README.md

node-webrtc-examples

This project presents a few example applications using node-webrtc.

• audio-video-loopback: relays incoming audio and video using RTCRtpTransceivers.
• ping-pong: simple RTCDataChannel ping/pong example.
• pitch-detector: pitch detector implemented using RTCAudioSink and RTCDataChannel.
• sine-wave: generates a sine wave using RTCAudioSource; frequency control implemented using RTCDataChannel.
• sine-wave-stereo: generates a stereo sine wave using RTCAudioSource; panning control implemented using RTCDataChannel.
• video-compositing: uses RTCVideoSink, node-canvas, and RTCVideoSource to draw spinning text on top of an incoming video.
• record-audio-video-stream using FFmpeg and RTCVideoSink.
• Broadcast example with one broadcaster forwarding to many viewers.

Usage

Install the project's dependencies and run the tests before starting the application server:

npm install
npm test
npm start

Then, navigate to http://localhost:3000.

Architecture

Each example application under examples/ has a Client and Server component. RTCPeerConnection negotiation is supported via a REST API (described below), and is abstracted away from each example application. Code for RTCPeerConnection negotiation lives under lib/.

RTCPeerConnection Negotiation

RTCPeerConnections are negotiated via REST API. The Server always offers (with host candidates) and the Client always answers. In order to negotiate a new RTCPeerConnection, the Client first POSTs to /connections. The Server responds with an RTCPeerConnection ID and SDP offer. Finally, the Client POSTs an SDP answer to the RTCPeerConnection's URL.

Client                                               Server
  |                                                     |
  |  POST /connections                                  |
  |                                                     |
  |---------------------------------------------------->|
  |                                                     |
  |                                             200 OK  |
  |  { "id": "$ID", "localDescription": "$SDP_OFFER" }  |
  |                                                     |
  |<----------------------------------------------------|
  |                                                     |
  |  POST /connections/$ID/remote-description           |
  |  $SDP_ANSWER                                        |
  |                                                     |
  |---------------------------------------------------->|
  |                                                     |
  |                                             200 OK  |
  |                                                     |
  |<----------------------------------------------------|

RTCPeerConnection Teardown

RTCPeerConnections can be proactively torn down by sending a DELETE to the RTCPeerConnection's URL; otherwise, ICE disconnection or failure, if unresolved within the timeToReconnect window, will also trigger teardown. The default timeToReconnect value is 10 s.

Client                                               Server
  |                                                     |
  |  DELETE /connections/$ID                            |
  |                                                     |
  |---------------------------------------------------->|
  |                                                     |
  |                                             200 OK  |
  |                                                     |
  |<----------------------------------------------------|