Understanding the Difference: CSAI vs SSAI for Video Ad Delivery

Rishabh Jain Jun 14th, 2024

Ad insertion in video streaming platforms has changed the way advertisements are delivered to the audience. The experience is more seamless and personalized. This technology has given liberty to advertisers to dynamically place ads. 

Video streaming platforms are used mostly by all companies today and have become one of the best ways to deliver advertisements at the right time to the right people.

Ads if placed wrongly can also change the perspective of viewers, both for the brand and the viewing platform. Therefore, a sophisticated approach has to be used to insert an ad. Enveu, being one of the most used video streaming solutions, leverages advanced ad insertion techniques. 

Before using Enveu or any other video streaming solutions, it is important to know about CSAI vs SSAI. By having an understanding of these two, the ad expert can learn how to optimize the ad delivery and also take care of a seamless viewer experience. 

What Is CSAI?


As the name suggests, CSAI, or client-side ad insertion, inserts ads on the client side using the video streaming engine. The video player will request ad content from the ad server and then integrate it seamlessly into the video streaming during playback.

The client request will be based on the type of data that is collected and exists during the viewing session.

This method offers flexibility and precise targeting as everything is happening on a real-time basis, and ad decision are based on location and user behavior. Here, both the video player and client application are responsible for handling the communication with the ad server.

Advertisers can also track ad performance and measure insights gained, interactions, and engagement received. However, ad blockers can be the only issue here, as they impact the video buffering and disrupt the viewing experience. 

How Does CSAI Work?

CSAI is an ad delivery method where ad content is fetched and inserted into the video stream on the user’s device. Here is the step-by-step process of how CSAI works: 

Step 1: Initiating ad request 

When a viewer watches a video, the video streaming platform, such as Enveu, will send a request to an ad server to deliver ad content. The request will have information like user demographics, location, and behavior. All these are shared to make sure the ad content is relevant.

Step 2: Decisioning

After receiving the request, the server will process it and pick appropriate ads based on the data shared. The selected content will then be shared back to the video player. 

Step 3: Integration of ad

After receiving the ad content, the video platform will integrate the ad into the video stream at breaks. These breaks are predetermined so that the insertion is handled correctly.

Step 4: Ad playback 

This is a crucial step for every video streaming platform. Here, the video player will track as the ad plays. It will record how you engage with the ad, such as recording impressions, clicks, and duration. 

Step 5: Video Continuation 

Once the ad is complete, the video will resume without any interruption. The data collected will be sent to the ad server team for analysis. 

Pros & Cons of CSAI

Let us now see the pros and cons of CSAI

Pros of CSAI

  • Concise targeting: CSAI allows the running of ads in real time, that is, when the viewer is streaming video on the video streaming platform. This helps in sharing targeted ads with the right users so that they can engage better.
  • Analysis: After the ad is delivered, the engagement is recovered on a real-time basis. Demographics, impressions, clicks, and engagement analysis can easily be done.
  • Flexibility: As it is real time, the data can easily be updated based on the viewer preference and platform ad request. 
  • Interaction: These ads will have clickable actions to increase engagement with the content. Viewers can engage with buttons like “Buy Now” or can answer quizzes. 

Cons of CSAI

  • Ad blocker: CSAI is vulnerable to ad blockers, which prevent ads from being displayed. In such a case, revenue will be blocked. 
  • Impact on buffering: When ad blockers are activated, the video might face some buffering issues, ultimately impacting the viewing experience.
  • Dependent on device: Ad delivery will depend largely on the user’s device’s performance. With this dependency, the delivery quality will be at huge risk. 

What Is SSAI?


Server-side ad insertion, or SSAI, is another method of ad insertion in a video that is done on the server side, as the name suggests. This is the direct approach of integrating advertisements into video streams. 

This enables a seamless viewing experience as the ad is stitched into the video content together. To stitch the ads into the video content, Manifest manipulation is used. 

It came out as one of the more sophisticated methods of delivering ad and video content together, as the viewing experience is enhanced. There is a set of processes that run in the backend to make it look organized in the frontend. 

How Does SSAI Work?

Step 1: Viewing request 

The viewer will request to watch a video through a video streaming service like Enveu.

Step 2: Server request 

Once the server receives the request, it prepares the video content.

Step 3: ADS 

After server communication, the ad decision will be made via the ad decision server to finalize which ad to stitch in the video. The decision will be made based on the user data.

Step 4: Fetching of ads content 

After the decisions, the server will fetch the selected ads from CDN (Content Delivery Network).

Step 5: Manifest manipulation 

The server will modify the video content into segments at appropriate points.

Step 6: Stitching 

At the ad segment, the ads will be stitched into the video stream on the server side.

Step 7: Delivery 

The video with the ad will be delivered to the viewing platform, such as Enveu.

In this case, the server will track ad impressions when the viewer watches the video with the ads. 

Pros & Cons of SSAI

Below are the pros and cons of SSAI

Pros of SSAI

  • Resisting ad blocker: Ads in this case will be stitched on the server side; therefore, there is no role of ad blocker.
  • Seamless video experience: As there is no buffering issue, the viewing experience will be smoother.
  • Improved analysis: Server-side ad insertion brings in better usage of data collection and ad targeting.
  • Cross-platform smoothness: As ads will appear uniformly across multiple devices, there is no dependency on the user device.
  • Enhanced quality: The ad content provider will have more control over the quality of the ad. They will have more say on the placement and presentation of the entire video. 

Cons of SSAI 

  • Server load: As everything is done on the server side, the load will increase, making operations costly and complex.
  • Latency issue: Real-time stitching of ads can be challenging, and the scaling process can get difficult.
  • Ad inventory: As SSAI requires a compatible ad format, there can be ad inventory limitations.
  • Dependency on server: As the ad gets picked and stitched completely from the server, any issue on the server can disrupt the entire process. 

CSAI vs SSAI: A Complete Comparison

Ads DeliveryAds are delivered separately and inserted by the client’s video player.In this case, ads are stitched into the video stream on the server side.
Viewer ExperienceUser experience will be impacted because of buffering and interruption.Gives a smooth viewing experience.
Ad BlockingAds will be susceptible to ad blockers.As ads will be stitched on the server side, there is no chance of getting on the radar of ad blockers.
Technical IssuesTakes less server load.Takes more server load.
Personalized experienceHigh chances of delivering a personalized experience.Less chances of delivering a personalized experience. It relies on pre-fetched data.
ReportingMore detailed analysis reports can be prepared as data will be tracked in real-time.There are robust features to fetch data but may lack in giving exact reports as compared to real-time fetching.
ScalableThe scalability option is more as ads are inserted on the client side.Here scalability is challenging as everything depends on the server. It demands advanced infrastructure.
ImplementationThe process is simpler to deploy and can be managed at a low cost.This process requires complex and advanced infrastructure. The setup cost is higher at the initial level.
Cross-PlatformThere can be compatibility issues because the quality of the ad running will depend on the device and browser.The quality of the ad is uniformed as the ad is stitched on the server side.


CSAI vs SSAI is presented to give ad experts a clear idea about which ad delivery method to use. The decision should be taken based on the type of content and the audience they want to serve. CSAI offers easy implementation but can be a problem when it comes to ad blockers, which is again resolved by SSAI. Enveu can help in making this decision easy for you.

If you are planning to launch your own video monetization platforms, book a complimentary demo and let us guide you in making your VOD streaming journey a success!

Frequently Asked Questions (FAQ)

Ans: CSAI is susceptible to ad blockers, as ads are inserted and managed by the client-side video player. Users can use ad blockers to prevent ads from being loaded and displayed.

Ans: SSAI can bypass ad blockers more effectively because ads are stitched into the content stream on the server side. Since the ads are part of the same stream as the content, ad blockers have a harder time detecting and blocking them.

Ans: Yes, a hybrid approach can be used where SSAI handles the primary ad insertion for seamless playback, while CSAI can be used for additional interactive or personalized ads on the client side.

Ans: CSAI provides detailed client-side analytics, offering insights into user interactions and ad performance. SSAI can complicate analytics since ads are part of the content stream, requiring sophisticated server-side tracking to gather accurate data.

Ans: CSAI typically provides better ad targeting and personalization because it allows for more granular control and real-time decision-making based on user behavior and preferences directly on the client side.

Rishabh Jain - Director, Product Development, Enveu
Rishabh Jain is one of the co-founders and heads the Product Development at Enveu. A tech evangelist and deep tech advocate, he has been working in the Technology space, being part of many Big Data and IoT initiatives for over 10 years.

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