When showing viewers content via live stream, on-demand, or linear video, you will want to monetize the content with ads. But what’s the best way to do that? The two most popular methods for serving ads while viewers watch something are Client Side Ad Insertion (CSAI) and Server Side Ad Insertion (SSAI). Before choosing the method that’s best for you, it’s helpful to understand the difference between implementing CSAI and SSAI, how they work, and what the upsides and drawbacks are for each.


How Do You Place Ads in Video Content? – Ad Stitching

When viewers watch content, the advertisements they see must be placed in their video streams. The process of placing an ad in video content is called ad stitching. It’s basically what it sounds like – when it’s time to show viewers an advertisement, a method like CSAI or SSAI is used to ‘stitch’ the ad into the video stream. If you use CSAI, the ad stitching happens on the viewer device.

CSAI: What it is and How it Works

Client-Side Ad Insertion is when ads are included in a video stream through the viewer’s player. The player requests an ad from the associated ad server when the video playing hits an ad marker. The ad is retrieved, the video player places the ad content where the marker specifies it should go, and the ad is seamlessly integrated into the stream and displayed.

What Makes CSAI a Great Choice for Ad Stitching?

Multiple things make CSAI ideal for ad stitching. Here’s a list:

  • Easy to Implement One App/Device/Player – CSAI is an older technology than SSAI, meaning there are easy-to-set-up ways to create a CSAI experience if you only need to integrate one type of device or player.
  • Viewer Behavior Context – Compared to SSAI, CSAI offers more ability to gather details about viewer behavior with real-time context. Whatever the viewer does on their target device in real-time can be included in deciding what ad to serve the customer.
  • Interactive Advertising – Since ad stitching happens in the viewer’s video player client-side, it’s possible to make ads interactive for the viewer through some services. For example, you can create overlays with surveys or ask questions where the viewer chooses a response.
  • Metrics – CSAI offers detailed metrics about how ads are viewed and can decide what ad to serve next from metrics or ad responses in real time.

Reasons You Might Not Want to Use CSAI

After hearing the benefits of CSAI, including the incredible ad personalization possibilities and lower cost, why would you choose SSAI?

  • Ad Blockers – Because ads are stitched into video streams in the video player client side, a viewer can use an ad blocker and block most, if not all ads transmitted using CSAI. In one test, around 95% of ads were blocked on Windows-based machines and 74% on Mac-based browsers.
  • Issues with Interactive Ads (VPAID) – While overlays are great for collecting information from the viewer, they are prone to glitches and errors.
  • Content Quality Issues – Because CSAI does not prepare ads (transcoding/packaging) to fit the original stream, quality problems can arise.
  • Less Precise Ad Placement – For Video on Demand, CSAI can compromise the viewing experience by inserting ads at awkward moments since the client does not know when to cut. 

SSAI: What it is and How it Works

Server Side Ad Insertion (SSAI) is a method of ad stitching where ads are stitched into video on the server side. The video is delivered as a single stream to the video player with everything already assembled. The way it works for SSAI, is the server receives video and ad content from different sources. The server stitches the ad into the video using a technology called Manifest Manipulation.

As an example, our own broadpeak.io is a SSAI 😉

What Makes SSAI a Great Choice for Ad Stitching?

SSAI offers many benefits when it comes to ad stitching:

  • Ad Personalization – SSAI can use data about the viewer to deliver a targeted viewing experience.
  • Immune to Ad Blockers – Ads are stitched into content on the server side, and the video is delivered as a single stream, rendering ad blockers useless. If the viewer watches the video stream, your ad is getting seen.
  • Metrics – SSAI offers detailed metrics about ads, which can be incorporated later when considering how to better personalize content for viewers.
  • Flexibility – SSAI can deliver ads on demand for linear video, live streams, and video. If you implement this method, you can utilize it practically anywhere.
  • Consistent Viewing Experience – Since SSAI doesn’t place ads in real time, there are fewer delays, errors, and processing problems, resulting in a more seamless viewing experience. Quality is also higher, since SSAI doesn’t rely on the viewer’s device to do the ad stitching, it uses its own server resources to complete this task instead.

Reasons You Might Not Want to Use SSAI

While SSAI provides many benefits that CSAI doesn’t, there are still some drawbacks:

  • ResourceIntensive – SSAI requires ad transcoding/packaging and manifest manipulation. Setting this up can be technically challenging and resource-intensive. A SaaS like broadpeak.io can make this simple, cost effective, and ensure that your ads are seen.
  • Less Interactive Ads – Typically, you can’t create overlays with interactive content where viewers choose a response as you can with CSAI. However, broadpeak.io will soon roll out a solution that makes this possible with SSAI. Get your ads seen, and keep the interactivity of CSAI.
  • Less Viewer Behavior Context Information – Where CSAI can collect viewer behavior and react in realtime to their activities on the device, SSAI cannot. Ads can still be personalized with data about viewers’ watching habits.
  • Tracking – By being server-side, SSAI, by default, tracks the impression of the ads from the server, which is not as accurate as doing it from the server (you cannot ensure the display of the ads on the player from the server). Nevertheless, some SSAI, like broadpeak.io, propose an optional SDK that can be used on the client side to track the impressions accurately.


In conclusion, there are pros and cons for CSAI and SSAI.

CSAI offers more real-time information about viewer behavior and has the potential to offer interactive ads, but suffers from the effect of ad blockers and video quality problems. SSAI allows for ad personalization, better video quality, and the opportunity to get all advertisements seen by the viewer. The drawback is it can be more resource intensive due to transcoding and packaging. Fortunately, SaaS companies like broadpeak.io can eliminate this drawback.

On top of just SSAI, broadpeak.io also offers a hybrid option – use SSAI to get your ads seen and complimented with their SmartLib SDK, allowing you to track ads on the client side. In a future blog post, we will look at broadpeak.io’s hybrid offering.

Ready to make the best choice for serving ads to your viewers? Choose broadpeak.io for seamless ad insertion with SSAI and interactive capabilities with our upcoming SmartLib SDK.

Erikka Innes
Erikka Innes is a Developer Advocate that specializes in developer blog content and documentation. For 10+ years she's built documentation portals from scratch, created interactive API documentation, and developer demos. She is passionate about product and documentation usability that makes life easier for developers, and creating engaging, creative content.