Qualcomm just recently released their newest high-end mobile processor, Snapdragon 850. They claim this chip is 40 percent faster than its predecessor and that it was designed from the ground-up for 4K video playback. Though this high-res format is UltraHD, the implementation is slow and rather expensive.
4K means that the horizontal resolution has over 4,000 pixels. This is roughly twice as much as the current 1080p. Not surprisingly, consumer interest is rather low. Other companies, however, like Nvidia and Netflix are interested a want to support it in some way.
Qualcomm states they will not ship the chip to manufacturers until next year. This may be a good thing and smart marketing move allowing 4K to get bigger and showing that 1080p is the old way in HD resolution.