iPhones will be the star of the show at Apple's big Sept. 12 event. But two other major product refreshes are also rumored to be unveiled: A third-generation Apple Watch and -- our focus here -- a new Apple TV box.

The current version of the Apple TV was launched back in September 2015, alongside the iPhone 6S. Since then, plenty of top-tier content partners have added apps. And Apple's software updates have delivered new features such as single sign-on and a universal TV app.

But sales of the box, the base model of which retails for $149, £139 or AU$239, have lagged behind major streaming competitors, including market leader Roku. And with Apple simultaneously investing up to $1 billion in original content, we expect Apple will want to give its video platform a shot in the arm.

With that in mind, here's what we expect to be announced in Cupertino on Tuesday.

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What we expect

New hardware with 4K and HDR support: Expect an upgraded Apple TV box that finally adds compatibility with 4K and HDR video. That means the new box will deliver the best 3,820x2,160-pixel resolution and -- more importantly -- the improved color palettes and contrast ratios of high dynamic range (HDR) video when connected to compatible TVs.

4K and HDR content: Of course, being able to deliver that improved video is worthless without compatible content. Expect Apple to highlight the availability of 4K and HDR-enabled iTunes videos (assuming the company has smoothed over pricing disagreements with Hollywood studios). Third-party apps such as the recently added Vudu service may also add 4K and HDR compatibility, bringing their Apple TV features up to parity with their apps on Roku and other streaming platforms.

Amazon Video app: As confirmed by CEO Tim Cook back in June, Apple TV will finally get an Amazon Prime Video app. In addition to adding another provider with a strong catalog of original 4K and HDR content, the overdue inclusion of Amazon plugs the biggest remaining hole in Apple TV's app lineup.

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Other stuff we might see



Remote redesign: The current Apple TV remote has a lot of haters for two reasons. Its touch panel is ultrasensitive, so a mere brush of the finger can fire up your Apple TV unintentionally, switching it away from anything else you might be watching. The remote's symmetrical design compounds the problem as users always seem to end up holding it upside-down. Both issues seem relatively easy to fix with small design tweaks.

More single sign-on partners: In 2016, Apple TV added a nifty single sign-on feature. It meant that your TV subscription service username and password (cable, satellite or streaming) would automatically be passed on to the many so-called TV Everywhere apps. This meant you shouldn't have to tediously enter that information each time you installed apps for individual channels such as HBO, TBS, ESPN or Bravo. The problem? Some of the country's biggest cable TV providers -- most notably Comcast and Spectrum, also known as Charter and Time Warner Cable -- weren't on the list. Dish, DirecTV, PlayStation Vue, Sling TV and many regional providers, however, are. Securing those two big holdouts would make Apple TV a much more convenient cable box replacement for tens of millions of households. Screenshot by David Katzmaier/CNET

Better TV app and universal search: In 2016, Apple TV's big software add was the TV app. It was designed as a one-stop shop for accessing TV shows regardless of their source. For instance, "The Walking Dead" page will let you access that show's episodes from iTunes, Netflix or the AMC app. Depending on your subscriptions -- if you have Netflix or if you get AMC through your TV provider -- that means you could watch some or all of the episodes at no additional charge. Pretty cool, but will Apple fold archrival Amazon into that mix? We're guessing no. Compare that to Roku, which lets you access that show via Netflix, Amazon, Vudu and Fandango Now (though the latter three, like iTunes, require you to pay per episode or per season).

Price drop? With a starting price of $149, Apple TV costs many times more than competitors from Roku, Google and Amazon, which start at $30, $35 and $40, respectively. Step-up models with 4K and HDR generally start at costs between $70 and $100. Assuming the new Apple TV hits at the same price as the 2015 model, it would be a perfect opportunity to keep the "old" non-4K model on the market at a reduced price of, say, $99. Still, that's north of those competing products, and more than Apple was selling the pre-2015 model between March 2015 and October 2016, when it was discounted to $69.

HomePod integration: Apple's smart speaker, the HomePod, has already been announced for a December release. Showing off some additional AirPod tie-ins to Apple TV seem like a no-brainer. The obvious ones: Siri voice control of Apple TV without the need for the button push on the streaming box's remote, and stereo or surround sound for videos being played on Apple TV.

James Martin/CNET

"Real" gaming support: OK, this is a long shot, but hear me out. Apple TV already has a lot of games, and it supports console-style Bluetooth gamepads such as the Steel Series Nimbus. But with the new Apple TV presumably jumping from an A8 chip to something more like an iPhone 7-level A10, where are the more console-worthy games? Existing titles include Minecraft, Oceanhorn and Transistor. Those are fine, but there's no reason that older Grand Theft Auto games (already on iPhone and iPad) or maybe even something like Half-Life (on rival Nvidia Shield) couldn't run on Apple TV. Throw in improved "pause on Apple TV, resume on iPhone or iPad" support, and you've got a nice Nintendo Switch rival, too.

What we don't expect (for now)

A real TV: Apple would need a manufacturing partner to get 55- to 65-inch display panels, which would probably mean supply chain leaks in Asia -- and we've heard none. I also don't think Apple wants to deal with the logistical problems of moving these giant boxes in and out of their pristine retail stores. But I'd love to be wrong on this one.

An Apple cord-cutting service: The attraction of a one-stop service for live and on-demand TV is attractive to Apple fans who'd like a TV service to live alongside Apple Music. But, to date, Apple apparently hasn't been able to get content providers (including Disney, NBC Universal, Fox and CNET owner CBS) to sign on to a package at the price point that Apple wants to offer. Besides, if such a deal were in the works, that too would be ripe for leaks. And now that Apple TV already offers Sling TV, Hulu, DirecTV Now, Fubo and PlayStation Vue, customers who want cord-cutting alternatives to cable TV are well-served. It all means that an Apple service seems less critical than it was considered three to five years ago.

All questions will be answered on Tuesday

Of course, this speculation all becomes irrelevant by Tuesday afternoon. CNET will be covering the Apple event live, starting at 9 a.m. PT (noon ET, 5 p.m. UK, 2 a.m. AEST).

Apple Sept. 12 iPhone event live coverage: Follow CNET's liveblog in real-time.

iPhone X, iPhone 8: Everything we know about Apple's new iPhones.