“American Masters” (PBS, 9 p.m., check local listings) is always eager to seem up to date. But the TV premiere of “Pearl Jam Twenty” tonight only shows they’re only a couple of decades behind the curve.

Mostly they just purchased an anniversary movie already being made by the band as part of a 20th blitz that includes a book, disc and, very soon, a DVD of this very film.

Because Cameron Crowe is behind it all, it’s just about the best rock documentary you could imagine – touching on all aspects of the band, offering an overview for those who didn’t follow them so close while providing nuggets for longtime fans in the form of unseen concert footage from key concerts.

More than that, Eddie Vedder who has mostly played his cards very close to his vest all these years and not done his “60 Minutes” interview, is at last very expansive about the life of the band, as are the other members.

But is Pearl Jam the band you want to have this kind of overview? If you’re “American Masters,” and you really want to hail the heroes of grunge, wouldn’t you first do Nirvana’s life story? (Even Pearl Jam admits they’d be nothing without them).

They’re an admirable band, with a few great songs (mostly from the earliest part of their career), who should be congratulated for taking on Ticketmaster when hardly any other band did. But two hours for these flannel flyers? I’m not so sure.