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What is SSAI Ad Stitching & CTV Ad Pods?

Also known as: Ad stitching, Ad pod, Pod bidding, Manifest manipulation

Quick definition

Server-side ad insertion (SSAI) stitches ads directly into the video stream on the server, so a CTV or OTT viewer sees ads and content as one continuous stream; ad pods are the commercial breaks of several slots that the stitcher fills, increasingly through pod-level programmatic bidding.

How it works

  1. 1Player requests a stream; the stitcher reads ad break markers (SCTE-35 or VMAP cue points)
  2. 2Stitcher or SSP sends an ad request for the pod: number of slots, total duration, competitive separation rules
  3. 3Returned VAST creatives are transcoded to match the stream's renditions
  4. 4Manifest (HLS/DASH) is rewritten so ad segments play inline with content
  5. 5Impressions and quartiles are beaconed server-side or by the client, then reconciled

Key points

Why SSAI
Avoids ad blockers, buffering and black screens between content and ads on living-room devices with limited client logic.
Pod logic
OpenRTB 2.6 added pod signals (pod ID, sequence, duration ranges) so DSPs can bid on positions and sellers can enforce brand separation and frequency within one break.
Measurement gap
Server-side beacons come from data-centre IPs, so the stitcher must forward the real device IP and user agent (X-Forwarded-For / X-Device headers) or verification vendors cannot validate the view.
Fraud vector
SSAI spoofing fakes server-side impressions at scale; mitigations include signed requests, app-ads.txt checks and vendor-certified stitchers.

Benefits

  • Broadcast-like, seamless viewer experience
  • Higher fill and fewer client playback failures
  • Pod bidding raises yield and creative control per break

Trade-offs

  • Harder third-party measurement and verification
  • Repeated or clashing ads when pod de-duplication is weak
  • Discrepancies between stitcher, SSP and DSP counts are common

FAQ

SSAI vs CSAI: what is the difference?

Client-side insertion (CSAI) lets the player call ad servers and switch to ad files; SSAI merges ads into the stream on the server. SSAI gives smoother playback, CSAI gives easier client measurement.

Why do viewers see the same ad twice in one break?

The pod was filled by multiple independent requests without creative de-duplication. Pod-level bidding and creative ID separation rules fix most of it.

How should buyers verify SSAI inventory?

Require forwarded device signals, accredited SSAI vendors, app-ads.txt authorization for the CTV app and IVT filtering that understands server-side traffic.

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Official sources

Last reviewed 2026-11-03. Explanations are written by AdTech Radar; consult the official specification for implementation.