TV networks are increasing efforts to attract viewers to their online streaming programming without cannibalizing their TV broadcasts. Ad revenue plays a role in both concerns, the SF Gate reports.

Online growth is expected to be a major point of discussion for attendees of the National Association of Broadcaster's annual meeting, beginning today in Las Vegas.

Another topic on the NAB agenda is the development of new online ad formats for use within streaming shows. Options include a combination of behavior and location targeting.

Networks have enjoyed a general rise in CPM rates, attributable to improved performance measures available online. Additionally, the 'net does something TV does not: The ability for viewers to directly engage an ad.

But while ad rates have risen, the audience has not grown to the point where it represents a significant percentage in comparison to broadcast figures. Some networks have tried offering new shows online before TV debuts, in an effort to start buzz and gain an audience, but so far those tests are limited.

NBC and CBS offer programming on sites beyond their own. NBC streams shows on Hulu and CBS syndicates some to multiple destinations.