Streaming audio

Streaming images with Socket.IO is great. However, we can use WebSockets in combination with WebRTC to stream audio from one user's microphone to another.

WebRTC (Web Real-Time Communication) is an API that supports browser-to-browser real-time media sharing for applications such as voice calling, video chat, and peer-to-peer file sharing. WebRTC is still a relatively new technology. While WebRTC has support in most browsers, at the time of writing this book, Internet Explorer and Safari do not yet support it.

For two browsers to directly communicate over WebRTC, there is a handshake process that needs to take place. This means that one client makes an offer containing a description of the offer. The second client must then accept the offer and pass a reciprocal description. When the first client receives the answer to their offer, it must set the remote description that is contained in the offer answer. At that point, both clients have agreed to create a WebRTC connection...