AncillaryNode.sendMetadata() method
Send a metadata message (eg ID3 timed metadata, or KLV)
The pts may be specified, in which case it should correspond to the same program (e.g. obtained from a receieved message from that program), or it may be omitted to send "now". If omitting the pts, the node must subscribe to an audio or video stream from the target program in order to fix the latest timestamp to consider "now".
Signature:
sendMetadata(key: StreamKey, info: MetadataSendMessage): void;