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Despite the fact that 4K is moving into mainstream, there are still some things that are typically misunderstood. One of my favorites is that if we follow standard naming conventions, 480i being 480 vertical lines, 720p being 720 lines, 4K should be called 2160. The 4K name comes from the around 4000 horizontal lines, depending on the standard. Why change which side is measured? Let’s face it, 4K sounds way better than 2160.
Beyond just the naming conventions there are some other pretty big misconceptions about 4K. As is often the case, bigger doesn’t always mean better.
Beyond just the naming conventions there are some other pretty big misconceptions about 4K. As is often the case, bigger doesn’t always mean better. The first misconception really centers around how to move that much data from point A to point B. Everyone knows 4K means more resolution, but what does that really amount to? Lastly, do more pixels really mean a better picture? Here are some things you should keep in mind when considering 4K.
3G, 6G, 12G
So what is the difference between 3G, 6G, and 12G? The number before the G is simply the bit rate, measured in gigs of data transferred a second. Typically these numbers refer to the amount of data passing through cables, for instance 3G is sufficient for HD video up to 1080. Once you make the jump for 4k you have a couple of options; 3G alone isn’t going to cut it, so your options are to use multiple 3G cables or higher capacity 12G. Using 4 3G cables is called a Quad link. For those of you have been doing this video thing a while, it’s similar to using the old RGBHV for video. Back in the day, HD video was transferred over 5 bonded cables; 3 RBG one each for Red, Blue, and Green color channel and then 2 HV for Horizontal and Vertical sync. Similarly in 4K, quad link splits the image into 4 sections. Each section is transferred over its own cable. In fact, if you are currently using a RGBHV signals and your cables are rated 75 ohm BNC coax cables that support at least 1.5 Gb/s of bandwidth, it’s possible your current HD cable may be rated high enough to simply jump to 4K quad link.
6G is a standard developed by Blackmagic, who apparently got tired of waiting for 4K to standardize. This might be great if you are using Blackmagic products, but make sure all the components in your signal chain are compatible with the resolution you are trying to achieve. It is not safe to assume just because something is labeled “4K” that it’s compatible with what you are using.
Resolution
4K means four times the resolution of 1080, and in a 3G system, this means four times the cabling. However, the question remains, “Does the picture look four times better?” Unfortunately there is no easy answer to this, because there are a lot of variables that come into play. One such variable is “visual acuity,” or how good the viewer’s eyesight is. More pixels typically means more space for information, and smaller pixels which result in sharper images. However, there are several different resolutions that are 4K. Much of the difference stems from where the media is being consumed. For example, on TV and consumer media, 3840 × 2160 (4K UHD) is what most everyone recognizes as 4K. However, in the movie industry, 4096 ×2160 (DCI 4K) is the dominant 4K standard. An internet search of 4K resolutions, especially as it relates to monitors, will result in terms like: WQUXGA, WQHD+, DFHD. All of these are technically 4K, so they are similar but they are not the same.
If you spend more time scouring the internet for information on 4K you will discover one of the big factors is viewing distance. At that point you will find calculators and charts and all kinds of information about how to figure out optimal viewing distance. For a real-world example of how this works I used one of these online distance calculators and the measurements of our auditorium screen of 16 feet by 9 feet to do some calculations. If we are projecting SD content on that screen (which we were when it was installed) the viewing distance based on visual perception is 76.8 feet--which is the about the depth of our auditorium. However, if we change the content to 1080, the optimal viewing distance drops to 28.8 feet. If you are like me, your knee-jerk reaction to that is “how does upping the resolution lower the viewing distance?” Easy, that distance is based on what the human eye can resolve. The bigger pixels in the SD content mean you can be further away and still resolve the image. At the same 76-foot distance your eye can’t resolve the individual pixels and details of the higher resolution. At that point the larger SD pixels are better. So when my church made the jump to HD what we actually did was worsen the image for the people at the back of the room, leave it the same for the middle distances and improve it for the people in the first 4-6 rows. Meaning somewhere between 1/2 and 2/3 of the congregation saw the same, no noticeable change, when we made the jump.
This one is key to keep in mind: don’t assume the screen you have in place will still get the job done.
Now imagine my church making the same jump to 4K, and leaving all other parameters the same. If doubling the resolution by going to HD cut the viewing distance by over half, what do you suppose would happen if we then took that HD resolution and ramped it up 4 times? You guessed it, it would cut the viewing distance again. So it means visually the best seats in the house would be closer to the front and there would be less of them. Which is great if all your elders sit in the first few rows. If they all sit in the back, you might have a harder time making a solid argument for the budget you spent on going to 4K. So in our case if we want to maximize the viewing distance and move the best seats in the house further back than the first row, we would have to increase the size of our screen, as well. This one is key to keep in mind: don’t assume the screen you have in place will still get the job done.
Now I want to be clear, I am talking about this in very broad strokes. Chances are good you and your team are true videophiles, like most video guys I know, and will be able to tell the difference between the higher resolutions even at a distance. Most of these calculators are referring to OPTIMAL viewing distance and, let’s face it, they are provided by manufacturers that are trying to sell you something. So you should take all of this with a grain of salt.
Going to 4K probably isn’t necessary for every church to do right now, but if it is something you are considering, I cannot stress enough how important it is for you to do your homework and to get an integrator involved who can support you.
Summing it up
Right now, 4K is still a little bit of the Wild West. It’s getting better, but it has some opportunity for improvement. While there are many flavors of 4K, they tend to be different across the medium of consumption. This makes it very important that you and your integrator confirm that your 4K monitor will play nice with the 4K coming off your switcher, because they might not be exactly the same. It’s also important to confirm the infrastructure. If you have 3G cables, make sure you know how much it will cost to replace them with 12G.
Lastly, churches and their integrators should not make any assumptions about the old infrastructure when transitioning to 4K. Do the research, confirm, and triple check the current infrastructure before you buy. Going to 4K probably isn’t necessary for every church to do right now, but if it is something you are considering, I cannot stress enough how important it is for you to do your homework and to get an integrator involved who can support you. The absolute last thing they want is to spend a lot of money with no perceived improvement--or worse, spend a lot of money and have the final product look worse.
