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gandalf.html
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gandalf.html
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<!DOCTYPE html>
<html>
<head>
<title>Gandalf</title>
<style>
body {
margin: 0 0;
padding: 0 0;
}
div.gandalf-video {
display: block;
}
div.gandalf-video > video {
display: block;
width: 100%;
height: 100%;
}
</style>
<script type="text/javascript">
/* "A wizard is never late, nor is he early, he arrives precisely when he means to." */
window.AudioContext = window.AudioContext || window.webkitAudioContext;
//Media must be a "good enough" loop
const SOUND_URL = './epic_sax_guy.wav';
const VIDEO_URL = 'anim1.mp4';
//If you want to run all connected instances at once using P2P, set to false
const GANDALF_AUTOPLAY = true;
//Display debug canvas below video
const GANDALF_DEBUG_ENABLE = true;
class SynchronizedAudioPlayer {
#START_BPM = 131;
constructor(autostart = true) {
this.autostart = autostart;
this.context = new AudioContext();
//Audio source
this.aud = new Audio();
//MediaSource Node: Connects to the audio element
this.src = this.context.createMediaElementSource(this.aud);
//Lowpass Biquad filter to detect beats
//this.filter0 = this.context.createBiquadFilter(); this.filter0.type = "lowpass";
//FFT analyzer
//this.fft0 = this.context.createAnalyser(); this.fft0.fftSize = 2048;
//Destination Node: Device Speakers for AudioContext or AudioBuffer for OfflineAudioContext
this.dest = this.context.destination;
/**
* Connection:
* Source node[Audio element] -+-> Destination node[Speaker]
* +-> BiquadFilter[Lowpass] -> AudioBuffer node
*/
//TODO: once I figure out how to do this, connect properly
this.src.connect(this.dest);
//this.src.connect(this.filter0);
//this.filter0.connect(this.fft0);
//Never allow to pause
this.aud.addEventListener('pause', event => this.aud.play());
this.bpm = this.#START_BPM;
this.beat_start_time = 0;
this.last_ct = this.beat_start_time;
setInterval(this.#bpmPulse.bind(this), 20);
}
#bpmPulse() {
if (this.last_ct > this.aud.currentTime)
this.last_ct = this.beat_start_time;
else if (this.aud.currentTime - this.last_ct >= 60 / (this.bpm * this.aud.playbackRate))
this.last_ct = this.aud.currentTime;
this.syncBeat(this.aud.currentTime, (this.aud.currentTime - this.last_ct) * (this.bpm*this.aud.playbackRate) / 60);
}
async load(url) {
this.aud.src = url;
this.aud.loop = true;
this.aud.playbackRate = 1;
await new Promise((resolve, reject) => {
this.aud.addEventListener('canplay', event => {
if (this.autostart)
this.play();
resolve();
});
this.aud.addEventListener('error', event => reject());
});
}
/* Start playing */
play() {
this.aud.play();
}
/* Data to let other Peers know when to sync */
getSyncData() {
return {
pos: this.aud.currentTime
}
}
/* To sync video with the song's beat phase */
syncBeat(audio_time, beat_phase) {}
}
class GandalfPlayer extends SynchronizedAudioPlayer {
#PLL_PARAM_TUNE_RATE = 0.1;
#PLL_FREQ_DIVIDE = 1;
#PLL_RATE_BIAS = 1;
constructor(autostart, show_debug = false) {
super(autostart);
this.sync_acc = 1;
this.show_debug = show_debug;
this.phase_hist = [];
this.vid_container = document.createElement('div');
this.vid_container.className = "gandalf-video";
this.vid = document.createElement('video');
this.vid_container.appendChild(this.vid);
this.dbg = new DebugPhaseRenderer();
}
add(elem) {
elem.appendChild(this.vid_container);
if (this.show_debug) {
this.dbg.add(elem);
this.dbg.beginRendering();
}
}
async #load_video(vid_url) {
this.vid.src = vid_url;
this.vid.style.display = "none";
this.vid.loop = true;
this.sync_acc = 1;
return new Promise((resolve, reject) => {
this.vid.addEventListener('canplay', event => resolve());
this.vid.addEventListener('error', event => reject());
});
}
async load(audio_url, vid_url) {
let aud_promise = super.load(audio_url);
let vid_promise = this.#load_video(vid_url);
await aud_promise;
await vid_promise;
}
play() {
super.play();
this.vid.style.removeProperty("display")
this.vid.play();
}
fullscreenToggle() {
if (!document.fullscreenElement)
this.vid_container.requestFullscreen();
else
document.exitFullscreen();
}
//Sync video using a PLL
syncBeat(audio_time, beat_phase) {
let vid_phase = (this.vid.currentTime / this.vid.duration);
let v_phang = vid_phase * 2 * Math.PI;
let b_phang = beat_phase * 2 * Math.PI;
let v_phsq = vid_phase > 0.5;
//Frequency divide
while (beat_phase > 1 / this.#PLL_FREQ_DIVIDE) beat_phase -= 1 / this.#PLL_FREQ_DIVIDE;
let b_phsq = beat_phase > 0.5 / this.#PLL_FREQ_DIVIDE;
let phase_diff = v_phsq ^ b_phsq;
this.dbg.setPhase1(v_phang);
this.dbg.setPhase2(b_phang);
if (Number.isNaN(phase_diff)) phase_diff = 0;
this.phase_hist.push(phase_diff);
if (this.phase_hist.length > 200) this.phase_hist.shift();
if (this.phase_hist.length > 0)
this.sync_acc = this.phase_hist.reduce((a, x) => a+x) / this.phase_hist.length;
let phase_error = 2*(this.sync_acc - 0.5);
this.dbg.setPhaseDiff(phase_error);
//Plotting phase graph
this.dbg.phHist({p: phase_diff, m: this.sync_acc});
//FIXME: Improve this, doesn't seem to work. This magic number seems to be pretty okay for now
//It (phase difference) should approach 0 when this function is called, so we need to change playback rate using feedback
//let x = this.#PLL_RATE_BIAS + phase_error * this.#PLL_PARAM_TUNE_RATE;
//this.vid.playbackRate = Math.max(0.25, Math.min(x, 4));
this.vid.playbackRate = 0.928;
}
}
class DebugPhaseRenderer {
constructor() {
this.ca = document.createElement('canvas');
this.ctx = this.ca.getContext('2d');
this.ca.width = 600;
this.ca.height = 200;
this.phase1 = 0;
this.phase2 = 0;
this.phase_diff = 0;
this.phase_hist = [];
}
add(elem) {
elem.appendChild(this.ca);
}
setPhase1(phase) {
this.phase1 = phase;
}
setPhase2(phase) {
this.phase2 = phase;
}
setPhaseDiff(pd) {
this.phase_diff = pd;
}
phHist(hist_data) {
this.phase_hist.push(hist_data);
}
beginRendering() {
window.requestAnimationFrame(this.render.bind(this));
}
render(ts) {
let px, py;
this.ctx.clearRect(0, 0, this.ca.width, this.ca.height);
while (this.phase_hist.length > this.ca.width-40) this.phase_hist.shift();
this.ctx.strokeStyle = "black";
this.ctx.beginPath();
this.ctx.fillStyle = "red";
px = 40 + Math.cos(this.phase1) * 20;
py = 40 + Math.sin(this.phase1) * 20;
this.ctx.arc(px, py, 5, 0, 2*Math.PI);
this.ctx.fill();
this.ctx.beginPath();
this.ctx.fillStyle = "green";
px = 40 + Math.cos(this.phase2) * 20;
py = 40 + Math.sin(this.phase2) * 20;
this.ctx.arc(px, py, 5, 0, 2*Math.PI);
this.ctx.fill();
this.ctx.strokeRect(40 - 20, 110, 40, 20);
this.ctx.beginPath();
this.ctx.fillStyle = "yellow";
px = 40 + this.phase_diff * 10;
this.ctx.arc(px, 120, 10, 0, 2*Math.PI);
this.ctx.fill();
this.ctx.beginPath();
for (let x = 0; x < this.phase_hist.length; x++) {
let px = 20+x;
let py = 100 - this.phase_hist[x].p * 30;
if (x === 0)
this.ctx.moveTo(px, py);
else
this.ctx.lineTo(px, py);
}
this.ctx.stroke();
this.ctx.beginPath();
this.ctx.strokeStyle = "red";
for (let x = 0; x < this.phase_hist.length; x++) {
let px = 20+x;
let py = 100 - this.phase_hist[x].m * 30;
if (x === 0)
this.ctx.moveTo(px, py);
else
this.ctx.lineTo(px, py);
}
this.ctx.stroke();
window.requestAnimationFrame(this.render.bind(this));
}
}
//https://www.youtube.com/watch?v=t-_VPRCtiUg
//TODO: Generalize this class
//Synchronize a player by crowd averaging over WebRTC P2P
class WRTCSynchronizer {
constructor(player) {
this.player = player;
this.itv = null;
//Local peer connection
this.pcon = new RTCPeerConnection();
//All remote connections that connect to us. Key is the offer SDP
this.remotes = {};
//Just one sync channel for timestamps. We can't share audio as that will kill the bandwidth
this.sync_channel = this.pcon.createDataChannel('sync');
this.#generateLocalOffer().then(offer => this.#letTheWorldKnow(offer));
//Fullscreen only possible with user-event
window.addEventListener('dblclick', () => {
this.player.fullscreenToggle();
});
}
start() {
this.itv = setInterval(this.#synchronizeSend.bind(this), 1000);
}
stop() {
clearTimeout(this.itv);
this.itv = null;
}
#generateLocalOffer() {
return new Promise((resolve, reject) => {
this.pcon.createOffer()
.then(offer => this.pcon.setLocalDescription(offer))
.then(() => resolve(this.pcon.localDescription))
.catch(reject);
});
}
#letTheWorldKnow(localOffer) {
//We can let other peers know about our existence by any means, as long as this offer is sent to them
//console.log(localOffer);
//setTimeout(() =>this.player.play(), 2000);
}
#synchronizeSend() {
//console.log(SOUND_BPM);
//let real_aud_time = this.player.aud.currentTime;
}
//TODO: synchronizeRecv
#synchronizeRecv() { }
}
//Initialize
const gd = new GandalfPlayer(GANDALF_AUTOPLAY, GANDALF_DEBUG_ENABLE);
const sync = new WRTCSynchronizer(gd);
gd.load(SOUND_URL, VIDEO_URL).then(() => sync.start());
window.addEventListener('load', ()=>gd.add(document.body));
</script>
</head>
<body></body>
</html>