The title of the autobiographical documentary co-directed by Beyoncé Knowles comes from the ancient round “Row, Row, Row Your Boat,” but it also says more than perhaps the superstar intended about how much of a gloss the film puts on her life and career.

“Life Is But a Dream,” co-directed by Ed Burke and billed by HBO as “an intimate, revealing documentary,” isn’t really, but there are enough moments that pass for authenticity to make it a benignly informative glimpse into a rarefied existence.

Just before the Super Bowl, the TV show “TMZ” aired a segment that was legitimately revealing about Beyoncé, simply because, of course, she didn’t have anything to do with it. The singer was surprised as she and her entourage headed into a nondescript New Orleans building where she would rehearse her halftime act for the big game.

There are genuine moments in “Life Is But a Dream,” but they’re deeply sandwiched among admittedly dazzling production numbers from recent live performances.

We get a sense of the “real” Beyoncé from home movies of the singer and her sisters when they were kids, from her frequent video-diary entries and from behind-the-scenes footage of the singer in rehearsal. She explains why she had to declare her professional independence from her father, but there are scant references to Destiny’s Child, or to Beyonce’s siblings.

The film would just be a big, glitzy promotional piece for the multi-Grammy winner, were it not for the fact that she comes across as an admirably confident professional without exhibiting huge diva moments, sincerely in love with husband Jay-Z, equally credible as she expresses the pain she felt when her first pregnancy ended in a miscarriage and about tabloid stories that she would use a surrogate for her second pregnancy in order to preserve her figure. She tenderly displays her swollen body not long before the birth of her daughter, Blue Ivy Carter, and the image speaks volumes.

It’s not really Beyoncé’s fault that even those moments of authenticity seem far removed from the day-to-day lives of the rest of the world, adding unintended irony.