“If it’s too loud,” the ancient wisecrack about youth music goes, “you’re too old.”

The documentary film version of that saying might be, “If it’s too long, it’d damn-well better be about the Holocaust.”

“Turn it Around! The Story of East Bay Punk,” befitting its subject matter, breaks that film rule and gives us two and a half THOROUGH hours of the music scene where punk arrived in the late 1970s — and never really left.

As musical tastes waxed and waned, punk turned to hard core/thrash, seemed to die, then burst into radio-and-MTV-friendly punk pop with Green Day, the most famous band to emerge from San Francisco’s East Bay scene.

So there’s this long, talk-to-EVERYbody oral and cartoon-illustrated history of Hippytown Punk because, uh, Green Day is getting nostalgic in their proto-punk dotage? They’re the climax, the end-destination of the picture and they have producing credits (They got it made).

But this is much more than just an East Bay to Broadway (“American Idiot”) tale. Director Corbett Redford — a longtime member of that scene, so don’t take his name at face value — tracked down generations of Bay Area punks and tells as complete a story of the music, ethos, lifestyle and politics of this movement as anyone could want.

Musicians from Jello Biafra to Davey Havok,  Kevin Seconds and Mike Dirnt, scene participants with equally self-chosen monikers like Marshall Stax, Steve List (he compiled weekly lists of every underground punk performance, its venue, etc., and handed out The List every weekend at various shows) tell the story.

Those deep into the music, then or now, should be enthralled. And speaking as an outsider — I’ve ducked my head into many a thrash bar, and ducked back out again before tinnitus set in — it’s a fascinating history.

See the earliest stirrings of the West Coast music inspired by The Ramones, chart it through its many incarnations — Riots Girls, Thrash/Hard Core, Grunge.

Iggy Pop narrates the picture, a Detroit punk who never aged out of the ethos and is the perfect sardonic observer to the locale that produced Dead Kennedys, Rancid, Avengers, 7 Seconds and hundreds of other bands.

Punk — Iggy narrates — “is a conversation with society. Often, it’s an argument.”

So it was never just “about the music, man.” It’s spiked hair and piercings, more tattoos than any living body can use, brutally violent mosh pits, confronting Nazi skinheads when they seek to take over the clubs and seize the “scene.”

Writer/actress/filmmaker Miranda July staged her first punk play at the Gilman St. club which was the nexis of everything punk in East Bay.

And of interviews connect East Bay to the punk-turned-to-grunge music scene in Seattle and Olympia, Washington, cross-pollinating.

And yes, Green Day arrives, punk’s Apotheosis. The documentary makes it a side-mission to dismiss the cries of “sell-out” that the faithful have long slapped on the trio who had the ambition, talent and discipline to make the music popular to the masses.

Interest, for me, faded in and out, owing to the excessive length and repetition of “Turn it Around!” I enjoyed the animation — designed to look like the work from self-published/hand-penned and hand-drawn music ‘zines of the pre-Internet era.

But as valuable as it can be to call oneself an insider when plunging into a subject, maybe an outsider should have edited this. For all the old home movies of Green Day and those who preceded them, all the glorious black and white club photos of scene-photographer Murray Bowles dedicated to “showing people having a good time,” all the eyewitness accounts and opinions, “Turn it Around!” turns out to be too much of a good thing.

Trimming, polishing and shaping something into a tight, best-quotes-only/best-footage-only doc isn’t the antithesis of punk. Remember, the songs were long considered too long if they lasted more than two minutes.

MPAA Rating: Unrated, with profanity, photos of nudity

Cast: Iggy Pop, Billie Joe Armstrong, Miranda July,  Jello Biafra, Kirk Hammett, Tre Cool, Murray Bowles, Marshall Stax, Anna Joy Springer, Kathleen Hanna, Mike Dirnt, Michelle Gonzalez

Credits: Directed by Corbett Redford, script by Anthony Marchitiello and Corbett Redford

An Abramorama release.

Running time: 2:37