Why Snow and Confetti Ruin YouTube Video Quality


Have you ever noticed that video of falling
snow or confetti can look pretty terrible? As soon as there’s stuff floating around in
the air, suddenly the quality of the video you’re watching
collapses. You can see it on this incredible clip of
200 kilos of confetti being blasted at Ed Sheeran on the UK’s X
Factor. Now, if you already understand compression,
you can pick another video. Everyone else: let’s talk bitrate. I’m not actually in Norway, by the way, if
that wasn’t obvious. I could have tried to find some actual snow
or bought a load of confetti, but this way I can test things with carefully-controlled
digital effects. Which has the added bonus that I don’t need
to clean up afterwards. So, to put the problem in one sentence: there are only so many ones and zeros to go
around. Back in the days of analogue television, video
was uncompressed. The TV camera scanned the signal, it was transmitted over the air, and your television played it back. And yes, it was only standard definition, but pretty much every bit of detail the camera
caught appeared on your screen. And that’s fine when there are only a few
television channels and they’re literally going over the air. But that’s really wasteful. The reason that digital television can have
so many channels, and that web video works at all, is because of compression. If you tried to actually transmit every pixel
of an HD video, in perfect quality, you’d need somewhere around a gigabit a second
sent over the wire. As I record this, that would max out over 100 average American
broadband connections simultaneously, or over 50 average South Korean broadband
connections. So if you want YouTube to work: that amount
of data, that bitrate, is going to need to get cut down. Step 1 is regular, everyday image compression. Pretty much every photo on the internet is
compressed, mainly by throwing away small bits of detail
that the eye probably won’t notice. At least until it gets screenshotted and reposted twenty different times by twenty different
Instagram accounts. You can take every individual frame of the
video and apply that compression to it. Step 2 is interframe compression. Until there’s a big scene change, why bother
storing whole frames when you can only store the changes between
them? After all, if I’m just talking against a plain
background, you don’t need to keep sending new data for
that background every time. Just tell the video player to repeat what
was there before. Or if I move my body a little as I talk, just tell the player to move that block of
pixels a bit to the right, and maybe tweak a bit of colour here and there. That’s how you cut down gigabits of video
per second to something you can load on your phone: Maths. Lots of maths. But I think a practical demonstration would
be better, so: I’m going to limit the bitrate of this video, the number of ones and zeros per second that
are being used to encode it. And yes, YouTube will mess about with this
after I upload it, but it can’t magically put detail back in: so even if you’re watching in the best quality
you can, what you’re seeing now is still the limited
version. This is two hundred kilobits a second, two hundred thousand ones and zeros going
over the wire every second. Doesn’t look too bad with modern encoding, you might lose some fine detail on my face
or hair or hand gestures, but you can still see what’s going on pretty
clearly. But now, let’s add a bit of snow. And suddenly, those bits aren’t all being
spent on rendering me. Instead, they’re also being used to track
the stuff that’s flying around. It’s chaotic, it keeps changing direction,
it’s complicated, so just saying “move these pixels here” won’t
work either. Let’s add some confetti, too, all colourful
this time. There we go, now it’s all starting to fall
apart. The more stuff there is moving in the frame, more confetti, there we go, the more spread out those two hundred kilobits
have to be. More confetti! Here we go. No matter much the encoder tries to optimise
for faces and skin tones, it just doesn’t have the bits spare. More
confetti! More snow! Now, even if I turn the bitrate back up, put this in the highest quality I can, it still won’t look good right now. I don’t know why I’m yelling, I’m adding the
wind noise in later. But it’s not really about the confetti itself.
It’s about the movement. If we freeze all this stuff in mid-air, and make it into a background: over the next couple of seconds, the quality of the video will come back. That’s why the picture falls apart when your
sports team wins and the confetti drops. Video literally isn’t what it used to be. [Translating these subtitles? Add your name here!]

100 thoughts on “Why Snow and Confetti Ruin YouTube Video Quality

  1. The moment the compression examples (and the word compression) appeared on my screen YouTube decided to change from Auto1080p to Auto360p. It took me a whole minute to realize it wasn't a meta gag.

  2. Am I watching the REAL Tom Scott or the video of him in a video clip inside a video editor?
    My brain feels all pixelated…

  3. When they forced the transition to digital TV here, they promised that image quality would increase compared to the older analog TV. Then we got absolutely hideous compression artifacts all over the place, especially in such scenes.

    (One of the major problems with digital TV, at least here, is that it was developed and forced onto the market in the absolutely worst of times. This was the era of MPEG-2 and DVDs. The enormously better MPEG-4 encoding format was still upcoming or in its infancy. Thus analog TV went with MPEG-2, which is just hideous. What's worse, due to limited carrier bandwidth, not only is it the same MPEG-2 format as used in DVDs, it's in fact using significantly less bitrate than DVDs. Which means that it looks a lot worse than your average DVD. If they had just waited 10-15 years before forcing digital TV onto the market, they would have got significantly better image quality for the same bitrate. But no. And now we are stuck with the horrendous sub-DVD quality digital TV.)

  4. Brilliant ant to the point explanation! The more movement, the more bit rate. Seems logical. The more fps per second, the more bit rate… unless not much movement.

  5. So what I got from this is if you add more snow and confetti, you can make people lag so hard they see in 1 fps, that’s nice to know.

  6. I'm a fan of Kpop, where confetti and ever changing colorful backgrounds are commonly used for live performances and I noticed ages ago that it lowered the quality of video recordings. Thanks for explaining why!

  7. 1:31 or about an infinite amount of German broad band connections.
    Seriously our internet is like trying to cut your way through stones/extremely thick jungle (the jungle, only if you have good internet) whilst everyone else in the world uses Warp Ships or at least high velocity tube trains.

  8. Solution: avoid "too much going on" in videos.
    Solution B: get ISPs to stop being cheap bastards and give us decent speeds (I'm stuck at 10Mbps and there is nothing I can do to get more speed short of paying a different ISP almost a grand to upgrade THEIR infrastructure to get to my house so I can then pay them monthly to provide me "up to 50Mbps, which is the maximum speed available in my location).
    Solution C: Embrace the chaos and crappy quality. Anyone who has lived through the dialup internet age has probably fapped to incredibly bad quality porn. It worked.

  9. It’s weird that I got this video recommended. My latest vlog had that issue in between the cuts of the intro and the main video. I haven’t posted something in years and I noticed that. I haven’t looked for a “solution” online though. So it’s kinda creepy how accurate it is hahaha

  10. i thought this was going to be about how if you use effects every five seconds people will think your video's dumb and juvenile

  11. RED cameras, the digital cameras for cinema, actually use about 200MB per second for an HD video in their raw uncompressed format, there's more in there than you actually need but you can only go as low as 150MB/s

  12. That explains why Markiplier's Five Nights at Freddy's videos turn to 144p whenever there's static.

  13. This video is sooooooooooooo damn great on explaining bitrate. Really I think you need to add "bitrate" to the title, otherwise it's so hard to reach this video by searching.

  14. Worse than compression is the cyclic redundancy check (CRC) which eats up half of your downloaded video kilobytes and kills your processor too.

  15. Join me at perris airport ca Tom love the show let's work on the air going over the wing instead of under I will through u out of an airplane to test these theories lmao

  16. i looked at the thumbnail of this video and was like "oh i know why….. compression, right?" and i watched it anyways because seeing it is just as entertaining to me as learning something new

  17. In the late 90's my family switched from analog cable to digital satellite. I remember being excited about all the new channels . Soon after I noticed alldark scenes looked atrocious to the point you could hardly see what was going on. I also noticed the "confetti" effect. I seemed to be the only one that noticed. It seems most people don't care as much as I did. I tried to explain it it to people but it just went over their heads.

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