How does server-side ad insertion work on CTV?

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Last updated: April 8, 2026

Quick Answer: Server-side ad insertion (SSAI) on Connected TV (CTV) works by dynamically stitching ads into video streams at the server level before delivery to viewers, enabling seamless ad experiences without buffering. This technology emerged around 2015 as CTV adoption grew, with major platforms like Hulu and Roku implementing it by 2017. SSAI typically reduces ad load times by 50-70% compared to client-side insertion and supports targeted advertising using viewer data. By 2023, over 80% of major CTV platforms used SSAI for most ad-supported content.

Key Facts

SSAI dynamically stitches ads into video streams at server level before delivery
Technology emerged around 2015 with major CTV platform adoption by 2017
Reduces ad load times by 50-70% compared to client-side insertion
Supports targeted advertising using viewer demographic and behavioral data
Over 80% of major CTV platforms used SSAI by 2023

Overview

Server-side ad insertion (SSAI) is a technology developed specifically for streaming video platforms, particularly Connected TV (CTV) devices, to deliver advertisements seamlessly within video content. The technology emerged around 2015 as CTV adoption accelerated, with household penetration reaching 82% in the United States by 2022 according to Nielsen. Traditional client-side ad insertion, where ads are loaded separately from content, caused buffering and poor viewer experiences on CTV devices. Major streaming platforms like Hulu began implementing SSAI in 2016, followed by Roku and Amazon Fire TV in 2017. The global SSAI market was valued at $2.1 billion in 2021 and projected to reach $5.8 billion by 2028, driven by CTV growth. Key technology providers include Google (with its Dynamic Ad Insertion), AWS Elemental, and Brightcove, who developed specialized SSAI solutions between 2015-2020.

How It Works

SSAI operates through a multi-step technical process that begins when a viewer requests video content. First, the video player sends a request to the content delivery network (CDN), which communicates with the SSAI server. The server identifies ad opportunities based on content metadata and cue points, typically every 15-30 minutes in a streaming session. It then queries an ad decisioning server, which selects appropriate ads based on viewer data like location, demographics, and viewing history. The SSAI server dynamically stitches the selected ads into the main video stream at the server level, creating a single continuous stream. This unified stream is delivered to the viewer's device through HTTP Live Streaming (HLS) or MPEG-DASH protocols. The entire process happens in milliseconds, with ads encoded at matching bitrates (typically 2-15 Mbps for CTV) to prevent quality disruptions. The system also tracks impressions and performance metrics in real-time through beacons sent back to analytics platforms.

Why It Matters

SSAI matters because it fundamentally improves the CTV viewing experience while enabling more effective advertising. By eliminating buffering between content and ads, it reduces viewer frustration and abandonment rates by approximately 30% compared to client-side insertion. This technology enables precise ad targeting on CTV devices, allowing advertisers to reach specific demographics with 70-80% accuracy rates. For content providers, SSAI increases ad completion rates to over 95% and supports dynamic ad replacement, allowing ads in older content to remain relevant. The technology also enables addressable advertising at scale, with projections suggesting 50% of CTV ads will be addressable by 2025. This creates a sustainable revenue model for streaming services while providing viewers with free or reduced-cost content options.