1 00:00:00,000 --> 00:00:04,240 Life is full of situations where it makes sense to just take a shortcut, right? 2 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 3 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 4 00:00:12,880 --> 00:00:18,000 screens are compressed in some fashion in order to prevent overwhelming our connections, and today 5 00:00:18,000 --> 00:00:22,640 we're going to talk about a special kind of compression called chroma subsampling. 6 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 7 00:00:27,680 --> 00:00:32,800 technique that takes advantage of the fact that our eyes are more sensitive to differences in 8 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, 9 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 10 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 11 00:00:48,880 --> 00:00:54,800 allow for more luminance information. So that means the picture has enough contrast to remain clear 12 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 13 00:00:59,920 --> 00:01:06,880 chroma subsampling specifications, you might see numbers like 422 or 420. This basically means 14 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 15 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 16 00:01:19,200 --> 00:01:24,000 but applied to only one half or one quarter as many colors. 17 00:01:24,000 --> 00:01:30,160 Chroma subsampling is a widespread standard for movies and TV, which typically use the 420 method. 18 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 19 00:01:35,440 --> 00:01:40,320 buffering. And even non-streaming options like home Blu-ray players make frequent use of it. 20 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 21 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 22 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 23 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, 24 00:02:04,240 --> 00:02:10,080 especially if your screen is connected to a computer. You see, chroma subsampling is fine for 25 00:02:10,080 --> 00:02:15,200 content with smooth gradations like movies and sporting events and even many video games. 26 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 27 00:02:21,120 --> 00:02:26,400 sharp edges can look smudged and blurry. This typically is not an issue for actual computer 28 00:02:26,400 --> 00:02:32,160 monitors as these are usually designed to display a 444 signal. But televisions are notorious for 29 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 30 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 31 00:02:41,840 --> 00:02:46,880 fringing. Pretty hard to read, depending on the background color. Nowadays, though, many modern 32 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. 33 00:02:52,080 --> 00:02:57,040 Typically, if you can locate a setting called something like UHD color, deep color, RGB, 34 00:02:57,040 --> 00:03:02,720 or something similar, switching to it should force the TV to display your images in 444. 35 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 36 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 37 00:03:14,560 --> 00:03:21,440 or HDR, make sure the television can support these bells and whistles simultaneously with 444. 38 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 39 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. 40 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 41 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 42 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, 43 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 44 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.