BFI Open Day

[ppppenguin]

The BFI in Berkhampstead was open today as part of Heritage Open Days. Ruth and I went. It was a great visit, they had gone to a lot of trouble to provide talks, and demos.

The photos are:

A Vitaphone 16" disc, from the late 1920s. Early talkies were done this way. The discs run at 33rpm and play from the inside out. A single disc matches a 20 minute standard reel of 35mm film.

The videotape archive contains everything from 2" quadruplex to VHS and DVD. The VTR is an Ampex AVR2, one of the last quad machines ever made.

[Terry]

A Vitaphone 16" disc, from the late 1920s. Early talkies were done this way. The discs run at 33rpm and play from the inside out. A single disc matches a 20 minute standard reel of 35mm film.

If anybody is puzzled by this back to front method, the answer is simple. Shellac discs are easily damaged, particularly at the edges. By making the disc start in the centre it was easier to get the lip-sync correct at the beginning of the reel and maintain it to the end but, if the edge of the disc was damaged, lip-sync problems were confined to a short time at the end of the reel.

[ppppenguin]

All (I'll regret saying that) other discs, 78, 45, 33, 16, play from outside in. CDs play from inside out.

[peter scott]

That's interesting about the lip sync. I wonder if the lower torque at the inside might also have let them place the arm before starting the turntable?

Peter

[ppppenguin]

Don't think torque was an issue. The disk was on a geared drive from the projector - I can't imagine there was any lack of oomph. Don't know if the disc was locked down to prevent slippage.

If a film was damaged then the bad frames had to be replaced by blank ones to maintain lipsync.

[Terry]

I and a colleague once had a guided tour of the projection box at the State cinema in Grays. The original projectors installed when the cinema first opened in 1938 were still in use and our guide pointed to the spigot at the back which drove the sound on disc system. Presumably the projectors were second hand even then because the sound on disc system only lasted until 1931!

We were also shown a piece of mild steel sheet of which the projectionist was very proud. CinemaScope didn't exist until 1953 and required removing the normal lens and replacing it with a special anamorphic one. The problem was that the focusing positions for the two types of lens were completely different.

The steel plate had been cut away at one end so that it was a different width. When a lens was changed, the appropriate end of the plate was held against the projector body and the lens moved back until the two met. It then required only a slight tweak at the beginning of the first reel on each projector to get the focusing spot on.

I couldn't resist a smile when I spotted the source of the interval music between films - a BSR UA8 autochanger in a crude plywood plinth on top of a shelving unit!

[Raditechman]

Sound on disc made a brief comeback in the 1990's as one of the digital sound systems.  The DTS  sytem used sound on a CD with sync pulses from the film.
The other digital sound film systems used tracks on the film.
https://en.wikipedia.org/wiki/DTS_(sound_system)

All history now as film seldom shown these days.

John

[Terry]

Sync pulses!

I don't think the Vitaphone system used anything so advanced!

However, thinking of the problems that lack of sync could cause, and bearing in mind that the disc was driven from the motor that moved the film through the gate so that the two were locked together, I wonder if a 'pip' or something similar was recorded on the disc coincident with the 6 second film run in.

Moving the disc back and forth under the pick-up after the film run-in had been set would have been no different to the method used to preset the start point of discs in broadcasting.

Thinking about that reminds me of, I think, my second visit to the Earls Court Radio Show in 1959. A superb demonstration on the BBC stand involving four turntables, a rack of discs and one operator who, live, presented a high speed history in sound of the 1930s, 40s and 50s. The discs literally flew on to and off the turntables at breakneck speed with not one hiccup throughout the whole performance. As she was literally no more than a foot from the front of the watching crowd, I wonder if she found it more nerve wracking that doing it in the peaceful surroundings of Broadcasting House.

[ppppenguin]

In Vitaphone the disc drive was geared from the projector. So sync was assured. There was a sync mark on the disc to show where to put the pickup. If the film got damaged, any frames that were cut out had to be repalced with blank film to maintain sync.

[peter scott]

Just a few days ago I started watching a film on TCM on Virgin and the sound was not just out of sync. it was minutes out of sync! How did that happen?

Peter