Function debugVideoCaptureStart

src/engineDebug.js:593–665

Start capturing video * @memberof Debug

()

/** Start capturing video
 *  @memberof Debug */
function debugVideoCaptureStart()
{
    ASSERT(!debugVideoCaptureIsActive(), 'Already capturing video!');

    if (!debugVideoCaptureIcon)
    {
        // create recording icon to show it is capturing video
        debugVideoCaptureIcon = document.createElement('div');
        debugVideoCaptureIcon.style.position = 'absolute';
        debugVideoCaptureIcon.style.padding = '9px';
        debugVideoCaptureIcon.style.color = '#f00';
        debugVideoCaptureIcon.style.font = '50px monospace';
        document.body.appendChild(debugVideoCaptureIcon);
    }
    // show recording icon
    debugVideoCaptureIcon.textContent = '';
    debugVideoCaptureIcon.style.display = '';

    // setup captureStream to capture manually by passing 0
    const stream = mainCanvas.captureStream(0);
    const videoTrack = stream.getVideoTracks()[0];
    const captureTimer = new Timer(0, true);
    const chunks = [];
    videoTrack.applyConstraints({frameRate:frameRate});

    // set up the media recorder
    const mediaRecorder = new MediaRecorder(stream, 
        {mimeType:'video/webm;codecs=vp8'});
    mediaRecorder.ondataavailable = (e)=> chunks.push(e.data);
    mediaRecorder.onstop = ()=>
    {
        const blob = new Blob(chunks, {type: 'video/webm'});
        const url = URL.createObjectURL(blob);
        saveDataURL(url, 'capture.webm', 1e3);
    };

    let audioStreamDestination, silentAudioSource;
    if (soundEnable)
    {
        // create silent audio source
        // fixes issue where video can not start recording without audio
        silentAudioSource = new ConstantSourceNode(audioContext, { offset: 0 });
        silentAudioSource.connect(audioMasterGain);
        silentAudioSource.start();

        // connect to audio master gain node
        audioStreamDestination = audioContext.createMediaStreamDestination();
        audioMasterGain.connect(audioStreamDestination);
        for (const track of audioStreamDestination.stream.getAudioTracks())
            stream.addTrack(track); // add audio tracks to capture stream
    }

    // start recording
    try { mediaRecorder.start(); }
    catch(e)
    {
        LOG('Video capture not supported in this browser!');
        silentAudioSource?.stop();