From 656ddfe28773afaa57baf6dc8797d5709853484f Mon Sep 17 00:00:00 2001
From: Faye Li <si.fi.faye.li@gmail.com>
Date: Tue, 3 Jan 2017 09:27:33 -0800
Subject: [PATCH] audio level calculation in tabletUI.js

---
 scripts/system/tablet-ui/tabletUI.js | 33 ++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/scripts/system/tablet-ui/tabletUI.js b/scripts/system/tablet-ui/tabletUI.js
index 077485ea35..50c76d6b0f 100644
--- a/scripts/system/tablet-ui/tabletUI.js
+++ b/scripts/system/tablet-ui/tabletUI.js
@@ -67,4 +67,37 @@
     Script.update.connect(updateShowTablet);
     // Script.setInterval(updateShowTablet, 1000);
 
+    // Initialise variables used to calculate audio level
+    var accumulatedLevel = 0.0;
+    // Note: Might have to tweak the following two based on the rate we're getting the data
+    var AVERAGING_RATIO = 0.05;
+    var AUDIO_LEVEL_UPDATE_INTERVAL_MS = 100;
+
+    // Calculate audio level with the same scaling equation (log scale, exponentially averaged) in AvatarInputs and pal.js
+    function getAudioLevel() {
+        var LOUDNESS_FLOOR = 11.0;
+        var LOUDNESS_SCALE = 2.8 / 5.0;
+        var LOG2 = Math.log(2.0);
+        var audioLevel = 0.0;
+        accumulatedLevel = AVERAGING_RATIO * accumulatedLevel + (1 - AVERAGING_RATIO) * (MyAvatar.audioLoudness);
+        // Convert to log base 2
+        var logLevel = Math.log(accumulatedLevel + 1) / LOG2;
+        
+        if (logLevel <= LOUDNESS_FLOOR) {
+            audioLevel = logLevel / LOUDNESS_FLOOR * LOUDNESS_SCALE;
+        } else {
+            audioLevel = (logLevel - (LOUDNESS_FLOOR - 1.0)) * LOUDNESS_SCALE;
+        }
+        if (audioLevel > 1.0) {
+            audioLevel = 1.0;
+        }
+        return audioLevel;
+    }
+
+    Script.setInterval(function() {
+        var currentAudioLevel = getAudioLevel();
+        // TODO: send the audio level to QML
+
+    }, AUDIO_LEVEL_UPDATE_INTERVAL_MS);
+
 }()); // END LOCAL_SCOPE