People trying to post stolen video content online must now contend with Johnny--an automated “fingerprinting” system by video-sharing service Guba that blocks the uploading of copyrighted material.

YouTube visitors upload 65,000 videos every day and download 100 million of them. Since all those videos have to come from somewhere, it's no surprise that many are pirated -- that is, copied from commercial TV broadcasts and movies and posted without the permission of the copyright holders.

YouTube and similar video-sharing services deal with these copyright violations after they occur: by taking down the material if they receive a complaint from the legitimate copyright holder. But given the sheer number of videos uploaded to the Internet every day, it's a losing battle.

What's needed, say researchers in digital rights management, are ways to automatically screen out pirated videos before they're uploaded, and to track down people who make pirate copies.

And, as it turns out, such technology is nearing the point of widespread adoption. One video-sharing site, Guba, has already begun to filter out copyrighted videos using a home-grown system dubbed "Johnny." The system reduces a video file to a mathematical representation and then excludes it from the site if its "fingerprint" matches one in a database of commercial videos.

Media-technology companies such as Philips and Thomson are also working on ways to thwart video pirates. Thomson has introduced a system that embeds invisible "watermarks" in movies, allowing studios to trace online copies of movies recorded by camcorder users to the specific theater and movie showing where they were pirated.

These new technologies have their own limitations, though. For one, it's not clear that fingerprinting technology can keep up with the thousands of hours of TV programming broadcast every day. And watermarking a movie doesn't help catch the pirates themselves. But these new copyright-protection mechanisms may at least help video-sharing sites avoid the fate of the infamous music-trading sites Napster and MP3.com, which closed down after legal attacks by content owners.

Pirated video makes up about one-fifth of the moving-image content uploaded to video-sharing sites, according to Tom McInerney, founder and CEO of San Francisco-based Guba. And while the sharing sites benefit indirectly from pirated videos, which generate Web traffic and advertising impressions, hosting this material is often more trouble than it's worth.

In a well-publicized case in February, for example, NBC threatened legal action against YouTube if the site refused to remove a video of a popular "Saturday Night Live" skit (a skit that would not have become popular, ironically, if it hadn't been posted on YouTube). YouTube complied, but caught flak from hundreds of its users for supposedly buckling under to a giant "old-media" company. And in July, the helicopter pilot who filmed the beating of trucker Reginald Denny during the 1992 riots in Los Angeles sued YouTube for hosting a pirated copy of his video. He's demanding $150,000 in damages for every viewing of the video.

Clearly, life would be easier for the owners of video-sharing sites if copyrighted content could be blocked before it's posted. And that's what Guba claims Johnny can do. The company was founded in 1998 to build a tool that could search for still images and videos posted to Usenet discussion groups. But as soon as the company began to aggregate such content, it started receiving complaints and takedown requests from copyright holders. "We wanted to make it easier to find things, but we ended up demonstrating how much copyrighted content is really out there," says McInerney.

That inspired them to switch gears and start developing Johnny (named after the Keanu Reeves character in "Johnny Mnemonic"). "We needed a system that could identify and classify [copyrighted] video without human assistance," McInerney says.

The centerpiece of the system is a huge database of digital fingerprints for copyrighted video. Each fingerprint is created using wavelet compression technology that distills the video signal into a few compact mathematical representations. It does the same for the audio track, and it uses computer vision technology to measure the frequency of scene changes, providing a kind of time signature. The compressed video and audio signals and time signature together make up the file's fingerprint.

Johnny extracts a fingerprint from every video uploaded to Guba, and if it matches a fingerprint already in the database, the file gets quarantined and flagged for review by a human. The system is so effective, McInerney says, that only one percent of the flagged video files turn out not to be copyrighted.

Guba may eventually license Johnny to other video-sharing sites; but for now the technology -- and the company's commitment to copyright protection -- are giving it an advantage in negotiating with networks and movie studios for the rights to sell downloads. Already, Guba is hosting downloads of full-length films from Warner and Sony.

Nevertheless, digital rights management experts aren't convinced that fingerprinting technology will be a silver bullet against video piracy, even though it has been used successfully by the music business. One problem is simply the burgeoning amount of copyrighted content needing fingerprinting. "The universe of music tracks to be fingerprinted is relatively tractable, compared to copyrighted video clips such as every day's newscasts on television networks and stations throughout the world," writes Bill Rosenblatt, editor of Jupitermedia's DRM Watch. "Updating such a large and fast-growing fingerprint database, and making it efficient enough to be used in the filtering of copyrighted material from a site like Guba, seems utterly impractical."

But to survive, says Guba's McInerney, video download services "are going to need to make efforts to scrub the copyrighted stuff off their sites -- and we think the best solution is a technological solution."