Sony first revealed its 4K streaming service, Ultra, back at the Consumer Electronics Show in January. Now, the company's home video arm (Sony Pictures Home Entertainment) has announced that it will launch on April 4.

The service, accessed via an Android app, will be available exclusively on Sony's new 4K TV sets. There won't be a rental option at launch; instead, users will pay $30 to purchase a movie. This was apparently a "commercial decision," but Sony said if there turns out to be a demand for rentals, the company could introduce the feature "pretty quickly."

Initially, you'll only be able to rent movies from Sony Pictures, but the company said it wants to add content from other studios. "Over time, we want to expand the breath and depth of the content," said Sony Pictures Entertainment VP Jake Winett

Once bought, titles will be stored in Sony's Ultraviolet cloud service, probably due to the TVs not possessing enough onboard storage to hold 4K movies.

There will be around 40 to 50 titles available on Ultra when it launches, including newer movies such as Concussion and The Walk, as well as older ones like Crouching Tiger, Hidden Dragon. The company plans to add TV programs at a later date, but it hasn't revealed which ones or how much they'll cost.

The service will also offer people the opportunity to upgrade SD and HD movies from their Ultraviolet library to 4K for $12 to $15.

As a way of promoting the Ultra service, Sony is giving away four movies for free to anyone who purchases one of the company's new 4K TV sets this summer.