TURN-ONS AND TURN-OFFS IN CURRENT HOME ENTERTAINMENT RELEASES : ****Excellent ***Good **Fair *Poor : VIDEOCASSETTES

“Janis.” MCA. $29.95. There’s not much attempt in this 96-minute 1975 documentary by Howard Alk and Seaton Findlay to explain the dark side of Janis Joplin’s life (she died in 1970 of a drug overdose). But the ample concert footage demonstrates why she is considered by many to be the most compelling female singer ever in rock--someone whose soul-deep performances varied (depending on her mood) from celebratory and defiant to tender and desperate. A bonus: some marvelous interview sequences, including bittersweet reflections during a press conference at her high school reunion in Port Arthur, Tex. Information: (818) 777-4315. ***