Just when Sony’s (NYSE: SNE) Blu-ray may have thought the Hi-Def video war was over, the format is likely to face a much tougher challenge from Comcast’s (NSDQ: CMCSA) Wideband internet service. Comcast will launch Wideband in “millions of homes” this year, said the cable operator’s CEO Brian Roberts, speaking to Reuters at CES. The service’s promise of four-minute HD movie downloads, compared with the six-hours it takes for DSL is the centerpiece of its VOD initiative, dubbed “Project Infinity.”

Still, Roberts remained vague about how many of Comcast’s 24 million subs will initially get to try Wideband, which works its magic by bonding four channels together, making it possible for download speeds to go up from 12-16 megabits per second, which is average for DSL, to over 100 mbps. As the AP points out Verizon (NYSE: VZ) FiOS offers has speeds up to 50 mbps.

By the end of the year, Project Infinity expects to have a library of 1,000 HD choices of channels and VOD programming. As many as 300 VOD movies may be available for free or included in a subscription or a pay-per-view service. Eventually, it will have more than 6,000 movies a month with more than 3,000 of them in HD.

While still the number one cable operator when it comes to the number of subs, Comcast has been losing subscribers and it has warned of further reductions. Wideband, along with its Fancast online video site, is considered key for Comcast to beat back the challenge coming from Verizon and AT&T.

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