1
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Class, teacher’s gotta bit of a hangover.

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I... I can’t do it today, so

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we’re gonna watch a mooooovie!

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Let me just whip out the ol’ Filmosound, here…

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[projector whirrs to life, and muffled speech is heard coming from it]

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This is a Bell & Howell 16mm film projector.

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As you might have guessed from its name Filmosound,

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plus the fact that it has a volume and tone control,

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plus the fact that sound is coming from it,

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this thing is not only capable of recreating the illusion of movement through rapidly projecting a series of still images onto a screen,

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but it can also play a soundtrack synchronized with that moving imagery
to recreate a true audio-visual experience.

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Just like the movies in a theater!

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But where is that sound coming from?

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Film is an optical medium,

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and doesn’t sound come only on discs or magnetic tape?

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Well Jimmy, it’s time we learned a littlebit about sound on film.

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The 16mm film that this projects was a very
commonly used sort of mid-tier format.

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As a matter of fact it’s still used in some production environments.

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Sitting between the cheap-but-limited 8mm film used for home movies

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and the expensive-but-highly-detailed 35mm film used in Hollywood,

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16mm found widespread use where that middle-ground was appropriate

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such as for television productions, industrial and educational films, and the like.

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But, as ever, exceptions abound
and some theatrical releases were shot on 16mm film

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and plenty of television productions were shot on 35mm film

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so there are no hard and fast rules here.

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*slurp*

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Looking at the film itself we can see a series of images in the center, 
plus sprocket holes on one side of the film...

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and an Audacity waveform on the other.

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That’s… interesting.

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I wonder if that’s the soundtrack.

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It is.

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But before we get to how the projector reads that,
which is trust me - very exciting

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we should probably talk a little bit
about how the projector handles the film it projects.

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Because that itself is pretty fascinating.

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The basics are pretty straightforward.

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Obviously the projector shines a bright light through the film so that a lens can throw a big blown-up image of that film at a screen,

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and it’ll just show one image after the other real fast and boom -
The Illusion of Movement.

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But be warned.

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It might be tempting to simply move the film
through the projector smoothly.

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But try that and you’ll be disappointed.

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Instead of seeing anything coherent on the screen,
you’ll see a blurry mess of shapes moving quickly upward.

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To actually see anything, every image on the
film needs to be still while it’s projected,

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and that’s why projectors like this are elaborate mechanical contraptions
which make that trademark projector noise.

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[that trademark projector noise]

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Here, let’s look behind the lens.

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This part is known as the film gate and it’s absolutely critical.

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The lamp and its condensing lens blasts light through this hole 
and thus through a single frame of the film,

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and when the projection lens is in place
it essentially magnifies that tiny frame and throws it at a screen.

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To the left of the light hole are three metal fingers.

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This is the film advance mechanism, known as the shuttle,

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and those fingers engage with the sprocket holes on the film.

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If I slowly turn the projector mechanism by hand, you’ll see that these fingers repeatedly stick out, move down, then retract and move back up.

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An awful lot like the feed dog on a sewing machine.

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With the help of this pressure plate to provide a bit of friction,

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the result is a stepped, rather than continuous, film motion.

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Every frame of film is held stationary so it can be projected clearly,

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and after a small fraction of a second the film is quickly advanced to the next frame.

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To keep you from seeing that movement, a rotating shutter synchronized with the mechanism blocks out the lamp’s light while the film is in motion.

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Once the next frame is in position and the film has stopped,
light is allowed to pass once more.

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In a motion picture camera, the same mechanism is used - however in that case,

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the film is collecting light from a lens to capture photographic images,

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and the shutter not only prevents it from getting exposed while advancing to the next frame

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but also can change the length of time it is exposed through varying the size of the opening on the shutter -

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and that’s why they use "shutter angle" in the movie business
and not fractions of a second.

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Anyway, in a projector the constant opening and closing of that shutter
means that the projected image is in fact flashing.

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Early on this was very noticeable

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and the frantic flicker on the silver screen
 is where the slang term “flick” comes from,

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fun fact.

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Later projectors, in an effort to make this less noticeable,
have shutters which block the light multiple times with each projected image.

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Although the frame rate is still 24 frames per second,
this projector displays each frame three times

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meaning that the image actually flashes 72 times per second,
which is too fast for most people to notice.

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Since the film can only move when the shutter is blocking the light,

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and that happens three times per frame,

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this means that the film advance movement happens
in one half of one third of 1/24 of one second -

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or 1/144th of a second.

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Or one grossth of a second.

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That means the film advance mechanism is yanking the film down…

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real fast.

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Now, when you actually do the math it works out to
about 2 and a half miles an hour so it’s not…

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that fast but still, that’s pretty stressful on the film.

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And to help with that, the film follows an elaborate path through a pair of rotating sprockets that are, again, mechanically linked to the film advance and shutter.

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Threading this thing is… a pain

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and involves slipping the film over this sprocket,

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down through the film gate,

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then up over this second sprocket,

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around this mysterious thing,

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then back under that second sprocket, before finally taking a spin around these roller guides on its way to the take-up reel.

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After it’s all threaded you close in these little film guides and pray.

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I’ve only messed this up several times!

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Anyway, the sprockets advance the film smoothly
and you’ll notice that there’s an area above and below the gate

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where the film just sorta hangs loose.

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These are there to provide some slack before and after the gate 
in order to reduce the stresses caused by the jerky film advance.

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If you forget to leave this slack there when threading,

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congratulations you’ve just chewed up some film!

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But when threaded correctly and operating,
we’re left with a relatively straightforward (if mechanically elaborate) device.

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The first sprocket steadily pulls film from the supply reel, maintaining a few frames of slack as the film turns downward to pass through the gate.

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There it is repeatedly advanced one frame at a time, and between movements
the shutter opens to project the image on the film.

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After it exits the gate at the bottom,

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another short length of slack is maintained
as it turns again into a second sprocket which,

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moving at the same exact speed as the first,
pulls the film steadily away from the gate.

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Looking at the transition space between the
herky-jerky gate and the smoothly-turning sprockets is fascinating.

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It comes across better in-person, in fact it’s almost freaky in-person,

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but you’ll notice that near the sprocket
(and in fact anywhere else along the film path)

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the film is just a blur.

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It’s moving smoothly so you can’t focus on any of the images it contains.

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As it gets closer to the gate, though, 
its periodic stillness allows you to pick out film frames,

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and right near the gate you can actually see motion in the imagery on the film.

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It appears upside-down because the lens flips it during projection.

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You can see the same thing as it exits the gate, but it becomes a blur again
as it approaches the second sprocket.

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Now, if this were a silent projector this would be the end of its job -

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the film could simply go straight to a take-up reel after this point.

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But this ain’t no silent projector, now is it?

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No it’s not.

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But before I explain the sound this thing reproduces,

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I think it’s important that we go over how flicks became talkies.

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The technologies of sound reproduction and the motion picture 
were both fairly well understood by the turn of the 20th century.

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We knew how to capture and reproduce sound with phonograph records,

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and we knew how to make movies to be projected in a theater.

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It seemed pretty obvious that these two technologies should be connected,

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but there were two big problems.

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The first was that early acoustic sound reproduction
technology

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wasn’t suitable for the large audiences you’d find in a theater.

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The devices of the time simply weren’t loud enough
to reach the people in the back.

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But the second and arguably bigger problem was sound synchronization.

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That would prove tricky.

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Recording sound and filming action at the same time wasn’t a difficult concept.

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In fact, people were trying to make talking movies happen

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for about as long as movies and talking machines coexisted,
but satisfactory results were stubbornly elusive.

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Every time you were finished shooting you were left with two separate recordings:

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one visual, one sound.

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Playing them back together wasn’t exactly rocket surgery,

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but for a convincing experience,
they needed to be reproduced at the exact same time

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and crucially neither one could drift from the other
so the playback speeds had to be exact.

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Otherwise, y’know, Singin’ in the Rain,
and all that.

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By the 1920’s electronic sound amplification
was starting to be a thing,

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and that solved the volume problem.

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But we still had the synchronization problem.

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Some early sound films did use phonograph
records as their sound source,

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including the technically first feature-length talkie The Jazz Singer.

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These systems involved mechanical interlocks
between projector and phonograph to keep them in sync,

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but it required projectionists to carefully align each device 
with cue marks at the start of every reel

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and was susceptible to a bumped record player
completely ruining the moviegoing experience.

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But what if the sound could be stored on the film itself?

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Putting both visuals and audio onto the same
physical object would guarantee they’d stay in sync,

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but how could we do that?

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Magnetic tape won’t be invented until 1928
so that’s not gonna work,

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and besides that would be complicated to manufacture.

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You’d have to, like, bond this theoretical
tape stuff to the film somehow.

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Now film works by blocking light in specific parts to make an image -

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what if we used that concept to store sound?

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Great idea, several people in 1919.

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In a classic case of contrived collaboration, Lee de Forest -

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who you may recognize as an electronics pioneer
who invented the first amplifying vacuum tube -

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would work with Theodore Case and Earl I Sponable
to invent an optical sound-on-film process,

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building on earlier work in optical sound transmission.

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See, we had already learned that we could modulate light to carry sound -

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in fact Alexander Graham Bell, the telephone guy, had demonstrated this in 1880.

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That concept was then used by the navy.... and fast forward to 1919

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and de Forest is granted a patent which uses the photographic properties
of motion picture film to carry a sound signal.

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You might have noticed that 1919 was before 1927.

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Yes, in an odd twist, sound-on-film predates synchronized sound-on-disc by…

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well it kinda does and kinda doesn’t.

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Hollywood for whatever reason was much more enamored with discs,

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that is once they were finally convinced talkies might just be more than a fad,

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and that’s why the Jazz Singer used the Vitaphone system,
but the Phonofilm system was in use in 1923…

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just not in Hollywood.

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Anyway, glossing over a ton of history, let’s get on with it.

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This projector uses essentially the same sound-on-film
technology that de Forest patented.

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In fact, from the 1930’s and into the 1990’s
sound technology in movies shown in theaters remained largely unchanged.

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A long, long time ago I showed you what the film looks like.

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Along the edge opposite the sprocket holes is the soundtrack

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and its resemblance to the waveforms you might see
in modern sound recording software is no coincidence.

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This is a physical representation of an audio signal,

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and thanks to the fact that the film moves, 
we can reproduce it with elegant simplicity.

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You might have thought that this projector has but one lamp: 
this nasty little 1,000 watt light bulb

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that will light up the screen
and also burn a nice little hole in the film should it get stuck.

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But when you switch on the audio amplifier,

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you’ll discover that there is in fact a second one.

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That one’s not important though,
it’s just to help you see a little bit in a dark projection booth.

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Wait a minute though and you will find a third lamp lighting up this little red dot.

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This is the exciting one.

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This lamp is called the exciter

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and its job is to shine a light through the film’s soundtrack.

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That mysterious thing I mentioned during the
threading process is the sound section,

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and when threaded the soundtrack on the film lies
between the exciter lamp and a light-sensitive doohickey of some kind

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that will generate a voltage or maybe current proportional to how much light hits it.

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I’d be more specific but the technologies
changed a bunch over the years

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and I couldn’t tell you if this is a photodiode
or a selenium light cell or a photoresistor or what.

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It doesn’t really matter, though, the specific specifics aren’t important,

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what is important is that the light sensor,
when it picks up changes in brightness,

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will generate a signal which we can amplify.

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The light sensor lives here, tucked behind this large silver drum thing.

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The large silver drum thing, called the sound drum,

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serves a similar function to the capstan in a tape recorder,
and the film is threaded around it.

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It’s a little different as it’s not powered,

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but inside the projector we find a large flywheel that the drum attaches to.

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Like a tape recorder’s capstan, the rotating mass of the flywheel smooths out any small variances in film speed that would be audible as flutter -

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and since everything in here is driven by mechanically-locked gear trains,

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while the motion of the sprockets might look smooth,
they’re actually much too jittery for pleasant sound reproduction.

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When threaded properly, these spring-loaded rollers put tension on the film
to keep it snugly in contact with the drum,

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and once the drum is up to speed they’ll just sort of float up and down as needed.

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In essence, the floating rollers constantly absorb the tiny bits of slack introduced by the slightly jittery turning of the sprocket,

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and the inertia of the drum keeps the film moving as smoothly as possible
through the sound section.

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This is by far the most fiddly part of the threading process on this projector

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and I hate it!

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You need there to be enough tension on the film
for those floating rollers to actually float,

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which means you kinda have to slip the film in the top section of the sprocket,
lock in the guard, bring it around the drum,

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and then keep constant tension on it as you slip it under the bottom half of the sprocket and the film engages with the teeth.

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You only have about one film frame of tolerance, here,

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and if there’s enough slack that those rollers don’t ride on the film
the sound will either sound muffled and warbly

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or just won’t come through at all.

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Now, to be clear, not every projector works like this one does -

213
00:16:18,071 --> 00:16:25,339
this is an older and relatively simple projector,
in fact it’s old enough to have a vacuum tube amplifier.

214
00:16:25,339 --> 00:16:31,519
Newer and fancier units featured automatic
threading or just a generally less annoying design.

215
00:16:31,519 --> 00:16:35,887
Anyway, now that we have a way to make the film move smooth as butter,

216
00:16:35,887 --> 00:16:37,786
we’re done, right?

217
00:16:37,786 --> 00:16:39,520
Well, not quite.

218
00:16:39,520 --> 00:16:45,650
Simply shining light through the soundtrack
section and onto a light sensor won’t work well.

219
00:16:45,650 --> 00:16:51,520
The sound signal on the film is, in this case,
modulated using the variable-area technique.

220
00:16:51,520 --> 00:16:55,603
The width of the clear sections corresponds to the signal amplitude -

221
00:16:55,603 --> 00:17:01,698
more clear area means more light will pass through the film
and thus we get a stronger signal from the sensor.

222
00:17:01,698 --> 00:17:05,153
And of course that varies along the length of the film -

223
00:17:05,153 --> 00:17:11,266
combine the changing width and linear movement of the film and you’ve got an amplitude that changes with time -

224
00:17:11,266 --> 00:17:14,328
just like sound pressures do in the real world.

225
00:17:14,328 --> 00:17:17,975
But in order to reproduce that signal with any degree of fidelity,

226
00:17:17,975 --> 00:17:23,592
we need the sensor to be able to discern rapid changes in amplitude
like you see here.

227
00:17:23,592 --> 00:17:32,164
To do this, the exciter lamp shines through a slot and lens
which projects only a tiny slit of light onto the film.

228
00:17:32,164 --> 00:17:41,660
That literally narrows the area being scanned which makes the signal we receive more precise and allows us to recreate the nuances of the waveform.

229
00:17:41,660 --> 00:17:45,031
And the fidelity that’s possible here is frankly not bad,

230
00:17:45,031 --> 00:17:51,798
especially considering that this is 16mm film
which only moves at a hair over seven inches per second.

231
00:17:51,798 --> 00:17:55,130
Here are some samples taken from this projector.

232
00:17:55,812 --> 00:18:00,904
[Narrator]
Printing is a process of transferring an image from one surface to another.

233
00:18:02,914 --> 00:18:04,182
[sad bagpipe toot]

234
00:18:04,792 --> 00:18:10,042
[normal bagpipes]

235
00:18:11,172 --> 00:18:19,434
Note that 35mm film, which is what you’d be seeing in a commercial theater,
moves at a much faster 18 inches per second.

236
00:18:19,434 --> 00:18:24,156
With more than twice the speed, 
high-frequency sounds are reproduced much more accurately,

237
00:18:24,156 --> 00:18:26,808
and the fidelity is greatly improved.

238
00:18:26,808 --> 00:18:33,820
Still, though, the sound on 16mm is perfectly acceptable - 
and with a fancier projector, I imagine this would sound better.

239
00:18:34,896 --> 00:18:41,100
[Narrator with acoustic guitar in background]
For right handers: feet apart, left foot forward.

240
00:18:41,100 --> 00:18:45,710
Bring the ball in front of your chest, then above your shoulder.

241
00:18:46,643 --> 00:18:48,658
Steady the ball with your left hand.

242
00:18:49,519 --> 00:18:51,549
Hold the ball with your right.

243
00:18:52,662 --> 00:18:56,238
Shift your weight to your left foot as you throw.

244
00:18:57,565 --> 00:19:00,150
[70’s flutes in background]
There’s nothing there I really don’t understand.

245
00:19:00,150 --> 00:19:01,210
[Narrator]
Excellent.

246
00:19:01,210 --> 00:19:04,530
Then perhaps you can tell us what this code does.

247
00:19:04,530 --> 00:19:05,530
How should I know?

248
00:19:05,530 --> 00:19:11,270
Sure, I can read the language… but how can I understand
unless you tell me what the names stand for?

249
00:19:12,024 --> 00:19:16,919
[more very groovy mid-seventies instructional flute-music]

250
00:19:18,390 --> 00:19:20,403
Something doesn’t add up.

251
00:19:20,403 --> 00:19:24,230
And that’s exactly what Crookes thought when he invented this device.

252
00:19:25,091 --> 00:19:27,240
Now, nature isn’t wrong.

253
00:19:27,240 --> 00:19:29,295
The theory’s wrong.

254
00:19:29,295 --> 00:19:32,477
Instead of demonstrating the pressure of light,

255
00:19:32,477 --> 00:19:35,301
he must have been demonstrating something else.

256
00:19:35,301 --> 00:19:39,650
[Narrator]
The correct position for the head is slightly tilted back.

257
00:19:39,650 --> 00:19:41,725
When the arms are in their correct position,

258
00:19:41,725 --> 00:19:48,330
a pole can be placed on the bridge of the nose and the ends of it will rest between
the thumb and forefinger of each hand.

259
00:19:48,330 --> 00:19:54,370
All the windows in our house have wooden doors outside.

260
00:19:57,635 --> 00:20:02,610
They must be opened every morning, and that’s my job.

261
00:20:02,610 --> 00:20:05,228
[Narrator]
Communicore, with its central location,

262
00:20:05,228 --> 00:20:07,190
is the hub of Future World.

263
00:20:07,190 --> 00:20:10,678
In a sense, it’s also the heart of EPCOT Center,

264
00:20:10,678 --> 00:20:15,033
for here are the computers that control many of the attractions.

265
00:20:15,822 --> 00:20:19,572
[Narrator]
Sometimes he went stalking with his Highland uncles.

266
00:20:20,288 --> 00:20:22,619
[birds chirping]

267
00:20:23,625 --> 00:20:29,647
Once, after staying still for a long time,
Wee Gillis couldn’t hold his breath

268
00:20:29,647 --> 00:20:31,123
[exhales]

269
00:20:33,137 --> 00:20:35,151
[clopping hooves]

270
00:20:35,900 --> 00:20:38,418
and he frightened away the deer.

271
00:20:40,690 --> 00:20:46,144
[more incredibly ‘70s flute music,
but now with harpsichord!]

272
00:20:52,854 --> 00:20:55,159
[Narrator]
It’s much like the Golden Rule.

273
00:20:55,751 --> 00:20:59,009
If you read programs critically when you get a chance,

274
00:20:59,009 --> 00:21:01,184
apply some of the ideas we’ve covered,

275
00:21:01,184 --> 00:21:03,699
and use tact with personal criticisms,

276
00:21:03,699 --> 00:21:06,784
you and your colleagues will be a lot more successful

277
00:21:06,784 --> 00:21:09,336
and so will your programs.

278
00:21:10,125 --> 00:21:13,326
There are some interesting things to point out about the sound, here.

279
00:21:13,326 --> 00:21:19,674
Of course, that buzzing is mainly the result of an old amplifier
that probably could do with new capacitors.

280
00:21:19,674 --> 00:21:24,165
But did you hear a sort of metallic sound throughout the recordings?

281
00:21:24,165 --> 00:21:29,315
One of the downsides of analog optical audio
is that it’s susceptible to vibrations -

282
00:21:29,315 --> 00:21:35,341
if the film physically moves even just a tiny bit
in a way that affects how much light hits the sensor,

283
00:21:35,341 --> 00:21:37,708
you’ll hear that movement.

284
00:21:37,708 --> 00:21:41,960
And the sound drum on this machine doesn’t spin silently.

285
00:21:41,960 --> 00:21:45,351
If I give it a quick spin we hear a similar sound.

286
00:21:45,351 --> 00:21:51,220
I believe that is getting transferred into the signal,
though it could also be one of the rollers.

287
00:21:51,220 --> 00:21:53,418
In any case, it’s just interesting.

288
00:21:53,418 --> 00:21:57,090
Something else to point out is what signal noise sounds like.

289
00:21:57,090 --> 00:22:03,245
For instance, when the translucent leaders at the head and tail of a film
travel through the sound section,

290
00:22:03,245 --> 00:22:10,536
what we hear is a scratchy sound not unlike a phonograph needle sliding on the surface of a record before it locks in the groove.

291
00:22:10,901 --> 00:22:14,702
[buzz as amp switches on, then scratchy surface noise]

292
00:22:14,702 --> 00:22:17,610
[clicking and popping]

293
00:22:17,610 --> 00:22:22,264
Little bits of dust or scratches on the soundtrack will have a similar effect.

294
00:22:22,264 --> 00:22:26,854
And since even a silent section will have tiny little variations in it,

295
00:22:26,854 --> 00:22:30,574
there is a noise floor just like you find on vinyl records.

296
00:22:30,574 --> 00:22:37,784
Anyway, it’s just interesting that the noise is much more like a phonograph
and much less like magnetic tape.

297
00:22:37,784 --> 00:22:42,028
You may have already guessed that since the sound section is here

298
00:22:42,028 --> 00:22:46,197
but the projected frame is all the way back there,

299
00:22:46,197 --> 00:22:49,808
that the sound is recorded onto the film ahead of the images,

300
00:22:49,808 --> 00:22:52,465
in fact by 26 frames.

301
00:22:52,465 --> 00:23:00,310
At the beginning of many films there will be a brief beep on the soundtrack
26 frames ahead of a marker which will flash on the screen,

302
00:23:00,310 --> 00:23:02,942
and that helps assure that the sound is in sync.

303
00:23:02,942 --> 00:23:07,386
Threading mishaps can cause film to bunch up in unexpected ways

304
00:23:07,386 --> 00:23:10,191
so it’s nice to have that confirmation.

305
00:23:10,191 --> 00:23:16,280
However, the sync can easily be off by a frame or two thanks to the slack section after the gate.

306
00:23:16,280 --> 00:23:21,960
It’s easy to vary how much film is left floating here, and that will affect sound sync.

307
00:23:21,960 --> 00:23:26,341
Luckily, if it’s off by just a couple of frames most people won’t notice.

308
00:23:26,341 --> 00:23:29,306
Like how it was slightly off in this entire shot.

309
00:23:29,751 --> 00:23:32,832
Another thing to point out about these soundtracks is that,

310
00:23:32,832 --> 00:23:38,253
while you might assume these are in stereo
thanks to the two waveforms right next to each other,

311
00:23:38,253 --> 00:23:40,920
this is in fact just a mono recording.

312
00:23:40,920 --> 00:23:44,059
The two parallel waveforms are identical.

313
00:23:44,059 --> 00:23:47,300
So, why bother having two of them?

314
00:23:47,300 --> 00:23:49,511
Is there some magic to be had?

315
00:23:49,511 --> 00:23:50,820
Yes, actually!

316
00:23:50,820 --> 00:23:56,679
This, like most of the films I have,
is a dual-bilateral variable-area soundtrack.

317
00:23:56,679 --> 00:23:58,760
Say that five times fast.

318
00:23:58,760 --> 00:24:03,204
Two parallel soundtracks help reduce what’s
known as azimuth distortion -

319
00:24:03,204 --> 00:24:09,450
which is basically how well or poorly centered
the scanning beam is on the soundtrack.

320
00:24:09,450 --> 00:24:14,477
With a single waveform running in the center,
a slightly misaligned scanning section

321
00:24:14,477 --> 00:24:19,449
(which could happen for a number of reasons including
a slightly out-of-tolerance exciter lamp)

322
00:24:19,449 --> 00:24:25,735
might miss the edges of the waveform and thus
that sound information wouldn’t get through.

323
00:24:25,735 --> 00:24:32,042
Having two identical soundtracks right next to each
other means that if the scanning beam is slightly off,

324
00:24:32,042 --> 00:24:38,687
the signal is less likely to be damaged
as at least one of the two waveforms will be completely captured.

325
00:24:38,687 --> 00:24:42,501
Some manufacturers would go on to take this concept to the extreme

326
00:24:42,501 --> 00:24:47,213
and produce soundtracks with four or even six identical waveforms.

327
00:24:47,213 --> 00:24:48,415
Did it help?

328
00:24:49,097 --> 00:24:50,097
Maybe.

329
00:24:50,671 --> 00:24:56,929
OK, so we understand how the projector makes sounds
from those wiggly waveforms on the film,

330
00:24:57,324 --> 00:25:00,391
but how did they get there in the first place?

331
00:25:00,391 --> 00:25:04,123
Well, have you ever seen one of those laser light show thingies?

332
00:25:04,123 --> 00:25:06,670
Think that, but itty bitty.

333
00:25:06,670 --> 00:25:14,274
A device called a mirror galvanometer was used to bounce a tiny spot of light
onto a strip of photographic film.

334
00:25:14,274 --> 00:25:21,059
That mirror, when fed an audio signal, would vibrate
and wiggle that spot of light left and right.

335
00:25:21,059 --> 00:25:27,770
The stronger the signal, the more it vibrated,
and thus the wider a line it would appear to make.

336
00:25:27,770 --> 00:25:32,560
Without a signal it wouldn’t vibrate at all and it would remain a spot.

337
00:25:32,560 --> 00:25:39,230
Running photographic film past this wiggly light would produce waveforms like this once developed with a reversal process.

338
00:25:39,918 --> 00:25:44,877
I’d love to know more about the specifics
of how films like this were mass-produced.

339
00:25:44,877 --> 00:25:51,670
For instance, most of the color films I have are quite severely faded,
but the soundtracks are not.

340
00:25:51,670 --> 00:25:57,099
Indeed, the soundtracks were made using conventional
black-and-white, silver-halide film chemistry

341
00:25:57,099 --> 00:26:02,485
and then bonded somehow to the dye-based color film print.

342
00:26:02,485 --> 00:26:06,137
However that was done, the soundtrack must be very very thin

343
00:26:06,137 --> 00:26:09,470
as you can’t feel a ridge of any kind.

344
00:26:09,470 --> 00:26:16,150
Or perhaps the film was made with two emulsions on it,
but given what I now know about how film is manufactured

345
00:26:16,150 --> 00:26:17,727
(thanks Destin)

346
00:26:17,727 --> 00:26:19,605
that seems unlikely.

347
00:26:19,605 --> 00:26:22,723
Anyway, I don’t want to dwell on this but I am very curious.

348
00:26:22,723 --> 00:26:29,019
Oh, and while all of my films have variable-area soundtracks,
that wasn’t the only way to do it.

349
00:26:29,019 --> 00:26:34,546
In fact, de Forest’s original Phonofilms used a variable-density scheme.

350
00:26:34,546 --> 00:26:38,733
Here, rather than wiggle a constant light to make different shapes,

351
00:26:38,733 --> 00:26:42,544
we change the brightness of a light source projected through a slit.

352
00:26:42,544 --> 00:26:52,270
In essence it’s the same exact concept as we see in the projector,
but with a fast-acting light source exposing the film to record sound onto it.

353
00:26:52,270 --> 00:26:57,687
That makes a soundtrack in which the recorded
sound looks more like banding than a waveform

354
00:26:57,687 --> 00:27:01,405
but it will block light in much the same way when being reproduced

355
00:27:01,405 --> 00:27:06,373
so it is entirely compatible with this or any other optical sound projector.

356
00:27:06,373 --> 00:27:09,731
And, although much rarer in the grand scheme,

357
00:27:09,731 --> 00:27:15,718
there are films in which the audio section
is indeed a strip of magnetic tape bonded to it.

358
00:27:15,718 --> 00:27:19,742
They probably offered higher fidelity especially on 16mm film,

359
00:27:19,742 --> 00:27:22,919
but they required a compatible projector.

360
00:27:22,919 --> 00:27:26,994
Speaking of projectors, before we get to the part about Digital Sound On Film -

361
00:27:26,994 --> 00:27:29,106
that’s right, that’s a thing -

362
00:27:29,106 --> 00:27:33,648
I want to talk a little bit more about the lost art of projection.

363
00:27:33,648 --> 00:27:39,819
You might be wondering how long of a film
the projector can show before it runs out of film.

364
00:27:39,819 --> 00:27:48,006
Well, a big 15 inch reel like the one I’m using as a takeup-reel 
can hold 2200 feet of film which, side-note,

365
00:27:48,006 --> 00:27:51,240
did you know that’s where the term “footage” comes from?

366
00:27:51,240 --> 00:27:54,024
As in, “where’s that sasquatch footage?”

367
00:27:54,024 --> 00:27:56,907
Motion picture film is measured in feet!

368
00:27:56,907 --> 00:27:59,519
And some quantity of it is footage!

369
00:27:59,519 --> 00:28:02,354
There are even little gauge marks on the reels.

370
00:28:02,354 --> 00:28:06,787
Anywho, since 16mm film has relatively small frames,

371
00:28:06,787 --> 00:28:12,451
at 24 frames per second a full 2200 foot reel will run for an hour.

372
00:28:12,451 --> 00:28:20,804
That’s a pretty uncommon size, though, and the 1600 foot reel, 
which ran for 44 minutes, was commonly used for feature films

373
00:28:20,804 --> 00:28:26,575
with 800 foot reels like these common for short-subjects or educational films.

374
00:28:26,575 --> 00:28:30,540
This means that feature films came on multiple reels.

375
00:28:30,540 --> 00:28:39,188
And on 35mm film with its much larger frames,
a 90 minute movie might be split up onto five 2000 foot reels

376
00:28:39,188 --> 00:28:42,188
which held a maximum of 22 minutes runtime.

377
00:28:42,188 --> 00:28:49,409
And for many years 1000 foot reels were standard,
meaning the same film would need to be on 9 reels.

378
00:28:49,409 --> 00:28:55,110
So… how did movie-going audiences get to
watch a seamless performance?

379
00:28:55,469 --> 00:28:59,364
Well, have you ever watched a home-video release of an old movie

380
00:28:59,364 --> 00:29:03,610
and caught one of these little dots showing up in the corner?

381
00:29:03,610 --> 00:29:08,170
If you’re too young you probably haven’t
as these are generally edited out these days,

382
00:29:08,170 --> 00:29:10,901
but those are cue marks.

383
00:29:10,901 --> 00:29:16,299
See, although a projector in a cinema could
only show 11 or 22 minutes of film at a time,

384
00:29:16,299 --> 00:29:18,591
through the Magic of Having Two Of Them,

385
00:29:18,591 --> 00:29:25,689
you could have another projector standing by ready to go
and switch to it the moment the first one runs out of film.

386
00:29:25,689 --> 00:29:31,030
Those cue marks appear at 8 seconds and 1 second before the end of a reel.

387
00:29:31,030 --> 00:29:34,410
The first signals to the projectionist to get ready to switch,

388
00:29:34,410 --> 00:29:37,029
and the second says “now’s the time”.

389
00:29:37,029 --> 00:29:39,245
This used to be entirely manual,

390
00:29:39,245 --> 00:29:46,837
and projectionists would have to quickly cover the first projector’s lens with a shutter and open up the second which was rarely seamless,

391
00:29:46,837 --> 00:29:52,296
but eventually this process was semi-automated
and merely required the push of a button.

392
00:29:52,296 --> 00:29:57,886
As you can imagine, back in the day a projectionist’s job was pretty hands-on.

393
00:29:57,886 --> 00:30:01,492
They’d have to constantly be getting the next projector ready -

394
00:30:01,492 --> 00:30:09,063
as soon as they hit the changeover, they had to immediately unload the first projector, then start threading the next reel and cue it up.

395
00:30:09,063 --> 00:30:13,442
Then they could rewind that first reel (assuming they had a separate rewinder)

396
00:30:13,442 --> 00:30:18,355
and after that they’d be on the lookout for the cue marks
to do it all over again.

397
00:30:18,355 --> 00:30:22,970
These folks were really watching the same
movies again and again and again

398
00:30:22,970 --> 00:30:29,611
which was undoubtedly tedious but also meant they could
get really good at timing the changeovers.

399
00:30:29,611 --> 00:30:32,771
If they were good enough, the audience wouldn’t even notice.

400
00:30:32,771 --> 00:30:37,091
Unless they were looking back at the projection booth like some kinda nerd.

401
00:30:37,091 --> 00:30:38,606
Like me.

402
00:30:38,606 --> 00:30:47,897
Eventually, though, most theaters would upgrade to large platter systems
which could store an entire spliced-together feature plus trailers.

403
00:30:47,897 --> 00:30:50,694
And those could be loaded from the center,

404
00:30:50,694 --> 00:30:56,750
meaning the film just shuttled between two platters
and didn’t ever need rewinding.

405
00:30:56,750 --> 00:31:00,508
This meant a projectionist only had to start a film

406
00:31:00,508 --> 00:31:05,626
and could wander around to other screens in a multiplex
and just keep tabs on them.

407
00:31:05,626 --> 00:31:12,299
Plan some sort of schedule for screen times
and you might only need a single person to manage a dozen screens.

408
00:31:13,053 --> 00:31:15,709
That’s what they call progress, I guess.

409
00:31:15,709 --> 00:31:23,230
Speaking or progress, starting in the ‘80s people got a taste of sound
made not from shapes, grooves, or magnetic flux

410
00:31:23,230 --> 00:31:25,707
but from ones and zeroes.

411
00:31:25,707 --> 00:31:31,244
They also liked the idea of sound coming from
many different places in a theater.

412
00:31:31,244 --> 00:31:36,420
The advent of digital surround sound meant that
sound-on-film was gonna need an update.

413
00:31:36,420 --> 00:31:39,228
And it looked like this!

414
00:31:39,228 --> 00:31:41,867
This is a 35mm film trailer,

415
00:31:41,867 --> 00:31:46,497
and you probably recognize our old friend dual-bilateral variable-area!

416
00:31:46,497 --> 00:31:49,230
Though in this case, it actually is stereo -

417
00:31:49,230 --> 00:31:55,905
professional projection systems used much more precise sound heads to correctly scan both waveforms separately.

418
00:31:55,905 --> 00:31:59,129
By the 1970’s, stereo sound was pretty standard

419
00:31:59,129 --> 00:32:08,898
and Dolby Stereo - a way to derive Left, Right, Center, and Surround channels from a cleverly-modulated stereo source - offered basic surround sound using this technology

420
00:32:08,898 --> 00:32:11,461
starting in 1976.

421
00:32:11,461 --> 00:32:14,822
But anyway, that’s not the only soundtrack on here.

422
00:32:14,822 --> 00:32:16,472
In fact it has not one,

423
00:32:16,472 --> 00:32:17,549
not two,

424
00:32:17,549 --> 00:32:18,696
not three,

425
00:32:18,696 --> 00:32:21,428
but four different soundtracks!

426
00:32:21,428 --> 00:32:28,159
To the left of the analog soundtrack we find Dolby Digital sound
 hanging out in the middle of the sprocket holes.

427
00:32:28,159 --> 00:32:35,966
First used in 1992, these QR-lookin’ matrix barcodes,
complete with an adorable little Dolby logo in the middle,

428
00:32:35,966 --> 00:32:41,132
encode a Dolby AC-3 bitstream at 320 kilobits per second.

429
00:32:41,132 --> 00:32:48,636
There’s some error correction built in, of course - by my rough count I think
the raw data rate is closer to 530 kilobits a second

430
00:32:48,636 --> 00:32:58,524
but anyway to upgrade your cinema a new digital sound head that scans this area using what you can describe as basically a tiny high-speed camera…

431
00:32:58,524 --> 00:33:01,287
(sigh) that’s gonna ruffle some feathers.

432
00:33:01,287 --> 00:33:08,513
There’s a scanner thingy that uses the same tech that’s in a camera sensor to read the datastream with the help of backlight, let’s just leave it at that -

433
00:33:08,513 --> 00:33:15,468
that thing gets installed somewhere on your projector’s film path
and now you’ve got digital surround sound!

434
00:33:15,468 --> 00:33:22,449
And a fun thing about being digital is that
you no longer needed to put the sound head in exactly the correct place.

435
00:33:22,449 --> 00:33:29,309
Just like 16mm film, oddly enough,
the sound data is 26 frames ahead of the projected image.

436
00:33:29,309 --> 00:33:34,440
But you could easily put the sound head a little
bit further ahead and simply buffer the data

437
00:33:34,440 --> 00:33:39,049
to delay the sound by however many fractions
of a second you need to attain synchronization.

438
00:33:39,659 --> 00:33:40,840
That’s pretty neat.

439
00:33:40,840 --> 00:33:46,808
Oh, and the fact that the physical location of the sound
is well ahead of the projected image

440
00:33:46,808 --> 00:33:51,320
gives the MPAA preview approval cards a second purpose:

441
00:33:51,320 --> 00:33:58,394
at every film splice, there’s gonna be a little over a second of silence in the audio before the picture catches up,

442
00:33:58,394 --> 00:34:03,217
and since multiple trailers would get spliced
together onto the start of a main feature,

443
00:34:03,217 --> 00:34:06,191
there will always be a series of gaps.

444
00:34:06,191 --> 00:34:08,432
Might as well use those for this thing.

445
00:34:08,432 --> 00:34:11,412
To be clear that also happened with analog audio

446
00:34:11,412 --> 00:34:14,760
but I only thought of it at this point in the scriptwriting process.

447
00:34:14,760 --> 00:34:19,983
Now, to the left of the Dolby Digital soundtrack
you’ll find another very digital one.

448
00:34:19,983 --> 00:34:22,379
In fact this one is even more digital!

449
00:34:22,379 --> 00:34:24,530
As in, it has a higher bitrate.

450
00:34:24,530 --> 00:34:27,060
This is Sony Dynamic Digital Sound,

451
00:34:27,060 --> 00:34:30,171
also known as SDDS, also known as

452
00:34:30,171 --> 00:34:34,495
of course Sony made another sound format
they just can’t help themselves!

453
00:34:34,495 --> 00:34:43,758
Hitting theaters in 1993, it’s scanned in much the same way as Dolby Digital
and encodes 8-channel audio at 2.2 megabits per second,

454
00:34:43,758 --> 00:34:45,777
much greater than Dolby.

455
00:34:45,777 --> 00:34:51,279
However, very few movie studios embraced mixing in that particular format

456
00:34:51,279 --> 00:34:55,974
and since the data is placed on the edge of the film where it’s
vulnerable to damage,

457
00:34:55,974 --> 00:35:04,876
reportedly this often suffered from dropouts and yeah it was the
least popular format for cinemas when film projection was still the norm.

458
00:35:04,876 --> 00:35:06,646
Are you really surprised?

459
00:35:06,646 --> 00:35:09,091
But I said there’s a fourth format.

460
00:35:09,091 --> 00:35:10,688
Where’s that one?

461
00:35:10,688 --> 00:35:12,999
Why, it’s right here!

462
00:35:12,999 --> 00:35:21,280
This is Digital Theater Systems surround sound,
also known as DTS, which also first hit the screen in 1993.

463
00:35:21,280 --> 00:35:26,960
You may notice that this is hardly any data at all
compared to Dolby Digital and SDDS.

464
00:35:26,960 --> 00:35:30,670
Did they discover some sort of really magic compression format?

465
00:35:30,670 --> 00:35:36,086
No, as a matter of fact this is merely a timecode as DTS did a throwback

466
00:35:36,086 --> 00:35:38,209
to sound-on-disc.

467
00:35:38,209 --> 00:35:45,853
Special CD-ROMs containing a 5.1 channel mix
encoded at 882 kbit/sec stored the sound,

468
00:35:45,853 --> 00:35:53,390
and this data stream simply identified what
film or trailer was playing and the exact time of the projected frame.

469
00:35:53,390 --> 00:35:59,143
Offboard equipment with the loaded discs would
simply monitor this code and cue up the correct audio.

470
00:35:59,143 --> 00:36:02,345
This made the scanning equipment much simpler

471
00:36:02,345 --> 00:36:09,787
but meant that the sound was technically not on the film anymore and of course required more off-projector hardware

472
00:36:09,787 --> 00:36:12,170
plus the wrangling of the discs.

473
00:36:12,170 --> 00:36:17,018
But anyway, one nice benefit of the DTS system
from a producer’s point of view was that,

474
00:36:17,018 --> 00:36:21,930
like Dolby Digital, it was also a 5.1 channel system.

475
00:36:21,930 --> 00:36:25,221
Since it used ~essentially~ the same sound mix,

476
00:36:25,221 --> 00:36:33,950
a production studio could master in either one and get essentially the same experience between a DTS or Dolby-equipped cinema.

477
00:36:33,950 --> 00:36:37,140
Which was another nail in the coffin for SDDS.

478
00:36:37,140 --> 00:36:38,905
But don’t be blue, Sony.

479
00:36:38,905 --> 00:36:41,671
Eventually you’ll win one of those format wars.

480
00:36:41,671 --> 00:36:47,639
Oh, and while off-film discs might have made
the projectionist’s job a bit more complicated,

481
00:36:47,639 --> 00:36:50,480
that technique was theoretically more future-proof

482
00:36:50,480 --> 00:36:56,011
as it could be easily upgraded to DVD-ROM which could store more channels with more bits,

483
00:36:56,011 --> 00:37:01,073
though I’m not sure this was ever done in theaters
before film projection faded away.

484
00:37:01,073 --> 00:37:03,651
But at this point, I think we’re done.

485
00:37:03,651 --> 00:37:06,348
And that means it’s time to rewind the film!

486
00:37:06,348 --> 00:37:11,403
On this projector, that means depressing this latch
to lift the take-up reel into this position,

487
00:37:11,403 --> 00:37:15,954
then grabbing the tail of the film and wrapping
it around the supply reel a few times.

488
00:37:15,954 --> 00:37:18,802
After that’s done, set the projector to reverse.

489
00:37:18,802 --> 00:37:22,068
Oh, did I mention you can watch anything backwards?

490
00:37:22,068 --> 00:37:28,103
That’s fun and/or necessary sometimes because a piece of masking tape got caught in the gate somehow.

491
00:37:28,126 --> 00:37:30,083
.terr sall wus yeep ziT

492
00:37:30,083 --> 00:37:31,687
.ssip moes sey vaaawW

493
00:37:31,687 --> 00:37:32,905
.sez yeep ziP

494
00:37:32,905 --> 00:37:35,476
.swup g'nosh gelwozwod wilno wunnondazI

495
00:37:35,476 --> 00:37:36,928
.herri hunai pumeH

496
00:37:37,251 --> 00:37:44,609
Anyway, after it’s set to reverse you can hit this button which engages a clutch to make the supply reel go backwards real fast!

497
00:37:44,609 --> 00:37:46,508
Reel. Fast.

498
00:37:46,508 --> 00:37:50,898
Then at the end, you can watch it go fwip fwip fwip fwip for as long as you like.

499
00:37:50,898 --> 00:37:54,081
Though you should probably shut it off before too long.

500
00:37:54,081 --> 00:37:56,695
This stuff is fragile, y’know.

501
00:37:57,628 --> 00:38:00,098
♫ cinematically smooth jazz ♫

502
00:38:02,459 --> 00:38:03,501
[inhales]

503
00:38:06,041 --> 00:38:07,490
wheeeeee

504
00:38:11,259 --> 00:38:12,356
Eugh

505
00:38:12,864 --> 00:38:13,957
The 16...

506
00:38:13,957 --> 00:38:14,728
The - hmph.

507
00:38:14,728 --> 00:38:15,537
Heh heh.

508
00:38:15,537 --> 00:38:16,443
Heuh!!

509
00:38:16,443 --> 00:38:20,008
As a matter of fact it’s still used in some production environments.

510
00:38:20,008 --> 00:38:23,382
Sitting between the [film moves] that’s
gonna be really loud, isnt it?

511
00:38:23,382 --> 00:38:25,990
Every frame of film is held stationary.

512
00:38:26,668 --> 00:38:28,234
[confusion]

513
00:38:28,869 --> 00:38:32,185
Stationary still... that’s what’s written there?

514
00:38:32,185 --> 00:38:33,794
“stationary, so.”

515
00:38:33,794 --> 00:38:35,625
There's just a redundant word.

516
00:38:35,625 --> 00:38:37,721
Thanks, spell check for not catching that.

517
00:38:37,721 --> 00:38:40,731
You kinda have to slip the film in the top section of the shproc…

518
00:38:40,731 --> 00:38:43,259
shection of the shprocket.

519
00:38:43,259 --> 00:38:45,650
A shection of the shprocket.

520
00:38:47,810 --> 00:38:51,063
In a world where Technology gets Connected

521
00:38:51,063 --> 00:38:54,544
the fate of all humanity lies in the hands of one man.

522
00:38:54,544 --> 00:38:58,725
He must convince people to buy powdered dishwasher detergent.

523
00:38:58,725 --> 00:39:01,039
Will he succeed?

524
00:39:01,039 --> 00:39:03,550
In theaters this Christmas.