More than 20 minutes of unseen footage of Led Zeppelin playing live at the Pontiac Silverdome in 1977 has emerged online

23 minutes of previously unseen footage of Led Zeppelin playing live at the Pontiac Silverdome in Pontiac, Michigan, on April 30, 1977, has emerged online.

The film of the show, which saw 76,200 attendees (then a world record for a single-act show) pay $10.50 each for a ticket, has appeared on a YouTube channel dedicated to the archive the late Jim Kelly, better known as 'Speedy'. Kelly was a professional photographer and music fan who regularly shot 8mm footage of the shows he attended in the 1970s, including Van Halen, Alice Cooper, Yes, Queen, Rush and Pink Floyd.

The Pontiac footage is something of a team effort, with the film being transferred to digital by the Genesis Museum (who worked on the recently released 4K remaster of Genesis's 1973 Shepperton Studios set) and production by fellow Genesis fan ikhnaton, while film restoration work and syncing to bootleg audio was carried out by two familiar names from the Led Zeppelin collectors' community, respectively Etienne and LedZepFilm.

"Usually I take the audio source as gospel and sync the film accordingly that way," says LedZepFilm. "Sometimes I may adjust the audio if it runs too fast or slow to my ears and then go from there. Some clips may be adjusted differently than others. But of course as you probably know, the speed can never truly be 100% correct because both sources are analog!"

Viewers may note that there are film cameramen dotted around the stage, but that doesn't necessarily mean that other, more official footage resides in the Jimmy Page archive. The cameramen were employed by production company Worldstage, who would project live footage of the band onto the large video screen above John Bonham's kit, but it is believed that this footage was not saved.