Maybe the "on/off" button and adult/child dialogue are too low-tech for parents concerned about sexual and scatological references in home-viewed Hollywood films. But it was probably inevitable that content-filtering technology would come to home DVD players, and it has, if in some fairly limited ways.

Sanyo Fisher is introducing DVD players fitted with Principal Solutions' TVGuardian technology, which has been available in set-top boxes since 1998. The device checks the DVD's closed-caption signal and compares it against an electronic dictionary of objectionable words and phrases. When an objectionable word comes up, TVGuardian either mutes the sound completely or inserts a substitute word in its place.

The technology's not fool-proof; the TVGuardian Web site touts filtering rates of between 95-100% for most movies. And the results can be unintentionally comical; the device substitutes the word "hugs" for "sex," which could result in characters talking about undergoing a "hugs change," for instance. The only such distinctions of meaning the device makes are with religious terms; the TVGuardian claims the device can be set to allow "non-expletive" uses of words like "God" and "Jesus."

The TVGuardian technology is available on six different Sanyo and Fisher DVD, VHS, and DVD/VHS models.

Another approach to DVD content filtering comes from ClearPlay, software that runs in tandem with a DVD and instructs the DVD player to mute or even skip over portions of a film that contain nudity, graphic language, or gratuitous violence. The current version of the software only runs on Windows-based PCs, though plans are in the works for a set-top DVD player application. It also only works on films for which ClearPlay staff have created a software "guide;" the company had guides for 150 titles in early March and says it's adding 25 titles per month.

Both ClearPlay and TVGuardian acknowledge that their technology isn't seamless. While ClearPlay says that its staff makes every effort to maintain story continuity, it admits that the mutes and cuts will be noticeable, as are TVGuardian's word replacements. But they both promise the results are no more jarring than edited-for-TV versions of R-rated films, for what that's worth.

Of course, multirated discs authored using DVD's seamless branching capability can do a much less intrusive job of editing content, but those are few and far between. According to Jim Taylor's DVD FAQ (www.dvddemystified.com), DVD players can also be set to parental levels to block playback of discs that overstep that threshold, and password-protected to maintain those levels. But that approach goes well beyond the in-play content filtering to which the latest parental-controls technologies aspire.