What is Server-Side Ad Insertion (SSAI)?

Nowadays, as more and more people watch videos online, the costs of making and delivering these videos are going up. Companies that make videos, like TV stations and streaming services, seek more ways to monetize to keep their businesses growing.

While some companies charge viewers to watch videos (like Netflix), others offer free or cheaper access and make money from ads. This is where ad insertion occurs—the technology inserts ads into videos. There are two main ways to do this: Server-Side Ad Insertion (SSAI) and Client-Side Ad Insertion (CSAI). SSAI is the preferred choice, at least in CTV applications.

According to Pixalate’s data, 78% of CTV apps across Roku, Amazon Fire TV, Samsung Smart TV, and Apple TV employ SSAI for open programmatic advertising. Given this widespread adoption, in this article, we’ll focus on SSAI—explaining how it works and discussing the challenges it can bring.

What is Server-Side Ad Insertion (SSAI)?

Server-side ad insertion (SSAI), or ad stitching, is used in digital advertising to insert ads into online video content at the server level before delivering the content to the end user’s device.

Think of it as when you’re watching your favorite TV show, and it smoothly transitions into the ad break. With server-side ad insertion (SSAI), it’s just as seamless. You’re not stuck waiting for the ad to load—it’s all part of the flow.

You get a continuous viewing experience with no annoying pauses or awkward breaks between the content and ads.

Moreover, it can be applied across various connected or over-the-top (OTT) video environments, including social media platforms. However, the predominant demand stems from the remarkable expansion of Connected TV (CTV).

SSAI technology has become so prevalent that ad tech firms leverage it for video bidding. By handling ad insertion at the server level, SSAI offers several advantages:

• Ad Blocking Resistance – Since ads are inserted at the server level, they are less susceptible to ad blockers commonly used on client-side technologies.
• Improved User Experience – SSAI allows smoother transitions between content and ads, reducing buffering or playback interruptions that can occur with client-side ad insertion methods.
• Better Ad Targeting – Server-side insertion enables more precise ad targeting by leveraging real-time user data and analytics.
• Monetization Flexibility – Content providers have greater flexibility in managing ad inventory and optimizing revenue streams through ad insertion.

How Does SSAI Work?

To understand why ad stitching is essential, let’s look at how most video ads are served nowadays. Videos and ads usually come from different places – videos often come from a content delivery network (CDN). In contrast, ads come from third-party ad servers like Sevio Ad Manager or Criteo. When people start watching, these two pieces of content must be brought together in real-time.

But with server-side ad stitching, things work differently. Instead of this happening on the user’s end, it’s all sorted out behind the scenes. So when you hit play, the video and ad content are mixed seamlessly. This means:

• No choppy breaks – The ads fit smoothly into the stream, like commercial breaks on regular TV.
• Targeted ads – You might see different ads from your friend watching the same movie because they can be chosen based on your interests.
• Better experience – Overall, it’s a smoother and less disruptive way to watch videos with ads.

SSAI vs. CSAI: How Does Server-Side Ad Insertion Differ from Client-Side Ad Insertion?

Now that you understand the basics of SSAI, it’s important to avoid mixing server-side ad insertion (SSAI) with client-side ad insertion (CSAI) because they are different and, dare we say, opposite.

These two processes may seem similar from an auction, transaction, and measurement perspective. However, the crucial difference is where each process occurs – either on a server or in the user’s browser. 

Client-side ad insertion operates by fetching video content from a content delivery network (CDN) upon user request. A CDN is a geographically distributed storage system optimized for fast video delivery. Simultaneously, the user’s device reaches out to a separate ad server, a digital marketplace for advertisements. The ad server, leveraging user data and demographics, selects relevant commercials and transmits them to the device.

Once the video content and ads arrive, the user’s device assumes the responsibility of merging them on the fly. This process can sometimes lead to brief interruptions or choppiness in playback as the ad integrates into the video stream. Ultimately, the user experiences the video with breaks for the inserted commercials.

Server-side ad insertion, on the other hand, offers a more streamlined approach. The video content and advertisements come together before reaching the user’s device. An SSAI service is an intermediary between the CDN and the ad server.

When a user initiates playback, the video content travels from the CDN to the SSAI service. The SSAI service concurrently retrieves ads from the ad server. However, unlike CSAI, the SSAI service doesn’t simply transmit the video and ads as separate entities. Instead, it effortlessly stitches them into a unified stream, ensuring seamless transitions between the video content and the embedded advertisements. This final, pre-integrated video stream with embedded ads is then delivered to the user’s device for playback.

The user experiences the video with pre-programmed commercial breaks, akin to traditional television, with the benefit of potentially receiving advertisements tailored to their interests.

CSAI vs. SSAI: In a Nutshell Comparison

CSAI vs. SSAI: Pros and Cons

CSAI Pros

• Flexibility and Control – You can tailor ad creatives and frequency in real-time based on user behavior during viewing.
• Rich Analytics – Since ads run on the viewer’s device, CSAI provides detailed metrics on user interactions like clicks and ad engagement.
• Format Compatibility – Client-side players can handle various ad formats, including interactive elements, making for a more engaging experience.

CSAI Cons

• Disrupted Viewing – CSAI can cause buffering or latency issues as the video pauses to load ads, potentially frustrating viewers.
• Device Dependence – Effectiveness relies on the viewer’s device capabilities, leading to inconsistencies across different platforms.
• Ad Blocker Vulnerability – The ad fetching process makes CSAI more susceptible to ad blockers that can disrupt ad delivery.

SSAI Pros

• Reduced Ad Blocking Impact – SSAI was initially developed to avoid ad blockers. And that’s because streamlining video ad delivery is useless if the ads fail to reach the audience. Stitched ads are more complex for ad blockers to identify, potentially leading to higher ad fill rates (impressions served).
• Seamless Viewing – Ads are stitched directly into the video stream, resulting in a smooth viewing experience with minimal disruptions.
• Consistent Delivery – Since ads are pre-integrated, SSAI offers consistent ad delivery across various devices and platforms.

SSAI Cons

• Susceptibility to Fraud – While SSAI might seem secure because it happens on the server-side, fraudsters can still exploit it. Studies show that a significant portion (around 17%) of SSAI traffic can be fraudulent on CTV. Why is SSAI vulnerable? To avoid flagging legitimate ads, SSAI servers are often whitelisted by default. This creates a security gap that fraudsters can exploit by spoofing user data and mimicking real devices. Moreover, since the ad insertion happens on the server, it’s harder to detect fraudulent activity than on the client side, where user behavior can be monitored.
• Limited Real-Time Control – SSAI pre-fetches ads, so you can’t dynamically adjust them based on individual user behavior within a session.
• Creative Limitations – SSAI might not fully support some interactive or dynamic ad formats.
• Measurement Challenges – Metrics like ad viewability and user interactions may require additional tracking mechanisms with SSAI.

SSAI vs. DAI: Is Server-Side Ad Insertion the Same with Dynamic Ad Insertion?

Besides the clash with CSAI, SSAI also deals with some confusion regarding DAI. Many people mix SSAI and DAI, thinking they’re the same thing. While that’s not entirely wrong, it’s not completely correct either.

SSAI and DAI may sound similar, but they’re different.

SSAI, or Server-Side Ad Insertion, is a method used to seamlessly insert ads into online video content at the server level before delivering it to viewers’ devices. This ensures smoother transitions between content and ads, enhancing the viewing experience.

On the other hand, DAI, or Dynamic Ad Insertion, is a broader term encompassing various techniques for inserting ads dynamically into content.. While SSAI is one form of DAI, DAI can also refer to client-side ad insertion (CSAI) or other methods where ads are inserted dynamically based on factors like viewer demographics or real-time bidding.

So, while SSAI and DAI involve inserting ads into video content, SSAI specifically refers to server-side insertion. In contrast, DAI is a more general term that includes various methods of dynamic ad insertion.

Final Thoughts

Understanding how ads get into online videos, primarily through Server-Side Ad Insertion (SSAI), is super important for both publishers making content and those trying to sell through ads.

As more people watch videos online, SSAI becomes a big deal because it smoothly puts ads into videos, making the whole experience better for everyone.

SSAI comes with loads of perks, like making it harder for ad blockers to mess things up, giving viewers smoother video-watching without annoying pauses, and helping advertisers target their ads better. But it’s not all sunshine and rainbows. There are some downsides, too, like the risk of fraud and the inability to change ads on the fly.

Understanding the differences between SSAI and other ad methods, like Client-Side Ad Insertion (CSAI) and Dynamic Ad Insertion (DAI), is key to making smart choices in online ads.

So, as the world of online videos keeps changing, knowing your way around SSAI and ad insertion tech will be essential for anyone making or watching videos online.