Paul Davies
Head of Marketing, Yospace
Yospace has been a leader in dynamic ad insertion (DAI) for many years now, and as such, we are used to people approaching us to learn about the latest innovations in the technology. At last month’s NAB Show, we were often asked about server-guided ad insertion (SGAI) and how it differs from server-side ad insertion (SSAI). This article explains the key differences between the various ad insertion methods to help you understand where SGAI fits in.
We’ll break down three of the most popular types of ad insertion:
We’ll explain what each one does, where it performs best, where its limitations are, and offer some guidance on key considerations to maximise DAI's revenue potential.
Let’s begin.
With CSAI, the video player (usually referred to as the client, hence the name ‘client-side’) is responsible for pausing the content, fetching an ad from the server, and then resuming playback. This approach has the potential to provide detailed user tracking, as the client can monitor what has actually been viewed (as opposed to just stitched), as the player's interaction with the ad tech system allows for cookie and IP-based tracking.
However, CSAI has several limitations. The ads placed directly on the video player side make it much easier for ad-blocking software to intercept and remove the ad breaks. Technical issues also arise, such as buffering and inconsistent video quality. These shortcomings restrict CSAI’s ability to monetise live streams, where timing and the ability to scale are critical.
SSAI addresses many of CSAI’s limitations by moving the responsibility of ad insertion to the server. In this solution, the server stitches ads directly into the video before it is delivered, effectively appearing as one full video with ads included. This provides a smoother playback experience and prevents ad blockers from detecting the ads and removing them, as all they see is one continuous video.
Traditionally, SSAI tracking comes from the server side when an ad is stitched into the stream. This data does not require any client-side development; however, it does lack the real-time frame accuracy of client-side. This issue is easily addressed by combining server-side stitching with a simple client-side SDK, which offers the best of both worlds (including viewability measurement).
Alternatively, one of our latest innovations is to provide client-side tracking based on the playhead location without the need for an SDK. This technique is included in the latest Common Media Client Data v2 (CMCDv2) standard and can be used to deliver lighter-weight frame-accurate measurement.
Ad Operations teams in the digital realm expect ad data to be available in a format that provides actionable insights. Yospace’s real-time log data can be surfaced in real-time dashboards to improve campaign performance (see an example with DIRECTV here).
SGAI is a relatively recent development in ad insertion technology. It’s a move towards a new ad stitching standard built on HLS Interstitials and MPEG-DASH Events (which will be ratified any day now). SGAI combines the benefits of CSAI and SSAI in sharing responsibility between the server and the client. In this hybrid model, the server identifies ad opportunities and sends instructions to the client to fetch and insert ads at the appropriate moments during playback.
SGAI reduces server-side resources for live streaming, making it more cost-effective and compatible with low-latency streams or streams that are delayed or lag behind the live event. At NAB Show 2025, Yospace demonstrated historically resolved ad breaks during extended DVR windows, creating new ad opportunities for rights holders (see more info on our NAB demo here). We typically see around 12% of live streams enter DVR mode, so the additional revenue potential is significant.
For VOD, SGAI allows for dynamic ad decision-making and insertion during playback, which improves start-up times because it avoids resolving all break opportunities up front. This also avoids the cost and campaign management issues associated with wasted ad calls. Additionally, because all ad breaks are resolved in real time, custom business logic relating to adload can be configured to reduce the duration of ad breaks for users who have already watched through previous ad breaks. SGAI also maintains the smooth playback experience and resistance to ad blockers that SSAI provides.
One feature of SGAI that is proving popular is its potential to simplify the use of new ad formats, such as squeeze-backs (L-shaped ads wrapped around the main content) or side-by-side ads (see an example from our NAB Show demo with Bitmovin here).
SGAI is generating significant excitement within the industry, but it's important to recognise that this is more of an evolution than a revolution. While SGAI refines ad insertion techniques, it doesn't fundamentally change the landscape. Instead, it optimises the existing approaches to make ad insertion more flexible, efficient, and cost-effective.
It’s also important to note that neither CSAI, SSAI, nor SGAI, in isolation, addresses the core issue of scaling ad tech systems to large audiences, particularly during live events.
”If you use just-in-time ad resolution, what we have found is that 90% of the ad requests to the ad server occur in about 1.5 times a video segment duration.”
David Springall, Founder, Yospace
The crowding of ad calls into such a short period of time causes tremendous bursts of ad requests to SSPs. In unpredictable live event situations, the wider adtech ecosystem can end up being flooded with ad calls that overwhelm the ad server and, of course, any downstream SSPs. In such situations, ad-requests will start to timeout, or the SSP may even assume valid requests are fraudulent traffic, resulting in the highest value ad opportunities going unfilled and a significant loss of revenue for the service operator.
Intelligent prefetch solutions mitigate against such threats by pacing out ad requests and ensuring that every ad spot is filled and that it achieves its maximum ad revenue value. Whether you’re using SSAI or SGAI, a fully featured prefetch solution is required to deliver monetisation at mass scale.
There are plenty of other factors to consider when planning an SSAI or SGAI monetisation strategy, including broad device support to monetise a full audience and measurement. If you’d like to speak with one of our experts to find the right solution for you, drop us a note here.
Read more about scaling dynamic ad insertion in our white paper, Scaling Up, which you can download here.
