Server-Side Vs Client-Side Ad Insertion

Server-Side Vs Client-Side Ad Insertion: What’s The Difference?

Ad personalization is the most popular way for content aggregators to generate maximized revenue via their content & drive growth through online video monetization platform. The key purpose here is to initiate major ways of increasing subscriber base. Ads initiates this in a better way by technically employing them into videos – either through CSAI which is known as client-side ad insertion and SSAI or server-side ad insertion

There are plenty of opportunities on ad personalization, since you can connect with individual viewers in many ways. Audiences can freely consume content either for free or by watching the ads without paying or subscribing to the service.  Having said that, ad insertion growth quests for broadcasters, pay TV operators, content programmers & several video providers, to meet various needs of the business & target audience??

Let’s look into those criterions in this article.. 

As per statista, in 2021 the most ad-supported video-on-demand service other than YouTube was nearly chosen by 18% of respondents in North America such as Facebook Watch, Twitch & more.

What is CSAI?

CSAI is the method used in delivering ads to devices like desktop, mobile, CTVs, gaming consoles where the video player requests the ad server to stream an advertisement when it reaches certain ad-markers in the stream or technically known in the manifest file (HLS/DASH).

What is CSAI?

Upon receiving the request from the player/device the ad server then responds with the strategic ad for it on the basis of data collected from other information such as campaigns & audience preferences. 

It functions in accordance with the video player then pauses the content, in between the ad is been played. After that, the content or the video playback resumes. Here it takes the major responsibility of the client to report on the ad performance through various metrics & dimensions. Some of them are:  

  • VAST (ad metadata)
  • VMAP (ad timing)
  • VPAID/SIMID (interactive ads) and
  • OMID (viewability measurements)

How does Client-Side Ad Insertion Work?

Now in this section, let’s take a glimpse through the working or processes of how CSAI  (Client-Side Ad Insertion) works. 

How does Client-Side Ad Insertion Work
  • In the beginning, the player downloads the file from the CDN before the video playback commences. For instance, in a pre-roll ad, the ad begins to play before the video sets in. 
  • When the video player reaches an ad-marker, it makes an API call to the ad server, requesting for an ad in the playback  
  • Typically, the ad insertion server, will respond with a VASY XML that contains data about the ad, the ad’s media as well as tracking information
  • The video player uses the VAST tag in order to play back the ad 
  • After the ad has run, the video player continues playing the video stream 
  • Usually, streaming platforms embed their video players with SDK support provided by 3rd party ad services
  • SDKs monitor the position of the ad playback, completion rates, errors, etc & report back to servers recurrently with this data 
Thinking Of Starting Your Own Video Monetization Platform?

What is SSAI?

SSAI which is commonly known as server side ad insertion is a way of stitching an ad directly into the video that’s being streamed at the server but not the client/player. Basically, it is different from how CSAI work. 

What is SSAI

SSAI has its own merits and demerits that we would be seeing the next couple of sections below. The key advantage is that the client is no longer making any server calls which informs us about how hard it is to block ads inserted using SSAI. 

Moreover, SSAI functionality is further emphasized, when the request sent contains viewer data, that is required to pick a personalized ad. 3rd party ad server can now quickly respond with an advertorial to the SSAI module. 

How does Server-Side Ad Insertion Work?

Server side ad insertion is a combination of many individual functionalities. It starts with manifest manipulation, ad server communication, ad bitrate with resolution normalization. 

How does Server-Side Ad Insertion Work

Manifest manipulation talks about personalizing the video experience for every viewer when a stream is requested with video & audio segments. It is then, accompanied by a manifest file  which acts as a playlist & control the playback order

Secondly, ad servers help advertisements to store & serve them to online web pages. Moreover ad server communication is facilitated by advertisements trafficking which provides analytical insights on ad performance. 

Thirdly, when we relate insights with video bitrate, we know that bitrate is simply number of bits of video information that is then transmitted per second – either in kilobits/sec or megabits/sec. 

Furthermore, when a video is compressed, you’ll have to command the video compression software to not to exceed certain bitrate. 

Next, video resolution plays a major role in which it affects what your user is seeing. Most video players adjust themselves according to the viewing window or device’s screen resolution 

All of these happens on the server-side architecture before presenting a manifest to clients. SSAI is also referred as dynamic ad insertion or ad stitching. 

Differences between CSAI and SSAI

Generally speaking, SSAI said to be a little high in terms of cost factor than CSAI, despite having effective results in ad impressions. In the case of integration of client’s-side server ads, they aren’t always been available to play due to ad blockers. This typifies the errors that happen on client side, time outs during loading an ad or error in VPAID ads, etc. 

Difference Between CSAI vs SSAI

Let’s look into both similarities & dissimilarities in its nature more..

Server-Side Ad Insertion vs Client-Side Ad Insertion Pros & Cons

Pros of CSAI Cons of CSAI 
Publishers & Advertisers can create bountiful experiences with surveys, click-throughs, overlays,
via transitional ad serving techstack.
Viewing Experience: In CSAI ad stitching is done in downstream by player that results in frame drop in video.
It is easy to set up a detailed tracking in the case
of CSAI.  Capacitates with lot of data for ad-tracking services
In CSAI the player needs to request ad-server for an ad to be delivered. Apparently, it induces latency
With the help of CSAI technology, lot of highly personalized ads can be servedIf the ad-server isn’t orderly, the video player doesn’t request the correct bitstream which can lead to buffering
In CSAI system, players usually stitch the ads with content. Therefore there is in need of itThere is no perfect solution which is able in handling live streaming seamlessly
Pros of SSAI Cons of SSAI
SSAI delivers a broadcast-like experience for users by stitching the ad directly to the streamAd-blockers via SSAI advertising may block origin of ad providers & end-users can’t view it in first place
Ad-insertion in the server is taken cared by SSAI, so it supports devices where at times it becomes hard to insert codeSpoofing in SSAI: The end-devices usually send HTTP headers to ad-servers. With this anyone can setup servers & spoof this data
With varying bandwidth conditions, SSAI can effortlessly deliver a smooth playback experience which improves quality in streamingLower degree of personalization: 
If SSAI vendor wants to provide per-used custom manifests, then there’s massive drain on resources
In SSAI system, the ads are stitched in upstream which reduces the need of players since HTML5 is used for the videoManifest caching issues: Since customizability is done on server-side per-user manifests is difficult which stays inefficient for caching services

Why should You choose CSAI or SSAI? 

As far as streaming is concerned, the ad-serving technology for VOD has been a primary takeaway since it is dependent on monetization of your entire video on demand platform/app. Certainly, it rules.. 

Having said that, CSAI & SSAI have their own pros and cons.. There’s no doubt on that.. 

However, if one feels worried about either constantly sticking to CSAI, or moving to SSAI, I feel the first thing they should do, in my opinion is to engage with an ad-tracking service, whether its in 3rd party or independent one.. Additionally, one needs to get a thorough understanding with regards to basic data on how the ads are actually performing.. Some of the probabilities are below: 

  • Is there any sort of latency, or  buffering?
  • Where are the most of errors expected from? 
  • What’s the cost of maintaining CSAI on any device that’s supportive? 
  • What is the duration of ad-rates completion? Are people interested in watching the content after the commercials? 
  • Are there any kind of ‘my’ marketing campaigns dependent on inner streaming operations? 
  • And the list goes on. 

All of these get connected to gaining raw data that can help the publisher to decide either to choose CSAI or SSAI. Ultimately, data-driven decisions will have its positive implications on the revenue making process, keeping user experience in mind!! 

Key Takeaway:

The ability to personalize viewing experiences is one of the important criteria that  separates itself since the advent of online TV against the traditional one. Since customer expectations are steadily rising, be it for quality or value it is essential to showcase content at a granular level. Meanwhile, content providers also need to make an effort in managing regional rights restrictions in order to safeguard content’s integrity. This counts monetization with ad serving too. 

As we have discussed, the dynamic ads can be implemented in two ways. One with CSAI & other with SSAI. We have seen its individual importance!! 

Ad severs and ad networks provide tracking, trafficking & analytical solutions for both collaborators: advertisers & publishers. Some of the key parameters are considered in targeting ads which include the following: 

  • User profile (based on location , OS, browser, etc.) 
  • Audience Behavior 
  • Context of content & many more 
If You Already have an idea about launching a Video Monetization Platform, Schedule a free demo and We’ll Get You On The Road To VOD Streaming Success!

Movie streaming blogger and VOD Expert in CONTUS VPlayed. Interested in digging deep into VOD streaming platform media business tools and Love to discuss and share views on the latest technologies tips, and tricks.


  1. Sarah Reply

    Thanks for sharing about the what is Client-Side Ad Insertion advertising. Professionally produced Ad delivered to highly engaged audiences through CSAI curated user experiences in a brand-safe context. Well explained.

  2. John Mark Reply

    Looking for a server side ad insertion and have some questions about dynamic specific functions of the monetize experience. Also looking for some pricing that would be passed on to clients.

  3. Michael Reply

    We would like to consider you as a possible partner as we move forward and introduce significant new with what is CSAI. Thanks in advance

  4. Alakbar Reply

    Hi, we are interested in a dynamic server side ad insertion solution. Currently, we are looking for platform, including front & back end support, content delivery + licensing support. We can discuss other details over the conference call. Please feel free to contact me in case of any questions. Thanks in advance!

  5. Stephen Reply

    Hello, We are curious about what is ssai advertising offering and its platform. We have an App with another ad insertion platform, but our contract is up for renewal and we are exploring alternatives.
    Thanks, Stephen

  6. Franklin Reply

    Greetings, I am interested in your dynamic ad insertion server and advertising service. Please have someone contact me.
    Thank you, Calvin Franklin

  7. Elijah Reply

    I am currently looking for the meaning of CSAI vs SSAI for the video ad insertion & launch of a streaming platform.

  8. Amelia Reply

    Hello, We are looking to purchase the server side ad insertion of SSAI. Please let us know which of these features you currently support and/or if your platform supports ad insertion servers growing into the needed items in a reasonable timeframe.

  9. WilliamDj Reply

    Hi, I would like to see a demo of the Vplayed server side ad insertion(SSAI). Specifically, I am interested in csai vs ssai & these features: TVOD, SVOD, PVOD, video/audio streaming, and DRM. Thanks!

  10. Benjamin Reply

    We’re looking for a professional dynamic ad insertion platform for Indian Music and wanted to loop at an API for the same. We wanted to know the CSAI vs SSAI AVOD services you offer, your rates, and whether you have any monetized algorithm-related features (recommendations, statistics, etc).

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