EchoStar Communications Corp. and DirecTV Inc. will be upfront about how much set-top hard drive space customers will have to give up in order to enjoy subscription video-on-demand (SVOD) services offered via satellite.

That full disclosure is important because the current DBS architecture isn't capable of offering two-way VOD over a network like cable does, but instead is reliant on a fixed amount of hard drive storage to offer its version of on-demand services.

In the case of DirecTV's SVOD trial with Starz Encore Media Group, consumers who "opt-in" for the service will have to give up about 10 of the 35 hours of storage available on their DirecTV/TiVo receivers, noted Greg DePrez, vice president of SVOD for Starz Encore Group.

Launched in mid-September, that six-month trial is available to DirecTV Starz Super Pak subscribers who also own DirecTV receivers with TiVo-based on-board personal video recorders. Those who opt-in for the free trial will get access to five SVOD titles that will be refreshed on a weekly basis. Those titles are expected to absorb about 28 percent of the hard drive's 35-hour capacity. DirecTV, at least in the short-term, will not "push" SVOD content to receivers as it does for program guide data, but will instead "flag" SVOD titles that are scheduled to run during off-peak hours and direct the receiver to record them.

DePrez added that DirecTV's SVOD trial customers would also be able to "opt-out" of the trial.

EchoStar, which offers a DishPVR box, is also looking at SVOD as a future service, said Dave Kummer, EchoStar's senior vice president of engineering and systems. Although not all of EchoStar's SVOD details have been solidified, the satellite service provider won't push or record SVOD content to a receiver's hard drive unless a subscriber requests it, he said.

Kummer said running out of storage capacity for satellite-based on-demand services won't present much of a problem for DBS, as hard drive technology continues to ride a curve of denser and cheaper technology. Echo-Star's most massive DishPVR model so far houses a 120-gigabyte hard drive, enough to store a maximum of about 120 hours of video.