Google’s own Shaka sdk (video playback with ads) gives ad markers in the initial video manifest so that they can be marked on the timeline, so hopefully it’ll be trivial. Usually (but not always) with SSAI, the ads are spliced into the stream just before being sent to the client. That way if a user has just recently watched an ad pod, the server can choose to ignore that marker for a better UX in hopes that they don’t bounce if ads are too frequent.