HackerTube
HomeLongsLikedHistoryWatch laterCategoriesPlaylistsSettings

How a TV Works in Slow Motion - The Slow Mo Guys

The Slow Mo Guys2 HN recommenders · recommended in 2 months, 2022-2026
YouTube
45.7M views · 8 years ago · explainer · evergreen

The Slow Mo Guys film a TV and screens with a high-speed camera to show how displays build an image. The footage includes CRT-style scanning and how pixels light up over time.

Frequently linked as visual proof of how a CRT's raster scan and phosphor decay work.

Audio & video engineeringEveryday physics & science demos#crt#rasterscan#slowmotion#phosphorpersistence#screens

8 comments from Hacker News

@kevincox2026 · in “JPEG Compression”

That's not quite true. Only one pixel is being activated at a time but the phosphors continue to emit light for many pixels. In practice you get a handful of lines lit to varying degrees at at time. Maybe 1-2 lines quite brightly lit and then a trail of lines that are fading pretty significantly (but still emitting light). They yes, our persistence of vision fills in the rest to provide the appearance of a fully lit screen. This video has some great slow-mo of CRTs ▶ this video

RecommendsView on HN
@retrac2025 · in “How does a screen work?”

CRTs are still slightly magical to me. The image doesn't really exist. It's an illusion. If your eyes operated at electronic speeds, you would see a single incredibly bright dot-point drawing the raster pattern over and over. This YouTube video by "The Slow Mo Guys" shows this in action: ▶ this video

RecommendsView on HN
@rcxdude2025 · in “Blur Busters Open Source Display Initiative – Refresh Cycle Shaders”

They frequently flicker or are only showing part of an image in video footage or photos, for exactly this reason. They're a right headache to film clearly. (see this youtube video showing one in slow-motion to get an idea: ▶ this video )

CitesView on HN
@chongli2023 · in “Checkmate 19" IPS Retro Monitor”

That's an oversimplification of the physics. CRT televisions have very low persistence phosphors. If you look at high-speed video of a CRT during a raster scan, the line is visible for far less time than the entire frame [1]. This technique relies on persistence of vision [2] to create the illusion of a complete frame. If you want to calculate the response time of a single dot on the phosphor, it is way down into the microseconds. I don't know enough about OLED displays to comment. I do know that LCDs don't even come close to the speed of CRTs at transitioning through high contrast images, the key to producing fast and responsive motion of sprites (which are high contrast against the background by design in most retro games). [1] ▶ this video [2] link

CitesView on HN
@mortehu2023 · in “Simple streetlight hack could protect astronomy from urban light pollution”

If you look at high speed footage of a CRT monitor, you'll see that only a few scan lines are lit at a time. ▶ this video

CitesView on HN
@aimor2023 · in “How Games Used to Look: Why Retro Gaming on a CRT Looks Different [video]”

"The video makes it seems that there's no temporal bleeding on CRTs. This sounds unlikely to me..." There is, but I don't remember it being noticeable even on cheap TVs. I still miss the lack of motion blur that CRTs gave by default. I found a forum post where someone lists these values: "Phosphors in current use for CRT-applications: Red: phosphor = Y2O2S:Eu3+. Lifetime (1/e time) = 150 us, single exponential. Green: phosphor = Zn2SiO4:Mn2+. Lifetime (1/e time) = 10-15 ms. Clearly, this is quite long and is the limiting factor in increasing frame-frequency. Note: the emission decay has a highly non-single-exponential decay --> at long times (~1 s) still some emission can be observed by the eye. This can be seen clearly by looking into the green CRT directly after the image was switched off. However, the intensity is too low to cause problems in an active image when the image-frequency is below ~100 Hz. Blue: phosphor = ZnS:Ag,Cl. Lifetime (1/e time) = ~100-200 us. Note: not single-exponential decay, but no emission at long times. (Source: Shionoya & Yen, "Phosphor Handbook", 1998.)" link And in this high framerate video of a CRT you can see the different colors decay at different rates. Here the blue seems to decay the fastest. But they're all imperceptibly dark by the time the scan line comes around again. I have no idea if there's any cumulative effect that's perceptible. ▶ this video link

CitesView on HN
@iforgotpassword2023 · in “Secret Colours of the Commodore 64”

It's said later in the article that you'd need two colors with similar brightness to avoid perceivable flicker. CRTs did have some afterglow but it wasn't even for a full frame, let alone two. ▶ this video

CitesView on HN
@rasz2022 · in “Video codecs and 4k”

1. As GL1zdA already pointed out in blog comments 1992 Creative Video Blaster CT6000 was a single frame screen grabber and not a video encoding/decoding accelerator. YT "Creative Videoblaster CT6000 in action" link shows what it does. link "converts a standard full-motion video image (composite video source) into a format for display on a computer graphics monitor" emphasis on the _image_. "It can position and scale the video image onto the output display and allows the video image to be merged with computer graphics for interactive multimedia applicaiton." means overlay analog video on VGA monitor. The first true video decoding accelerator on PC market came out of David Sarnoff Research Center owned by RCA, later purchased by GE, then finally video tech carved out and sold to Intel. Called Digital Video Interactive link it did in fact "real time audio and video decompression, 30 frames per second with a resolution of 320x240". Intel repackaged it into one chip i750 and called it Indeo. Creative released a product based on it in mid 1994 - Video Blaster RT300. PCI bus was already mainstream in 1994, as were Pentiums. You most likely blurred those two together into one product. 2. "so the quality could be very high. Streams of 8 to 12 mbit of data for a single channel were no exception." SD video DVD bitrate is 10Mbit, and here we have OTA stations pushing 720p/1080i at same or lower bw using same codec (US mpeg2). Whole multiplexer in ATSC offers ~20Mbit, and then TV st

CitesView on HN
Filming the Speed of Light at 10 Trillion FPS13:06

Filming the Speed of Light at 10 Trillion FPS

The Slow Mo Guys
42.1M views • 7 years ago
Lines of Light: How Analog Television Works16:47

Lines of Light: How Analog Television Works

Technology Connections
1.5M views • 9 years ago
These Are Not Pixels: Revisited17:04

These Are Not Pixels: Revisited

Technology Connections
611K views • 8 years ago
Visualizing video at the speed of light — one trillion frames per second2:47

Visualizing video at the speed of light — one trillion frames per second

Massachusetts Institute of Technology (MIT)
12M views • 14 years ago
How Analog Color TV Works:  The Beginnings13:14

How Analog Color TV Works: The Beginnings

Technology Connections
503K views • 8 years ago
what did you do22:13

what did you do

Noodle
1.5M views • 11 months ago
CD / Color7:00

CD / Color

Captain Disillusion
2.9M views • 6 years ago
1 million fps Slow Motion video of bullet impacts made by Werner Mehl from Kurzzeit10:00

1 million fps Slow Motion video of bullet impacts made by Werner Mehl from Kurzzeit

Matt Rece
15.6M views • 17 years ago
Reveal Invisible Motion With This Clever Video Trick14:20

Reveal Invisible Motion With This Clever Video Trick

Steve Mould
2.8M views • 6 years ago
A laser pointer at 2 billion fps makes the speed of light look... kinda weird29:22

A laser pointer at 2 billion fps makes the speed of light look... kinda weird

AlphaPhoenix
6M views • 1 year ago
Watch electricity hit a fork in the road at half a billion frames per second26:29

Watch electricity hit a fork in the road at half a billion frames per second

AlphaPhoenix
3M views • 2 years ago
LCCS: The LCD / CRT Hybrid from JVC12:16

LCCS: The LCD / CRT Hybrid from JVC

Technology Connections
2.3M views • 7 years ago
Slow Motion Flipping Cat Physics | Smarter Every Day 586:26

Slow Motion Flipping Cat Physics | Smarter Every Day 58

SmarterEveryDay
11.3M views • 14 years ago
Racing the Beam Explained - Atari 2600 CPU vs. CRT Television38:26

Racing the Beam Explained - Atari 2600 CPU vs. CRT Television

Retro Game Mechanics Explained
400K views • 5 years ago
E-paper hacking: fastest possible refresh rate27:55

E-paper hacking: fastest possible refresh rate

Applied Science
582K views • 9 years ago
But why would light "slow down"? | Visualizing Feynman's lecture on the refractive index28:34

But why would light "slow down"? | Visualizing Feynman's lecture on the refractive index

3Blue1Brown
2.9M views • 2 years ago
CRS-6 First Stage Landing0:23

CRS-6 First Stage Landing

SpaceX
5.5M views • 11 years ago
Imaging at a trillion frames per second | Ramesh Raskar11:02

Imaging at a trillion frames per second | Ramesh Raskar

TED
3.2M views • 14 years ago
How Do Night Vision Goggles Work?27:16

How Do Night Vision Goggles Work?

Veritasium
8.4M views • 3 years ago
AT&T Archives: Similiarities of Wave Behavior (Bonus Edition)28:03

AT&T Archives: Similiarities of Wave Behavior (Bonus Edition)

AT&T Tech Channel
473K views • 14 years ago