Chan Marshall, known by her stage name Cat Power, will supply the voice narration for the upcoming Janis Joplin documentary “Janis” from director Amy Berg.

The documentary will have its world premiere at the Venice Film Festival, where it was selected Wednesday to screen out of competition.

The film will include Marshall reading Jolpin’s own letters to her family and lovers, while the soundtrack will have her hits “Cry Baby,” “Summertime” and “Piece of My Heart.”

“After attempting to get this film off the ground for seven years, I am ecstatic that the film is finally ready to be seen,” Berg said. “This has been a labor of love, and I cannot wait to share Janis’ unique, intimate story with the world. Chan Marshall (Cat Power) has delivered a beautiful, introspective voice of Janis’ by reading her letters.”

Footage includes Joplin performing at Monterey Pop in 1967, Woodstock in 1969 and Festival Express in 1970, as well as witness interviews with her family, friends and rock star contemporaries. Joplin died in 1970 of a drug overdose.

The Joplin Estate is supporting the film. Alex Gibney produced through his Jigsaw Productions banner with Berg and Jeff Jampol from Jam Inc. The documentary is exec produced by Susan Lacy, Michael Kantor, Noah Haeussner, Michael Raimondi and Stacey Offman.

Disarming Films, Jigsaw Productions and Thirteen Productions LLC’s “American Masters” co-produced “Janis” in association with Sony Music Entertainment and UEG. Content Media is overseeing worldwide sales for “Janis.”