Three World Cup football matches being played in Brazil this summer will be streamed in ultra-high-definition (UHD), the BBC has announced. The format, also known as 4K, offers four times the resolution of 1080p high definition video. The matches - including the quarter final and the final - mark one of the first times a live event has been streamed over the air in UHD in the UK. They will only be made available to a limited number of TVs at BBC sites. But it could pave the way for more widespread use of the technology. One of the biggest challenges of distributing UHD TV to the home is how to make it compatible with existing broadcast and broadband capacities.