From 34caec99a766e4cfdbb3c30dbd0f6143c7e9f879 Mon Sep 17 00:00:00 2001
From: Tracy Pearson <tracypearson@tracypearson.com>
Date: Mon, 20 Jul 2020 23:59:14 -0400
Subject: [PATCH] initial commit

---
 BrownNoise.html | 119 ++++++++++++++++++++++++++++++++++++++++++++++++
 README.md       |   1 +
 2 files changed, 120 insertions(+)
 create mode 100644 BrownNoise.html
 create mode 100644 README.md
diff --git a/BrownNoise.html b/BrownNoise.html
new file mode 100644
index 0000000..e59993e
--- /dev/null
+++ b/BrownNoise.html
@@ -0,0 +1,119 @@
+<html>
+<head>
+<script src="http://ajax.googleapis.com/ajax/libs/jquery/2.0.3/jquery.min.js"></script>
+</head>
+<body>
+<button id="white-demo">
+White Noise
+</button>
+<button id="pink-demo">
+Pink Noise
+</button>
+<button id="brown-demo">
+Brown Noise
+</button>
+<script type="text/javascript">
+(function(AudioContext) {
+	AudioContext.prototype.createWhiteNoise = function(bufferSize) {
+		bufferSize = bufferSize || 4096;
+		var node = this.createScriptProcessor(bufferSize, 1, 1);
+		node.onaudioprocess = function(e) {
+			var output = e.outputBuffer.getChannelData(0);
+			for (var i = 0; i < bufferSize; i++) {
+				output[i] = Math.random() * 2 - 1;
+			}
+		}
+		return node;
+	};
+
+	AudioContext.prototype.createPinkNoise = function(bufferSize) {
+		bufferSize = bufferSize || 4096;
+		var b0, b1, b2, b3, b4, b5, b6;
+		b0 = b1 = b2 = b3 = b4 = b5 = b6 = 0.0;
+		var node = this.createScriptProcessor(bufferSize, 1, 1);
+		node.onaudioprocess = function(e) {
+			var output = e.outputBuffer.getChannelData(0);
+			for (var i = 0; i < bufferSize; i++) {
+				var white = Math.random() * 2 - 1;
+				b0 = 0.99886 * b0 + white * 0.0555179;
+				b1 = 0.99332 * b1 + white * 0.0750759;
+				b2 = 0.96900 * b2 + white * 0.1538520;
+				b3 = 0.86650 * b3 + white * 0.3104856;
+				b4 = 0.55000 * b4 + white * 0.5329522;
+				b5 = -0.7616 * b5 - white * 0.0168980;
+				output[i] = b0 + b1 + b2 + b3 + b4 + b5 + b6 + white * 0.5362;
+				output[i] *= 0.11; // (roughly) compensate for gain
+				b6 = white * 0.115926;
+			}
+		}
+		return node;
+	};
+
+	AudioContext.prototype.createBrownNoise = function(bufferSize) {
+		bufferSize = bufferSize || 4096;
+		var lastOut = 0.0;
+		var node = this.createScriptProcessor(bufferSize, 1, 1);
+		node.onaudioprocess = function(e) {
+			var output = e.outputBuffer.getChannelData(0);
+			for (var i = 0; i < bufferSize; i++) {
+				var white = Math.random() * 2 - 1;
+				output[i] = (lastOut + (0.02 * white)) / 1.02;
+				lastOut = output[i];
+				output[i] *= 3.5; // (roughly) compensate for gain
+			}
+		}
+		return node;
+	};
+})(window.AudioContext || window.webkitAudioContext);
+</script>
+<script type="text/javascript">
+var audioContext;
+var whiteNoise;
+var whiteGain;
+var pinkNoise;
+var pinkGain;
+var brownNoise;
+var brownGain;
+
+var enableAudio = function() {
+    audioContext = new (window.webkitAudioContext || window.AudioContext)();
+
+    whiteNoise = audioContext.createWhiteNoise();
+    whiteGain = audioContext.createGain();
+    whiteGain.gain.value = 0;
+    whiteNoise.connect(whiteGain);
+    whiteGain.connect(audioContext.destination);
+
+    pinkNoise = audioContext.createPinkNoise();
+    pinkGain = audioContext.createGain();
+    pinkGain.gain.value = 0;
+    pinkNoise.connect(pinkGain);
+    pinkGain.connect(audioContext.destination);
+
+    brownNoise = audioContext.createBrownNoise();
+    brownGain = audioContext.createGain();
+    brownGain.gain.value = 0;
+    brownNoise.connect(brownGain);
+    brownGain.connect(audioContext.destination);
+};
+
+var toggleDemo = function(text, gain) {
+    var handler = function(e) {
+	enableAudio();
+        if (gain.gain.value == 0.0) {
+            $(e.target).text("Stop");
+            gain.gain.value = 0.03;
+        } else {
+            $(e.target).text(text);
+            gain.gain.value = 0.0;
+        }
+    };
+    return handler;
+};
+
+$("#white-demo").click(toggleDemo("White Noise", whiteGain));
+$("#pink-demo").click(toggleDemo("Pink Noise", pinkGain));
+$("#brown-demo").click(toggleDemo("Brown Noise", brownGain));
+</script>
+</body>
+</html>
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diff --git a/README.md b/README.md
new file mode 100644
index 0000000..7cb663c
--- /dev/null
+++ b/README.md
@@ -0,0 +1 @@
+A javascript based brown noise generator
\ No newline at end of file
