HOLLYWOOD — Listening to News Corp. chief operating officer Peter Chernin and Viacom chairman-CEO Sumner Redstone talk last week about costs in the film biz, one could be forgiven for being puzzled.

On the one hand, the cost of making movies is apparently spiraling out of control; on the other, not spending bigtime means not being able to reap the big rewards downstream.

And producing a successful movie at all is very hit and miss anyway.

Or is it?

With so many ancillaries and so many new ways to package, reformat and remake just about every bit of content produced by these congloms, it would seem that sooner or later every film must make money.

And with so many marketing mavens and cost-controllers analyzing every last project and its potential return, it would seem unlikely that many duds on the order of “Gigli” or “Pluto Nash” make it through the greenlight process and to the screen.

Right now the congloms are in labor talks with screenwriters, so they’re more reluctant than usual to intimate that they’ve done their very best to take a lot of the risk out of the moviemaking equation.

But no one ever asks about that at these panels. It’s always “How do you plan to get costs under control?” Not “How much of the guess-timating has been taken out of the process of determining what a film might eventually bring in to the studio?”

My bet about the latter question: a lot.

Most of the recent surprises at the box office have in fact been happy ones: Few, for example, thought a film in Aramaic and Latin about the passion of Christ would bring in $400 million … or that there was a vast untapped audience out there in middle America that wanted something different.

On the other hand, it’s hard to get anyone at a studio to admit that any film (at their studio) was more than “a mild disappointment” — except, refreshingly, for producer Joe Roth who readily admitted that his “Gigli” was a dud.

Not that the razor-sharp Chernin and the scrappy Redstone weren’t instructive, each in his own way, in responding to the inevitable query about costs. They were speaking at a panel session on Media and Entertainment April 28 organized by the Milken Institute.

Their differences are not just in personal style: The studios they run, Fox and Paramount, respectively, are grappling with the problems facing the film biz in decidedly different ways.

Following the lead of his boss Rupert Murdoch, Chernin’s mantra at the moment is that costs have to be brought under control. That means fewer stars, tighter controls on talent deals and only a few megabuck projects.

He pointed to several upcoming tentpoles that cost more than $200 million to make — none from his studio, he insisted — and perhaps $100 million more to promote and market. (Chernin claims it’s hard to read “a single bit of truth” about film budgets in the press.)

One of the upcoming tentpoles, he suggested, will inevitably, in his words, “not make it” and a writedown of $175 million to $200 million could shake the biz “to its foundations,” he claimed.

(He may be right, though execs at the studio in question are likely to insist that they’ll make it all back in DVD or in foreign — or that the press exaggerated the budget in the first place.)

Seemingly unfazed by Chernin’s prognostication, Redstone put the emphasis elsewhere. In his view, being too risk-averse hasn’t been paying off for Paramount. The company hasn’t had a $200 million grosser since “Mission: Impossible 2” four years ago.

“I saw last fall that the creative community was not going to Paramount. If we’re too risk-averse, there are fewer rewards,” Redstone said.

(Presumably, just hitting singles and doubles has kept the studio in the black but hasn’t sufficiently fed all those ancillaries.)

Not that Redstone intends to let his studio bosses be profligate, but he says he wants his “still-hot team” of Jonathan Dolgen and Sheri Lansing to get back into the tentpole game. That apparently means bigger stars, richer deals and more tentpoles.

Whether Chernin’s or Redstone’s compass proves true will be determined by box office seasons to come.