Details of the 4K Apple TV pop up in the HomePod firmware

It's hard keeping products a secret when you have to release firmware code for other, connected products you've already announced, and the code that developers have got their hands on for the Apple HomePod has already revealed some iPhone 8 secrets.

Yet more digging into the HomePod data by iOS developer Guilherme Rambo has revealed references to a "4kHDR", "HDR10" and "Dolby" display modes, suggesting this smart speaker is indeed going to be able to beam content to a brand new, 5th-gen, 4K Apple TV.

Such a box definitely feels overdue at this point, with most new TVs on the market 4K-compatible, and the rumors have been swirling for a while that Apple has one in the works. Rival devices like the Amazon Fire TV and the Google Chromecast Ultra are already fully 4K prepped.

Video editor Marc Bach weighed in to note that the "HLG" or Hybrid Log Gamma mode is in fact a third HDR mode, giving the new Apple TV support for three different HDR formats, on top of the 4K resolution for movies, TV shows, and maybe even a few games.

HDR or High Dynamic Range boosts brightness and contrast to give a better range of colors in a picture - it gives more detail in darker and lighter areas of a picture. No one can decide on one HDR format though, which is why it looks like the Apple TV is going to support HDR10, Dolby Vision, and Hybrid Log Gamma.

Other details of the upcoming Apple TV are pretty thin on the ground: 4K support is a given, but a bigger hard drive and more complex apps have also been mooted, as well as improved Siri support. Late 2017 is looking like the most likely launch window.