gistfile1.txt

#!/usr/bin/env node
const spawn = require("child_process").spawn;

const input_rtmp = 'rtmp://127.0.0.1/feed/1';
const loop_rtmp  = 'rtmp://127.0.0.1/feed/2';
const out_rtmp   = 'rtmp://127.0.0.1/feed/3';
const timeout    = 10; // in 1/10th of a second


var fallback=0;

function initInputStream(){

	let toReturn = spawn("ffmpeg", ("-f live_flv -i "+input_rtmp+" -c copy -f mpegts -").split(" "));
	toReturn.on("exit", (code) => { console.log("ffmpegIn exited with code " + code); ffmpegIn = initInputStream() });
	toReturn.stdout.on("data", onData);

	return toReturn;
}

function initLoopStream(){

	let toReturn = spawn("ffmpeg", ("-f live_flv -i "+loop_rtmp+" -c copy -f mpegts -").split(" "));
	toReturn.on("exit", (code) => { console.log("ffmpegIn exited with code " + code); ffmpegLoop = initLoopStream() });
	toReturn.stdout.on("data", onDataLoop);

	return toReturn;
}

const ffmpegOut = spawn("ffmpeg", ("-fflags +genpts -re -f mpegts -i - -c copy -acodec libmp3lame -ar 44100 -f flv "+out_rtmp).split(" "));
ffmpegOut.on("exit", (code) => { console.log("ffmpegOut exited with code "+code+"! Exiting..."); process.exit(code); });

var ffmpegIn = initInputStream();
var ffmpegLoop = initLoopStream();

function onData(videoData) {

	console.log('sending input frames');
	ffmpegOut.stdin.write(videoData);
	fallback=0;
}

function onDataLoop(videoData) {
	if(fallback > timeout){
		console.log('sending loop frames');
		ffmpegOut.stdin.write(videoData);
	}
}

setInterval(function(){
	fallback++;
}, 100);