When the player is embedded in a mobile application it is necessary to pass idfa or gaid parameter.

iOS Identifier for Advertising (idfa)

On iOS 6+ devices use:

NSString *idfaString = [[[ASIdentifierManager sharedManager] advertisingIdentifier] UUIDString];

Note that the user can opt-out from the iOS Device Advertising ID, so the application must handle cases where this ID is not available and send an empty ID.

https://developer.apple.com/documentation/adsupport/asidentifiermanager

Google Advertising ID (gaid)

Google Advertising ID can be retrieved from Google Play services. Please follow the official documentation:

https://developers.google.com/android/reference/com/google/android/gms/ads/identifier/Advertisin gIdClient

Note that the user can opt-out from the Google Device Advertising ID, so the application must handle cases where the ID is not available and send an empty ID.