"If we played together in the house for a couple of hours and if two people stopped by we considered that a gig," explains Cobain. "That was good enough, if we had an audience of two people; locals who hated our guts and thought it was terrible music."

Cobain's daughter, Frances Bean, served as executive producer on the project alongside director Brett Morgen as the pair worked on the definitive biography of the late Nirvana frontman.

"Montage Of Heck" will see its broadcast premiere on HBO on May 4, and an accompanying soundtrack album will feature unreleased material from Cobain's personal achives.