Preconditioning ad content for digital program insertion

Methods are provided for inserting advertisements or the like and/or to perform grooming functions for a video, audio and/or data stream. Video programming is received in a network stream. Alternate content, such as advertisements, is received in content stream. The content stream is preconditioned to provide an entrance point therein for splicing the network stream to the content stream. Preconditioning of the content stream can also be performed to provide an exit point for splicing back to the network stream when the alternate content (e.g., advertisements) has concluded.