ESP32 | Walkie-Talkie based on Node.js Server for multi-clients (ft. PCM speaker)

ESP32_TTGO/Walkie-Talkie_Project/Server_NodeJS/package.json

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+{
+  "dependencies": {
+    "audio-speaker": "^1.5.1",
+    "express": "^4.17.1",
+    "package.json": "^2.0.1",
+    "ws": "^7.4.4"
+  }
+}

ESP32_TTGO/Walkie-Talkie_Project/Server_NodeJS/server.js

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+/////////////////////////////////////////////////////////////////
+/*
+  ESP32 | Walkie-Talkie based on Node.js Server for multi-clients (ft. PCM speaker)
+  Video Tutorial: https://youtu.be/vq7mPgecGKA
+  Created by Eric Nam (ThatProject)
+*/
+/////////////////////////////////////////////////////////////////
+
+////////////
+// States
+const states = {
+	IDLE: "Idle",
+	LISTENING: "Listening",
+	SPEAKING: "Speaking"
+};
+
+////////////
+// Speaker(Optional)
+// MacOS Issue
+// [../deps/mpg123/src/output/coreaudio.c:81] warning: Didn't have any audio data in callback (buffer underflow)
+// https://github.com/audiojs/audio-play/issues/15
+const Speaker = require("speaker");
+const Readable = require("stream").Readable;
+const pcmSpeaker = new Readable();
+pcmSpeaker.bitDepth = 32;
+pcmSpeaker.channels = 1;
+pcmSpeaker.sampleRate = 16000;
+pcmSpeaker._read = bufRead;
+pcmSpeaker.pipe(new Speaker());
+function bufRead(buf) {
+	if (buf instanceof Buffer) {
+		pcmSpeaker.resume();
+		pcmSpeaker.push(buf);
+	} else if (buf == null) {
+		pcmSpeaker.pause();
+	}
+}
+
+////////////
+// WebSocket
+const WebSocket = require("ws");
+const WS_PORT = process.env.WS_PORT || 8888;
+const wsServer = new WebSocket.Server(
+	{
+		port: WS_PORT,
+		perMessageDeflate: {
+			concurrencyLimit: 10,
+			threshold: 1024
+		}
+	},
+	() => console.log(`[Server] WS server is listening at ${WS_PORT}`)
+);
+
+wsServer.on("connection", (ws, req) => {
+	console.log("[Client] Connected!");
+	ws.timestamp = getTimestamp();
+	ws.id = wsServer.getUniqueID(ws.timestamp);
+	ws.state = states.IDLE;
+
+	ws.send(ws.timestamp);
+	ws.on("message", (event) => {
+		messageHandler(ws, event);
+	});
+});
+
+wsServer.getUniqueID = function (timestamp) {
+	function s4() {
+		return Math.floor((1 + Math.random()) * 0x10000)
+			.toString(16)
+			.substring(1);
+	}
+	return timestamp + "-" + s4();
+};
+
+function messageHandler(ws, event) {
+	ws.timestamp = getTimestamp();
+	if (event instanceof Buffer) {
+		if (event.length == 1) {
+			console.log("[Client] Ping from: " + ws.id);
+		} else if (event.length > 1) {
+			sendDataClients(ws, event);
+			bufRead(event); // Resume Speaker Out
+		}
+	} else {
+		if (checkAllClientState()) {
+			ws.state = states.SPEAKING;
+			ws.send(event);
+		} else {
+			ws.state = states.IDLE;
+			bufRead(null); // Pause Speaker Out
+		}
+		sendDataClients(ws, event);
+	}
+}
+
+function sendDataClients(d_client, data) {
+	var timestamp = getTimestamp();
+	wsServer.clients.forEach(function each(client) {
+		if (d_client != client) {
+			client.timestamp = timestamp;
+			console.log("[Client] Client Id: " + client.id + " Client State: " + client.state);
+			if (client.state == states.IDLE) {
+				// OTHER CLIENTS, IDLE -> LISTENING
+				if (data instanceof Buffer) {
+					// NO ACTION REQUIRED
+				} else {
+					client.state = states.LISTENING;
+					client.send(timestamp);
+				}
+			} else {
+				// OTHER CLIENTS, LISTENING -> IDLE
+				if (data instanceof Buffer) {
+					client.send(data);
+				} else {
+					client.state = states.IDLE;
+					client.send(timestamp);
+				}
+			}
+		}
+	});
+}
+
+function getTimestamp() {
+	var last8digit_Timestamp = Date.now().toString().slice(-8);
+	return parseInt(last8digit_Timestamp);
+}
+
+function checkAllClientState() {
+	var result = false;
+	wsServer.clients.forEach(function each(client) {
+		if (client.state != states.IDLE) {
+			result = false;
+			return;
+		}
+		result = true;
+	});
+	return result;
+}
+
+function checkAlive() {
+	console.log("[Server] Total number of connected clients: " + wsServer.clients.size);
+	wsServer.clients.forEach(function each(client) {
+		if (client.state == states.IDLE) {
+			console.log(
+				"[Check Clinet Alive] Client Id: " +
+					client.id +
+					" Timestamp DIFF: " +
+					(getTimestamp() - client.timestamp)
+			);
+			if (getTimestamp() - client.timestamp > 10000) {
+				// 10sec
+				console.log("[Client TimeOut] Client Id: " + client.id);
+				client.close;
+				wsServer.clients.delete(client);
+			}
+		}
+	});
+}
+
+setInterval(function () {
+	checkAlive();
+}, 5000);