Broadcaster
A broadcaster running ad-supported live streams whose fill rate is depressed by client-side ad-blocker penetration or by player ad calls that miss the SCTE break window
Streaming platformReady to pilotBuilt by Professional ServicesLast updated 29 July 2026
Server-Side Ad InsertionPersonalised ad breaks stitched into the live stream
Ad inventory that has already been sold never reaches the viewer because the player-side ad call is blocked, dropped or simply never made - and the broadcaster finds out after the campaign, not before. Server Side Ad Insertion stitches personalised ad breaks into the stream itself on the server, so blockers cannot intercept the call, playback never stalls waiting for a creative, and the ad is delivered as part of the video segment rather than as a separate request.
SSAI on AWS MediaTailorPersonalised per viewerSCTE-35 triggered breaksServer-side impression tracking
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The problem this solves
Client-side ad insertion puts the ad call in the player, which means it is exposed to ad blockers, network failures on the viewer's device and the latency of a round-trip to an ad server at exactly the moment playback needs to continue. The result is missed impressions, buffering at break points and an experience that signals to the viewer that an ad is coming - making a block even more likely.
For live streams the problem is compounded: SCTE markers in the manifest define the break window, but if the player-side call does not complete within that window the slot is simply lost. VOD is more forgiving but still suffers from fill-rate drops whenever the ad call fails or the creative takes too long to load. In both cases the revenue loss is silent and accumulates across every viewer session.
Who this is for
This is relevant if you are:
Rights holder
A rights-holder or VOD operator whose campaign reporting shows a gap between sold inventory and delivered impressions that cannot be attributed to targeting or creative issues
Telco
A telco or MVPD delivering linear or catch-up content to subscribers and looking to insert operator-specific or regionally personalised ads without modifying downstream players
How it works (SSAI Live)
- 1An SCTE-35 marker in the live manifest signals that an ad break has opened.
- 2AWS Elemental MediaTailor rewrites the HLS manifest in real time and stitches the ad segments into it before the player asks for them.
- 3The ad decision server returns a targeted creative, with the targeting signals passed server-side rather than from the player.
- 4The player receives one continuous stream through CloudFront: no separate ad request, and no stall at the break point.
What makes it different
Client-side insertion treats the ad as a separate fetch the player makes; server-side insertion treats it as part of the content the server assembles. That single architectural difference closes the gap that ad blockers exploit, removes the player-side latency at break points and makes impression measurement a server fact rather than a client promise. The MediaTailor-based implementation means the ad decision, the transcode and the stitch all happen within AWS infrastructure, so there is no additional origin hop and the latency added to the break is minimal.
Current status & next steps
Ready to pilotReviewed 29 July 2026
SSAI is ready to pilot. Both variants - live stream insertion triggered by SCTE markers and VOD insertion via cue points - are built and demonstrated on this page. The AWS Elemental MediaTailor integration, the ad decision flow and the server-side beaconing are all operational.
The next step is a pilot against a customer's live or VOD workflow, where fill-rate improvement and impression accuracy can be measured against their existing client-side baseline.
Interested in a pilot conversation?
Tell us whether your priority is live or VOD, roughly what your current fill rate looks like, and we will tell you what a MediaTailor pilot would involve.