Comcast, which is under federal investigation for blocking some file-sharing traffic, is investing in a startup that delivers high-definition video using file-sharing techniques. Seattle-based GridNetworks on Monday said that Comcast would make an unspecified investment in the company and collaborate on developing so-called peer-to-peer file-sharing techniques that are "friendly" to Internet service providers.

Comcast hampers some file-sharing traffic by its subscribers in an attempt to keep the traffic from slowing down Web surfing by other subscribers. Complaints by consumer groups and legal scholars that the company is discriminating against particular software have led to an investigation by the Federal Communications Commission.

Comcast has said that it will stop targeting specific types of traffic by the end of the year. It has also reached out to file-sharing companies to try to develop mutually acceptable techniques.

File-sharing applications like BitTorrent are frequently used to spread pirated movies and music. But GridNetworks and a dozen other startups are instead developing the technology as a way to deliver legal files, like rented high-definition movies, cheaply over the Internet.

The Comcast deal was announced at the Cable Show in New Orleans, hosted by the National Cable and Telecommunications Association.