Difference Between CSAI vs SSAI: What It Is & How It Works

In the world of digital video advertising, two major technologies shape how ads are delivered to audiences: CSAI (Client-Side Ad Insertion) and SSAI (Server-Side Ad Insertion). Both methods serve the same purpose — delivering ads during video playback — but they work in completely different ways and have unique advantages for streaming platforms like cAfrica.

What Is CSAI? (Client-Side Ad Insertion)

CSAI is the traditional method most platforms have used for years. In this model, the video player on the user’s device is responsible for requesting, loading, and playing ads.

How CSAI Works:

1. The viewer presses play on a video.

2. The video player pauses the content and sends a request to an ad server.

3. The ad server returns an ad (VAST or VMAP).

4. The video player loads and plays the ad.

5. Once finished, the content resumes.

Advantages of CSAI:

• Great for interactive ads, click-throughs, and companion banners.

• Easier to measure impressions directly from the device.

• Flexible for advertisers who need tracking pixels.

Disadvantages:

• More susceptible to ad blockers, especially on web browsers.

• Can cause buffering because ads load separately from the content.

• Higher risk of “ad playback failed” errors on slow or unstable networks.

What Is SSAI? (Server-Side Ad Insertion)

SSAI, also known as ad stitching, is a more advanced method where ads are merged with the video stream on the server before reaching the viewer. To the device, it looks like one seamless video.

How SSAI Works:

1. The viewer presses play.

2. The server receives the request and contacts the ad server.

3. Ads are “stitched” into the video stream in real time.

4. The viewer receives a single continuous stream with content + ads combined.

Advantages of SSAI:

• Ad-blocker resistant because ads appear as part of the video.

• Provides a smoother viewing experience with no buffering between ads.

• More consistent ad delivery across devices, smart TVs, and streaming sticks.

• Ideal for live streaming, where timing is critical.

Disadvantages:

• Harder for advertisers to track clicks or interactive elements.

• More complex and expensive to implement compared to CSAI.

Which Is Better?

Both CSAI and SSAI have their place. Many modern OTT platforms — including cAfrica — use a hybrid approach, combining SSAI for smooth playback and CSAI for interactive features like overlays or companion ads.

Choosing the right method depends on your goals:

• Use CSAI for interactivity and precise analytics.

• Use SSAI for seamless viewing and ad-blocker protection.

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CSAI vs SSAI, Client-side ad insertion, Server-side ad insertion, Video ad stitching, How SSAI works, How CSAI works