Why OMID and SIMID are Essential for Measuring Viewability on CTV

Let's dive deep into the Connected TV (CTV) landscape, and talk about why OMID and SIMID are Essential, but first the CTV landscape which is no longer an emerging frontier; it is the established heartland of modern media consumption. Billions of advertising dollars are flowing into platforms like Roku, Hulu, YouTube TV, and Peacock, chasing audiences who have decisively cut the cord. Yet, for all its premium allure, the world of CTV advertising has been grappling with a fundamental, persistent challenge: measurement.

Advertisers aren't just buying impressions; they're buying verified, viewable, and impactful moments with their target audience. But in the complex, fragmented ecosystem of CTV, proving that an ad was actually seen has been notoriously difficult. The industry's old tools, forged in the era of desktop browsers, crumbled under the unique pressures of the living room screen. The most infamous of these was VPAID, a standard now effectively dead for CTV. Its demise has paved the way for a more sophisticated, secure, and purpose-built solution: the tandem of OMID and SIMID. This is the story of why that transition was necessary and how these new standards are finally bringing clarity to CTV measurement.

The Ghost of VPAID: Why the Old Standard Haunted CTV

To understand where we're going, we must first understand the failings of the past. VPAID (Video Player Ad-Serving Interface Definition) was the IAB's initial attempt to solve for ad interactivity and measurement in a single package. In the desktop world, it worked—to a degree. A VPAID ad unit was essentially a piece of executable JavaScript that took over the video player. It could render the ad, create interactive overlays, and, crucially, run its own measurement logic to track viewability, completion rates, and other vital metrics.

When advertisers tried to apply this model to CTV, the entire framework collapsed for three critical reasons:

1. Crippling Performance Issues: CTV devices—from smart TVs to streaming sticks like a Fire Stick or Roku—are not high-powered desktop computers. They operate on varied, often underpowered, operating systems with limited processing power and memory. Executing a heavy, all-in-one VPAID JavaScript file directly on these devices often led to disastrous results: increased ad latency, frustrating buffering wheels, and even application crashes. The very tool meant to measure the ad experience was actively ruining it.

2. Massive Security Vulnerabilities: For a CTV app owner (the publisher), allowing a VPAID tag to run is like handing over the keys to their house. Because VPAID is arbitrary JavaScript, it grants the third-party code unfettered access to the app's environment. This creates a significant security risk, opening the door to malicious code that could potentially scrape user data, disrupt the app's functionality, or compromise the device itself. Publishers, rightly, refused to take this risk, effectively blocking VPAID at the gate.

3. Intense Fragmentation: The CTV world is not a monolith. It’s a patchwork of disparate operating systems: tvOS (Apple TV), Android TV (Sony, Google TV), Fire OS (Amazon), Tizen (Samsung), webOS (LG), and Roku OS. A single VPAID creative built for a web browser would not work across these diverse, non-browser environments. This required bespoke, costly development for each platform, making scalability an impossible dream.

The verdict was clear: VPAID was the wrong tool for the job. It was insecure, inefficient, and fundamentally incompatible with the CTV environment. A new approach was needed—one that separated the core functions of ad delivery, measurement, and interactivity.

The New Guard: OMID and SIMID Unbundled for a Better Future

The IAB Tech Lab recognized the VPAID crisis and went back to the drawing board. The solution was elegant in its simplicity: unbundle the monolithic ad unit. Instead of one script trying to do everything, the new model separates responsibilities. This gave birth to OMID and SIMID.

OMID (Open Measurement Interface Definition): The Viewability Verifier

OMID is the industry's answer to the viewability problem. It is not an executable ad unit; it is a standardized API—a common language—that allows a video player to communicate securely with a measurement script.

Think of it like this: The CTV app's video player is a locked, secure black box. OMID acts as a standardized, secure "data port" on the side of that box. A third-party verification vendor (like IAS, DoubleVerify, or Moat) can plug their lightweight, certified measurement script into this port. This script doesn't control the player or the ad; it only listens. It receives signals from the player about the ad creative's geometry (e.g., its size, its coordinates on the screen, and whether it's obstructed) and other playback events (impression, start, quartile completions, pause, mute).

Because the OMID API is standardized, a single measurement script from a vendor can work across any CTV player and platform that has integrated the Open Measurement SDK (OM-SDK). This solves the fragmentation problem. And because the script is only receiving data through a controlled API and not executing freely, it solves the security problem. Publishers can confidently integrate the OM-SDK, and advertisers can finally get the trusted, third-party verification they demand.

SIMID (Secure Interactive Media Interface Definition): The Interaction Enabler

With OMID handling measurement, what about the "interactivity" part of VPAID? That's where SIMID comes in. SIMID is the successor to VPAID for handling rich, interactive ad experiences. It works in concert with the ad creative, allowing an interactive layer to run in a sandboxed, secure environment (an iframe or web view) that is separate from the main video player.

This interactive layer can communicate with the player through a secure, limited channel defined by the SIMID standard. It can ask the player to pause the primary video to display an interactive overlay (like a product carousel or a store locator) and then resume it. Because it's sandboxed, it can't harm the player or the publisher's app, neatly solving the security concerns that plagued VPAID.

Together, OMID and SIMID create a complete, modern framework:

• The VAST tag delivers the ad creative (the video file).
• OMID provides a safe, standardized channel for third-party viewability and performance measurement.
• SIMID provides a safe, standardized channel for interactive ad elements.

Implementation Within a VAST Tag

For ad operations professionals, advertisers, and developers, understanding how this works in practice is key. The magic happens within the VAST (Video Ad Serving Template) tag, specifically within a new node called <AdVerifications>.

This node is added to the VAST response to signal to the player that one or more third-party measurement scripts should be executed for verification purposes. It sits alongside the <MediaFiles> and <TrackingEvents> nodes.

Where the <AdVerifications> Node Goes in a VAST Tag

Here is a simplified VAST 4.x structure showing the placement of the <AdVerifications> node. It is a child of the <InLine> or <Wrapper> ad element.

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<VAST version="4.2">
  <Ad id="20011">
    <InLine>
      <AdSystem>...</AdSystem>
      <AdTitle>...</AdTitle>
      <Description>...</Description>
      <Error>...</Error>
      <Impression>...</Impression>

      <!-- THIS IS THE KEY SECTION FOR OMID -->
      <AdVerifications>
        <Verification vendor="VendorName.com-omid">
          <JavaScriptResource apiFramework="OMID" browserOptional="false">
            <![CDATA[https://verification-vendor.com/omid-validation-script.js]]>
          </JavaScriptResource>
          <VerificationParameters>
            <![CDATA[{"accessMode": "limited", "vendorKey": "ABC123XYZ", "partnerName": "PublisherX"}]]>
          </VerificationParameters>
        </Verification>
      </AdVerifications>
      <!-- END OF THE KEY SECTION -->

      <Creatives>
        <Creative>
          <Linear>
            <Duration>...</Duration>
            <TrackingEvents>...</TrackingEvents>
            <VideoClicks>...</VideoClicks>
            <MediaFiles>
              <MediaFile ...>
                <![CDATA[https://cdn.example.com/ad-creative.mp4]]>
              </MediaFile>
            </MediaFiles>
          </Linear>
        </Creative>
      </Creatives>
    </InLine>
  </Ad>
</VAST>

Dissecting a Typical OMID Script Resource

Let's break down the <Verification> block:

• <Verification vendor="VendorName.com-omid">: This identifies the measurement provider. The -omid suffix is a convention to signal that this vendor supports Open Measurement.
• <JavaScriptResource apiFramework="OMID" browserOptional="false">: This is the heart of the declaration.
  • apiFramework="OMID": This explicitly tells the player that the script inside is designed to work with the OMID API. The player's OM-SDK will know exactly how to handle it.
  • browserOptional="false": This attribute indicates whether the resource is essential for the ad's execution. For measurement, it's typically set to false in CTV environments, meaning the player should not play the ad if it cannot execute this verification script.
• <![CDATA[https://verification-vendor.com/omid-validation-script.js]]>: This is the URL to the vendor's lightweight JavaScript measurement script. The OM-SDK in the player will fetch and execute this script.
• <VerificationParameters>: This CDATA block contains vendor-specific configuration data, often in JSON format. It can pass necessary identifiers, keys, or settings that the measurement script needs to properly categorize and report the data it collects.

The Way Forward: A Measured and Trusted Future

The shift from VPAID to OMID and SIMID is more than a technical acronym swap; it represents a maturation of the CTV advertising ecosystem. It's a move toward a model built on collaboration, security, and standardization, where all parties—advertisers, publishers, and verification vendors—can operate using a common, trusted language.

For advertisers, it means they can finally invest their burgeoning CTV budgets with confidence, knowing that their ads are being measured against reliable, third-party viewability standards. For publishers, it means they can open their premium inventory to verification without compromising their user experience or platform security.

The road to 100% adoption is ongoing, but the path is clear. As the OM-SDK becomes ubiquitous across CTV platforms and the VAST 4.x standard becomes the norm, the measurement challenges of today will become the trusted metrics of tomorrow. The impression will no longer be enough; the future of CTV advertising is verified, viewable, and built on the solid foundation of OMID.