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How to set up a video preroll zone and get its VAST URL

Applies to: Publishers

A preroll plays a video ad before your own video starts. Most video players (JW Player, Flowplayer, Video.js and others) can request ads from a VAST URL, so you create a video ad zone, copy its VAST URL and paste it into your player's ad settings.

Before you start#

  • Add the website that hosts the player: How to add a website.
  • Your player must support VAST ad tags. Check its documentation for "VAST", "ad tag" or "advertising" settings.
  • Know which player you use. If it is a plain HTML5 <video> element, JW Player, Kernel Video Sharing or Flowplayer, the zone can also give you a ready-made player code.

Steps#

  1. Open Adzones and click New Ad Zone.
  2. Fill in Name your ad zone (for example "Player preroll"), choose Video Ads under Adzone Type, and pick the site under Select your website.
  3. In Video Ad Settings:
    • Video type: Preroll. Midroll and Postroll are listed when your network offers them.
    • Player type: the player you use (Html5 Video, JW Player, Kernel Video Sharing or Flow Player). This only changes the player code, not the VAST URL.
    • Enable Skip Button and Skip Time: let viewers skip after the number of seconds you set.
    • Capping: how often one viewer may see an ad from this zone.
    • Country Filter: optional, to run the zone only in (or not in) certain countries.
  4. Click Save. The zone reopens with its tabs.
  5. Open the Ad Zone Code tab. Under VAST URL, click Copy ad code.
  6. Paste that URL into your player's ad tag / VAST setting and save the player configuration.

Pick Preroll, your player and the skip time.

Copy the VAST URL into your player.

Which URL to use#

Block on the code tab Use it when
VAST URL Your player requests ads by itself. This is the normal case.
XML VAST URL (linear) Your player asks specifically for a linear (in-stream) VAST tag.
Ad Code / iframe Code You play the video with the zone's own player code or your own controller instead of handing a VAST URL to a player.

The width and height in the player code are a maximum; the video scales with your own CSS.

Check it worked#

  1. Open a page with the player, with ad blockers off, and press play. An ad plays before your video when a campaign is available for that visitor.
  2. Paste the VAST URL into your browser: it returns XML. An empty <VAST> answer means no campaign matched this request, not that the setup is wrong.
  3. The next day, the zone's Statistics tab shows views.

Troubleshooting#

Symptom Likely cause Fix
The player shows no ad The VAST URL was pasted into the page instead of the player settings. Put the URL in the player's ad tag field.
Ads never play, the XML is always empty No video campaign targets this zone, country or device. Ask your account manager, or (on your own platform) assign a video campaign on the Whitelisted Campaigns tab.
The ad plays only on some pages A different player configuration on those pages. Use the same ad tag setting in every player configuration.
The player shows a VPAID error The campaign serves a VPAID creative your player cannot run. Use a player with VPAID support or ask for MP4 creatives.
Viewers cannot skip Enable Skip Button is off. Switch it on and set Skip Time, then save.