What’s it like to be Nick Cave? Oh, the usual — having imaginary conversations in your car with Kylie Minogue and Ray Winstone, poring over old photos and writings as if on an archaeological dig, kicking back with the kids and watching “Scarface.” And occasionally bounding on stage and transforming into one of the most magnetic and enigmatic songwriters today.

How much are we to believe of the documentary “20,000 Days on Earth,” co-directed by Iain Forsyth and Jane Pollard? None of it, and all of it. None of it, in the sense that much of what we see on screen was clearly created for the camera to fit in with the Nick Cave mythos. All of it, in that within that fiction Cave reveals a lot of truths about who he is and the man he’s become after 20,000 days on earth.

The film, now out on DVD and Blu-ray this week from Drafthouse Films, portends to look at a day in the life of Cave as he wakes up, goes to work on the 2013 album “Push the Sky Away” with his band the Bad Seeds, and ruminates about his life in voiceover and in conversations. Except those conversations are clearly engineered, as when he’s talking with Winstone about the delicate nature of performance, or describing his first sexual experience to an actor playing his shrink. There are impressionistic flashbacks to Cave’s first band The Birthday Party, which he describes as eventually becoming less about the music and more about fans coming to fight. As befitting an artist with as cinematic a songwriting voice as Cave’s, the film is strikingly beautiful, especially when the Aussie singer muses about his adopted home of Brighton, and the forbidding weather that rolls in from the sea. “My moods control the weather,” he quips. “But I can’t control my moods.”

Here’s the rub — within the artifice, Cave reveals a lot of himself. He’s a man who believes in the power and allure of transformation, especially into that creature he becomes in his life shows (Minogue memorably describes him as being like a foreboding old tree, the kind seen in silhouette in a Hitchcock movie.) Cave believes that that transformation allows him to step out of daily life and become something else, and the songs are powerful talismans that take him there. “The song is heroic, because the song confronts death.”

If that sounds a little pretentious, Cave is also just as willing to take the piss out of himself, telling funny and self-deprecating stories about his childhood, or the time the Bad Seeds opened for a terrifying Nina Simone. And despite the mythos that Cave has built around himself, a body of work full of forbidding spirits and fallen women and damned souls, there’s a serenity and a simplicity to what he does. He writes, and writes, and writes, and keeps moving forward.

As he says in the film, “To act on a bad idea is better than not acting at all. Because the worth of the idea isn’t known until you do it.” Making the strange and entrancing “20,000 Days on Earth” was a very good idea, illuminate some corners of Cave’s fevered mind while keeping the mystery alive in others.