Hollywood studios and the National Football League are seeking to block the maker of the popular TiVo television recorder from expanding its service so that users could watch copies of shows and movies on devices outside their homes.

In filings with the Federal Communications Commission, the organizations say the new technology could compromise the copyrights of shows that broadcasters send over the airwaves in digital form, which offers much higher sound and video quality than what viewers typically get today.

The organizations fear that computer enthusiasts would capture those programs and begin trading them online in the same way that millions of music files are shared daily, which record companies have said has cut into their profit. TiVo Inc. insists its system will not allow such mass Internet distribution.

The battle is one of several being waged in federal agencies and on Capitol Hill this summer, as content companies such as the movie and music companies seek to keep control of copyrighted works that increasingly can be digitally stored, copied, manipulated and distributed by users. In turn, several public advocacy groups and technology companies warn that the content companies are trying to revoke long-standing consumer rights to "fair use" of artistic works.

With 1.6 million subscribers, TiVo is the leading provider of the digital recorders that are revolutionizing television viewing. In addition to copying shows for later viewing, consumers can pause live shows, skip commercials and use other features to control the TV experience.

To date, users generally have been unable to send copied programs to another device, although some digital recorders include "burners" that allow programs to be copied to a DVD and played elsewhere.

TiVo wants to make copies more portable, in stages. Sometime this fall, the company plans to roll out a system that will allow programs to be transferred from the TiVo box to a computer via a small device attached to the PC.

The program could then be sent to other devices within the home and viewed on them. Such devices, including laptops or desktop computers, would be registered with the company and would share encoding and decoding technology that prevents viewing by nonregistered devices.

Next year, TiVo plans to expand the system to allow programs to be transferred to registered devices outside the home, such as at an office, vacation cabin or even a friend's house across the country. A maximum of 10 devices could be registered by the subscriber.

"TiVo has an interest in keeping everything secure," said its Washington attorney, James M. Burger. "We are trying to bring innovation to consumers."

But the system alarms the content industry, which promised to roll out more digital programming over free television networks only after insisting that the FCC adopt rules requiring makers of recording devices to certify that they have technologies to prevent mass Internet distribution.

Digital programming is far more appealing for online distribution because the quality does not degrade as it is copied over and over.

TiVo was one of 13 companies that asked the FCC for approval, arguing that its copy-protection system met the requirements. The Motion Picture Association of America, Hollywood's lobbying arm, and the NFL then filed objections to TiVo's plan.

"Our concern is grounded in the fact that the remote access is not limited to the recipient's summer home or boat or office," said Fritz Attaway, the MPAA's Washington legal counsel. "The people that can receive the programming can be totally unrelated in any place on the globe."

Attaway said that even if TiVo's system prevents mass Internet distribution, if each of TiVo's customers add 10 devices to a registered group, many potentially unrelated users would be able to see the copied show.

The NFL, meanwhile, is concerned that a user could send a copy of a game to someone in another time zone, where the game is blacked out. Burger responded that at current bandwidth, such a transfer would take 144 hours.

Burger would not say what would happen if the FCC rules against TiVo's system, saying the company respects the content owners' concerns and wants to work with them. But TiVo would be at a significant disadvantage if its device is not certified for the coming increase in digital programming.

Mike Godwin, policy counsel for Public Knowledge, an advocacy group for consumer digital rights, said the fight highlights the danger of requiring technologies to be approved by government agencies.

"We've always thought that once the FCC got into the role of approving content protection technologies that the content companies would leverage this to use the agency to throttle various technologies," he said.

An FCC official, who spoke on condition of anonymity because he is not authorized to speak for the commission, said a decision on approved technologies is scheduled to be made in the next couple of weeks.

Meanwhile, yesterday, the House Judiciary Committee approved a bill that would significantly broaden user rights. The bill would exempt from copyright law technologies enabling users to zap objectionable parts of shows and movies to make the programming more suitable for children.

Directors and studios oppose the bill as giving people the right to alter copyrighted material.

On the flip side, the Senate Judiciary Committee will hear testimony today on a bill that would ban any technology that "induces" a copyright violation, in a direct attack on file-trading services.

One of those scheduled to testify is Marybeth Peters, the government's register of copyrights, who will endorse the bill, according to prepared testimony obtained by The Washington Post. Peters plans to testify that Congress might need to change the law to invalidate a Supreme Court decision that established a key underpinning of fair-use rights, which is that developers of technologies cannot be held responsible for the actions of those who might use them to violate copyrights.