WEBVTT 00:00:00.000 --> 00:00:04.240 Life is full of situations where it makes sense to just take a shortcut, right? 00:00:04.240 --> 00:00:08.240 I mean how many of us are guilty of just sticking a vase on top of a scratch table instead of 00:00:08.240 --> 00:00:12.880 refinishing the thing? And so it is with video signals. Most of the things we consume on our 00:00:12.880 --> 00:00:18.000 screens are compressed in some fashion in order to prevent overwhelming our connections, and today 00:00:18.000 --> 00:00:22.640 we're going to talk about a special kind of compression called chroma subsampling. 00:00:22.640 --> 00:00:27.680 No, this is not when you decide to try a bunch of sandwiches at once, but rather refers to a 00:00:27.680 --> 00:00:32.800 technique that takes advantage of the fact that our eyes are more sensitive to differences in 00:00:32.800 --> 00:00:37.680 light than differences in color. Think about what it's like to watch a black and white movie, 00:00:37.680 --> 00:00:43.040 although you might miss the colors, it's still very easy to tell exactly what's going on on the 00:00:43.040 --> 00:00:48.880 screen, right? So chroma subsampling throws out some of the video feed's color data in order to 00:00:48.880 --> 00:00:54.800 allow for more luminance information. So that means the picture has enough contrast to remain clear 00:00:54.800 --> 00:00:59.920 to us while using much less video bandwidth. But how does this work? Well, when you're looking at 00:00:59.920 --> 00:01:06.880 chroma subsampling specifications, you might see numbers like 422 or 420. This basically means 00:01:06.880 --> 00:01:12.960 that if you take a 4 by 2 block of pixels, only one half or one quarter, respectively, of the 00:01:12.960 --> 00:01:18.560 original color data will be retained. The luminance data for each pixel is retained fully, that's the 00:01:19.200 --> 00:01:24.000 but applied to only one half or one quarter as many colors. 00:01:24.000 --> 00:01:30.160 Chroma subsampling is a widespread standard for movies and TV, which typically use the 420 method. 00:01:30.160 --> 00:01:35.440 It's a big part of the reason you can watch 4K Netflix or YouTube without a constantly 00:01:35.440 --> 00:01:40.320 buffering. And even non-streaming options like home Blu-ray players make frequent use of it. 00:01:40.320 --> 00:01:45.040 And although this might sound like you'll end up not seeing accurate colors, our eyes simply 00:01:45.040 --> 00:01:50.880 can't tell the difference in many cases. Given that a 420 subsampled video file only takes up 00:01:50.880 --> 00:01:57.520 about as half as much space as an uncompressed or 444 file, it's not surprising that it's very 00:01:57.520 --> 00:02:04.240 commonly used. But are there times when 444 is actually important to have? The answer is yes, 00:02:04.240 --> 00:02:10.080 especially if your screen is connected to a computer. You see, chroma subsampling is fine for 00:02:10.080 --> 00:02:15.200 content with smooth gradations like movies and sporting events and even many video games. 00:02:15.200 --> 00:02:21.120 But if the display you have hooked up to your PC is subsampling, text and other UI elements with 00:02:21.120 --> 00:02:26.400 sharp edges can look smudged and blurry. This typically is not an issue for actual computer 00:02:26.400 --> 00:02:32.160 monitors as these are usually designed to display a 444 signal. But televisions are notorious for 00:02:32.160 --> 00:02:36.640 undesirable subsampling, which you may have seen for yourself if you've ever tried to type a word 00:02:36.640 --> 00:02:41.840 document or read an article in your browser on your living room TV. An artifact sometimes called 00:02:41.840 --> 00:02:46.880 fringing. Pretty hard to read, depending on the background color. Nowadays, though, many modern 00:02:46.880 --> 00:02:52.080 TVs can be specifically told that they're connected to a PC and therefore should not subsample. 00:02:52.080 --> 00:02:57.040 Typically, if you can locate a setting called something like UHD color, deep color, RGB, 00:02:57.040 --> 00:03:02.720 or something similar, switching to it should force the TV to display your images in 444. 00:03:02.800 --> 00:03:08.640 Other times, simply selecting a PC or computer mode on your TV will also do the trick. But if 00:03:08.640 --> 00:03:14.560 you're connecting your computer to your TV to enjoy high bandwidth features like 4K at 120Hz 00:03:14.560 --> 00:03:21.440 or HDR, make sure the television can support these bells and whistles simultaneously with 444. 00:03:21.440 --> 00:03:26.160 Recently, there was a bit of a scandal with one of LG's OLED TV lineups because the TVs 00:03:26.160 --> 00:03:32.480 would chroma subsample when set to 4K120, resulting in bad looking text when connected to a PC. 00:03:32.560 --> 00:03:38.720 Even though the display's HDMI 2.1 ports should have delivered enough bandwidth to not have to 00:03:38.720 --> 00:03:43.920 subsample. LG fixed the issue with a firmware update, I guess, but this is just the kind of stuff you 00:03:43.920 --> 00:03:49.120 can expect when you're bold enough or rich enough to be an early adopter. So thanks for watching, 00:03:49.120 --> 00:03:53.600 guys. If you liked this video, give it a thumbs up, hit subscribe, and check us out. Hit us up in 00:03:53.600 --> 00:03:59.440 the comments section with your own original ideas of topics that we should cover in the future.