Video Ad Serving Template (VAST)

Video Ad Serving Template, or VAST for short, is the video technology that standardizes video players and ad servers. This allows publishers to use different ad servers without having to make any modifications to their videos or video players. This effectively allows publishers to both scale and simplify their ad stack, resulting in more effective video ad monetization.

VAST utilizes extensible markup language (XML). Within this language, the video player can control many different aspects of the ad.

Functionalities of VAST

The VAST format allows video players to control a variety of different aspects of the video ad serving process. Among them include:

• Control which ad to play
• How long the ad should last
• How the ad should be displayed
• Whether ad is skippable or not
• Video ad interactivity
• Viewability measurement
• Ad stitching (bypass ad blockers)

VAST Versions

Differences Between Different VAST Versions – Parameter Difference

A table representation of the various VAST feature upgrades with each additional version of VAST, courtest of adtagmacros.com. Note that that each new version of VAST adds new features and is backwards compatible with all previous features. For example, VAST 3.0 has all the features of VAST 2.0 and VAST 1.0.

A Note on VPAID

Video Player Ad Interface Definition (VPAID) allows for publishers and advertisers to both implement and measure more advanced features such as viewability and interactivity. VPAID was released with earlier versions of VAST, and filled the VAST gap to allow interactive video ads and additional measurement tactics for video players. Today, VAST 4.0 can actually provide many of the features that VPAID had done in the past. In an ideal world, everybody would use VAST 4.0. However, roadblocks such as a lack of awareness, lack of resources for implementation, and waiting for the other side to implement VAST 4.0 first all pose major challenges for this to happen.

New Features with VAST 4.0

Some new VAST 4.0 features explained below via IAB.

• Separate video file and interactive file: The complexity of digital video has given rise to the need to separate the linear video file from any creative interactive API files. While the VAST media file has accepted a variety of media files in the past, interactive APIs cannot always be executed. A VAST tag that provides the video file separate from APIs can display more successfully across platforms and devices.
• Server-side support: While client-side ad execution and tracking has been the recommended way to track ad impressions and other metrics, digital in-stream video ads are often served to devices (clients) that cannot execute and track ads using traditional display methods. VAST 4.0 supports the increasingly common “ad- stitching” method for stitching linear video ads into a video content stream and sending it to players with limited capabilities.
• Mezzanine file: To support advertising across video platforms that include long-form content and high-resolution screens, VAST 4.0 features include support for the raw, high-quality mezzanine file. The mezzanine file is very large and cannot be used for ad display, but ad-stitching services and other ad vendor use it to generate files at appropriate quality levels for the environment in which they play.
• Ready-to-serve files: Along with support for including the mezzanine file, VAST 4.0 provides guidance on providing three ready-to-serve video files, each at different quality levels, to ensure that a linear video ad can always play. The IAB Digital Video Ad Format Guidelines offers guidance on video file specifications for linear ads.
• Universal Ad ID: While VAST has offered a creative identifier in the past, it has been used inconsistently. The new Universal Ad ID feature is used specifically for including a creative identifier that is maintained across systems. The existing adId attribute for creative can still be used to log creative IDs specific to the server.
• Ad Verification and Viewability Execution: Verification vendors have been using VPAID for measurement verification instead of using it for ad interaction as VPAID was intended. VAST 4.0 offers a designated space for inserting ad verification APIs, enabling a more streamlined process for executing files strictly intended for ad verification. In addition, a secondary impression element, the <ViewableImpression> element, has been added to allow publishers the option to track viewability on their inventory.
• Support for categories: Ad categories help video publishers separate competing ad creative and improve brand safety. VAST 4.0 ad categories support these efforts.
• Conditional ad declaration: In programmatic environments, a VPAID unit is sometimes used to decide whether or not to place an ad. If this “conditional ad” never results in an ad to display, the publisher may have to forfeit any revenue from the resulting lost inventory. A declaration in VAST for a conditional ad helps publishers prevent and reclaim any potentially lost inventory revenue in programmatic ad delivery.
• New error codes: Along with support for the mezzanine file and other new features, added error codes provide additional troubleshooting support.
• Standardized time stamp: Trackers used in VAST often include timestamp macros, but its use has not been consistent. In VAST 4.0, the [TIMESTAMP] macro and the format for time has been standardized to enable more consistent time-sensitive tracking.

Sources

• https://www.totalmediasolutions.com/blog/vast-4-0-elephant-room/
• https://www.iab.com/guidelines/digital-video-ad-serving-template-vast-4-0/
• https://digiday.com/media/what-is-vast/
• https://adtagmacros.com/difference-between-vast-2-0-and-vast-3-0-vast-4-0/

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