Viacom Inc reported a rise in quarterly profit, defying weak box-office sales and a challenging advertising environment.

The company said on Thursday that fiscal fourth-quarter net income rose 12 percent to $643 million even though revenue fell 17 percent.

"At the end of the day, I think they are really focused on operating efficiency," said Brian Wieser, an analyst with Pivotal Research Group. "It's a company that can still grow its margin even in a weak advertising market."

Viacom has been challenged by a drop in ratings at its once- popular cable networks MTV and Nickelodeon. Domestic advertising revenue declined 6 percent in the latest quarter, but affiliate fees - reaped from contracts with cable operators that pay to air Viacom's channels - were up 12 percent.

Also during the quarter, Viacom and satellite pay-TV provider DirecTV Group had a showdown resulting in a bruising nine-day blackout this summer of Viacom's channels on DirecTV. The dispute was over a contract regarding affiliate fees. Viacom said it had negotiated higher fees in the new deal.

The company's filmed entertainment unit, which consists of Paramount Pictures, said revenue fell 39 percent on tough comparisons to last year when the studio released "Transformers: Dark Side of the Moon".

Still, the company managed to increase operating income in that division 5 percent because of TV and digital deals and cost cuts.

For the fourth quarter, total revenue was $3.36 billion, roughly in line with analysts' expectations of $3.40 billion, according to Thomson Reuters I/B/E/S.

Viacom posted adjusted earnings per share of $1.21 compared with analysts' forecast of $1.17.