TiVo and Comcast are jointly developing an advertising system that inserts up-to-date commercials into previously recorded programming. The announcement follows news that TiVo has begun testing new advertising format that will appear as users fast forward through commercials on its digital video recorder service.

According to reports, the venture was announced by Comcast Chief Executive Brian Roberts at the cable industry's annual trade show on Monday. Roberts revealed that the system will replace commercials recorded in days or weeks past with newer, more relevant ads.

Roberts made the case that DVR software will make advertisers "big winners." There is also a trend toward product placement in programming as an alternative to traditional commercials.

Last month, TiVo announced that it would provide Comcast with specialized versions of its DVR recorders beginning in mid-2006. The units will eventually become available to Comcast's estimated 21 million customers. Comcast is the first cable provider to partner with TiVo.

TiVo's partnership with Comcast comes on the heels of DirecTV's unveiling of its own DVR technology at CES 2005, an event that cast doubt on DirecTV's business relationship with TiVo.