Convert Youtube to mp3, mp4?

Question

YouTube

Interested in converting Youtube "on the fly" or on the server side.
Is it actually possible to convert or "separate a separate stream" by video URL to mp3?
Are there libraries in npm to do this?
The backend of the project is written in NodeJs, an Angular 7 client.
Constructive responses and suggestions are appreciated.

Answer 1

mp3 cannot be streamed.
And according to the task, just read the stream, tear out the audio.
On c#,c++,delphi it's quite easy.
I won’t say it in the node, but it’s unlikely without native modules.