Once, they call it. There’s a song by that name in the film, but the title could just as well be writer/director John Carney’s private joke about how often this premise can be expected to work: Two talented musicians, one of them very young and not yet famous; the other no longer young and probably as famous as he’s likely to become, meet cute on the streets of Dublin and spend a couple of days pining away for one another in song. Their songs. We get to watch Frames frontman Glen Hansard and Czech singer-songwriter Markéta Irglová perform them, live and for the most part, in their entirety. Risky, but it works, probably because of the two leads’ relative obscurity as musicians (in the U.S., at least) and their not-quite-total inexperience as actors, rather than in spite of it.

The same can be said for the shot-on-video picture’s threadbare production values. It looks like it probably cost less than a used Prius, and one suspects there’s a reason all of the “extras” in the Dublin street scenes keep looking at the camera. (Most of whatever they did spend probably went into making sure the all-important tunes were recorded and mixed properly.) All of this is a big help to those of us who are predisposed to come to a romance with more skepticism than we bring to a Die Hard sequel — we can’t help but be disarmed by the film’s modesty, in scope if not in theme.

Although Hansard and Irglova aren’t playing themselves, exactly, there’s a Prince-in-Purple Rain kind of thing happening here. But it’s weirder than that: Hansard and Irglová had co-written several of the songs heard in the film for last year’s The Swell Season album before they were both cast in the film. Carney’s original plan was to cast Batman villain and zombie-dodger Cillian Murphy in Hansard’s role. It’s hard to imagine how this could have worked: Trying to explain how a guy who looks like Murphy and sings like Hansard remains an unknown street musician in Dublin for 20 years would necessarily push the movie out of the realm of realism and into the realm of, at best, Elvisism — or far, far worse. In real life, Hansard’s band, the Frames, have had a strong following in Ireland—and who knows, maybe they’re huge in the Czech Republic, too—for a decade or so. Over here, well, let’s just say there was plenty of room to stretch out at their fine 9:30 Club appearance back in April.

In any case, this alternate-universe Hansard lives with his da and works in the family vacuum-cleaner repair shop while busking on the streets of Dublin. Because he apparently needs the spare change people drop in his guitar case when he plays Van Morrison covers, he dares perform his own songs only at night, when the crowds have gone. His songs are good, but not, you know, so good that it’s impossible to believe he’s made it past his mid-30s without making at least enough cash to get out of Da’s attic. He’s got talent, but he lacks confidence. What he needs is a muse.

Mercifully, as said muse, Irglová isn’t just a cipher put here to prod along the awakening of Hansard’s character. (The film never gives them names — they’re “Guy and “Girl” in the closing credits, which sounds pretentious but doesn’t play that way.) Their age difference of nearly 20 years actually makes sense, partly because it’s impossible to imagine Irglova’s character giving his the time of day once she’s experienced any of the good things about adulthood — everything we find out about her suggests it’s pretty much all been about duty and obligation for her so far — but more importantly, because this film is mature enough not to pretend their attraction to one another is forever. It’s honest in a way that movie romances almost never are.

Once is playing at the Landmark E Street Cinemas. Check their Web site for tickets and showtimes.