# Activate your webcam In this section we're going to learn how to use your webcam to capture the video. We're also going to polish our work and make it presentable to users. ## Change the source of data Instead of using a video file, we're going to use your webcam. We simply need to change the source of data and instruct MARTINS.js to use your webcam. We'll do it with 1 new line of code! ```js title="ar-demo.js" hl_lines="20-22" async function startARSession() { if(!Martins.isSupported()) { throw new Error( 'Use a browser/device compatible with WebGL2 and WebAssembly. ' + 'Your user agent is ' + navigator.userAgent ); } const tracker = Martins.Tracker.ImageTracker(); await tracker.database.add([{ name: 'my-reference-image', image: document.getElementById('my-reference-image') }]); const viewport = Martins.Viewport({ container: document.getElementById('ar-viewport') }); //const video = document.getElementById('my-video'); // comment this line //const source = Martins.Source.Video(video); // comment this line const source = Martins.Source.Camera(); const session = await Martins.startSession({ mode: 'immersive', viewport: viewport, trackers: [ tracker ], sources: [ source ], stats: true, gizmos: true, }); return session; } ``` Let's also comment (or remove) the `