Client Side & Server Side Ad Insertion

Client Side Ad Insertion (CSAI) and Server Side Ad Insertion (SSAI) are two ways in which advertisements can be packaged with online video, to be delivered to a viewer. So, why is it important? Depending on how the ads are served, either via CSAI or SSAI, will impact the simplicity of their deployment and impact on how easily the ad can be interrupted or turned off with an ad blocker.

Going Big Screen_ Bringing Video to LG WebOS-1


Client Side Ad Insertion (CSAI) is the traditional method of inserting advertisements into an online video. Through this method, advertisements and video are served separately to the video stream and integrated into the video on the client side. This traditional type of ad insertion makes it easier for ad blockers to recognise the ad content, and block it.

Content Monetization with Server-Side Ad Insertion

The benefit of CSAI is that it is easy to implement and integrate. As it has direct contact with the ad server it also allows advertisers to better track metrics. Client side advertisements are especially useful for video-on-demand, since advertisements in the stream (inserted on the server-side) can be easily skipped.

As mentioned, the biggest drawback with this approach is that users can install ad blockers and prevent the advertisement from playing. As a result, playing advertisements on the client side cannot always be guaranteed. One way to solve this is to block playback when an ad blocker is detected.


On the server side, the advertisement is directly inserted in the stream: the broadcaster indicates when advertisements may be inserted by providing cues (hints) in the stream. The content is then forwarded to an ad insertion server, which replaces the dummy content with actual advertisements. That way, the advertisements are part of the stream. This makes it harder to detect by an ad blocker.

Server-Side Ad Insertionv4

Server side advertising works best for live, where the users cannot skip content, unlike with
Video-on-Demand. In addition video advertisements cannot be prevented by the ad blocker
software given the advertisement is part of the stream. Even if the ad blocker could detect and
block the advertisement, the viewer would be presented with a black screen. Commercial
video players have the ability to handle server side advertisements out of the box due to the
fact that they are part of the stream.

More challenging is how a video player should detect that an advertisement is playing, adjust
the user interface and add a link to the advertised company. At this point, there is no
specification on how this should be done, so every server side ad insertion might have a
different way of providing this information. For instance, YoSpace does this by using ID3 data within the track. You need a video player that is able to detect this information and react accordingly.

Any questions left? Contact our THEO experts.

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