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  • [High-pitched CRT TV noise]

  • Film is a very straightforward technology.

  • It just involves taking a two-dimensional image,

  • and focusing it on to a two-dimensional piece of film, and there you have a photo.

  • But video, and by that, I mean moving electronic images,

  • has a very different history with a lot of changes that have really transformed the way it works.

  • This video was sponsored by B&H Photo,

  • which is kind of fitting because that's where I get a lot of my gear to make these videos.

  • So I'll tell you more about them later, but now it's off to San Francisco.

  • I'm going to meet with a guy who knows a lot about old video gear and he's got some he's gonna show me.

  • - Richard, nice to meet you.

  • - Nice to meet you Derek. Come on in. Welcome to LabGuy's World.

  • - [Laughs.] That's a cool spot you got here.

  • - Thank you.

  • - The fundamental problem of video is taking this two-dimensional light image

  • and turning it into a one-dimensional electrical signal.

  • So how do you do that?

  • Well, the solution actually comes from the first ever fax machine,

  • which believe it or not, was invented in 1843 by Alexander Bain.

  • Now he was a clock maker.

  • His invention involved a transmitter and receiver which each had a pendulum,

  • and those pendulums were synchronized.

  • So what would happen is, at the transmitter, there would be a metal sheet

  • on which something was written or drawn using a non-conducting ink.

  • - So a finger at the transmitter,

  • an electric finger, would stroke over the paper and wherever there was iron, it would conduct,

  • and that conducting signal was sent to the other end,

  • which was applied to paper with a chemical that would turn dark when electricity flowed through it,

  • and it would reproduce a very accurate image of the handwritten note you just made.

  • - Now Alexander Bain only ever transmitted static images,

  • but some people have called him the real father of television,

  • because he invented scanning.

  • This idea of moving back and forth across an image,

  • breaking it down into lines.

  • But if you really want to get moving images,

  • well, you need to be able to scan much faster.

  • So we have to jump forward to 1884, and a 23-year-old German University student named Paul Nipkow.

  • He patented what is called the Nipkow disk,

  • which is basically a big disc with a spiral of holes in it.

  • - The inner pinholes do the scanning,

  • and if I go fast enough you can see the scanning.

  • - You would put a light behind this Nipkow disk

  • and so you'd have a spot of light which scans across your subject, say a person.

  • And then there would be a reflected light off that person which would be picked up by some light sensors.

  • That would create an electrical signal which you could transmit over distance to a receiver.

  • Now at the receiver you use that electrical signal to modulate the brightness of a light source,

  • and then in front of that you place a synchronized Nipkow disk,

  • and so the result is a recreation of the image from the transmitter.

  • - So it was just barely at the limits of the ability to make a viewable picture,

  • and it was actually broadcast for a couple of years in Britain,

  • and in America and other countries did experimental broadcasts using this technique.

  • - This is arguably the first-ever broadcast television image.

  • It was broadcast for a few hours a day for several years,

  • and it was used by engineers to perform experiments and try to improve the quality of the broadcast.

  • - What it proved was that this wasn't the way to do it. [Laughs.]

  • - So by 1939 mechanical TV was all but phased out,

  • and it was replaced by all-electric TV.

  • Specifically the cathode-ray tube.

  • So this is a glass vacuum tube with an electron gun at the back.

  • And the electron gun would fire a beam of electrons at the screen,

  • where it was coated in a chemical which produced light when it got hit by the electrons that's called a phosphor.

  • And using magnetic fields, this beam was scanned across the screen

  • top-to-bottom, left-to-right,

  • and you would vary the brightness of the beam by varying the voltage on a control electrode,

  • essentially determining how many electrons would get sent out in that beam at any instant to hit the screen.

  • So, if you send out a lot of electrons you get a bright spot,

  • if you don't then you get a dark spot,

  • and in that way you can produce a nice black-and-white image.

  • And if you're wondering about color TV,

  • well, there were a number of dead ends along the path

  • to the red-green-blue pixel system that became the standard.

  • Like this TV with a spinning color wheel.

  • - I named the project Goldmark I in honor of Dr. Goldmark.

  • The television part is a standard black-and-white picture tube.

  • - It displayed 24 frames per second but each frame required six scans: blue-green-red, blue-green-red.

  • It worked really well, but it wasn't backwards compatible with black-and-white TVs.

  • And this is a mini triniscope,

  • so named for its three cathode ray tubes, one for each color.

  • And their images were combined with prisms.

  • - The downside of a triniscope monitor

  • is that for every inch you add diagonally to your screen

  • the volume of the cabinet increases by like the power of something like three and a half.

  • They get huge fast.

  • - So the ultimate solution was to have red, green, and blue phosphors for each pixel,

  • and three electron guns to determine their relative brightness.

  • - Now, the number of lines those electron beams make across the screen is, in theory,

  • 525 every thirtieth of a second.

  • But this is achieved by scanning every other line each sixtieth of a second,

  • so it actually takes two scans to make one frame.

  • This is called interlacing.

  • And what you'll notice watching this is that most of the time you're actually staring at a blank screen.

  • The illusion of a continuous moving image is made possible by our persistence of vision,

  • that is, we don't stop seeing something instantaneously after light stops entering our eyes.

  • - So, initially I was thinking this wouldn't be too hard to film

  • I mean, a thirtieth of a second or a sixtieth of a second, that's not terribly fast.

  • But then if you think about it, 262 and 1/2 lines being drawn every sixtieth of a second,

  • that is 15,750 lines drawn per second.

  • That is fast,

  • so if you want to be able to see the lines being drawn on,

  • you need to shoot faster than 15,000 frames per second,

  • a lot faster, really, to be able to see this clearly.

  • and so I am using the Phantom v2512.

  • That is the beast

  • that is allowing me to produce these images.

  • Now the actual resolution of these TVs turned out to be around 480 lines,

  • so when you select 480p on YouTube, that's why this is an option.

  • And I guess it's worth pointing out that the "tube" in "YouTube"

  • is this thing, a cathode-ray tube.

  • So in the time before light-sensitive chips like we all use in our cameras today,

  • how did you actually create the image to display on a television?

  • Well, there were many vacuum tube designs.

  • One of the most common was the image orthicon tube,

  • sometimes called Emmy for short.

  • In fact, that's where the name Emmys comes from.

  • So the way it would work is you use the camera lens to focus an image

  • onto the front of the image orthicon tube, and that was coated with a photoelectric substance,

  • so it would release electrons in proportion to the light that hit them.

  • Now those electrons were collimated by magnetic fields and sent straight back.

  • So essentially you had an electron version of the image sent straight back to a target,

  • which was a very, very thin glass plate.

  • And of course where there's more electrons, that creates a more negative spot on this target.

  • From the back of the tube you'd send forward an electron beam to scan across the target.

  • And so these electrons as they came in,

  • the more negative a spot that was on the target, the more that beam would get reflected.

  • And so that reflected beam was amplified in the tube,

  • and then used as the signal to essentially determine how bright that part of the image should be.

  • So this is how television images were created and displayed for decades.

  • But here is the crazy thing:

  • there was no way to record them.

  • I mean the purpose of video or the purpose of electronic images

  • was really to transmit something from one place to another.

  • "Television" literally means "seeing at a distance."

  • It's not about recording for replaying later as film was.

  • - The thing that blew me away was

  • realizing that video cameras existed for a couple decades before video tape.

  • - That's right. That was the the era of live broadcasting

  • - But this introduced some problems.

  • For example in North America, in the US, a lot of the TV programs were produced out in New York,

  • and there was a coaxial cable which went across the whole of the US,

  • and that could deliver programming to, say, Los Angeles.

  • But it was at the wrong time.

  • I mean a news broadcast from New York at 6:00 or 7:00 p.m.

  • couldn't just be broadcast live at 3:00 or 4:00 p.m. on the West Coast.

  • It just didn't make any sense,

  • So you needed to time-delay it.

  • So how did they do it?

  • Well the answer was to take a film camera,

  • a cinema camera, and point it at a television screen,

  • and actually film the television screen.

  • Then you would quickly develop the film

  • and bring it back three hours later to broadcast it live,

  • to scan it in and broadcast that film as though it were live.

  • - But now when I bring it back to the TV studio and stick it into the telecine,

  • [Laughs.]

  • the picture doesn't look right.

  • The lines aren't lining up right,

  • and besides you're trying to sample two sets of lines back together and they don't!

  • - This became such a prevalent method of doing business for the TV networks

  • that by 1954 the television networks, to time-delay their programming,

  • were using more film than all the film studios in Hollywood combined.

  • This is absurd and expensive and wasteful,

  • so a different method was really needed.

  • And that came along in 1956 with the invention of the first workable video tape recorder.

  • It was the size of a large desk and it cost a fortune.

  • It ran on this two-inch magnetic tape with little video heads spinning at 14,000 RPM.

  • We're talking as fast as a jet engine.

  • That is the kind of technology it took before video became what we kind of know it as today,

  • a method of recording and storing images,

  • rather than a way of just transmitting vision from one place to another.

  • But we've come a long way since then,

  • miniaturizing the tape stand into VHS and Beta,

  • and eventually down to DV and mini DV, and now we are on to solid state storage.

  • And you know I've glossed over a lot of the history here,

  • but now we're in a situation where video is better than film.

  • You can see that in 2012, that was the inflection point between

  • people using film to shoot the top-grossing movies, changing over to people using digital.

  • And what this has done for people like you and me,

  • is it's made it possible to make really good images. [Music]

  • And the question I have is, what does this do to a society?

  • What might it do when people can share every part of their lives with video?

  • This part of this video was sponsored by B&H Photo, literally one of my favorite stores in the world.

  • They have all the greatest and newest camera gear, plus pro audio and lighting and computers,

  • basically anything you could need to make high-quality video.

  • And every time I'm out in New York, I go and visit the store.

  • The last time I was there I asked them for a gimbal,

  • because I've been seeing all these comments saying my videos were too shaky,

  • and so they recommend that this one right here,

  • and I've really loved it. It's so smooth. I can hold it with one hand.

  • It is pretty lightweight and it's just been great and I think it's really improved the quality of my videos.

  • And when I'm back here in LA, I still shop with them online,

  • because there is no shop like that in LA.

  • In fact, this camera, the Sony a7R III, I'd highly recommend it,

  • I bought it for my wife for Christmas the Christmas before last,

  • and it was backordered, but you can actually sign up through their website to get notified when it's in stock,

  • and I did that and managed to get it in time for Christmas,

  • so it's a really great shopping experience.

  • The people are so knowledgeable, it's a mom-and-pop shop, it's got anything you could ever want.

  • I highly recommend that you check out B&H Photo. I'll put a link to them in the description.

  • And thanks to B&H for sponsoring this video.

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視頻是如何發明的? (How Was Video Invented?)

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    林宜悉 發佈於 2021 年 01 月 14 日
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