It’s part of the canon of classic-rock movies, with the likes of “The Wall,” “Woodstock” and “Tommy.”

Yet Led Zeppelin made “The Song Remains the Same” into a unique hybrid, mixing concert footage from a trio of nights at New York’s Madison Square Garden in 1973 with fantasy sequences imagined by each of the musicians.

Now, 31 years after releasing the 1976 soundtrack album, the surviving members of Led Zeppelin on Tuesday issue an expanded, remastered version of “The Song Remains the Same.” The two-disc set features new liner notes by Cameron Crowe and six songs left off the original, including a blistering version of “Since I’ve Been Loving You,” “The Ocean” and “Over the Hills and Far Away.”

It’s not the band’s best live performance – go with clips from “Led Zeppelin,” the 2005 two-DVD collection, for that – but “The Song Remains the Same” is an iconic set, not least because of the way the songs are tied to the film, for anyone who has seen it. Remember the trippy medieval-themed cut-away sequence during “No Quarter”?

The new soundtrack is missing the visual element, which detracts from Jimmy Page’s violin-bow shtick on the 23-minute version of “Dazed and Confused” and John Bonham’s impossibly excellent drum solo on “Moby Dick.”

Some things, though, don’t require visuals: Robert Plant shrieking “Twenty-five!” over and over during “Dazed and Confused,” or one of the best cheesy moments ever on a concert recording, when Plant asks in the middle of “Stairway to Heaven,” “Does anybody remember laughter?”

What’s truly striking, though, is how powerful the band sounds (credit Kevin Shirley for mixing the re-issue), particularly Page and Bonham.

Page’s guitar is positively depilatory on “The Ocean”; his bluesy intro on “Since I’ve Been Loving You” is the work of a master.

Bonham’s drumming is equally fierce, from his opening salvo in “Rock and Roll” to the steady, titanic rhythm he lays down on “Heartbreaker.”

The film project was from the start a self-indulgent way for Zeppelin to blow through a pretty big chunk of cash (which wasn’t helped by news, captured in the movie, that $200,000 of the band’s money was stolen from a hotel safe in New York). But the musicians were rock stars of the highest order, and rock ‘n’ roll excess was as much a part of the ’70s as platform boots. It doesn’t change the fact that Led Zeppelin was one of the best bands in the world.