Amazon is rumoured to be working on a 4K version of its Fire TV streaming box.
A patent for the device was filed with the Federal Communications Commission in the US. While it wasn't registered by Amazon, blogger Dave Zatz claims the company filing it is under Amazon's umbrella.
4K is also known as Ultra HD (or UHD), and has four times as many pixels as standard high definition.
4K content is thin on the ground at present. Some of Amazon Prime Instant Video's homegrown shows are available in the resolution, as are a selection of Netflix's.
Recently, Amazon Prime Instant Video became the first paid-for streaming service to offer offline viewing. If it is working on a 4K streaming box, it would seem Amazon is taking the fight to Netflix and the newly-announced Apple TV.
Amazon is also said to be launching a budget tablet in time for Christmas.