What can cause out of sync audio ?

[Fly-catchers]

I went to see an outside screening of "The Night of the Demon" AKA "Curse of the Demon" last night at the British Museum. It was a fresh digitally restored print from a 35mm neg. With both picture & audio cleaned up. It was pretty impressive but let down by the audio being out of sync! I find it hard to imagine that they had gone to all that trouble and not noticed that. Could the sync be lost in playback? I am guessing it was played from some digital media via a projector onto the screen. As it was a BFI production they "should" know what they are doing!

 

[j1clark@ucsd.edu]

I went to see an outside screening of "The Night of the Demon" AKA "Curse of the Demon" last night at the British Museum. It was a fresh digitally restored print from a 35mm neg. With both picture & audio cleaned up. It was pretty impressive but let down by the audio being out of sync! I find it hard to imagine that they had gone to all that trouble and not noticed that. Could the sync be lost in playback? I am guessing it was played from some digital media via a projector onto the screen. As it was a BFI production they "should" know what they are doing!

Since I wasn't there... don't know how the system is setup... all I can say is I have seen/heard sync problems with digital projection.

One element is that sound travels at about 1 ft/s, and so if you are 100 feet from the speakers behind the screen, you may have a 100 ms delay from the visual (light travels much faster...) and the audio. I recall reading that the middle seats are the 'target' for audio. With digital one could 'easily' adjust or misadjust the audio stream which should take this effect into account.

And then there's always 'bad transfer'... despite every effort to avoid that...