Viacom said it formed a partnership with Roku to deliver targeted advertising to over-the-top viewers.

Viacom will be able to used data from Roku to address messages to custom audience segments viewing on Roku devices. Roku users streamed 5.5 billion hours of content.

Viacom has complained that tradition ratings don't include viewers watching its content on digital devices. The agreement helps monetize some of that viewing.

Viacom bought a stake in Roku earlier this year.

"Viacom's unique partnership with Roku extends our game-changing ecosystem, bringing targeted advertising at scale in a way that - until now - was not available in the premium television environment," said Kern Schireson, executive VP, data strategy & consumer intelligence at Viacom. "With this partnership, we can deliver more relevant messages to Roku consumers for products and services that interest them. This is the first time dynamic, 1:1 advertising will be possible as part of a larger linear TV buy. Advertising experiences like this are more impactful for both consumers and marketers."