IAB Australia today published a technical explainer comparing client-side, server-side and server-guided ad insertion, arguing that the newest of the three has left the trial stage but still depends on player support that much of the installed television base does not yet have.

The document, titled Server-Guided Ad Insertion - An Explainer, was written by Jonas Jaanimagi, Technology Lead at IAB Australia, and released on August 6, 2026 under the organisation's Technical Standards and Specs category. It sets out how three deployment models put advertising into video streams, and what each choice does to measurement accuracy, ad-quality signalling, scalability and monetisation across broadcaster video on demand, connected television and live streaming.

According to IAB Australia, the choice matters most in the environments Australian broadcasters and publishers actually operate: BVOD, CTV apps and live linear channels. The accompanying member newsletter, circulated the same morning, framed the stakes plainly: with streaming video among the fastest growing investment areas, "measurement gaps can become an expensive problem," and the insertion model is one of the levers that closes them.

What server-guided insertion actually is

Server-guided ad insertion, abbreviated to SGAI, is described in the document as "a hybrid architecture that pairs server-controlled ad-break signalling with client-side ad resolution." The server marks where an ad break can occur inside the media manifest. The player detects that marker, requests a personalised ad pod, then resolves and plays it, commonly stitching the result on the device at playback.

IAB Australia is careful about the category label. SGAI is characterised as "an emerging implementation pattern rather than a settled category," with terminology still varying between vendors. Several established platforms now offer server-guided modes, and some run server-side insertion and server-guided insertion on the same infrastructure with per-session selection. The document argues the three models are better understood as a spectrum describing where decisioning, insertion and measurement work happens, rather than as three separate worlds.

That framing matters because the older two models are well established. Client-side ad insertion streams content and ads separately, with the player appending them just in time for viewing. Server-side insertion stitches video and ad content together at the server level ahead of playback, producing a single continuous stream.

Where the models diverge

The comparison table in the explainer runs across eleven dimensions, and the divergences are technical rather than promotional.

On ad experience, client-side insertion pauses content to load the ad, which can produce a gap or a jarring transition when the load is slow. Server-side insertion can deliver more seamless, television-like transitions, though playback quality still depends on encoding, ad preparation, content delivery network behaviour and the player. Server-guided insertion is placed alongside server-side on smoothness, while also supporting newer formats including L-bars, squeezebacks, side-by-side layouts and overlays. Those formats overlap with the six standardised CTV ad formats IAB Tech Lab published for public comment in December 2025.

On measurement, client-side insertion is described as the richest environment, because demand-side platform pixels, verification tags and the Open Measurement SDK can fire directly from the player. Server-side insertion often depends on server logs and beacons, particularly in CTV apps where JavaScript cannot run or the OM SDK is absent. Server-guided insertion can support richer player-side measurement where the OM SDK or an equivalent client integration is present, and otherwise falls back to server-side beaconing. The document is explicit that fidelity here is an implementation choice rather than an automatic property.

On ad-blocker resistance, server-side insertion is rated the most resistant, because ads are delivered inside the playback workflow and are hard to strip without disrupting content. Server-guided insertion is rated good but conditional. Manifest cues and player-side execution are harder to intercept than a pure client-side ad call, yet asset-list URLs served from a recognisable ad domain remain blockable. The explainer summarises server-side insertion itself as "resistant rather than immune."

On cost and start-up time, the trade-off runs the other way. Server-side insertion carries real server cost for ad preparation and per-session manifest generation, most acute during live peaks. Server-guided insertion keeps content manifests cacheable and resolves ads just in time, reducing central processing and improving video start time. The document names the offsetting risk directly: just-in-time resolution concentrates ad calls into a narrow window at the break, which can stress ad servers and supply-side platforms without prefetch and pacing. That pressure is not hypothetical. Pod-level auction changes at A+E Global Media cut ad server load by 84 percent in a case study published in March 2026, and Magnite's live soccer guidance addressed latency, audience spikes and bid failures ahead of the same tournament.

How the signalling works

SGAI is presented as the first insertion model built substantially on open streaming standards, and the explainer names the specific mechanisms.

HLS Interstitials, introduced by Apple in 2021, schedule interstitials using EXT-X-DATERANGE tags carrying the com.apple.hls.interstitial class and an asset-list reference, resolved late at the break. The document calls this the most widely used foundation for SGAI, while noting it is not the only one.

MPEG-DASH and DASH-IF guidance cover break signalling, manifest updates and ad insertion, including alternative-manifest and manifest-patch events. Those approaches were reworked through 2024 and 2025 for closer alignment with HLS, and DASH-IF interoperability guidance now covers both server-side and server-guided workflows. Implementation support varies by player and device.

For live and broadcast-derived streams, ad opportunities are commonly signalled with SCTE-35. Video-on-demand and client-driven workflows may instead use manifest metadata, VMAP, content management system metadata or player-side timelines. Where SCTE-35 is in use, preserving those cues intact through the encoding and packaging chain is described as a hard prerequisite.

One line in the document carries more weight than its length suggests: these standards govern how ads are signalled and stitched, not how impressions are counted. Measurement, on that reading, has to be designed separately.

From trial to a World Cup broadcast

The explainer dates SGAI's move out of the trial phase to the 2026 FIFA World Cup. Belgian broadcaster RTBF, its sales house RMB and technology partner Ad Insertion Platform deployed server-guided insertion on the Auvio platform, with the Belgium against Egypt match on 15 June 2026 cited as the reference case. The deployment delivered synchronised ad-break replacement across both live and replay content.

Ad Insertion Platform describes it as the first publicly documented SGAI deployment at a major broadcaster using a commercially available platform rather than a bespoke in-house build. IAB Australia treats that qualifier as the point of interest, noting that large streamers such as Disney had already deployed server-guided approaches at scale using their own technology. For Australian publishers, the document argues, the significance is the proof point rather than the vendor combination: server-guided insertion has now run through a major live sporting event, on live and replay inventory, using off-the-shelf components.

The tournament was already a stress test for live ad infrastructure. FIFA approved advertising during three-minute water breaks across all 104 matches, creating an in-game inventory category distinct from standard broadcast breaks. Live ad replacement had also been moving in parallel markets, with Bell Media and TELUS completing Canada's first live linear ad swap on streaming television in June 2026.

Measurement is not automatic

The explainer's most direct argument concerns what SGAI does not deliver on its own. Standards primarily govern ad-break signalling and playback, not a universal method for counting impressions, measuring viewability or performing third-party verification.

Where environments support it, IAB Tech Lab's Open Measurement SDK is named as the strongest route to player-side measurement, allowing approved measurement partners to receive standardised signals from web, app and CTV playback. Version 1.5 extended CTV coverage to Samsung and LG televisions through the web video SDK, which the document flags as material for the Australian smart-television base. OMID 1.6 is the current application programming interface version. OM SDK development has run through several iterations since the UniversalAdId integration in June 2025.

Device attestation arrived in OM SDK 1.6 in late 2025, using an adaptation of the IETF Privacy Pass protocol to provide manufacturer-verified device authenticity, initially on Apple and Fire TV devices. IAB Tech Lab had placed device attestation on its technical roadmap in January 2025. The explainer draws a boundary around what it proves: "It provides evidence that the device is authentic; it is not proof that a person was watching." Device spoofing in server-influenced streams remains an active problem, as the NewsJunkie scheme HUMAN Security disclosed in 2026 illustrated, and as the StreamScam operation had shown years earlier.

CMCD version 2 is positioned as complementary, providing structured client playback telemetry including player state and quality-of-experience signals. The document states clearly that CMCD is not an ad-verification or viewability standard.

One reconciliation detail is likely to surface in reporting disputes. Within IAB Tech Lab's Live Event Ad Playbook, a five-phase initiative for scalable live ad delivery, the Concurrent Streams API is final at version 1.0 and currently counts SGAI streams within SSAI streams rather than reporting them separately. The Forecasting API completed public comment on 20 March 2026 with finalisation pending. Standardised ad pre-fetching and creative readiness phases have not yet been delivered, and the pre-fetching phase speaks directly to the request surges server-guided insertion can create.

Why server-side insertion stays

The explainer resists framing the shift as a migration. For Australian broadcasters, server-side insertion retains two enduring advantages: device reach and simplicity. Because the device receives a single continuous stream, even constrained or older CTV hardware is covered, and that stream remains the hardest to block. Server-guided insertion depends on modern players supporting interstitial or alternative-manifest signalling, which is not yet universal and which some legacy devices may never qualify for.

The pragmatic path described in the document is hybrid: server-side insertion for broadest legacy reach, server-guided insertion for premium, live and interactive inventory, with per-session fallback between the two. Vendors increasingly offer that fallback as a product option. Google Ad Manager provides server-guided insertion through DAI Pod Serving with on-device stitching and client-computed verification pings, extending a dynamic ad insertion product line that has been in market for years. AWS Elemental MediaTailor supports SGAI via HLS Interstitials alongside its existing server-side insertion, including a per-session hybrid mode. Specialist vendors named as illustrative examples include Yospace, castLabs, Bitmovin, Dolby OptiView, Ad Insertion Platform and Penthera. IAB Australia states that vendor and platform names appear as examples only and do not constitute endorsement.

Why the Australian market cares

The commercial context is narrow and specific. BVOD accounted for approximately $500 million of Australia's $5.4 billion video advertising market in calendar year 2025, growing 7.1 percent year on year, the slowest growth rate of any video sub-segment. Social video grew 35.1 percent over the same period. BVOD's position is therefore one of premium inventory under pressure from faster-growing formats, and measurement has been identified in IAB Australia's own research as a persistent gap in the video market.

That gap has been the subject of sustained work. IAB Australia published a video measurement framework in December 2025 covering media delivery, brand impact and sales outcomes. In the first quarter of 2026, BVOD grew 10.1 percent as video reached $1.4 billion and 73.2 percent of display expenditure. Event-driven concentration is pronounced: BVOD sports audiences rose 65 percent in January 2026 during Australian Open coverage.

Insertion architecture is one of the levers that measurement gap responds to, according to the document. Continued investment in authenticated, logged-in first-party audiences is described as complementary to SGAI, helping offset the loss of third-party device signals within privacy constraints, while VOZ and VOZ Streaming supply the cross-platform layer that sits above the insertion question.

The checklist and what it implies

The explainer closes with eleven implementation items for publishers and platform teams evaluating server-guided insertion or running a hybrid model. They cover player and device auditing, ad server and dynamic ad insertion support, SCTE-35 cue integrity through encoding and packaging, measurement instrumentation decided in advance, a commercial agreement on the impression event and the source of truth, consent and privacy signal handling, creative readiness across codec and loudness and captions, fallback behaviour on no-fill and timeout and ad-block detection, pod rules for frequency capping and competitive separation, live scale planning through prefetch and pacing, and end-to-end reconciliation testing with demand-side platforms and verification partners before material spend shifts.

The recurring theme across those items is that responsibility is now shared between server, player and ad server, which makes the definition of a valid impression a commercial negotiation as much as a technical one. Measurement discrepancies in server-influenced environments have been a recurring theme in European guidance published in April 2026, which required disclosure of whether impressions are measured server-side, client-side or through a hybrid approach, and in DoubleVerify's transparency arguments from December 2025.

For media buyers, the practical consequence is that the insertion model behind a given piece of CTV inventory now changes what can be verified about it. That was true before server-guided insertion existed. It is now true across three models rather than two, with a fourth variable layered on top: whether a publisher runs a per-session fallback that switches between models inside the same campaign.

Timeline

Summary

Who: IAB Australia, through Technology Lead Jonas Jaanimagi, addressing buyers, agencies, publishers and platform operators. The explainer names Apple, Google Ad Manager, AWS Elemental MediaTailor, IAB Tech Lab, the Streaming Video Technology Alliance, and specialist vendors including Yospace, castLabs, Bitmovin, Dolby OptiView, Ad Insertion Platform and Penthera as illustrative examples rather than endorsements. The production reference case involves Belgian broadcaster RTBF, its sales house RMB and Ad Insertion Platform.

What: A technical explainer comparing client-side ad insertion, server-side ad insertion and server-guided ad insertion across eleven dimensions, covering signalling mechanisms including HLS Interstitials, MPEG-DASH and SCTE-35, measurement routes through the Open Measurement SDK and CMCD version 2, the reconciliation implications of LEAP's Concurrent Streams API counting SGAI within SSAI, and an eleven-point implementation checklist.

When: Published August 6, 2026, with the accompanying IAB Australia newsletter circulated the same morning. The production deployment it cites occurred on 15 June 2026 during the Belgium against Egypt World Cup match.

Where: Australia, with the analysis framed around the local BVOD and CTV market and its device mix. The deployment evidence comes from Belgium, and the underlying standards work is international.

Why: BVOD accounted for approximately $500 million of Australia's $5.4 billion video advertising market in calendar year 2025, growing 7.1 percent, the slowest rate within video. Measurement has been identified as a persistent gap in that market, and insertion architecture determines what can be measured. Server-guided insertion offers richer player-side signals and lower manifest cost, but depends on modern player support that legacy connected television devices may never reach, which keeps server-side insertion in place for broad reach.