CTV & video · also called SSAI, ad stitching, server-side ad stitching
SSAI (server-side ad insertion)
SSAI (server-side ad insertion) stitches video ads directly into the content stream on a server before it reaches the viewer, creating seamless, TV-like playback that ad blockers find hard to detect.
With client-side insertion, the video player on your device pauses the show, requests an ad and plays it separately. With SSAI, a server does that work: when an ad break approaches, the stitching server requests ads on the viewer's behalf, fetches the creatives, transcodes them to match the stream and splices them in, so the viewer receives one continuous video.
The benefits are smooth playback without buffering, support for devices with limited processing power such as many TVs, and resistance to ad blockers. That is why SSAI dominates CTV, FAST and live streaming. It is sometimes called dynamic ad insertion (DAI); see also dynamic ad insertion in audio.
The trade-off is measurement and trust. The ad server sees the SSAI server's IP address, not the viewer's, so SSAI vendors must forward the viewer's device details in headers, and impression tracking is often fired from the server. IAB Tech Lab guidelines standardise this, but it creates an opening for fraud: fake servers pretending to be SSAI systems, known as SSAI spoofing.
Think of it like this
SSAI is like a TV station editing adverts directly into a recorded programme before broadcasting it, instead of your TV switching between two tapes.
An example
During a live cricket match streamed in India, an SSAI server inserts personalised 20-second ads into each over break for millions of concurrent viewers, forwarding each viewer's device IP and user agent to the ad server.
Related terms
CSAI (client-side ad insertion)
CSAI (client-side ad insertion) is when the video player on the viewer's device requests and plays ads itself, pausing the content to switch to a separately loaded ad.
SSAI spoofing
SSAI spoofing is CTV and video fraud in which fraudsters imitate a server-side ad insertion system, sending fake ad requests that appear to come from real viewers watching real streams.
VAST
VAST (Video Ad Serving Template) is the IAB Tech Lab standard XML format that tells a video player which ad to play, where to fetch it and which tracking events to report.
CTV (connected TV)
CTV (connected TV) is any television connected to the internet, such as a smart TV, streaming stick, games console or set-top box, and the advertising shown in streaming apps on it.
Ad pod
An ad pod is a group of video ads played back to back in a single ad break, like a traditional TV commercial break, common in CTV and long-form streaming.
Sources: IAB Tech Lab CTV standards, IAB Tech Lab VAST