5 ms·

"This is an experiment [...] soundtrack was being read in the same way as the picture is – stopped 24 times per second? Would this be the ultimate flutter disto

"This is an experiment [...] soundtrack was being read in the same way as the picture is – stopped 24 times per second? Would this be the ultimate flutter distortion?" That bothered me like crazy - how did they scan the audio whilst the frame was physically stopped? Then I realized how it was done: the soundtrack of frame A is stored in frame B, where frame B is far enough away that it has constant velocity.

WalterBright 3y ago
> Then I realized how it was done Oh, I love ingenious solutions like that!
- thsksbd 3y ago
  Aint it neat?
stavros 3y ago
How does it have constant velocity? Is there a physical "buffer" for the stopped frame (ie slack in the reel)? Otherwise you can't stop one part of the reel while the other is still traveling.
- HPsquared 3y ago
  There must be some "slack", the entire reel isn't going to stop and start 24 times a second.
- thsksbd 3y ago
  Short: There is a buffer! Long: So the frame being projected has to stop. Otherwise you'll get blurring unless your shutter is very fast, but then you'd burn out the film from the intensity of the light. The film is stopped. But, of course, you cant start-stop a 15 lb spinning reel 24 times a second millions -> itll all fall apart. So the feed is a simple rotation at constant velocity (linear? Angular?). Then a piece of film ten to twenty (?) frames long gets put into a buffer (an empty box) and a mechanism akin to a sowing machine single steps through each individual frame. Now the stepping mechanism only has to start-stop ten frames worth of film, a negligible amount of mass compared to the mechanism itself and the projector can last a long time of heavy use with simple maintenance. Aint it neat?
  - stavros 3y ago
    That is pretty neat, is it on both sides of the lens (entry and exit)? The synchronisation mechanism between all these things also sounds very interesting.
    - thsksbd 3y ago
      I dunno! I know nothing about projectors except what I dug out when the sound issue started bothering me. I imagine the buffer on the exit is just slack. The sync though is actually pretty easy, at least compared to computers and electronics - shafts and gears ensure synchronization with little effort (or you'd brake a shaft!)
      - stavros 3y ago
        But you'd need very tight tolerances to do it over thousands of revolutions (or you'd cut the film reel!).
- wiml 3y ago
  Yes, if you look at a simple projector you can see it: there's a little half-loop of film before and after the shutter/lens assembly and you can see it vibrate as it buffers between the intermittent motion at the shutter and the smooth motion in the rest of the film path.
postmodest 3y ago
"Technology Connections Did It" https://m.youtube.com/watch?v=tg--L9TKL0I https://m.youtube.com/watch?v=tg--L9TKL0I

WalterBright 3y ago

> Then I realized how it was done Oh, I love ingenious solutions like that!

thsksbd 3y ago
Aint it neat?

stavros 3y ago

How does it have constant velocity? Is there a physical "buffer" for the stopped frame (ie slack in the reel)? Otherwise you can't stop one part of the reel while the other is still traveling.

HPsquared 3y ago
There must be some "slack", the entire reel isn't going to stop and start 24 times a second.
thsksbd 3y ago
Short: There is a buffer! Long: So the frame being projected has to stop. Otherwise you'll get blurring unless your shutter is very fast, but then you'd burn out the film from the intensity of the light. The film is stopped. But, of course, you cant start-stop a 15 lb spinning reel 24 times a second millions -> itll all fall apart. So the feed is a simple rotation at constant velocity (linear? Angular?). Then a piece of film ten to twenty (?) frames long gets put into a buffer (an empty box) and a mechanism akin to a sowing machine single steps through each individual frame. Now the stepping mechanism only has to start-stop ten frames worth of film, a negligible amount of mass compared to the mechanism itself and the projector can last a long time of heavy use with simple maintenance. Aint it neat?
- stavros 3y ago
  That is pretty neat, is it on both sides of the lens (entry and exit)? The synchronisation mechanism between all these things also sounds very interesting.
  - thsksbd 3y ago
    I dunno! I know nothing about projectors except what I dug out when the sound issue started bothering me. I imagine the buffer on the exit is just slack. The sync though is actually pretty easy, at least compared to computers and electronics - shafts and gears ensure synchronization with little effort (or you'd brake a shaft!)
    - stavros 3y ago
      But you'd need very tight tolerances to do it over thousands of revolutions (or you'd cut the film reel!).
wiml 3y ago
Yes, if you look at a simple projector you can see it: there's a little half-loop of film before and after the shutter/lens assembly and you can see it vibrate as it buffers between the intermittent motion at the shutter and the smooth motion in the rest of the film path.

postmodest 3y ago

"Technology Connections Did It" https://m.youtube.com/watch?v=tg--L9TKL0I https://m.youtube.com/watch?v=tg--L9TKL0I