AT&T announced earlier this year that was planning to introduce content filtering of some sort for all video passing across its network. Exactly what AT&T was thinking remained unclear: would the company truly attempt to reassemble the fragments of peer-to-peer transmissions, then extract video from all sorts of different codecs, then attempt to match it-in real time-to some database of copyrighted works? Would such a thing even be possible?

It's still not clear how AT&T plans to deploy its system, but the company is serious about it. Further evidence of that came today, when a brief Wall Street Journal writeup (subscription) pointed out that the company has just invested in Vobile.

Vobile's core product is a screening technology that it calls "VideoDNA." Like other systems of its kind, VideoDNA develops a unique signature from every frame of video. The signature is meant to be robust enough to survive various transformations and edits, and it can then be used to run matches against incoming content.

Vobile pitches its products as being especially suitable for content tracking and management purposes. Video-sharing sites could deploy the technology to flag user-uploaded content for possible copyright violations. But, as Vobile's site notes, VideoDNA is also quick enough to be deployed on video "when it's transported over a network."

AT&T has yet to publicly pick a winning technology (plenty of other companies are working on similar video identification technology), and it hasn't even revealed the scope of its plans. But the interest in video filtering doesn't appear to have faded after months of time in which executives could ponder the important questions of just how such a system would work and (perhaps more importantly) what customers would think of it.

Based on the complexity of the problem, we suspect that anything initially deployed by AT&T will fall far short of a robust P2P video filter. But should AT&T truly have its eyes on just such a prize, the company would be in a powerful position to impose its own policies on the entire US, since it owns major parts of the Internet backbone. It will also be in a plum position when it comes to dealing with the MPAA and with networks like NBC; both groups have been calling on ISPs to implement exactly this sort of filtering for months.

Vobile, for its part, is also serious about its work. Earlier this month, it added Gideon Yu to company's Board of Directors. Yu is the chief financial officer of Facebook, and also served as the CFO of a little startup called YouTube before it was sold to Google. Yu calls Vobile's tech "a revolutionary step forward for the industry." We may get a chance to find out just how excited consumers are about this revolutionary step forward if AT&T does end up adopting the Vobile VideoDNA tech.