add analyzer setup

static/pyrite.js

@@ -1,8 +1,10 @@
 var player;
 var pos_int;
+var analyser;
+var audio_data;
 
 function init() {
-	player = document.getElementById('player');
+	player = document.querySelector('#player');
 
 	player.addEventListener("ended", nextTrack);
 
@@ -13,6 +15,8 @@ function init() {
 	navigator.mediaSession.setActionHandler('nexttrack', nextTrack);
 
 	pos_int = setInterval(update_position, 300);
+
+	init_analyzer();
 }
 
 async function get_rand_track() {
@@ -77,4 +81,17 @@ function update_position() {
 		playbackRate: player.playbackRate,
 		position: parseInt(player.currentTime)
 	});
+
+	analyser.getByteTimeDomainData(audio_data);
+}
+
+function init_analyzer() {
+	let audioCtx = new AudioContext();
+	analyser = audioCtx.createAnalyser();
+	let source = audioCtx.createMediaElementSource(player);
+
+	source.connect(analyser);
+	source.connect(audioCtx.destination);
+
+	audio_data = new Uint8Array(analyser.frequencyBinCount);
 }