For many, many years now, people have been talking about doing a proper big-screen biopic of Janis Joplin. Just about every actress in Hollywood — from Bette Midler in her youth to Amy Adams — has been touted as the next person to play Janis.

Still hasn’t happened. One thing I always wondered about these efforts: Would the actress playing Janis sing in her own voice, or would they use Joplin’s recorded tracks?

Big question. Because nobody sounded like Janis Joplin.

A new documentary, “Janis: Little Girl Blue,” narrated by Cat Power, gives a reminder of the storytelling possibilities in Joplin’s saga.

Born in Port Arthur, Texas, in 1943, Joplin was a misfit kid whose beatnik attitude and bluesy voice led her eventually to the Haight-Ashbury scene in San Francisco.

And so she experienced the Summer of Love, hung out with the Grateful Dead, and bowled people over with her singing.

After getting together with Big Brother and the Holding Company, her rise to prominence was swift.

The fall was swift, too, because Joplin was dead in 1970, age 27. The emotional need that fueled her incredible stage performances found some relief in heroin and alcohol, until her substance abuse caught up with her.

Director Amy Berg interviews Joplin’s old colleagues, and it’s good to hear people speak of her without turning her into a plaster saint.

The members of Big Brother are articulate about Joplin, and so are her childhood friends and her well-spoken siblings.

Dick Cavett shares pieces of interviews with Joplin on his talk show — and also implies the two had an intimate relationship. An odd couple if ever there was one.

Old photographs help paint the story, too. Seeing Joplin’s parents in Eisenhower-era photos gives some sense of what kind of bombshell went off in their family when Janis arrived.

Of course, the real draw is the music and concert footage.

Berg is wise in letting a couple of significant Joplin performances play out in unedited glory, instead of just editing together snippets.

Janis Joplin’s personality, as it emerges in interviews and her own writing, is not merely the howling, bombastic belter of the stage. By turns cheerful, innocent, and determined, Joplin emerges as a fragile soul, her nerve endings exposed to the world.

But if you’ve heard her music, that will come as no shock.

“Janis: Little Girl Blue” (3 stars)

Documentary portrait of Janis Joplin, from misfit kid in Port Arthur, Texas, to psychedelic diva of the San Francisco scene. Interviews with friends and colleagues give a rounded portrait, and some well-handled live performance footage is eloquent testimony to Joplin’s unique power as a singer.

Rating: Not rated; probably PG-13 for language, subject matter

Showing: SIFF Uptown