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Author
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Topic: Dolby tone on tail pieces
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Warren Smyth
Expert Film Handler
Posts: 158
From: Auckland ,New Zealand
Registered: Aug 2003
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posted 09-26-2003 07:46 PM
With new development of the analogue track to cyan and the continued requirement to maintain correct Dolby level, I was wondering what the reaction would be to the following suggestion.
If a few seconds of Dolby tone were printed on the tail of the last reel of features, it would provide a ready reference for projectionists to check the level. Simply a glance at the meters as the tail is going through, would provide confirmation. When the processor is switched to non sync the meters are still fed with film audio as the switching is at a later stage in the system.
Now this may not suit Dolby Labs who may argue the need for a higher standard of quality control of all test films than would be provided by printing tone on a tail. The benefit of convenience however, I think is worth considering. More regular checks might be made by some projectionists if it doesn't involve threading a loop at the start of the day.
If the level is down, projectionists could still use a loop to make an adjustment, but if ready with a screwdiver it is feasible that an adjustment could be made in about five seconds.
Given the length of some tail pieces five to eight seconds of tone seems possible.
Now some may argue that projectionist would cut sections of the tail off for loops and before long there would be inadequate protection for the print with tails getting shorter and shorter. I believe that if tone were printed on EVERY tail piece there would be such a constant fresh supply that projectionists wouldn't bother.
If projectionists want a loop, film companies with whom I deal, would I know, be pleased to give away the tail pieces at the time a print is junked. This portion of the print as well as the leader in mosts cases hasn't seen a projector and is in perfect condition.
Now why should the film companies bother? Well, it's the quality standard or their product which may be enhanced. Also, now that we don't have to feel guilty about spoiling the environment by asking for a bit of optical track, ![[Wink]](wink.gif) this would be good public relations for certain sections of the industry who stand to save costs from producing cyan tracks. Any help to exhibitors who have had to pay for conversions may be appropriate at this time.
Please restrict comment to the merit of of the scheme rather than further debate on the merit of cyan tracks..
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Frank Angel
Film God
Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999
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posted 09-27-2003 04:38 PM
Gordon said quote:
it was brought up that it would be pretty bad sounding if it got played through the system with a tailing out of a print
If you missed a change-over and let the playout be heard throuh the system, it sounds pretty awful anyway, in fact, pink noise might actually be preferred to the usual gack that you hear, at least on optical tracks. Mag tends to contain less junk, although on a print of THE UNSINKABLE MOLLY BROWN, the playout treats you to the sound of a sound mixer's voice announcing the title, reel and production numbers!
I think Warren answered the main reason putting tones and p/n on prints didn;t catch on, and that because they are not reference material. You wouldn't want to start recalibrating the CP based on a print that was off spec. If the A-chain calibration becomes suspect playing a particular print, then an SMPTE test loop should be threaded to check the processor, not a release print where the values are not verified. Granted, if the processor were recalibrated to any reference audio on a particular print, you might be ahead of the game for that print, but if it was not quite on spec, then everything else that played on that system thereafter would be in error.
Frank
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Warren Smyth
Expert Film Handler
Posts: 158
From: Auckland ,New Zealand
Registered: Aug 2003
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posted 09-29-2003 09:32 AM
Thanks chaps for the comments. It seems from the response that the concept of Dolby tone on tail pieces is regarded as a non starter. I think the points you've made are valid, however there are some aspects which I didn't mention which may raise further debate. I realise also, that there is very little in the film industry that hasn't been thought of before.
The main idea of recording Dolby tone on tail pieces, was that it would provide quick and CONVENIENT CONFIRMATION of correct Dolby level. If there appeared to be a recalibration required then, as I said, a test loop could be played. I accept that an ajustment made during the playing of the tail (depending upon length) could be difficult.
Also as I stated, the tone recorded on the tail piece might not be regarded as being of high enough standard to be used as a reference, although it was hoped that with a constant supply of fresh stock, the tone level would be fairly accurate. Now here lies an aspect, which I thought some one might pick up on.
The significant factor, is that if the tone played on the tail was out, and, as Frank said quote:
if the processor were calibrated to any reference on a particular print, you might be ahead of the game for that print, but if it was not quite on spec, then everything that played on that system thereafter would be in error
Frank you are absolutely right. But let's think outside the square. If it became apparent that audio levels on films were not up to spec due to processing faults or fading over a period of time, wouldn't you like to know that you have the means by which you can ensure your system decodes the SR correctly for that film? It could mean borrowing a tail piece from another reel for a loop, but at least your system wouldn't be producing Dolby tracking errors for that particular title. A correction to standard Dolby level could be made for the next film.
Let me state that I'm NOT SAYING THAT CYAN TRACKS ARE GOING TO FADE but then I'm not saying that they're not either. As one writer has correctly stated "the sky hasn't fallen down" on the release of the first film in cyan, however, I prefer to have an open mind. I'm NOT entering into the contraversy. What I CAN say on the subject of longivity of the tracks is, the jury is still out and will be so for some years.
Now the concept of specing a reproducer to a particular recording which might require an adjustment for the next title may seem ridiculous. The fact is, that the practice has existed in the television industry for 50 years. Colour bars and tone are recorded at the beginning of productions routinely, so that tone, luminence and chroma levels can be checked and adjusted before replay.
If a similar practice were adopted for film, projectionists could continued to check with Dolby loops as routine, but tone on the tail might indicate a fault in the print. A difference in amplitude between the tail and a reliable test film would suggest such a fault and a decision could be made as to whether the system should be optimised for that particular title or not.
All of this assumes that Dolby tone is recorded on the tail as part of the master mix. There would be no point in having tone that was not referenced to that particular production's sound mix. On the subject of cost, which has been raised, the film stock for the tail is already required. It does means that the sound mixer has to press a button designated 'tone' on the sound desk and check the level. Not exactly a major expense. I wouldn't mind a dollar for every time I've done it in the last 26 years.
Ultimately, this is all about providing added convenience and knowlege for the projectionist. It also means that monitoring of analogue sound track amplitude of prints on circuit, would for the first time, be possible. This could provide a measure of deterioration , IF ANY, over a period of time and at least a chance to some extent, correct such.
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Frank Angel
Film God
Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999
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posted 09-30-2003 04:53 AM
Warren, quote:
Now the concept of specing a reproducer to a particular recording which might require an adjustment for the next title may seem ridiculous. The fact is, that the practice has existed in the television industry for 50 years.
....and in the recording and radio industry as well. When I worked for the LaBrie FM Radio Network -- a production house that produced prepackaged programing for FM stations -- we used to put a full 60 sec. of 12kHz tone and 30 sec of 10kHz as well as 60 sec of 25hz (for triggering automation) on all our copies in the mastering/duplicating studio so that azimuth alignment could be made to that copy at the playback machine when necessary. We prided ourselves on having the recording machines aligned as perfectly as possible, but in the rare event that one was off a bit, the station could make azimuth adjustments so that they didn't get flanging in their mono composite.
My reservation about doing this on theatrical release prints was due to the rather less-than-ideal booth environments in many multiplexs; our tapes were going to FM radio stations where there were engineers who knew how to make azimuth adjustments, and as you said, having a reference on the tape that the engineer could adjust to was a great tool. In the modern projection booth however, where exhibition's Holy Grail is to ELIMINATE any trained technicians who could properly make adjustments for a particularly off-spec print, I would worry about any of the majority of the "projection attendants" (as UA Theatres called them) laying a finger to a calibration tool.
Solution would be to put the ref tone/PN on the print, but never tell booth personnel what it's for....only the circuit technicians should know about it...just like only telephone technicians know all the secret system numbers that call up test routines, like voicing the number of the line they are testing or getting a ring-back signal, etc. Best not to let the masses know about this stuff!
Not only would the reference track be a useful tool (in the right hands) but it could also double as protection leader for the print. I'd put it at the head of the print as well as the tail and with distinctly visible framelines in the image area so the "attendant" can use it for threading, long before the SMPTE sync leader, protecting the print from misthreading damage as well as it being the physical "padding" so desirable for protecting the body of the print -- Brad would only have to add 25ft instead of 50ft protection!
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