Just about all premium TVs – and for that matter the $899 bargain at your local supermarket – now offer Ultra High Definition resolution. But sources of UltraHD content have been relatively slow to appear. Now Apple has joined in with what might be one of the most important new sources, thanks to a new version of the Apple TV, and an upgrade to iTunes content.

The new Apple TV 4K looks physically the same as the “old” – fourth generation – Apple TV. But it has a whole lot of upgrades that don’t look apparent on the surface.

First, there’s the stuff that Apple is promoting. Instead of full HD the HDMI output of the new model will deliver UltraHD output – that’s 3840 by 2160 pixels. Lower resolution material will be upscaled to UHD if your TV supports it. (HDMI devices always query the capabilities of the devices to which they are connected, and try to match their preferred resolution.)

In addition, it supports HDR and Dolby Vision. HDR – High Dynamic Range – is sometimes known as HDR10. It allows four times the number of steps from white to black compared to traditional formats, allowing for smoother graduations (no more of those paint-by-the-number colour bands) along with even brighter whites as TVs improve in the future. Dolby Vision expands that further, quadrupling the steps again and using “metadata” in the video stream to give the TV information on how best to display the material, scene by scene.

So, where are the movies and TV shows with these magical UHD and HDR or Dolby Vision characteristics? They are in places like Netflix and Amazon Prime video. And in iTunes.

If you rush into the Apple store when they become available on 22 September to buy one (hey, you can order from tomorrow), chances are you won’t be able to stream UHD Netflix straight away. Apple says that the “4K HDR content from popular video services, including Netflix” is “coming soon”. So it looks like they’re putting the finishing touches on a firmware upgrade to get that happening.

iTunes goes 4K

More important for those in the Apple entertainment ecosystem, iTunes is offering 4K content. Indeed, there a very important announcement that came with the Apple TV 4K announcement: