"Kurt Cobain: Montage of Heck" seeks to humanise Cobain from his now mythic status by offering unvarnished snapshots of his life along with interviews with those close to him, but ultimately it leaves room for viewers to make judgements.
"I believe that this intimacy adds power to the film," said director Brett Morgen, who called the production an "immersive ride into Kurt's life."
"Kurt Cobain: Montage of Heck" seeks to humanise Cobain from his now mythic status.
Cobain, consumed by heroin addiction and chronic depression, suddenly became a cultural icon in the early 1990s as the visceral sound of Nirvana turned the page on the previous decade's pop sounds.
Cobain, who had thought about suicide since his childhood, shot himself in the head in April 1994 at his home in Seattle. He was 27.
Morgen -- whose earlier works included 2012's "Crossfire Hurricane" about the Rolling Stones -- made the film with the blessing of Cobain's widow, fellow rocker Courtney Love, who handed the director 15 boxes of the singer-guitarist's belongings.
Morgen said that Love did not have editorial control. But the famously volatile Love has voiced approval of the film, shedding tears at recent screenings and making a rare joint appearance at the Los Angeles premiere Wednesday night with the couple's 22-year-old daughter Frances Bean Cobain, with whom she has had a rocky relationship.
Frances appears in one of the most haunting scenes of "Montage of Heck" as Cobain, high on heroin, holds her and Love -- also known for her drug use -- tries to cut the baby's hair.
"He's between his love for his daughter and his addiction -- the struggle you see all in a one shot. It's an incredibly uncomfortable scene. It was authorised by Frances," Morgen told AFP on the sidelines of the film's Paris premiere.
He said that Frances watched the footage in his office, where he left her with a box of tissues.
"'You gave me a couple of hours with my father. That meant everything,'" he recalled her saying.
'The most pure expressions'
Cobain rarely threw out his belongings and when Morgen sifted through the boxes, he found notebooks filled with song lyrics and drawings, as well as paintings, guitars and even shoes.
Among the most striking findings were more than 100 cassette tapes recorded by the rocker, who grew up in the lumber town of Aberdeen, Washington, where his parents' divorce had a crushing effect on him.
One tape reveals a young Cobain both experimenting with his own songwriting and covering earlier songs including the Beatles' "And I Love Her."
"When I first heard it, I was in the storage facility and I had no prior knowledge of it. I put it on and I immediately felt like there was some sort of portal into his mind, like it was one of the most pure expressions of Kurt that I encountered -- maybe more than in most of his songs ," Morgen said.
"I felt that within these mixtapes, all the different sides of Kurt were displayed -- the romanticism, the honesty, all of these different emotions."
"Montage of Heck" will be accompanied by a soundtrack, in which Morgen has promised previously unreleased material.
'Kitschy, funny, scary'
A month before his death, Cobain had tried to kill himself when Love and Frances joined him at a luxury hotel in Rome.
Love said that Cobain had taken 67 Rohypnols, the relaxant drug often used to treat insomnia, because he suspected that she was having an affair.
"I had said Kurt was very sensitive to critics and then she said that he was so sensitive that he could have been a psychic," Morgen said.
"Montage of Heck" -- the title is an allusion to a Cobain mixtape -- took eight years to make as Morgen researched and produced the film and then sorted out potential legal issues.
The film will come out in the coming months in cinemas around the world and will also be broadcast in the United States on HBO.
Morgen believes that the film presents different facets of Cobain -- "kitschy, funny, scary." But ultimately it does not seek to address his death directly.
"There's a lot of subtext in this film. But I ask the audience to conclude on their own," he said.
