How important is HDMI 2.0 to 4K Ultra HD?
HDMI 2.0 is the latest iteration of the HDMI specification. While the existing HDMI 1.4 standard can deliver 4K video, it's limited to 30 frames per second (or 30Hz). While this is fine for most movies, broadcasters are looking for higher frame rates for TV.
HDMI 2.0 increases bandwidth up to 18Gbps and supports 4K Ultra HD at 50/60 fps, with 12-bit 4:2:2 colour (you don't need any special cables for HDMI 2.0 interconnectivity, any current high-speed cable will work). However, only Panasonic currently offers an HDMI 2.0 compatible 4K TV, in the shape of the TX-L65WT600.
So where does that leave the remaining first generation 4K sets? Well both Philips and Samsung, whose 4K panels are coupled to separate connection boxes, say they'll simply introduce new tuners which owners can upgrade to.
Sony and others are looking to implement a firmware fix; by shedding colour sub pixels they reckon they'll be able to fit high frame-rate 4K down a HDMI 1.4 pipe, most likely with 8 bit 4:2:0 colour. How visible this kludge will be remains to be seen. For what it's worth, we've seen JVC's 4K e-Shift3 projectors running 4K at the same colour resolution, and they look spectacular so the omens are good.
Hang on, what about 8K?
If 4K offers four times the resolution of Full HD, then 8K will deliver 16 times the definition. 8K screens comprise a staggering 33 million pixels.
This is an order of magnitude beyond any display technology currently available, and only one broadcaster, Japanese state owned NHK, has publically said it intends to commercialise the technology.
Also known as Super Hi-Vision, a number of 8K trials have been conducted, including acquisition at the London 2012 Olympics. NHK has since pledged to shoot and transmit the 2020 Tokyo Olympics in the format.
Of course, bringing 8K to market is a formidable technical challenge. As with 4K, HEVC, is currently favoured as the best compression technology for the job.
However, because the benefits of 8K image definition only really become apparent on screens 84-inches and larger, the format is not seen as a commercially viable platform by most broadcasters and TV manufacturers. If you're waiting to jump from Full HD to 8K, you could be kicking your heels for quite some time.
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