字幕列表 影片播放 列印英文字幕 Hey, Vsauce. Michael here, and I just got back from VidCon. The entire convention was incredible, but the whole time I was there I thought a lot about video. We all watch video and many of us work with video, but what is it? I mean, what really is video? Well, guess what, today we're gonna take a look. To begin I think we should start all the way down at the bottom with language. What does the word record mean? The story behind the word 'record' is actually quite cool and makes me a little sentimental. The word 'record' comes from the Latin, where "re" means again and "cor" means the heart or the soul. So when you record something you are literally bringing it back into your heart, bringing it back into your soul, remembering it. Now, that sounds really nice and pretty, but it actually had more to do with the fact that ancient people thought that the heart was we were stored memories, not the brain. The reason a sequence of still images can appear to be moving is an effect known as "beta movement." If images move fast enough our brain can't comprehend them as separate images and the illusion of motion is created. Now, for a very long time we recorded moving images on photographic film, but later on a new way of capturing moving images came about and it was called "video." Video comes from the Latin for "I see" and rather than preserving a moving image chemically on celluloid photographic film stock, video is an electronic representation of the moving image. Now in the real world stuff just happens. The things just continuously happen. But in the world of a camera, whether it's film or video camera, it's almost always in the form of frame rates. Pictures of the world taken at a certain speed that are then quickly gone through producing, through beta movement, the illusion of movement. When a camera records at a lower frame rate, playback often looks jittery and skips like this. More frames per second means that more information is taken every second leading to more fluidity. But that leads to a whole can of worms, which is a great transition to a conversation I had with Dylan from HouseholdHacker at VidCon. Roll the tape. Hey, Vsauce. Michael here, and I am in the bathroom at VidCon and I've got a special guest. Right outside it's Dylan from HouseholdHacker. Hey, what's going on everyone? You know, I got a good question for you based on frame rates and what not. What would you say the human eye sees as a frame rate? Very good question. What frame rate do we see the world in with our eyeballs? I mean, how fast does information travel from our eye to our brain? It obviously can't be too low, because fast objects don't look like they're skipping, they look pretty fluid. Well, it's a little bit of a trick question because our eyes are not cameras. Instead, they track onto objects and receive a continuous flow of photons onto the retina sending information via a chemical reaction to the brain. Now, here's what we do now. The visual cortex in our brain usually holds that information from our retina for about a fifteenth of a second. So if an animation moves fifteen frames a second or faster, it's gonna look nice and fluid. But if it's lower than fifteen frames a second, our brain's not fooled by the beta movement and it'll look like it's skipping. So, basically, the faster the frame rate, the better everything's gonna look in the end. Here's the thing. If frame rates get higher and higher, you wind up with an image that can actually cause headaches when people watch it on the screen. Uhm... Here, I'll explain why. Hold this camera for a second. Oh yeah, no problem. So back to the point about our eyes tracking onto objects. If I do this - move my hand in front of my face and track it with my eyes - I can see my hand, it makes sense. But at a certain point my hand will move so fast that it's just a blur and the reason it's a blur is because my eye can only track so fast. And when objects move faster than our eyeballs can track, your brain adds in motion blur. That way we get a sense of movement happening, but we don't see something like a hand randomly appearing all over the place. But this becomes a problem with new high-definition programs on big televisions, because some of those programs are brought to your TV at frame rates as high as a 1000 frames a second. And objects, like a tennis ball, that normally travels so fast our eyes can't track them and they look blurry don't look blurry, because the camera is able to see them clearly. And when you watch that program on TV you can actually get a headache or get dizzy, so they're having to find ways to add blur back into HD pictures. Pretty neat, right? That's great information. How did you learn this? That's what I'm here for, man. Thank you. See you. See you. You know, the bathroom. You know. I heard you coming out. Did you wash your hands? Uhm, yeah. So there you go. Some cool facts about video that I learned while I was flying to and from VidCon from New York to LA. It was a long flight, but I learned a lot and I wanna end with some numbers about YouTube specifically. YouTube host videos from all over the world. Massive, massive amounts. In fact, every minute of the day people are uploading video to YouTube. And if you were to take all the video uploaded to YouTube at any given minute, all together it would equal 48 hours. That's right. Two full days of video are uploaded to YouTube every single minute. You guys are part of something gigantic. All right, now later this week I'll have a new episode of IMG. And soon enough we'll have episodes of DONG, LÜt, it's gonna be super cool, so be sure you're subscribed so you don't miss anything. And as always, thanks for watching. They're not, they're not the same person.