Unreal Engine -> Pion WebRTC -> RTP Receiver

This is a proof of concept demonstrating pixel streaming from Unreal Engine to Pion's WebRTC, with Pion then forwarding RTP video/audio to FFPlay.

Running the proof of concept

There are number of moving pieces to run this demo. We tested this proof of concept using FFPlay 4.3.1, NodeJS 15.5.1, GoLang 1.15.6, and Unreal Engine 4.25 - we recommend using similar version numbers to reproduce our results.

1. Get the "Pixel Streaming Demo" and run that in Unreal Engine.
2. Run the Cirrus signalling server bundled with Unreal Engine by calling run.bat or sudo node cirrus.js in Engine/Source/Programs/PixelStreaming/WebServers/SignallingAndWebServer/.
3. Run this RTP forwarder, go run main.go in this repository.
4. Play the forwarded video/audio streams in FFPlay, run play-stream.bat or play-stream.sh

Configuring the forwarder

There are a number of constants defined in main.go that may be of interest to those extending this proof of concept:

// CirrusPort - The port of the Cirrus signalling server that the Pixel Streaming instance is connected to.
const CirrusPort int = 80

// CirrusAddress - The address of the Cirrus signalling server that the Pixel Streaming instance is connected to.
const CirrusAddress string = "localhost"

// ForwardingAddress - The address to send the RTP stream to.
const ForwardingAddress string = "127.0.0.1"

// RTPVideoForwardingPort - The port to use for sending the RTP video stream.
const RTPVideoForwardingPort int = 4002

// RTPAudioForwardingPort - The port to use for sending the RTP audio stream.
const RTPAudioForwardingPort int = 4000

// RTPAudioPayloadType - The payload type of the RTP packet, 111 is OPUS.
const RTPAudioPayloadType webrtc.PayloadType = 111

// RTPVideoPayloadType - The payload type of the RTP packet, 102 is H264.
const RTPVideoPayloadType webrtc.PayloadType = 102

Configuring FFPlay

Currently FFPlay is passed details about the RTP streams using the rtp-forwarder.sdp file. Additionally, FFPlay is passed the -fflags nobuffer -flags low_delay flags to reduce latency; however, these may not be suitable in all cases.