Movie studios and retailers are starting to abandon Sony's Universal Media Disc (UMD) movie format.

UMD is an optical storage device that Sony developed for its PlayStation Portable gaming computers. The tiny disks are primarily designed to store games, but consumers can also purchase movies on the format.

The Hollywood Reporter, a sister publication of vnunet.com, reported that Wal-Mart, the largest retailer in the US, has drastically cut back the shelf space for UMD movies and may stop selling them altogether. 

Universal Studios and Paramount Pictures have ceased to offer movies on the small storage disks, and even Sony has cut the number of titles that it releases on UMD.

Michael Gartenberg, research director at Jupiter Research, told vnunet.com that the UMD movies have always had a difficult value proposition because they cost as much as a DVD, but can only be played on Sony's PlayStation Portable. 

"Sony has to build on that as a platform and get more ways for UMD to be viewed on different devices," he said.

Gartenberg stressed that UMD will stick around for PSP games. But for the device to succeed as a movie player, Sony will have to introduce additional accessories that allow consumers to hook up the devices to a television, for instance.