He never seems to stop smiling, and why should he?

Pop phenom Ed Sheeran can improvise at will, conjure lyrics, hooks, riffs and verses out of thin air, or so it seems in his cousin’s “Songwriter” documentary.

Kick around a dirty title of an “I’m dumping you” tune, in his pajamas on the tour bus and “Love Yourself” results.

“Gon’ get my laptop and write it down,” he croons in that famous Brit-falsetto, while producer/collaborator Benny Blanco (“Moves Like Jagger,” “Teenage Dream” (for Katy Perry) just grins and prognosticates.

“Instant classic.”

Sheeran also tosses “classic” around like a Coke exec in “Songwriter,” directed by his longtime personal filmmaker and cousin, Murray Cummings. But it’s disarming coming from Sheeran, and as we watch him collaborate with a seven fellow singer-songwriters, including Foy Vance and Julia Michaels as he pulls together his album “÷,” we get an earful of his talent and his work habits.

He travels from Malibu to New York, recording on the Queen Mary 2 and at legendary Abbey Road Studios, trotting out his Jackson/Timberlake/Bieber falsetto for tune after tune — the Gypsy influenced “Barcelona,” and “Galway Girl,” the charming Irish family history romp written with Irish band Beoga and performed on traditional Gaelic instruments.

As lyrics flow and riffs pile up on the laptop, he really does make it look ridiculously easy. Then you realize that’s all you see him doing — stockpiling material, saving up rhymes, for months, on his phone. Even his improvisations, his “fun” moments, instrument in hand, have a hint of “all business” about them.

“Songwriter” is all about the work, with little of the personal intruding in its  84 compact minutes. Sheeran’s certitude about his talent and his marketability has him boasting of bettering Adele’s sales records, even as he’s insisting on drowning one song in schmaltzy Abbey Road-recorded strings (only to realize his error later).
Cummings peppers the film with old home movies (as well as his first ever clips of Sheeran recording), not so much tracking the 27 year-old’s career from trying his hand at drums, bass and piano before settling on guitar and taking that to Youtube fame, and on to super-stardom as noting the focus that was there, from the first.
A personably impersonal behind-the-scenes documentary, “Songwriter” has less pathos than Katy Perry’s similar film, but his genuine chops and blunt treatment of songwriting as a craft lift him above the rest of his peers — Bieber, et al — who have been immortalized on film.

What’s not to love, or at least respect? He goes back to Thomas Mills High School in Framlingham to pay homage to Mr. Hanley, a teacher who “got him,” and gives the next generation of musicians brilliant advice. Songwriting it like a rusty tap in an abandoned house — “s— water” comes out at first, grit and dirt and rust. And then? The good stuff.

“When you know you’re writing a bad song, be sure to FINISH it,” he insists. “Get it out of your system.” The good stuff comes after.

Time will tell if this latest pop idol has staying power — the falsetto songs mostly run together in the ears of a non-fan — but even Sheeran doubters should appreciate the work ethic,  musicianship and wit of this chart-topping ginger tyro. As for right now, he’s got that tap turned wide open.

MPAA Rating: unrated, profanity

Cast: Ed Sheeran, Benny Blanco, Foy Vance, Julia Michaels, Murray Cummings

Credits:Directed by Murray Cummings. An Apple Music release.

Running time: 1:24