For Digital Video Ad Serving Template (VAST) ads (or creatives) that have the fallback rule enabled, TVSDK treats an ad with an invalid media type as an empty ad and attempts to use fallback ads in its place. You can configure some aspects of fallback behavior.
The VAST/Digital Video Multiple Ad Playlist (VMAP) specification states that for ads that have VAST fallback enabled, empty ads automatically trigger the use of fallback ads. When a VAST ad is empty, TVSDK looks for a valid HLS media type replacement among the fallback ads. When a VAST ad in a wrapper has an invalid media type, TVSDK treats this ad as empty. You can configure whether TVSDK should do the same for ads inline in a VMAP. For more information about the VAST fallbackOnNoAd feature, see Digital Video Ad Serving Template (VAST) 3.0 .
Zero Length Ads - When TVSDK encounters a VAST response that contains an ad of zero duration, or an ad break with no ads, it fires AD_BREAK_START / AD_BREAK_COMPLETE events for those zero-length ad breaks. This behavior applies only for VOD streams. TVSDK fires these events even when your app is using the SKIP ad policy.
TVSDK does not fire AD_BREAK_START / AD_BREAK_COMPLETE events for Live streams, or when a user employs trickplay or seek to go past the zero-length ad.