A group of TV and movie studios have unveiled a project that’s taken three years to make: UltraViolet ^[1], a cloud-based “locker” for users to store their purchased films and TV shows. The first movie available for UltraViolet’s library, The Green Lantern, came out Tuesday.

“We want to emphasize the concept of ‘buy once, play anywhere,’ ” says Thomas Gewecke, Warner Bros. ^[2]‘ digital-distribution president.

To use UltraViolet, a customer purchases a specially marked DVD or BlueRay disc that has a special 12-digit code. The code is entered in UltraViolet, and the movie appears in the program.

More than 75 companies have joined the Ultraviolet project, including tech companies like Microsoft ^[3] and Intel ^[4]. Video-streaming sites like Netflix ^[5] and Vudu ^[6] are members. Big name studios abound, like Paramount ^[7], Universal ^[8], and Sony ^[9]. But there are some notable hold outs: Disney ^[10], which is developing its own video locker, and Apple ^[11].

The biggest obstacle for the project will be maintaining and creating user accounts. But it’s a step toward combating a big problem. U.S. DVD sales last year were 43 percent below the peak year, 2006.

Read more at The Wall Street Journal ^[12].