mitsakis Expert Film Handler Posts: 242 From: Ag.Paraskevi, ATHENS, GREECE Registered: Sep 1999 posted 01-07-2006 11:08 AM                     Thank you Steve I did mean 2.2.5.3 but typing in a hurry gives these results. There is also another orthographical "in a hurry" error in my post. Christos.  |  IP: Logged Dominic Espinosa Phenomenal Film Handler Posts: 1172 From: California, U.S.A. Registered: Jan 2004 posted 01-07-2006 01:35 PM                     As you move the rollers the film is changing speed, wouldn't this cause some data to be read faster or slower? With the data moving faster the sound would be reproduced faster thus shortening the wavelengths and raising the pitch right?  |  IP: Logged Rick Raskin Phenomenal Film Handler Posts: 1100 From: Manassas Virginia Registered: Jan 2003 posted 01-07-2006 01:49 PM                     FWIW: As I read this thread I was somewhat confused as to how you could have WOW, which I understand to be an analog type defect, appear in a digital system. But then I read Mark's post about data block errors and realized that the incoming data is block oriented, allowing for some recovery mechanism in the upper layer protocols. I believe that what was identified as WOW is actually the digital system attempting to re-synchronize to the incoming data stream following a data loss (of less than 4 blocks) caused by a defective splice. Question: Is there a method to track CRC or similar errors on this system? If so, that would be a dead give away.  |  IP: Logged

All times are Central (GMT -6:00)

This topic comprises 7 pages: 1  2  3  4  5  6  7

Printer-friendly view of this topic

Hop To: Select a Forum: Category: Operations -------------------- Digital Cinema Forum Film Handlers' Forum Large Format Forum Ground Level Feature Info, Trailer Attachments & REAL Credit Offsets Category: Community -------------------- Film-Yak Film Handlers' Movie Reviews The Afterlife Bob Maar's Joke-A-Thon Category: Classified -------------------- Equipment and Supplies Wanted/For Sale Help Wanted/Seeking Employment Category: System -------------------- Software Beta Testing Forum

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.