Tom Petty & the Heartbreakers are celebrating their 30-ish anniversary with Runnin’ Down a Dream, a two-part multimedia project featuring a coffee-table book published this November by Chronicles which is inevitably overshadowed by the four-hour documentary directed by Peter Bogdanovich. It’s currently available as part of three-DVD/one-CD exclusive set from Best Buy (two DVDs are devoted to the film; one DVD is a homecoming concert in Gainesville; the CD is an excellent, if brief, collection of rarities) and will be airing tonight at 7 p.m. on the Sundance Channel (it will be re-run on Thursday at 3 a.m. and Saturday at 3 p.m.). That’s right: Runnin’ Down a Dream runs a gargantuan four hours, just about 20 minutes longer than Martin Scorsese’s epic Bob Dylan documentary No Direction Home. Scorsese’s film is gripping throughout its running time where Bogdanovich’s is considerably less so, slipping into a leisurely processional after a deceptively brisk beginning. During the first hour or so, Petty’s beginnings as a rocker — perhaps fated by an early childhood meeting with Elvis when the King was down in Florida shooting Follow That Dream — are quite absorbing, thanks in no small part to a clutch of home movies from his first band, Mudcrutch, which help punctuate new interviews with Petty, his two longtime bandmates guitarist Mike Campbell and keyboardist Benmont Tench, and other colleagues that floated through their orbit. Somebody within the Petty camp kept cameras rolling through much of the ’70s as there’s fascinating footage that pops up unexpectedly, most notably footage from the Damn the Torpedoes sessions where producer Jimmy Iovine and drummer Stan Lynch clash on camera.

Home movies aren’t the only source of rare delights here — there’s footage of the Heartbreakers in their prime performing on The Old Grey Whistle Test and a local Los Angeles TV story of a homecoming concert at the Whisky by a reporter with the rather improbable name of Billy Juggs — that keep things interesting for a while, but as Runnin’ Down a Dream sails past the 90-minute mark, momentum starts to sag as it becomes clear that despite there being plenty of fascinating stories within the Heartbreakers’ tale, there’s not a whole lot of drama there, either. Petty, Campbell, and Tench slugged it out with Mudcrutch during the early ’70s, but success came relatively quickly for the Heartbreakers — it took about a year for the 1976 debut to break, a long time but not quite a struggle — and they’ve been popular for three decades, withstanding battles with their record label, some bouts of excess, Petty turning his hand to powder during the ill-fated Southern Accents album, Howie Epstein’s tragic descent into drug addiction that led to his death, Petty leaving the band behind to go solo and to turn into a Traveling Wilbury, but the Heartbreakers never have had a grand rise and fall. They have some good stories, enough for a good two-hour documentary, not for a leisurely four-hour movie. Runnin’ Down a Dream plays like a director’s cut, but not one that was cobbled together after release; instead, it plays like the first cut, where all the footage was kept together without regard toward entertaining an audience. Surely, there are diehards that will savor all of this, but it’s possible to love Petty’s music and find this movie dull because it cuts against his greatest strengths. Petty & the Heartbreakers are a great band because they keep the classic three-minute rules of ’60s rock & roll alive, crafting tight addictive blends of ringing pop and raunchy rock designed to sound and feel good. Their best songs lack an ounce of fat — as Campbell says in this film, their credo is “Don’t bore us, get to the chorus,” so it’s with considerable irony that their legacy is being celebrated with a worthwhile but ponderous film that turns that mantra upside down.