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» Film-Tech Forum   » Operations   » Film Handlers' Forum   » Location of soundtrack on film (Page 1)

 
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Author Topic: Location of soundtrack on film
Ken Lackner
Phenomenal Film Handler

Posts: 1885
From: Atlanta, GA, USA
Registered: Sep 2001


 - posted 10-13-2003 12:08 AM      Profile for Ken Lackner   Email Ken Lackner   Send New Private Message       Edit/Delete Post 
I just wanted to confirm something. On the optical track, the sound is located 22 frames ahead of the picture, right? What about on the various digital tracks?

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Paul G. Thompson
The Weenie Man

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From: Mount Vernon WA USA
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 - posted 10-13-2003 12:15 AM      Profile for Paul G. Thompson   Email Paul G. Thompson   Send New Private Message       Edit/Delete Post 
I thought it was 20 (Inclusive)

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Stephen Furley
Film God

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From: Coulsdon, Croydon, England
Registered: May 2002


 - posted 10-13-2003 02:11 AM      Profile for Stephen Furley   Email Stephen Furley   Send New Private Message       Edit/Delete Post 
The other formats are:

Standard 8 magnetic 56 frames in advance
Super 8 magnetic 18 frames in advance
9.5mm optical 26 frames in advance
16mm optical 26 frames in advance
16mm magnetic 28 frames in advance
35mm magnetic 28 frames in retard
35mm Dolby Digital 26 frames in advance
35mm CDS in level sync
35mm SDDS is different on each edge, I can't remember the details, but there was a post about it a few months ago.

9.5 mm magnetic seems to vary, there were separate sound bases available some of which had a long path from the gate to the sound head. Also, some machines used a stripe on the left edge, and some on the right!

17.5 mm (the Pathe Rural version, all the other versions were far too early to have had a sound track) is an odd one, there were two standards, 20 and 26 frames in advance, one was used in Europe and the other in America, though the format was never very popular there. I can't remember which was used where.

Can anyone give me the figures for:

70mm Fox Grandeur optical.

The proposed 55.625mm six perf Cinemascope 55 release format.

Super 8 optical.

Standard 8 optical (I have seen a short sample, but I don't think the format was ever adopted).

Any others.

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Dean Kollet
Jedi Master Film Handler

Posts: 591
From: Florida State University
Registered: Jul 2003


 - posted 10-13-2003 06:45 AM      Profile for Dean Kollet   Email Dean Kollet   Send New Private Message       Edit/Delete Post 
I was also wondering about this....say that Dolby Digital is 26 frames ahead. Does a penthouse reader have a delay in it so that the sound syncs correctly? Our theater has a Dolby Basement reader, but it's been broken since before I've been there and I've never used it. I'm guessing the basement reader doesn't have delay and the penthouse does?
thanks

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Mike Rendall
Film Handler

Posts: 78
From: Southampton, Hampshire, UK
Registered: Nov 2002


 - posted 10-13-2003 07:01 AM      Profile for Mike Rendall   Email Mike Rendall   Send New Private Message       Edit/Delete Post 
I don't know the offset delay for SR-D, but both penthouse and basement readers have a delay. I think the sound is sufficiently ahead of the picture so the reader can be mounted anywhere on the projector.

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Stephen Furley
Film God

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From: Coulsdon, Croydon, England
Registered: May 2002


 - posted 10-13-2003 07:53 AM      Profile for Stephen Furley   Email Stephen Furley   Send New Private Message       Edit/Delete Post 
quote:
Does a penthouse reader have a delay in it so that the sound syncs correctly?
Not in the penthouse itself, the delay is handled by the digital processor or adapter.

The basement reader also needs a delay, as the digital reader is less than 26 frames below the gate. The delay can be set, in steps of one perf, up to a specified maximum, the details are in the digital processor/adapter manual.

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John Pytlak
Film God

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From: Rochester, NY 14650-1922
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 - posted 10-13-2003 08:18 AM      Profile for John Pytlak   Author's Homepage   Email John Pytlak   Send New Private Message       Edit/Delete Post 
The offset for 35mm analog optical sound is 21 frames, per standard SMPTE 40-2001. In other words, if you see a gunshot on a film, the sound modulation of the "bang" will be 21 frames ahead of the frame that shows the gun going off.

In most theatres, the projector is threaded with about a 20 frame offset between the picture and analog sound pickup, to allow for the approximately 1/24 of a second it takes for sound to go from the screen speakers to the center of the audience. For small screening rooms, drive-in theatres, or telecine, the 21-frame offset would be used.

Standards may be purchased from the SMPTE:

http://www.smpte.org/smpte_store/standards/

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Dominic Case
Expert Film Handler

Posts: 131
From: Sydney NSW Australia
Registered: Aug 2003


 - posted 10-14-2003 12:04 AM      Profile for Dominic Case   Author's Homepage     Send New Private Message       Edit/Delete Post 
SMPTE 40 shows 21 frames offset, but the Academy Leader (the one that counts in feet from 12 to 3) and some others provide marks for a 20 frame offset, which is also widely used.

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Brad Miller
Administrator

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From: Plano, TX (36.2 miles NW of Rockwall)
Registered: May 99


 - posted 10-14-2003 01:19 AM      Profile for Brad Miller   Author's Homepage   Email Brad Miller       Edit/Delete Post 
quote:
Standard 8 magnetic 56 frames in advance
Ummmmmm, I don't think so. [Wink] It's been way too long, but I think it's 18 frames in advance.

(Yeah, I know...probably a typo.)

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Phil Hill
I love my cootie bug

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From: Hollywood, CA USA
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 - posted 10-14-2003 02:53 AM      Profile for Phil Hill   Email Phil Hill       Edit/Delete Post 
Super8 is 18 frames in advance of the picture. I do think that Reg8 is 56 frames.

35MM Mag is 28 frame lag

70MM Mag is 23 frame lag.

If I remember right, I think SMPTE specs all with +/- 1/2 frame from the center of the pic to the associated audio.

Also, it is common as John mentions, to "short" thread an extra frame between the pic and sound for deep theaters to compensate for the sound delay.

>>> Phil

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Jeffry L. Johnson
Jedi Master Film Handler

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From: Cleveland, Ohio, USA
Registered: Apr 2000


 - posted 10-14-2003 07:38 AM      Profile for Jeffry L. Johnson   Author's Homepage   Email Jeffry L. Johnson   Send New Private Message       Edit/Delete Post 
"The Focal Encyclopedia of Film & Television Techniques", ©1969, SBN 8038-2268-5:
Film Dimensions and Physical Characteristics:
Sound Advance:
8mm Magnetic sound: 56 frames ahead of picture +/- 1 frame (Regular 8 or 8-mm Type R)
Super-8 Optical sound: 22 frames ahead of picture +/- 1/2 frame

I did a quick scan and do not see current SMPTE standards for these formats.

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Stephen Furley
Film God

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From: Coulsdon, Croydon, England
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 - posted 10-14-2003 07:58 AM      Profile for Stephen Furley   Email Stephen Furley   Send New Private Message       Edit/Delete Post 
Phil, thank you for the info on 70mm. 23*5/4=28.75 so just slightly longer than the path for 35mm.

Brad, not a typo, I'm pretty sure the 56 frame figure is correct, but if not, then it's a brain malfunction, not a fingers one.

I used the term 'Standard 8' which is almost universally used here, but I don't think it was ever officially used by Kodak. Phil used the term 'Regular 8', which is less common here. I don't know if this term was ever used by Kodak, they tended to just call it '8mm', which became rather confusing after the introduction of Super 8 in 1965.

To return to the sound advance question, it is much greater on Standard 8, than on Super 8. I think the 56 frame figure is correct, but I'll come back to that in a minute. This distance would, in some ways, make sense. Firstly, it would be the same distance as the 28 frame magnetic advance on 16mm, which would simplify the design of 16mm/Standard 8 dual gauge projectors. I don't know if any sound ones were actually built, but there were several silent ones, so it's possible. Secondly, the greater distance made it easier to design a separate sound base to be used with an existing silent projector. These certainly did exist, though they were more common for 9.5mm. Most silent projectors did not run at a constant speed, you adjusted the knob until it sounded right, and kept adjusting it as the machine warmed up!

Later, dual format Standard 8 / Super 8 sound projectors were introduced, and on these the difference in sound advance was a problem. I have one from the late '60s, which threads automatically through the gate, but manually from that point on. There are dotted lines cast into the metal casing of the projecter, showing the correct size lower loops for the two formats, and the Standard 8 one is very large. On later machines, which had fully automatic threading there was a horribly complex plastic guide system which formed the correct sized loop, depending on which gate was installed.

I few companies built 8mm projectors with reasonable sound systems in them, e.g. Elmo, but most were terrible, there was no proper sound drum, and certainly nothing like a 35/70 magnetic reader, just a system which would have been more at home in a tape recorder. Standard 8 sound was not common, I have a few shorts in my collection, it was purely a home movie system, and the equipment was very expensive for home use, few people bought it. The stripe was outside the perforations, exactly like the balance stripe on 16mm, and the combination of the rather large perforations alongside the track, the primative sound head design and the large loop of film flapping about made the system rather unstable. Super 8 was designed from the start to have magnetic sound, and in later years there were machines which could play a second track from the balance stripe. It is still possible to buy Super 8 prints with 4 channel (matrixed) tracks, and the sound is pretty good, I don't have any, the cost is not a great deal less than for a 35mm print! I think about 600 to 800 pounds for a full length feature.

Super 8 did have some non-home use as an exhibition format, the airlines used it, with optical sound, for a while before switching to video. It was also used to a limited extent in education, and was under serious consideration for television news work, but the idea was dropped when portable video equipment became available.

I have a couple of 8mm sound machines in my store, unused for several years. I have to go there in the next few days to get out a pair of Bell and Howell 666s which somebody is borrowing for a show, I'll check the sound advance on Standard 8 while I'm there.

Anyway, enough of this bootlace stuff, I'm heading up to york next month to hear (and see) the 70mm; anyone else going to be there?

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Paul G. Thompson
The Weenie Man

Posts: 4718
From: Mount Vernon WA USA
Registered: Nov 2000


 - posted 10-14-2003 11:46 AM      Profile for Paul G. Thompson   Email Paul G. Thompson   Send New Private Message       Edit/Delete Post 
John P is right. It is 21 frames (inclusive.)

I always seem to get "inclusive" and "non inclusive" screwed up.

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Ken McFall
Jedi Master Film Handler

Posts: 615
From: Haringey, London.
Registered: Apr 2001


 - posted 10-14-2003 12:18 PM      Profile for Ken McFall   Email Ken McFall   Send New Private Message       Edit/Delete Post 
Paul I have just refreshed my memory from the orange BKSTS manual that clearly states 20 frames!

Using a standard leader you laced a number in the gate, say 9, and the star that was printed before 10 lined up in the sound head. As the star was four frames before the number it was 20 frames.

Now I'm not too sure if this makes sense but if you consider the middle of the frame with the number and the corresponding star which is in the middle of the frame that would make it 19 frames!!!!!

I was always confused by this whole thing as trying to lace an FP20 with 20 (19) frames sync made for very small loops.

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Frank Angel
Film God

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From: Brooklyn NY USA
Registered: Dec 1999


 - posted 10-14-2003 12:19 PM      Profile for Frank Angel   Author's Homepage   Email Frank Angel   Send New Private Message       Edit/Delete Post 
There was a very sophistocated system years ago, circa 1960s from a company called Inner Space, that married a tape deck to the camera and projector. You sent them your S8mm camera and they modified it so that it could output a pulse for every frame advance. You used a portable tape deck, typically a Uher or Nagra which recorded the pulses on one channel and audio on the other. For playback, a reader on the projector shaft was fed to a controller which varied the speed of the tape deck by generating a drive voltage based on the projector shaft speed compared to the pulse count from the control track on the tape deck. It worked quite well, the only drawback being it your projector had really unstable speed problems, you could hear the speed varying in the sound. But any decent projector that kept reasonable steady speed worked fine.

You didn't even have to worry about starting the projector and the deck together because the system also included a circuit that saw a cue on the film and started the tape deck at the same time.

The big advantage over sound on film is obvious. You had the excellent fidelity of very good r-t-r tape transport without any of the limitations of the slow speed of the film and its miniscule mag stripe.

I also recall a system from Revere which supplied you with a tape that had lines printed on the base side and a small mirror that you positioned over the aperture to deflect the intermittent light from the projector onto the tape traveling through the tape deck. The strobe effect would make the lines look like they were standing still when the projector was at 18fps. You would have to continually control the projector speed manually, but it did work if you didn't need lipsync.

Then there were the add-on devices, one in particular that I recall that you put in place of the supply reel. It basically was a record/playback head that film which was mag striped ran through. From what I remember a salesman saying at the time, the sound was attrocious, and of course, it could only be used for adding music or sound effects -- no location sound.

Frank

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