Manifests and ad metadata insertion

During the ad stitching process, MediaTailor adds to the manifest the unique ID associated with each creative being stitched. MediaTailor obtains the unique ID of the creative from the id attribute value of that creative in the VAST response. If the creative lacks an ID attribute value, MediaTailor will publish an empty value (id="").

MediaTailor uses an in-manifest metadata signal to decouple dependencies between the client tracking API for ad creative metadata and timing/positioning within the overall timeline. This decoupling reduces playback latency (especially in VOD scenarios), where the player's user interface (UI) renders ad break positions in the timeline prior to initializing playback.

The added metadata takes the following forms:

• For HLS manifests, the added metadata takes the form of DATERANGE tags for each ad in the avail period.

• For DASH manifests, the added metadata takes the form of an Event element within each ad period.

The following JSON message body shows an example VAST response:

{
  "version": 1,
  "identifiers": [
    {
      "scheme": "urn:smpte:ul:060E2B34.01040101.01200900.00000000",
      "value": "creativeId",
      "ad_position": "adId",
      "ad_type": "adType",
      "tracking_uri": "trackingUri",
      "custom_vast_data":"customVastData"
    }
  ]
}

In the preceding example:

• creativeId is the Id attribute value of the Creative element for the ad

• adId is either the HLS sequence number associated with the beginning of the ad, or the DASH period ID of the ad

• adType is either avail or overlay, based on the VAST response

• trackingUri is the relative tracking endpoint for the MediaTailor session, in the format ../../../../tracking/hashed-account-id/origin-id/session-id

• customVastData is a value that MediaTailor extracts from the creative_signaling VAST extension. MediaTailor uses the contents of the CDATA node, if present. See the Ad Decision Server (ADS) interactions section for more details and a sample VAST response.