Working first pass

Seems roughly same as mic meter.  Works for other avatars, though
using agent avatars (crowd-agent.js + summon.js), seems not to work.

I'll investigate that...

interface/resources/qml/hifi/NameCard.qml

@@ -33,6 +33,7 @@ Row {
     property string userName: ""
     property int displayTextHeight: 18
     property int usernameTextHeight: 12
+    property real audioLevel: 0.0
 
     Column {
         id: avatarImage
@@ -91,7 +92,6 @@ Row {
         // VU Meter
         Rectangle { // CHANGEME to the appropriate type!
             id: nameCardVUMeter
-            objectName: "AvatarInputs"
             // Size
             width: parent.width
             height: 8
@@ -110,7 +110,7 @@ Row {
             Rectangle {
                 id: vuMeterLevel
                 // Size
-                width: (nameCardVUMeter.audioLevel) * parent.width
+                width: (thisNameCard.audioLevel) * parent.width
                 // Style
                 color: "#dbdbdb" // Very appropriate hex value here
                 radius: parent.radius

interface/resources/qml/hifi/Pal.qml

@@ -58,6 +58,7 @@ Item {
             // Properties
             displayName: myData.displayName
             userName: myData.userName
+            audioLevel: myData.audioLevel
             // Size
             width: nameCardWidth
             height: parent.height
@@ -190,6 +191,7 @@ Item {
                 // Properties
                 displayName: styleData.value
                 userName: model.userName
+                audioLevel: model.audioLevel
                 visible: !isCheckBox
                 // Size
                 width: nameCardWidth
@@ -292,7 +294,7 @@ Item {
     }
 
     property var userData: []
-    property var myData: ({displayName: "", userName: ""}) // valid dummy until set
+    property var myData: ({displayName: "", userName: "", audioLevel: 0.0}) // valid dummy until set
     property bool iAmAdmin: false
     function findSessionIndex(sessionId, optionalData) { // no findIndex in .qml
         var i, data = optionalData || userData, length = data.length;
@@ -343,6 +345,18 @@ Item {
                 userData[userIndex].userName = userName; // Defensive programming
             }
             break;
+        case 'updateAudioLevel': 
+            var userId = message.params[0];
+            var audioLevel = message.params[1];
+            if (!userId) {
+                myData.audioLevel = audioLevel;
+                myCard.audioLevel = audioLevel;
+            } else {
+                var userIndex = findSessionIndex(userId);
+                userModel.get(userIndex).audioLevel = audioLevel;
+                userData[userIndex].audioLevel = audioLevel;
+            }
+            break;
         default:
             console.log('Unrecognized message:', JSON.stringify(message));
         }

scripts/system/pal.js

@@ -119,7 +119,8 @@ function populateUserList() {
         var avatarPalDatum = {
             displayName: avatar.sessionDisplayName,
             userName: '',
-            sessionId: id || ''
+            sessionId: id || '',
+            audioLevel: getAudioLevel(id)
         };
         // If the current user is an admin OR
         // they're requesting their own username ("id" is blank)...
@@ -262,6 +263,49 @@ function onClicked() {
     pal.setVisible(!pal.visible);
 }
 
+var AVERAGING_RATIO = 0.05
+var LOUDNESS_FLOOR = 11.0;
+var LOUDNESS_SCALE = 2.8 / 5.0;
+var LOG2 = Math.log(2.0);
+var AUDIO_LEVEL_UPDATE_INTERVAL_MS = 100; // 10hz for now (change this and change the AVERAGING_RATIO too)
+var accumulatedLevels={};
+
+function getAudioLevel(id) {
+    // the VU meter should work similarly to the one in AvatarInputs: log scale, exponentially averaged
+    // But of course it gets the data at a different rate, so we tweak the averaging ratio and frequency
+    // of updating (the latter for efficiency too).
+    var avatar = AvatarList.getAvatar(id);
+    var audioLevel = 0.0;
+
+    // we will do exponential moving average by taking some the last loudness and averaging
+    accumulatedLevels[id] = AVERAGING_RATIO*(accumulatedLevels[id] || 0 ) + (1-AVERAGING_RATIO)*(avatar.audioLoudness);
+    
+    // add 1 to insure we don't go log() and hit -infinity.  Math.log is
+    // natural log, so to get log base 2, just divide by ln(2).
+    var logLevel = Math.log(accumulatedLevels[id]+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;
+    }
+    return audioLevel;
+}
+
+
+// we will update the audioLevels periodically
+// TODO: tune for efficiency - expecially with large numbers of avatars
+Script.setInterval(function () {
+    if (pal.visible) {
+        AvatarList.getAvatarIdentifiers().sort().forEach(function (id) {
+            var level = getAudioLevel(id);
+            pal.sendToQml({method: 'updateAudioLevel', params: [id, level]});
+        });
+    }
+}, AUDIO_LEVEL_UPDATE_INTERVAL_MS);
 //
 // Button state.
 //