The future got a lot brighter Tuesday for digital video recorder maker TiVo after the company struck an agreement with Comcast Corp. to develop a customized version of the TiVo service for the cable giant’s customers.

News of the alliance sent TiVo shares soaring more than 50 percent Tuesday morning as investors reacted to the news that TiVo had finally partnered with a cable company.

Under the deal, whose financial terms were not disclosed, TiVo will develop customized software for Comcast’s current DVR platform and incorporate that technology into the cable company’s existing network. The service will be marketed with the TiVo brand and should be available in the majority of Comcast’s markets by mid- to late 2006.

The alliance is a huge boost for TiVo, whose future has gotten cloudier in recent months. Though the company enjoyed a doubling of its subscriber base to more than 3 million in the 12 months ended Jan. 31, much of that growth came from its partnership with satellite operator DirecTV Group, the long-term future of which is in doubt. DirecTV, which in late 2003 came under the control of Rupert Murdoch’s News Corp., has repeatedly said it plans to rely less on TiVo for DVR technology in favor of software from NDS Group, a TiVo rival that is controlled by News Corp.

Until Tuesday’s announcement, TiVo was having a difficult time breaking into the world of cable, whose players have been more keen on developing their own DVR solutions.

On top of that, TiVo has experienced management turmoil, with Chairman and CEO Michael Ramsay announcing in January he was stepping down as CEO, and, a few weeks later, President Martin Yudkovitz announcing he too was resigning.

The addition of the TiVo service will enhance Comcast’s DVR product, which is currently developed by its main set-top box maker, Motorola, which until recently had been slow to unveil a DVR-equipped cable box. Comcast last week struck a deal with Motorola to buy $1 billion worth of set-top boxes and develop and license set-top box software for Comcast and other cable operators.