fix: adjust numbers based on real atem

src/__tests__/atem.spec.ts

@@ -1,5 +1,5 @@
 /* eslint-disable @typescript-eslint/unbound-method */
-import { Atem, DEFAULT_MTU, DEFAULT_PORT } from '../atem'
+import { Atem, DEFAULT_MAX_PACKET_SIZE, DEFAULT_PORT } from '../atem'
 import { CutCommand } from '../commands'
 import { promisify } from 'util'
 import { EventEmitter } from 'events'
@@ -35,14 +35,14 @@ describe('Atem', () => {
 				disableMultithreaded: true,
 				log: (conn as any)._log,
 				port: DEFAULT_PORT,
-				packetMtu: DEFAULT_MTU,
+				maxPacketSize: DEFAULT_MAX_PACKET_SIZE,
 			})
 		} finally {
 			await conn.destroy()
 		}
 	})
 	test('constructor test 2', async () => {
-		const conn = new Atem({ debugBuffers: true, address: 'test1', port: 23, packetMtu: 500 })
+		const conn = new Atem({ debugBuffers: true, address: 'test1', port: 23, maxPacketSize: 500 })
 
 		try {
 			const socket = (conn as any).socket as AtemSocket
@@ -56,7 +56,7 @@ describe('Atem', () => {
 				disableMultithreaded: false,
 				log: (conn as any)._log,
 				port: 23,
-				packetMtu: 500,
+				maxPacketSize: 500,
 			})
 		} finally {
 			await conn.destroy()

src/atem.ts

@@ -62,7 +62,7 @@ export interface AtemOptions {
 	/**
 	 * Maximum size of packets to transmit
 	 */
-	packetMtu?: number
+	maxPacketSize?: number
 }
 
 export type AtemEvents = {
@@ -89,7 +89,7 @@ export enum AtemConnectionStatus {
 }
 
 export const DEFAULT_PORT = 9910
-export const DEFAULT_MTU = 1500
+export const DEFAULT_MAX_PACKET_SIZE = 1416 // Matching ATEM software
 
 export class BasicAtem extends EventEmitter<AtemEvents> {
 	private readonly socket: AtemSocket
@@ -109,7 +109,7 @@ export class BasicAtem extends EventEmitter<AtemEvents> {
 			port: options?.port || DEFAULT_PORT,
 			disableMultithreaded: options?.disableMultithreaded ?? false,
 			childProcessTimeout: options?.childProcessTimeout || 600,
-			packetMtu: options?.packetMtu ?? DEFAULT_MTU,
+			maxPacketSize: options?.maxPacketSize ?? DEFAULT_MAX_PACKET_SIZE,
 		})
 		this.dataTransferManager = new DT.DataTransferManager(this.sendCommands.bind(this))
 

src/lib/__tests__/atemSocket.spec.ts

@@ -108,7 +108,7 @@ describe('AtemSocket', () => {
 			port: 890,
 			disableMultithreaded: true,
 			childProcessTimeout: 100,
-			packetMtu: 1500,
+			maxPacketSize: 1416,
 		})
 	}
 

src/lib/atemSocket.ts

@@ -13,7 +13,7 @@ export interface AtemSocketOptions {
 	debugBuffers: boolean
 	disableMultithreaded: boolean
 	childProcessTimeout: number
-	packetMtu: number
+	maxPacketSize: number
 }
 
 export type AtemSocketEvents = {
@@ -29,7 +29,7 @@ export class AtemSocket extends EventEmitter<AtemSocketEvents> {
 	private readonly _debugBuffers: boolean
 	private readonly _disableMultithreaded: boolean
 	private readonly _childProcessTimeout: number
-	private readonly _packetMtu: number
+	private readonly _maxPacketSize: number
 	private readonly _commandParser: CommandParser = new CommandParser()
 
 	private _nextPacketTrackingId = 0
@@ -47,7 +47,7 @@ export class AtemSocket extends EventEmitter<AtemSocketEvents> {
 		this._debugBuffers = options.debugBuffers
 		this._disableMultithreaded = options.disableMultithreaded
 		this._childProcessTimeout = options.childProcessTimeout
-		this._packetMtu = options.packetMtu
+		this._maxPacketSize = options.maxPacketSize
 	}
 
 	public async connect(address?: string, port?: number): Promise<void> {
@@ -107,7 +107,7 @@ export class AtemSocket extends EventEmitter<AtemSocketEvents> {
 	public async sendCommands(commands: Array<ISerializableCommand>): Promise<number[]> {
 		if (!this._socketProcess) throw new Error('Socket process is not open')
 
-		const maxPacketSize = this._packetMtu - 28 - 12 // MTU minus UDP header and ATEM header
+		const maxPacketSize = this._maxPacketSize - 12 // MTU minus ATEM header
 		const packetBuilder = new PacketBuilder(maxPacketSize, this._commandParser.version)
 
 		for (const cmd of commands) {