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Author Topic: Dolby Digital vs. DTS Darryl Spicer Film God Posts: 3250 From: Lexington, KY, USA Registered: Dec 2000 posted 12-30-2003 05:33 PM                    The big thing is is that raw data is a one time thing. Therefor the dolby processor can't go back in a milisecond to sample the source data again if there is a major fault. That is why there can't be any longer than four blocks of bad data. The processor just can't mask any more than four blocks. On a CD the source data can be read more than once. That is one reason why if a CD is badly scratched it will skip or keep repeating the same thing.  |  IP: Logged Antonio Marcheselli Phenomenal Film Handler Posts: 1260 From: Florence, Italy Registered: Mar 2000 posted 12-30-2003 06:25 PM                        is a "block" the data between two perforation? Bye A  |  IP: Logged Darryl Spicer Film God Posts: 3250 From: Lexington, KY, USA Registered: Dec 2000 posted 12-30-2003 06:28 PM                    That is correct Antonio.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 12-30-2003 06:31 PM                     That may be true but it seems to me that if there is that much capacity to store raw data in a DA-20 and then to keep on processing it that it might be possible to do it with a slight redesign. At any rate DTS seems to have made much better use of the buffered data and IMHO that is certainly something major that DTS has in favor going for it over the Dolby format. That deective reel 1 I ran into of The Last Samauri was a very good example of how well DTS stays in the digital mode with just a mere second or so burst of time code comming through every 3 seconds. Mark  |  IP: Logged Antonio Marcheselli Phenomenal Film Handler Posts: 1260 From: Florence, Italy Registered: Mar 2000 posted 12-30-2003 06:45 PM                        Mark, The main problem for me is that while DTS has all of the data it wants on the CD, the Dolby cannot play without the data on the film in good condition! If timecode is lost the DTS plays what it found on the cds. If CD is damaged DTS cannot play anything!!!! The same for DD, if DD datas is damaged, there is not buffer that can help... Bye A  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 12-30-2003 07:27 PM                     Apparently no one informed the general technical community about splice-caching? For quite some time now, the DA-20 has been able to do what Dolby calls splice-cache. How it works is that using one of the low-bit-rate data tracks, they replicate the audio information around the reel-change splice and this is stored in the buffer. In the event there is a loss of data around the reel-change splice the buffer data is inserted and the splice plays through without a drop out. This will only work for the reel change splices on those films so encoded and ones where the data track has not been so damaged to prevent the storage. This will not help poorly made reel repair splices or cutting out poor lab splices. Steve  |  IP: Logged Antonio Marcheselli Phenomenal Film Handler Posts: 1260 From: Florence, Italy Registered: Mar 2000 posted 12-30-2003 07:41 PM                        Steve, Yes, I remember that I read of that on this forum but I remember that it wasn't made on all films... Is the actual dolby's prints featuring this or is it just an idea or a future feature? Bye A  |  IP: Logged Rich Ferrando Film Handler Posts: 64 From: Royal Oak, MI Registered: Nov 2003 posted 12-31-2003 02:06 AM                       In our SRD house, we usually get dropouts or dips to SR between trailers (mostly because some folks here like to cut the trailers pretty tight, often not giving enough room for the Digital to recover before the sound kicks in - I usually like to leave at least 10-frames of black at the head and tail of each), but at reel changes such a thing is extremely occasional. We rarely have the luxury of getting a new print, so we're often at the mercy of whoever came before us. Most often, there's just the one-frame cut at the head of each reel, which never causes a dropout for us. However, we do have occasions where two or three frames are cut at the head (and once, FIVE) and those can give us a bit of a "pop", but usually don't cause the processor to switch to SR unless there's also an issue with the splice.  |  IP: Logged Jack Ondracek Film God Posts: 2348 From: Port Orchard, WA, USA Registered: Oct 2002 posted 01-01-2004 09:19 PM                        quote: In our SRD house, we usually get dropouts or dips to SR between trailers (mostly because some folks here like to cut the trailers pretty tight... I usually like to leave at least 10-frames of black at the head and tail of each) I'd bet there's something else afoot at your place, Rich. I don't do anything special for my Dolby house that I don't do for my DTS screens. I have no dropout problems in the Dolby auditorium, and I also tend to run a pretty tight sequence on my trailers. Obvious question here... you aren't possibly adding to the issue by using opaque splicing tape, are you?  |  IP: Logged Rich Ferrando Film Handler Posts: 64 From: Royal Oak, MI Registered: Nov 2003 posted 01-02-2004 12:08 AM                       Now that you mention it, yes. Our splicing tape is clear over the picture area and analog soundtrack, but does have yellow bands that cover the sprocket holes, thus blocking out a half-frame worth of digital soundtrack on either side of the splice. Oi! I'm not particularly perceptive of the obvious, I guess. I suppose, if I misalign the yellow bands on the splicing tape so that both the digital and analog tracks are uncovered, that would eliminate the issue. Of course, this would put one yellow band into the picture area, but that wouldn't be an issue during a black period between trailers. Or, maybe we should just buy all-clear tape.  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 01-02-2004 12:50 AM                     Buy all-clear splicing tape, or insist to your dealer that you buy "yellowline" tape from www.jackroeusa.com (Click on product link)  |  IP: Logged Antonio Marcheselli Phenomenal Film Handler Posts: 1260 From: Florence, Italy Registered: Mar 2000 posted 01-02-2004 06:59 AM                        Do you believe that DD can be read on a clear-tape made splice? I never did a test but seems strange to me that Digital reader can read anything throw two pieces of tape. Did someone made a test? Bye A  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 01-02-2004 09:12 AM                     Brad said in a previous post..... "Personally, I feel the Neumade tape wins out in durability and ease of removal. Quick splice tape (manufactured by Hudson Photographic) is probably the best tape to use for archival splices, as it is extra thin, applies evenly, but does not peel off as easy as Neumade." ________________________________________________________________ So are you now saying the JackRoe tape is better overall than the clear Neumade tape? Perhaps a product review of the Jackroe tape is in order. Personally I don't remember any other splicing tape comming back off as cleanly as the Neumade clear stuff does. The majority of our customers are using the clear Neumade tapr with no problems what so ever. Mark  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 01-02-2004 10:38 AM                     Both Jack Roe and Neumade have their virtues. Neumade certainly has the best adhesive out there if you don't want it to run. The tape always peels off clean. Jack Roe tape (trading under a couple of different names) is a UK product and is notably thinner and clearer than Neumade. I have not had any peeling problems (leaving glue behind) but some have noted that it does after a period of time. It is available in skinnier sizes so if you like 4-perf splices (19mm wide) you have a choice. Both Neumade and Jack Roe have 16mm tape but only Jack Roe has it with magenta or yellow stripes for 35mm film. Steve  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 01-02-2004 02:46 PM                     Mark, If you want clear tape, my personal preference is Neumade/Splycemar. It peels off EFFORTLESSLY and projectionists with "less than ideal" skills in splicing can make a better splice out of it than anything else. However a skilled splicer should be able to get a quality splice out of the Jack Roe clear tape. I've seen lately the Hudson Photographic (Quick Splice) tape is starting to have severe slitting issues, so that's pretty much getting thrown out of the option. Like Steve said, both are fine if you are going to make a splice and leave it. However for reel changes, nothing beats the Neumade because it peels off effortlessly and does not promote the chopping of another frame. As of current, if I am going to make mid-reel splices for archival use (never to be taken apart), I choose the Jack Roe clear. If the splice will ever be taken apart, I choose the Neumade/Splycemar. If you want a marked tape with lines (zebra type), then nothing beats the Jack Roe line of tape at any price. Oddly enough, the Neumade has peeling issues on their zebra stock, and only Jack Roe has gotten the yellow markings spaced properly. Again, if you want a marked tape, it's Jack Roe or nothing. They have 100% cornered the market. If you want solid opaque tape, then you are a terrible projectionist and should spend all eternity being wrapped in that opaque tape like a mummy. However if you JUST HAVE TO USE THAT CRAP, go with the Neumade.  |  IP: Logged

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