4K televisions are being displayed by multiple manufacturers, and are being touted as the last HD resolution you'll ever need in your home. The $17,000 LG 84LM9600 will be the largest LCD on the market, and the first with 4K resolution:
4K is the next frontier in High Definition video resolution: it refers to 4096x2304 pixels, four times the definition of 1080p. Another similar consumer-targeted resolution of 3840x2160 is being marketed as "Ultra HD" - the technical standard being named "Quad HD".
How big does 4K "feel"? Take a look at this image, keeping in mind that MOST content that you watch on your HDTV via cable or satellite is 720p, and Blu-Ray discs are 1080p:
That's a pretty impressive increase in pixels. Both 4K and 2K come to us from the world of cinema. George Lucas pioneered shooting digitally to avoid the cost of film stock, and originally shot "Attack of the Clones" in full 1080p HD. Digital Cinema Initiatives was formed in 2002 to determine global standards for digital cinema, and devised two standards: 2K (slightly larger than 1080p HD) and 4K.
So, what does all of this mean for online video? In short, we won't be seeing it for a long time, for 2 key reasons:
1) You don't need it:
Geoffrey Morrison's CNET article entitled "Why 4K TVs are stupid" goes into a good level of mathematical detail about why 1080p is really more resolution than the human eye can see anyway unless you're closer than 6 feet to your TV. The human eye with 20/20 vision can resolve 1 arcminute, or 1/60th of a degree. Doing some trigonometry based on your distance from your TV and its screen size can tell you whether a resolution greater than 1920x1080 even matters.
Other sources indicate a small sliver of distance/size where Ultra HD/4K may make a difference for you.
Of course, we're talking about online video, and TVs aren't the only display in town. What about Macs, PCs, tablets, and mobile devices? Panasonic has demonstrated an Ultra HD tablet intended for architects and other workers who may need super high resolution in a tablet form factor:
This could eventually lead to 4K screen technology in the home, but the bottom line is still that the price will have to reduce dramatically before the dubious value proposition to most consumers is anywhere near worth it.
2) You can't stream it:
Those of us with high-speed internet at home typically see speeds around 10Mbps. This can fluctuate, and while streaming 720p content is usually a pretty consistent experience these days, streaming 1080p content is often a buffer-fest.
1080p content (1920x1080 pixels) has 2.25 more pixels per frame than 720p content (1280x720), and consequently takes about 2.25 times greater bandwidth to download.
4K content (4096x2304 pixels) has 10.24 more pixels per frame than 720p content. Roughly, this means you'd need a connection providing around 45Mbps in order to stream 4K content.
In a world where home internet providers are moving towards monthly usage caps, the massive size of the video being downloaded is perhaps more of a challenge than even the daunting speed requirements.
One factor that could help here is the upcoming H.265 High Efficiency Video Coding standard. With claims of double the efficiency of H.264, 4K content comes a bit closer to the reach of users at home.
Do you think 4K will be relevant to our work in online video in the next few years?
My expert video compressionist friend Alex Zambelli did a lengthy analysis describing why H.265 will actually get us very close to being able to stream 4K some time soon. Check out his post here. The key exerpt (below) is that you cannot take current bandwidth requirements for 720p/1080p and do simple multiplication based on the number of pixels - the relationship is non-linear:
I believe that the relationship between bit rate and picture size is not linear, but closer to a power function...
In other words, I believe that as the pixel count gets higher a DCT-based video codec requires fewer bits to maintain the same level of visual quality.
Thanks for the detailed analysis, Alex!