Html5 if recording forwarding is implemented?

  node.js, question

I know how to get video and audio streams. The video stream is thus converted into a picture for forwarding (please let me know if there is any other processing method, thank you), but how is the audio stream forwarded?
How to process the received audio stream before playing it?
Taking node as an example, how to forward audio?
No webrtc.
Please find the forwarding principle. Thank you.

The Great God, please answer