Seattle--Coming soon to a computer near you: sponsored audio and visual programming. DoubleClick, New York, said Monday it will integrate its ad serving and tracking systems with the streaming audio and video network hosted by RealNetworks, Seattle. The move means programmers on RealNetworks will be able to offer lead-in advertising to audiovisual programs, rotating banners and timed, static banners. Marketers will be able to use DoubleClick to reach, track and manage audiovisual campaigns. ABC News, CBS.com and The Health Network are among participants in a trial of the service, scheduled to become commercially available by April 1.