By Jim Dalrymple, IDG News Service

Apple's iTunes Store is under fire from yet another competitor as SyncTV announced its entry into the downloadable television show market. SyncTV says its service is completely based on open standards, so it works with Windows PCs, Macs and Linux PCs, and in the future it will also work on TVs and portable players.

While the company didn't list all of the channels that would be on its service, it did mention that Showtime programs would be available.

SyncTV works differently than iTunes' pay-per-download model. With SyncTV the user subscribes to a channel and then can download any show that channel makes available. In many cases that will include every episode of every season of a particular show, the company said.

There is a "small" monthly fee for each channel subscription. SyncTV said a minority of channels will make their content available on a pay-per-download basis, but the focus of this model is clearly on subscriptions.

SyncTV is using the Marlin open-standards Digital Rights Management (DRM) system to protect its content. Using this system users are allowed to play back shows on up to five home devices, which means PCs and Macs now, and other home entertainment devices in the future. You will also be able to specify an additional ten portable devices when compatible devices become available.

SyncTV is currently in private beta.