diff -r 7e3156578f28 -r 31cea001a298 annot-server/static/js/pianoroll.js
--- a/annot-server/static/js/pianoroll.js	Wed Oct 22 09:18:15 2014 +0200
+++ b/annot-server/static/js/pianoroll.js	Thu Oct 23 09:16:16 2014 +0200
@@ -14,10 +14,31 @@
 var lineInterval = 5000; // means line every 5 seconds
 var nbLines = -1;
 var noteHeight = 110;
-var noteColor = 0xB74141;
+var noteColor = [0x2222FF, 0xB74141, 
+                 0x2222FF, 0xB74141, 
+                 0x2222FF, 0xB74141, 
+                 0x2222FF, 0xB74141, 
+                 0x2222FF, 0xB74141, 
+                 0x2222FF, 0xB74141, 
+                 0x2222FF, 0xB74141, 
+                 0x2222FF, 0xB74141, 
+                 0x2222FF, 0xB74141, 
+                 0x2222FF, 0xB74141, 
+                 0x2222FF, 0xB74141, 
+                 0x2222FF, 0xB74141, 
+                 0x2222FF, 0xB74141, 
+                 0x2222FF, 0xB74141, 
+                 0x2222FF, 0xB74141, 
+                 0x2222FF, 0xB74141, 
+                 0x2222FF, 0xB74141, 
+                 0x2222FF, 0xB74141, 
+                 0x2222FF, 0xB74141, 
+                 0x2222FF, 0xB74141, 
+                 0x2222FF, 0xB74141, 
+                 0x2222FF, 0xB74141];
 //var speed = 1; // container -x position at each frame. Speed = 1 ~ 100px for 2 seconds
 //var zeroTime = new Date("2014-10-06T12:16:43.000000Z").getTime();
-var noteDict = {};
+var noteDict = [{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{}];
 var pianoNotes = [1,0,1,0,1,1,0,1,0,1,0,1];//Do, Do#, Ré, Ré#, Mi, Fa, Fa#, Sol, Sol#, La, La#, Si
 // Visual config
 var drawPianoNotes = false;
@@ -121,13 +142,13 @@
     renderer.render(stage);
 }
 
-function addNoteInContainer(note, startTime, duration, velocity, pixelsPerSecond, container, prHeight){
+function addNoteInContainer(note, startTime, duration, velocity, pixelsPerSecond, container, prHeight, canal){
     //console.log("coucou 1", note, timeFromZero, ts, velocity, pixelsPerSecond, container, prHeight);
     var beginX = (offsetMusic + startTime) * pixelsPerSecond / 1000;
     var width = duration * pixelsPerSecond / 1000;
     // We draw the rectangle
     var graphics = new PIXI.Graphics();
-    graphics.beginFill(noteColor, (velocity / 128));
+    graphics.beginFill(noteColor[canal], (velocity / 128));
     var y = (128-note) * prHeight / 128; // (128-note) because y = 0 is for note = 128 and y = 128 for note = 0
     graphics.drawRect(beginX, Math.floor(y - (noteHeight/2) + ((prHeight / 128)/2)), width, noteHeight);
     graphics.endFill();
@@ -146,18 +167,21 @@
     var note = data.content[3];
     var velocity = data.content[4];
     if(velocity===0){
-        if(note in noteDict){
+        if(typeof noteDict[data.content[2]][note]!=='undefined'){
             // We close the note in container one
             //console.log("coucou 2", data);
-            var duration = data.content[1] - noteDict[note].ts;
-            addNoteInContainer(note, noteDict[note].ts, duration, noteDict[note].velocity, pixelsPerSecond1, container1, prHeight1);
-            addNoteInContainer(note, noteDict[note].ts, duration, noteDict[note].velocity, pixelsPerSecond2, container2, prHeight2);
+            var duration = data.content[1] - noteDict[data.content[2]][note].ts;
+            addNoteInContainer(note, noteDict[data.content[2]][note].ts, duration, noteDict[data.content[2]][note].velocity, pixelsPerSecond1, container1, prHeight1, data.content[2]);
+            addNoteInContainer(note, noteDict[data.content[2]][note].ts, duration, noteDict[data.content[2]][note].velocity, pixelsPerSecond2, container2, prHeight2, data.content[2]);
             // delete entry
-            delete noteDict[note];
+            delete noteDict[data.content[2]][note];
         }
     }
     else{
-        noteDict[note] = {ts: data.content[1], velocity:velocity};
+        if(typeof noteDict[data.content[2]]==='undefined'){
+            noteDict[data.content[2]] = {};
+        }
+        noteDict[data.content[2]][note] = {ts: data.content[1], velocity:velocity};
     }
 }