Some careers sputtered on the entertainment stage as social justice platform, while that of seriously committed Harry Belafonte took a new turn and rose higher. Coproduced by daughter Gina and titled from advice given him by Paul Robeson, at an hour and three-quarters Sing Your Song can deal with only a part of the life revealed in greater depth in recent memoir My Song. Given the subject’s participation and narration and six decades’ media coverage of his activities, what of necessity had to be omitted must be intriguing, so it was a shame that writer-director Susanne Rostok could not make a scheduled Q&A after her Sundance-premièred documentary at the African Diaspora International Film Festival.

The life itself is not precisely the focus, and although places and faces, dates and events are indicated, this is not cookie-cutter cradle-onwards biopic. The birth in Harlem and eight young years in Jamaica, the three wives and four children -- all interviewed -- World War II naval service followed by janitorial work, celebrity friends and even the apartments lived in, are adroitly worked in. But the thrust is the public person, the performer acclaim meshed with, ultimately become a vehicle for, a dedication to human rights that has widened its embrace up his present eighty-four years.

The relationship with first wife Marguerite could not survive the Hoover FBI’s machinations coming from his friendship with and commitment to Robeson and Martin Luther King, Jr., and the civil rights/anti-Vietnam War movements. Ex-second wife Julie recounts their shared enthusiasm for the world struggle for equality and dignity; but she, the children, and Belafonte himself acknowledge the unreconciled strains of combining marriage and fatherhood with the consuming drive for social causes even to real physical risk (as in Mississippi with old friend Sidney Poitier).

This involvement in so wide a gamut of humanitarian efforts is, amazingly, covered or at least touched on; the shunting to the background of the personal is understandable.

Handsome, resembling Yul Brynner, even now he adopts new causes, today that of redressing “the new slavery” incarceration of Afro-American and Latino youth (sparked by indignation at the handcuffing of an “unruly” nine-year-old girl). Indeed, many of his television appearances and choices of material -- e.g., “Scarlet Ribbons” -- have been geared to young people, and even in this age hardened to media shock, images of starving Ethiopian babies are brutal for him as UNICEF ambassador and for us.

At the Harlem American Negro Theatre with janitor’s gift comps, he got the acting itch, joined the theater’s company, and then became a student with others later to be ultra-famous at the New School Dramatic Workshop. “I was an activist before I was an actor,” but the first step up was as a nightclub singer of pop with a jazz flavor, to pay for those classes. Leadbelly (Huddie Ledbetter) at the Village Vanguard inspired a search into folk music at the Library of Congress and a mining of his family’s island roots for such hits as “Jamaica Farewell,” “The Banana Boat Song” and “Mama Looka Bubu.”

Purists decried what they felt was commercialization of their demesne when a third LP, Calypso, became the first million-seller gold album ever, and he used his popularity to introduce young stars from other genres and languages like “Singer of Freedom” Miriam Makeba and Nana Mouskouri

Tony, Grammy and Emmy awards came in but also slights, touring the South with Marge and Gower Champion; headlining in Vegas but barred from the front door, restaurant and pool (which he “integrated”); being stopped by police in white Beverly Hills; backlash against sponsors of the Nat “King” Cole show and his own integrated specials. And reaction against his appearing in films alongside white actresses, much less romancing them, though publicist Mike Merrick remarks that the controversy helped box office.

It needed only a phone call from the Rev. Dr. King for a “short talk” that lasted four hours, to channel his feelings into lifelong commitment and a closeness between the two articulate men. It was the activist-entertainer who convinced presidential aspirant JFK to intervene to save the minister from a Georgia chain gang for a traffic violation and as president to accept the August 1963 March on Washington and who, in his mentor-friend’s words, would “win [Attorney General RFK] to our cause.”

In that unmistakable throaty voice, Harry Belafonte talks of his triumphs and shortcomings, but nary a word about being a cancer survivor. A high-visibility activist before the day of mega-celebrity activism, he remains involved, stung and spurred by present “chaos, disorder and violence” after so many have invested so much to change things.

Dr. Johnson characterized remarriage as “the triumph of hope over experience,” but in matters of marriage and social progress, Belafonte confesses himself an optimist regarding “the truth and hope of the people themselves.” The life is so rich, truthful and hopeful that admirable Sing Your Song can only give some idea of it.

(Released by S2BN Films; not rated by MPAA.)