SSAI

Server-Side Ad Insertion (SSAI) is a method for inserting advertising into video streams during delivery rather than in the client. It is commonly used with HTTP-based streaming formats such as HLS and MPEG-DASH. In SSAI, the ad decision and stitching occur on the server side, producing a single, ad-inclusive stream that the viewer device plays back.

When a viewer requests content, an ad decision server determines which ads to serve based on targeting information, frequency caps, and campaign rules. A stitcher or muxer combines the selected ads with the content and delivers a continuous stream or an updated manifest to the client. The client receives the same continuous playback without separate ad-loading steps. This approach helps reduce the likelihood of ad-block bypass and can improve playback continuity by integrating ads into the main stream.

SSAI provides a consistent viewing experience across devices and networks, protects ad inventory from tampering, and can simplify client-side logic since the client plays back a single stream. It can also help with resource efficiency, as ad loading happens alongside the main content.

Limitations include challenges in ad measurement and attribution, since impressions are generated on the server side and client visibility may be limited. Personalization can require broader data sharing with the ad decisioning server, raising privacy considerations. Debugging, logging, and scaling the ad stack can be complex, and compatibility with DRM, player implementations, and cross-provider workflows may vary.

Deployment considerations: SSAI is widely used by OTT platforms and content distributors to ensure consistent ad insertion, but in some cases it is complemented by client-side insertion to enable richer targeting or measurement. Related concepts include dynamic ad insertion, server-side stitching, and client-side ad insertion.