Warnings in core logs about aggregate messages can't be enabled when closed caption generation is turned on for MP4 playback with aggregation messages enabled for MP4
Because of Design Limitation, when closed caption generation is turned on, we cannot have Aggregate messages enabled for RTMP VOD playback. AMS would automatically disable Aggregate messages and would flag below error
Warning from libmp4.dll: Can't aggregate when caption generation is on. Disabling the aggregation for MP4 VOD playback.
In case, you want to use both the feature, it is better to store the captions in VOD itself, by first multi-point publishing it.
This article is applicable for Adobe Media Server 5.0.1