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VAST: video & audio

VAST - the Video Ad Serving Template - is the standard the IAB introduced to make video and audio ad serving work across players from different vendors. It uses an XML schema to carry an ad's metadata from the ad server to the video or audio player.

More information on VAST can be found here: https://www.iab.com/guidelines/vast/
Documentation on the last VAST version: https://iabtechlab.com/wp-content/uploads/2022/09/VAST_4.3.pdf

How does it work?

The player requests an ad from the ad server using a simple URL, and Adhese answers with a VAST XML document the player knows how to read. That document is assembled from two building blocks: advar templates, which supply the VAST markup, and creatives, where you provide the media itself. Such media can be provived in three ways:

  1. By uploading the material in Adhese
  2. By providing a link to material hosted on a different domain
  3. By providing a link to an external VAST tag. Adhese will in that case redirect to the external tag while maintaining the ability to track events

Because a template holds static VAST markup, each type / version of video or audio you want to serve, will require its own template.

Simplified response example

<VAST version="4.0">
  <Ad id="19787">
    <InLine>
      <AdSystem>Adhese</AdSystem>
      <AdTitle>Your creative</AdTitle>
      <Impression><![CDATA[ …/impression ]]></Impression>
      <Creatives>
        <Creative>
          <Linear>
            <Duration>00:00:15</Duration>     
            <TrackingEvents>              
              <Tracking event="start"> … </Tracking>
              <Tracking event="firstQuartile"> … </Tracking>
              <Tracking event="complete"> … </Tracking>
            </TrackingEvents>
            <VideoClicks>
              <ClickThrough><![CDATA[ …/click ]]></ClickThrough>
            </VideoClicks>
            <MediaFiles>                  
              <MediaFile type="video/mp4" width="640" height="360">
                <![CDATA[ …/creative.mp4 ]]>
              </MediaFile>
            </MediaFiles>
          </Linear>
        </Creative>
      </Creatives>
    </InLine>
  </Ad>
</VAST>

VAST ad types

Video | Linear Since VAST 1.0

In-stream video ads that interrupt the main video content. They include Pre-rolls (playing before the video), Mid-rolls (playing during), and Post-rolls (playing after). These usually include skippable or non-skippable formats (introduced in VAST 3.0). 

Video | Companion ads Since VAST 2.0

A companion ad is a image ad shown alongside a linear video ad, usually displayed on top of the player or on its side. It is displayed at the same time as the video ad and can continue to be displayed after the video has finished playing. 

Video | Outstream Since VAST 2.0

The video ad appears in non-video environments, typically embedded in text-based content such as articles or news feeds. An outstream video could for example be shown in typical display placements such as a 'medium rectangle'. 

Video | Non-linear Since VAST 2.0

The ad runs alongside the content, typically as an overlay, without interrupting playback.

Video | Ad pods Since VAST 3.0

A group of ads that play in sequence during a commercial break during long-form video content. Specifically, using IAB VAST, an ad pod is a group of sequential ads that can be served in one VAST tag.

Video | SIMID Since VAST 4.0
 
Audio | Linear Since VAST 4.1

Audio ads that play in a vendor's digital audio player. They are handled similarly to video creatives, except they only have audio and no video component.

Native audio arrived in VAST 4.1, when the separate audio spec (DAAST) was folded back into VAST - before that, audio was served through DAAST as its own template.

Audio | Companion ads Since VAST 4.1

An audio companion ad pairs a linear audio ad with a synchronized image on a screen. This setup allows advertisers to deliver a voice-driven message while providing a clickable asset for direct response. Ideal for music or podcast applications.

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