Wowza Streaming Cloud can receive AMF metadata from an encoder or other H.264 source that supports and sends it, but AMF metadata can’t be directly injected into a transcoder in Wowza Streaming Cloud. So, you will configure this AMF data in the encoder first and this data will be in the stream as you push it and it is ingested by Streaming Cloud.
Once it’s ingested by Cloud, it will need to be converted into ID3 for playback. The source AMF data must be in the correct format though:
( you can see an example of this “correct format” I mention for the AMF data from the encoder here. It’s an Engine article, but it still shows the same format that would also be required for ingest in Cloud. )
Regarding the metadata and the encoder itself, most Software encoders do not support operations like timed-text or AMF injection.
Generally for something like this, a hardware encoder is used like an Elemental, BlackMagic, or NewTek. Let me see what I can find on vMix, but you may need to check their documentation.