Viacom, owner of the Paramount movie studio and cable TV channels like MTV and Comedy Central, said quarterly net income rose 13 percent to $650 million, or $1.26 a share, even as revenue fell 17 percent to $3.36 billion. Viacom cut expenses by 26 percent to $2.31 billion. Revenue at its cable business was flat at $2.29 billion, and operating income fell 3 percent as ad sales slowed.