SGAI: a new frontier in dynamic ad insertion

Choosing the best way to insert addressable adverts into streams is one of the key technology dilemmas currently facing ad-supported streaming services.

Server-side ad insertion is often seen as the lynchpin of ad-tech in the streaming age, as media companies look to grow digital revenues to offset linear TV’s decline.

Historically, ads in OTT have either been inserted into a stream by the client (at the player or device level), or stitched into the stream by the server, without the need for client-side integration.

While client-side ad insertion (CSAI) can deliver granular targeting based on demographics, location or viewing habits, it is susceptible to ad-blocking; and buffering and latency may lead to a less-than-perfect viewing experience.

With server-side ad insertion (SSAI), ads are inserted or stitched into the stream before they reach the client device, ensuring that they cannot be blocked and that the viewing experience is smooth. However, SSAI comes with challenges including scalability (it requires additional processing power during peak viewing times due to the requirement to create a unique manifest for each viewer to deliver personalised ad breaks) and difficulty in tracking whether ads are delivered on time and to the right place. It has also been criticised as having limited ability to handle new in-vogue ad formats such as L-shaped banner ads around content.

Enter server-guided ad insertion (SGAI), which has been promoted as a concept that delivers the best of both worlds, with server and player working in tandem to deliver ads based on up-to-the-minute viewer data, enabling greater personalisation and innovation.

For some, SGAI, by combining the advantages of SSAI and CSAI while limiting their disadvantages, will be central to the next phase in the evolution of ad-tech.

Server-guided ad insertion

Tim Sewell, CEO of OTT ad insertion tech specialist Yospace, says his company is still seeing strong growth in live SSAI, fuelled by events such as the Olympics, as well as continued growth in ad-supported video-on-demand.

Read more  Yospace say Olympic moments offer up gold for advertisers

Referencing the summer of sport that boosted deployments, Sewell says that Yospace has evolved its SSAI solution over time to be able to handle big-event live streaming.

In addition to the need to create unique manifests per viewer (a disadvantage of SSAI that SGAI can claim to solve), one big challenge related to scalability is protecting the ad-tech ecosystem from large and sudden spikes in traffic often associated with major sports events via just-in-time ad resolution.

Ad servers were never designed to deal with these sudden spikes, leading to a slowdown in the process if the system is asked to make millions of ad calls within a single short video segment.

“That means you can see a significant drop in ad fill rates once the audience gets above a certain level because you can’t wait around indefinitely for the ad server to make a decision,” explains Sewell.

To overcome this problem, Yospace introduced a technique called pre-fetch almost a decade ago that allows the company to pace the rate that ad calls are made to an agreed rate of number of transactions per second to avoid swamping the primary ad server. Nevertheless, where the publisher is leveraging programmatic selling of inventory, the primary ad server may be reaching out to multiple sell-side platforms, requiring additional time for the decisioning and bidding process to take place across all the SSPs.

“That’s true whether you’re doing traditional SSAI or SGAI, because you still have to make unique ad calls for each viewer,” says Sewell. “So that scaling piece that people don’t think so much about is just as relevant with SGAI as SSAI.”

Turning to AVOD, Sewell notes that SSAI carries the potential disadvantage of potentially slower start-up times – compared with CSAI – because the playlist for the VOD file must be built at the point that a user starts to view the content.

Sewell says that Yospace has done a lot of work to optimise this. However, he says, SGAI is “particularly interesting” for AVOD applications. The technology can create a seamless ad experience when content is recorded by the viewer, or if the viewer “scrubs through” the asset – meaning using the timeline slider to forward and rewind.

One potential hiccup in the way of widespread adoption of SGAI is the slower progress of standardisation on the DASH side of the adaptive bit-rate equation, leading to what Sewell characterises as broadcasters not being able to deliver SGAI-based insertion to DASH devices with the full range of capabilities that currently are available for HLS devices.

SGAI taps ‘resolution points’ within adaptive bit-rate standards – HLS Interstitials in the case of HLS – to insert ads seamlessly. The location of these points is included in the streaming manifest delivered by the server, and the video player tracks these and requests ads from the server as required.

Standardisation within MPEG DASH is still a work in progress. Work around DASH Xlinks (Extensible Linking Language-based extension mechanisms in the DASH Media Presentation Description (MPD) manifest) has evolved to work on a standard built around DASH MPD events – a means of signalling additional information to a DASH client or underlying application with a start time and duration as part of the manifest file.

“Some of what’s being classed as SGAI is vendor-specific, non-standards-based player development, so some of the features that are being described as SGAI features are actually player features that could be implemented on a player with either traditional SSAI or SGAI – because SGAI is really just about where the stitching is taking place,” says Sewell.

Nevertheless, he says, some features that require scaling in SSAI, such as startover, rewind and pause live TV, will be more cost-effective to implement in SGAI.

Advantages of SSAI

Not everyone is convinced. Video tech company Broadpeak sits firmly in the SSAI camp with regards to ad delivery, offering technology to enable media companies to build their own infrastructure and offering SSAI as a service, where the company competes with the likes of AWS’s MediaTailor.

Read more Broadpeak to debut new monetisation services

Mathias Guille, VP, Cloud Platform at Broadpeak, says that Broadpeak’s cloud-based platform “can scale up when there are more requests for ads and scale down when there are fewer requests, so that helps us deliver really aggressive pricing.”

Broadpeak’s technology does not rely entirely on the server side. Guille says its ads can be tracked from the service, but Broadpeak also provides Interactive Advertising Bureau (IAB)-certified client-side tracking via an SDK library that can be installed at the client. This enables publishers and advertisers to help provide information about whether ads are delivered to the right place at the right time.

“This is very important for us because we typically see that people start deploying from the server side and, after a couple of months, they move tracking to the client side because they realise they can actually attract more advertisers that way,” he says.

Guille says that Broadpeak has tested SGAI and admits that the technology offers some advantages.

“When you do SSAI you need to create one manifest per user because you want to target ads per user. SGAI can help in that sense because you keep the original manifest for everyone and patch the ads in at a different location. So the number one benefit of SGAI is about scale and the cost of infrastructure,” he says.

However, according to Guille, the main challenge facing media companies today is how to fill their available inventory, rather than worrying too much about optimising the cost of infrastructure.

“What they are looking at right now is making sure they can sell the inventory,” he says. “A lot of publishers are very far away from that.”

Moreover, he says, publishers are often reluctant to rely on the client, “especially people who are not fully in charge of their own distribution.”

The most notable proponent of SGAI to date is Disney, which has tapped the technology for the ad-supported version of Disney+. Guille points out that Disney is in control of its own streaming infrastructure, including the client, and is well-positioned to take advantage of SGAI to reduce its costs. But HLS Interstitials is not supported by every player, and for a FAST channel provider relying on third-party infrastructure to deliver a service to TV screens, SSAI makes more sense.

Regarding new ad formats that can increase the overall ad inventory pie – another route to greater monetisation – Guille says that SGAI is not necessary to deliver the likes of L-shaped banners, arguing that Broadpeak’s ad tracking technology can do the same job.

Player perspective

From the player side, on the other hand, James Varndell, Senior Director of Product Management at Bitmovin, says that SGAI does bring advantages in its ability to support new ad formats such as picture-in-picture or L-shaped ads. With SGAI, he says, “the player has some control over how to present the ads to the viewer based on their device, based on their profile, and the type of content they’re watching.”

Read more Bitmovin and Yospace join forces

With events such as live sports, this means that service providers can deliver ads that don’t disrupt the content.

Varndell says that SGAI has emerged in parallel with growing interest in the multi-view and multi-view playback capabilities of players such as Bitmovin’s, which allow multiple streams from sports events, for example, to be played back simultaneously.

“There’s thinking about how you could have SGAI indicating where the ad should be inserted combined with multi-view playback,” he says.

These ad format capabilities are probably more important in promoting SGAI than reducing the infrastructure costs, he says.

More generally, Varndell says that giving the player more control over when and how to request ads can be particularly useful for platforms such as smart TVs and may also be helpful in making late decisions about ad placements and in delivering greater potential for personalisation.

On the downside, he says that SGAI can be associated with a higher risk of errors and buffering at the transition point between ads and content if, for example, the content is DRM-protected and the ad is in the clear, which may be challenging for players on older smart TVs or low-power set-tops. SGAI may also revive the potential for ad blockers to interfere with ad placements, although Varndell says that Google and other partners that Bitmovin works with have expressed a degree of confidence that this can be averted.

In general, Varndell says that most interest in SGAI is “from customers who currently implement client-side insertion who can see SGAI is like a nice step forward” rather than from those who have invested in SSAI.

Future-proof solution

Yospace’s Sewell believes that adoption of SGAI is more about bringing the cost of scaling down and enabling features like live pause and rewind, and to enable scrubbing and DVR applications.

While he agrees that “fill rates and maximising monetisation are the number one priority” for broadcasters, managing cost is also a key focus, he says.

The ability of SGAI to deliver accurate measurement of campaigns more efficiently is of less importance, he says, because SDKs are already available to set service providers to do this on the client side while implementing SSAI. Similarly, formats such as L-shaped banners can be created with custom implementations of a commercial player, or via open-source player implementations, rather than by deploying SGAI, he argues.

“SGAI is really an enhancement of SSAI, the difference being that the ad stitching is being performed by the client as opposed to on the server, but with all other things that you must consider in ad insertion – normalisation of the ad content so that audio and video levels match the linear stream – handled by the ad server,” he says.

Sewell says that people are currently focused on SSAI because of “the breadth of platforms that it gives you access to” and perhaps because of a reluctance to get too involved in player-based technologies.

However, he cautions that media companies are unlikely now to “implement a solution that isn’t future-proof in terms of its ability to enable SGAI on those platforms and players that support it.”

As with all situations where the future standard way of doing things is not clear, the advantages of SGAI may be strong enough for broadcasters and streamers who haven’t already made another choice to consider hedging their bets.

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