Dolby Digital Print ID and Automation?

[Joe Redifer]

Anyone remember Dolby Digital? Anyway I was going through this marketing brochure from Dolby which came out right before the format officially launched. Reading through it I noticed something interesting about the Dolby Digital data, then known as Dolby Stereo Digital and SRD (rhymes with "turd"). The brochure talks about each track containing a Picture ID. Not sure where this could be shown as the DA10/20 certainly had no display for it, and the later processors like the 500 or 650 didn't display the title that I ever saw. It also talks about automation. I wonder what they had in mind for potential automation uses at the time. Any ideas?

SRDautomation1.jpg SRDautomation2.jpg

[Carsten Kurz]

Yeah, it's a bit sad that they didn't pursue the automation option. Probably at the time the cinema industry was not ready for TC based automation systems. They would have needed a different, much more developed (and expensive) user interface than the existing foil switch/proximity based systems. Given that very quickly every trailer had SRD with TC and Print-IDs, it would have been very easy to build complete automation, and in a very flexible way. The same would have been possible with the DTS-TC track. Back then I though about using the DTS-TC to build our own automation, but, unfortunately, most trailers did not have DTS tracks, and unlike with DTS, it was not possible to get access to the SRD TC and print IDs. Would the serial debug/monitor interface of the Dolby SRD units show TC and print number?

[David Ferguson]

I'm not sure about the picture id, but every Dolby Digital block contains the block number and the reel number, and this is output over serial from the DA10/20 and CP500 (I think the CP650 is different, but I don't have one to test). In that way, it's remarkably similar to DTS.

However, there's one incredibly annoying way they're different - there was no standard to what the first block number is - Dolby just say it's "about 277", and then leave it up to the labs to actually decide. So it's actually fairly useless at very precise timing, because you need to calibrate it against your print. The same title, printed at different labs, could (and do, in my experience) have different start block numbers.

[Sam Chavez]

Dolby worked on a film based automation before Ray Dolby committed to what became SR.D. The idea was to flash bar code in real time on each release print as it was being processed. With high speed printers running at over 2,000 Ft/Min, this was daunting. There was a Model 278 automation unit produced and beta tested. (There's still one working at Grand Lake in Oakland, CA.)

The bar code was read by a slot reader in the film path. Since the automation hardware was ready before the print flashing technology, Dolby went ahead and produced bar code labels to be applied to the print.

This project went by the wayside when Ray Dolby and the company went all in on SR.D. CDS had shown a certain amount of success and a lot of potential despite being completely unreliable and DTS definitely had gathered an impressive screen count.

Dolby got seriously to work and we had readable sound on film in ninth months if memory serves. Seems like just yesterday but it was 30 years ago.

[Ioannis Syrogiannis]

There must have been something of a TC on that, for Dolby ScreenTalk to sort and synchronize the subtitles, right?
(I haven't heard of that until arriving to the island.)

[David Ferguson]

Dolby ScreenTalk used the block numbers out of the SRD to sync. My assumption is because it was just subtitles, it didn't need millisecond accuracy, so it could cope with the block numbers being a little bit out?

I did measure the SRD block number of the first frame with picture on some of my prints a while back, and from memory they didn't vary much, maybe only be a max of like 5 or 6. So sad this couldn't have been standardised!

[Joe Redifer]

CDS had shown a certain amount of success and a lot of potential despite being completely unreliable

It still amazes me that CDS and Dolby Digital co-existed as competing digital sound formats for around 2 months or so. I always felt like CDS existed and died long before what became the mainstream digital sound formats.

[Sam Chavez]

It was like that Bruce Willis movie. Everyone knew they were dead except CDS. "Days of Thunder" blunder at the Chinese ended it for sure.

[David Ferguson]

"Days of Thunder" blunder at the Chinese ended it for sure.

You can't just tease like that and not elaborate! I'm aware that for one showing CDS had psu problems, due to lack of ventilation, was this it?

[Bobby Henderson]

It still amazes me that CDS and Dolby Digital co-existed as competing digital sound formats for around 2 months or so. I always felt like CDS existed and died long before what became the mainstream digital sound formats.

IIRC, the co-existence of CDS and SR•D was limited to the 1991 holiday season. One movie, Final Approach was released in 35mm CDS during that period. Star Trek VI: The Undiscovered Country was the first movie to get an unadvertised test run of Dolby Digital. Newsies would be another one early in 1992.

CDS logos appeared in some of the pre-release advertising for the movie For The Boys, but I'm pretty sure that movie had no CDS prints and was released in 70mm Dolby mag and 35mm Dolby optical instead. Apparently there were plans for Steven Spielberg's Peter Pan film Hook to be released with CDS prints, but testing went badly and those plans were scrapped. It's no wonder Spielberg would later invest in DTS' dual system approach.

Universal Soldier reportedly had a one-time screening in 35mm CDS at the Kinepolis in Belgium in March 1992. That very much seems like an "asterisk" release. I wonder if the CDS track played successfully. By the time Dolby Digital made its official debut with Batman Returns the CDS format was dead.

Dolby made its first announcements about Dolby Stereo Digital a year and half before they had an actual working system that could run in a theater booth. CDS' notorious playback reliability issues (with no analog backup track) combined with industry knowledge Dolby Digital was on its way pretty much doomed CDS from the start.

I wonder if the staff at Dolby was influenced by the failures of CDS playback with how they designed the Dolby Digital format for 35mm. I think Dolby's team had always intended to include SR optical and a digital track on the same 35mm print so it could be printed as a single inventory item. The CDS audio drop-outs to dead silence underscored the importance of the analog track as a fail-safe. Then there was the matter of audio compression. CDS used a staggering bit rate, over 6 million bits per second. The version of Dolby Digital released in theaters went completely in opposite direction, using data spots big enough to be clearly visible to the eye.

The SR•D track had a total of 550 kilobits per second of data. Only 320kb/s of that was the actual audio track, the rest of the data was for error correction. How did they decide on that 320kb/s data rate? Did they try printing and testing DD audio tracks at higher data rates? The standard AC-3 codec at that time had a max bit rate of 640kb/s. Or did they just err on the side of caution after seeing dumpster fire incidents with CDS?

"Days of Thunder" blunder at the Chinese ended it for sure.

The Days of Thunder fiasco was early into the CDS run. The format had a few more releases going into 1991. Still, with theater industry people knowing Dolby was working on its own digital format, that gave theater operators every incentive to hold off with CDS installations.

[Sam Chavez]

"Days of Thunder" opened at the Chinese on a very hot day. Paul Haggar, VP of post production was skeptical of the CDS format and had arranged a 70mm print be standing by. At the first sign of trouble which came pretty quickly, the 70mm print was deployed. Variety called it the "Thunder Blunder".

CDS had worse problems than reverting to silence. It would break into 100% modulation snats that were loud enough to destroy speakers.
Dolby always planned a fully redundant system. Just a safer approach.

Dolby always went with approach to work and improve what was there, as in cassette players. American film projectors were pretty crude (Ballantyne) agricultural, some would say.

[John Eickhof]

the biggest nail in the coffin for CDS imho was the dual print inventory since their track replaced the standard analog track with no back up and requiring separate prints be struck and shipped to the correct customers! I went over to ORC after the initial demonstration of CDS and argued with the powers that be over the obvious problem, it landed on deaf ears. Later on when a few prints were in circulation, I got an emergency call from a the Marysville drive in, he complained of static noise and no audio tracks on his print, it appeared the SF exchange sent him a CDS print! He was dark all weekend until an analog print could be shipped! At least DTS, Dolby and Sony had the best intentions in mind by making their tracks available withour disturbing the analog SVA optical tracks,

[Brad Miller]

The Chinese booth was very hot and overheating would cause the issues Sam spoke of. That being said, the specific failure at the Chinese on Days of Thunder was due to the installation technician using very thin wire for the exciter lamp in the penthouse, and at a great distance to the sound rack. The manual called for 10 gauge wire which was ignored by the installer.

[Sam Chavez]

I worked at USL with the late Roger Hibbard who had been an engineer with CDS. One of the many problems he commented on was a very shallow depth of field on the imaging lens. The system could not deal with less than perfect focus off the film. Little chads from splicing tape would stick to the sound drum and lift the film off the drum. That was all it took to crash the system.

CDS sounded spectacular, better than anything else off 35mm film before, but it was doomed from the start by a number of showstopping issues with no graceful fallback.

[Bobby Henderson]

I thought the 70mm CDS presentation of Edward Scissorhands sounded wonderful at the Ziegfeld cinema in Manhattan. Danny Elfman's music score was arguably the best element of the sound mix. But I was at the theater under probably the best of circumstances: the first public show the Friday it opened.

IIRC, some of the people who worked on CDS at ORC moved over to Sony to develop SDDS. Some of the philosophy behind CDS carried over to SDDS, such as an audio bit rate that pushed the limits of what could be mass printed on 35mm reliably.

It seems like a small miracle the SR•D, SDDS and DTS formats used different portions of a 35mm film print, making quad format prints feasible.