Server-side tracking with server-guided ad insertion (SGAI)

Session initialization: The player requests the HLS multivariant playlist with aws.insertionMode=GUIDED. Server-side reporting is the default (no aws.reportingMode parameter is needed). Unlike stitched mode, the session initialization response does not include a trackingUrl.

Cacheable manifest: MediaTailor returns a cacheable manifest containing EXT-X-DATERANGE tags with CLASS="com.apple.hls.interstitial" and X-ASSET-LIST attributes pointing to the MediaTailor interstitial asset list endpoint.

Asset list with beacon metadata: When the player encounters an ad break, it fetches the asset list. MediaTailor returns a JSON response where each ad URI includes encrypted beacon metadata:

{
  "ASSETS": [
    {
      "DURATION": 30.0,
      "URI": "https://cdn.example.com/ad/master.m3u8?awsBeaconData=<encrypted>&awsBeaconDomain=<MediaTailor-endpoint>&awsConfigurationName=<config-name>"
    }
  ]
}

When server-side reporting is active, the response does not include a TRACKING section. The ad URIs carry all beacon data.

HLS variable substitution: The player fetches the ad multivariant playlist. The ad manifest uses #EXT-X-DEFINE:QUERYPARAM directives to pass the beacon parameters from the URI query string into segment URLs via HLS variable substitution:

#EXTM3U
#EXT-X-DEFINE:QUERYPARAM="awsBeaconData"
#EXT-X-DEFINE:QUERYPARAM="awsBeaconDomain"
#EXT-X-DEFINE:QUERYPARAM="awsConfigurationName"
#EXTINF:5.0,
{$awsBeaconDomain}/segment/hash/{$awsConfigurationName}/{$awsBeaconData}/0/0?aws.segmentRelativePath=asset_00001.ts

The player resolves the {$awsBeaconData}, {$awsBeaconDomain}, and {$awsConfigurationName} variables using the values from the ad manifest URI query string, and then requests each ad segment through MediaTailor.

Beacon firing on segment request: As the player requests each ad segment, the request routes through MediaTailor. The service decrypts the beacon data, determines the segment's position within the ad (impression, first quartile, midpoint, third quartile, or complete), and fires the appropriate VAST tracking beacon to the ad server. MediaTailor then redirects the player to the actual ad content segment.