{"id":6582,"date":"2026-06-23T10:31:01","date_gmt":"2026-06-23T10:31:01","guid":{"rendered":"https:\/\/www.5centscdn.net\/blog\/?p=6582"},"modified":"2026-07-13T10:01:24","modified_gmt":"2026-07-13T10:01:24","slug":"what-is-ssai-server-side-ad-insertion","status":"publish","type":"post","link":"https:\/\/www.5centscdn.net\/blog\/what-is-ssai-server-side-ad-insertion\/","title":{"rendered":"What Is SSAI? Server-Side Ad Insertion Explained"},"content":{"rendered":"
<\/div>\n

SSAI (server-side ad insertion) is a streaming technology that stitches ads directly into a video stream on the server before it reaches the viewer, so content and ads arrive as one seamless, buffer-free stream that ad blockers cannot easily separate.<\/strong><\/p>\n\n\n\n

If you run an OTT service, a FAST channel, or any ad-supported stream, SSAI is the technology that decides whether your ads play smoothly \u2014 and whether they actually generate revenue. It is also frequently called dynamic ad insertion (DAI). This guide explains what SSAI is, how it works, how it differs from client-side insertion, and the part most articles skip: how much publishers realistically earn with it.<\/strong><\/p>\n\n\n\n

Because ads are stitched in before delivery, the global CDN<\/a> carrying the stream plays a central role in how reliably those ads reach viewers \u2014 which is exactly where SSAI lives in the pipeline.<\/p>\n\n\n\n

What does SSAI stand for?<\/strong><\/h2>\n\n\n\n

SSAI stands for Server-Side Ad Insertion<\/strong>. The \u201cserver-side\u201d part is the whole point: the work of inserting the ad happens on a server in the cloud, not on the viewer\u2019s phone, browser, or smart TV. The viewer\u2019s device simply plays one continuous stream and never knows where the content ended and the ad began.<\/p>\n\n\n\n

How SSAI works<\/strong><\/h2>\n\n\n\n
\"Five-step
How SSAI works<\/strong><\/figcaption><\/figure>\n\n\n\n

Here is the end-to-end flow, simplified into five steps:<\/p>\n\n\n\n

    \n
  1. A viewer presses play. The player requests the stream and its manifest \u2014 the playlist that tells the player what segments to load and in what order.<\/li>\n\n\n\n
  2. The SSAI service spots an upcoming ad break, usually flagged by an SCTE-35 marker embedded in the stream.<\/li>\n\n\n\n
  3. It queries an ad decision server (ADS)<\/strong> using a VAST or VMAP request, passing context like device, geography, and content metadata so the right ad is chosen.<\/li>\n\n\n\n
  4. The chosen ad is transcoded to match the stream\u2019s bitrate, resolution, and codec, then stitched into the manifest at the break point.<\/li>\n\n\n\n
  5. The CDN<\/a> delivers the unified stream \u2014 content and ad as one \u2014 to the viewer with no visible transition.<\/li>\n<\/ol>\n\n\n\n

    The technical signaling behind step 2 (SCTE-35 cue markers, marker pass-through vs. CDN-side insertion, VAST tag setup) is a topic on its own. If you are ready to implement, our SCTE-35 support & SSAI workflow guide<\/a> walks through the hands-on configuration.<\/p>\n\n\n\n

    Under the hood, SSAI works by manipulating the HLS<\/a> manifest \u2014 the playlist defined in RFC 8216<\/a> \u2014 swapping in ad segments while preserving the bitrate ladder so adaptive streaming keeps working.<\/p>\n\n\n\n

    SSAI vs CSAI: what\u2019s the difference?<\/strong><\/h2>\n\n\n\n
    \"Comparison
    SSAI vs CSAI Comparison<\/strong><\/figcaption><\/figure>\n\n\n\n

    The alternative to SSAI is CSAI (client-side ad insertion)<\/strong>, where the viewer\u2019s player requests and loads each ad separately at the break. The transactional and measurement steps look similar; the difference is where<\/em> the insertion happens \u2014 on a server, or on the device.<\/p>\n\n\n\n

    Factor<\/strong><\/th>SSAI (server-side)<\/strong><\/th>CSAI (client-side)<\/strong><\/th><\/tr><\/thead>
    Where ads are inserted<\/td>On the server, before delivery<\/td>On the viewer\u2019s device\/player<\/td><\/tr>
    Viewer experience<\/td>Seamless, no buffering at transitions<\/td>Possible spinning wheel \/ lag<\/td><\/tr>
    Ad-blocker resistance<\/td>High \u2014 ads are part of the stream<\/td>Low \u2014 separate ad calls can be blocked<\/td><\/tr>
    Scale (live, high concurrency)<\/td>Excellent \u2014 centralized<\/td>Heavier load per device<\/td><\/tr>
    Interactivity<\/td>More limited<\/td>Richer (SDK-driven formats)<\/td><\/tr>
    Best for<\/td>CTV, FAST, live, VOD at scale<\/td>Mobile apps, browser, interactive units<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

    Why SSAI matters for monetization<\/strong><\/h2>\n\n\n\n