Family drama turns volume a bit too loud

“August: Osage County” travels from the stage to the screen with much of its theatricality intact. Too much. For all the scenic prairie panoramas and lived-in look of the big, rural Oklahoma house that is the setting, it still feels like a play – with Meryl Streep, Julia Roberts and pretty much everybody else projecting to the back row.

It’s a sharp-tongued melodrama of cruelty, comical cursing, “big scenes” and shocking revelations. Pulitzer Prize-winning playwright Tracy Letts kept it all in there and then some in this all-star serving of Oscar bait.

Streep tosses moderation away as the salty, testy matriarch, Violet Weston, a pill-popping cancer patient who has spoken her mean-spirited mind for so long she can’t control her tongue.

“I’m just truth-telling,” she says, laughing off the pained or furious reactions of those who feel her wrath. “Damn fine day to tell the truth.”

And that “damn fine day” is the day of her husband’s funeral. We’ve met the sweetly poetic drinker Beverly Weston (Sam Shepard) in the opening scenes. We’ve seen the bigoted, bullying martinet he endures, every day. When he disappears and Violet summons her sister (Margo Martindale) and daughters (Roberts, Julianne Nicholson and Juliette Lewis), we know he’s not coming back. Death was just an extreme means of escape.

Menfolk show up, too. There’s Charlie (Chris Cooper), who has always joked away Violet’s mean streak and winked through the sarcasm it brings out in his own wife, Violet’s sister, Mattie Fae (Martindale). “Little Charlie” (Benedict Cumberbatch, showing a vulnerable side) is their clumsy, put-upon son. Dermot Mulroney is Steve, the Ferrari-driving Florida hustler whom Karen (Lewis) brings home.

And college professor Bill (Ewan McGregor) may be secretly separated from Barbara (Roberts). But he’s there as moral support to his short-tempered, foul-mouthed wife and their messed-up 14-year-old daughter (Abigail Breslin).

Letts wrote wonderful, distinct characters, and the film is so well cast that you buy into this version of the Weston clan. The men are thinly drawn cliches, but the women are clever variations on a mean theme. You sense inherited bitterness in the lot of them, even when they’re smiling and drinking too much red wine. The marvelous exceptions are Karen, who fled the family, and Ivy (Nicholson), who stayed behind – both played as wounded women trying not to flinch at the next assault they know is coming.

The big, ugly moments come from Violet and her oldest. Streep and Roberts give us contrasting visions of what it means to commit to a role. Streep, pale, with chemo-thinned hair not really hidden by a wig, staggers and lurches between bemused incoherence and unbottled rage, lashing out at Barb, the only one to really stand up to her. Roberts doesn’t let herself look as timeworn and grief-stricken as you’d expect. But she ratchets up the volume to the point where you fear violence.

There are melodramatic flourishes aplenty, with actors breaking off into two- or three-character scenes (very theatrical) to tell each other anecdotes of the maudlin or life-is-misery variety.

Director John Wells (“The Company Men”) presides over this in a way that makes the filmed version of this toxic, caustically amusing tale a spectacle we gawk at, slack-jawed in wonder at the depth of the dysfunction.

But does it make us or even allow us to feel anything? Not really. “Osage County” does offer up one almost heartbreaking moment. But it’s so icky that you kind of want to wash it out of your mouth – with supermarket merlot – rather than savor it.