What is SSAI (Server-Side Ad Insertion)

Created by Andrew Baritz, Modified on Wed, 25 Jun at 12:52 PM by Andrew Baritz

SSAI (Server-Side Ad Insertion) for FAST Streaming is a technology used in Free Ad-Supported Streaming TV (FAST) services to deliver ads seamlessly within the stream—without buffering or visible transitions. It makes ad breaks look and feel like part of the original content, improving the viewer experience and increasing monetization opportunities.

? What is SSAI in Layman's Terms?

Imagine you're watching a live TV show on a FAST channel. Instead of the screen freezing and loading a commercial, the ads just appear—perfectly stitched into the program—like cable TV. That smooth insertion is thanks to SSAI.

?️ How SSAI Works (Step-by-Step)

Here's a breakdown of the SSAI workflow in FAST:

Step	Description
1. Stream Request	A viewer clicks on a FAST channel (like Pluto TV or Revry).
2. Manifest Request	The client device (Roku, smart TV, etc.) requests a manifest file (e.g., HLS `.m3u8` or DASH `.mpd`) from the SSAI server.
3. Ad Decisioning	SSAI server communicates with an Ad Server or SSP (via VAST or VMAP) to fetch ads targeted to the viewer.
4. Stitching	Ads are transcoded and stitched server-side into the video stream as new manifest segments.
5. Playback	The viewer receives one continuous stream—ads and content together—without switching players or buffering.

? Visual: SSAI Flow in FAST

arduino
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Viewer → Player → SSAI Server → [Ad Server + Content Server]                         ↓            Manifest + Ad Stitching → Player → Seamless Stream

? SSAI vs CSAI (Client-Side Ad Insertion)

Feature	SSAI	CSAI
Ad Insertion Point	Server-side (before it hits player)	Client-side (in the player itself)
Seamless Playback	✅ Smooth, buffer-free	❌ May buffer or crash
Ad Blocking	❌ Hard to block	✅ Easier to block
Device Complexity	Low (works across all platforms)	High (each platform behaves differently)

? Why SSAI is Ideal for FAST

Scalable: Works with live linear streams across millions of devices.
Consistent: No janky ad loads or client incompatibility.
Monetizable: Supports dynamic ad insertion (DAI) based on viewer targeting.
Bypasses Ad Blockers: Ads are stitched into content, not easily detected.

? Example Tech Stack for SSAI in FAST

Component	Example
SSAI Platform	Google DAI, AWS MediaTailor, Yospace
Ad Server	FreeWheel, SpringServe, Magnite
Player	Roku Player, Samsung Tizen, LG webOS
Streaming Protocol	HLS, MPEG-DASH

? Pro Tip for Publishers

When implementing SSAI for FAST:

Ensure ad markers (SCTE-35 cues) are properly set in your video content.
Work with an SSP that supports VAST 4.0+ for better tracking and transparency.
Validate your ad stitching performance across different devices and bandwidths.