If you wanted to beam an image to distant galaxies that communicated the look and meaning of the words “hipster rock star,” you could hardly do better than to send an image of Nick Cave. He was 58 years old when Andrew Dominik’s 3D black-and-white documentary “One More Time With Feeling” was shot, and he looks it, but quintessential rockers don’t age like the rest of us — they may acquire wrinkles, bags under the eyes, and so on, but they hold onto their aura, their ageless it factor. Cave undoubtedly has it. Tall and lean, with long stringy ink-black hair, clad in a jacket with tuxedo lapels that he wears with ironic elegance, he looks like a cross between Iggy Pop and Jim Jarmusch, though the years have also given this alt-pop dandy a pair of thickening eyebrows that are pure Richard Nixon.

As incongruous as that may sound, those thatchy knitted brows mesh perfectly with the lonely introspective mood of “One More Time With Feeling,” a movie that walks a delicate line between rapture and despair. It’s one of those music docs — and this is usually the laziest kind — in which the director simply hangs out in the recording studio and films the rock star in question making his latest album. Yet “One More Time With Feeling” is the art version of that form, and not just because the black-and-white images have the lustrous sharp glow of old Scavullo photographs. The movie, shot months after the death of Cave’s 15-year-old son, Arthur (who died in July 2015), turns out to be a meditation on grief. If it’s sometimes a rambling, indulgent experience, it’s also a beautiful one.

The movie doesn’t announce its theme — in fact, for the first hour, it barely references it, even though Cave, riding in the back of a car, alludes to dealing with a “trauma.” It’s likely that those who aren’t immersed in the career of this Australian cult rocker will have no idea what he’s talking about. For a good while, “One More Time With Feeling” lets Cave speak with a wry, forlorn acceptance about the verities of age, and about how it has changed his songwriting. He is no longer writing “narrative” songs — and that, he explains, is because he longer feels that his life is a narrative; it has become more fragmented and open-ended.

This seems a sane enough response to getting older, and when he goes into the studio with his long-time band, the Bad Seeds, to record “Skeleton Tree” (an album that’s due to be released just four days from now), we get a taste of his new non-narrative aesthetic, and it turns out to be gorgeous. He has, at least for now, moved beyond rock & roll — this is more like some lushly meditative fusion of Leonard Cohen and Julee Cruise, with long sustained chords and Cave warbling on top of them like some mournful, beaten-down version of Jim Morrison crooning “The End.” He has strayed from his usual alt-rock zone, but you can still hear why Cave songs have been tapped for so many soundtracks — not just in the movies, but in the age of post-“Sopranos” television. His spiky low-voiced gloom, laid atop music that percolates, can lend a scene a special mysterioso vibe. He’s just enough of a beatnik philosopher that he always seems to be singing about something under the surface, and sharing that secret.

Cave’s fellow Aussie, Andrew Dominik, would seem to be the perfect director to make this movie. Apart from the beauty of the images, though, Dominik doesn’t draw very much on his considerable craft. He can be an extraordinary director — in “The Assassination of Jesse James by the Coward Robert Ford,” and in the seriously underrated crime drama “Killing Them Softly” — but in “One More Time With Feeling,” he’s content to make a documentary that’s a loose, “impressionistic,” faux-1970s ramble. Even the way the film keeps calling attention to its own making (it opens with a botched setup, there is much chatter about the 3D camera, and Cave speaks periodically about how it feels to be collaborating on a movie about himself) is a promising conceit executed in a slapdash, haphazard manner.

Finally, after too much of this dithering, Dominik works around to the film’s underlying subject: the death of Cave’s son, Arthur. It’s a tragedy there are ultimately no words for, and Cave is eloquent about not having the words for it. At the same time, it should be noted that there’s something arguably cagey and protective about the way the basic facts of what happened are left out of the movie. We never learn how Arthur died: High on an overly hefty dose of LSD (and marijuana as well), he reportedly “freaked out” before falling off a cliff in Brighton, England, near their home. The movie achieves a quality of poetic loss by leaving out these details, and by never showing us a picture of Arthur. But given that Cave has admitted to his own intense battle with drug abuse (he is now clean), something seems amiss in his never remotely confronting the issue of whether he feels in any way responsible for the death of Arthur. It was Cave who approached Dominik with the idea to make this film, but on camera his exploration of grief remains overly circumspect.

It pours out, though, in his music. Late in the movie, Cave and the Bad Seeds record a song called “I Need You,” which is a kind of meditation in off-kilter slow-motion waltz time, built on three descending chords that keep repeating, and it’s all about the enormity of Cave’s loss. It’s such a haunting piece of music that it lifts the movie into a place of nearly religious sorrow and transcendence. “One More Time With Feeling” is set to play in select theaters around the world on Sept. 9, for one night only. But given that it’s the highly unconventional version of what would have been a fringe documentary to begin with, its prospects of finding an audience beyond that, even among the Nick Cave faithful, remain severely limited. Yet for those who see it, this exploratory, flawed movie culminates in a way that’s at once surprising and moving. It turns into a requiem.