diff --git a/samples/js/apprtc/apprtc.py b/samples/js/apprtc/apprtc.py
index bd609cef4a..e9e61c6edd 100644
--- a/samples/js/apprtc/apprtc.py
+++ b/samples/js/apprtc/apprtc.py
@@ -327,6 +327,10 @@ class MainPage(webapp2.RequestHandler):
     if debug == 'loopback':
     # set compat to false as DTLS does not work for loopback.
       compat = 'false'
+    # set stereo to false by default
+    stereo = 'false'
+    if self.request.get('stereo'):
+      stereo = self.request.get('stereo')
 
 
     # token_timeout for channel creation, default 30min, max 2 days, min 3min.
@@ -390,7 +394,8 @@ class MainPage(webapp2.RequestHandler):
                        'pc_constraints': json.dumps(pc_constraints),
                        'offer_constraints': json.dumps(offer_constraints),
                        'media_constraints': json.dumps(media_constraints),
-                       'turn_url': turn_url
+                       'turn_url': turn_url,
+                       'stereo': stereo
                       }
     if unittest:
       target_page = 'test/test_' + unittest + '.html'
diff --git a/samples/js/apprtc/index.html b/samples/js/apprtc/index.html
index e87bfd56c3..72a46dacad 100644
--- a/samples/js/apprtc/index.html
+++ b/samples/js/apprtc/index.html
@@ -125,6 +125,7 @@
                           'OfferToReceiveVideo':true }};
   var isVideoMuted = false;
   var isAudioMuted = false;
+  var stereo = false;
 
   function initialize() {
     console.log("Initializing; room={{ room_key }}.");
@@ -137,6 +138,7 @@
     // changing here.
     openChannel('{{ token }}');
     requestTurn('{{ turn_url }}');
+    stereo = {{ stereo }};
     doGetUserMedia();
   }
 
@@ -292,15 +294,19 @@
 
   function processSignalingMessage(message) {
     var msg = JSON.parse(message);
-
     if (msg.type === 'offer') {
       // Callee creates PeerConnection
       if (!initiator && !started)
         maybeStart();
-
+      // Set Opus in Stereo, if stereo enabled.
+      if (stereo)
+        msg.sdp = addStereo(msg.sdp);
       pc.setRemoteDescription(new RTCSessionDescription(msg));
       doAnswer();
     } else if (msg.type === 'answer' && started) {
+      // Set Opus in Stereo, if stereo enabled.
+      if (stereo)
+        msg.sdp = addStereo(msg.sdp);
       pc.setRemoteDescription(new RTCSessionDescription(msg));
     } else if (msg.type === 'candidate' && started) {
       var candidate = new RTCIceCandidate({sdpMLineIndex:msg.label,
@@ -535,6 +541,39 @@
     return sdp;
   }
 
+  // Set Opus in stereo if stereo is enabled.
+  function addStereo(sdp) {
+    var sdpLines = sdp.split('\r\n');
+
+    // Find opus payload.
+    for (var i = 0; i < sdpLines.length; i++) {
+      if (sdpLines[i].search('opus/48000') !== -1) {
+        var opusPayload = extractSdp(sdpLines[i], /:(\d+) opus\/48000/i);
+        break;
+      }
+    }
+
+    // Find the payload in fmtp line.
+    for (var i = 0; i < sdpLines.length; i++) {
+      if (sdpLines[i].search('a=fmtp') !== -1) {
+        var payload = extractSdp(sdpLines[i], /a=fmtp:(\d+)/ );
+        if (payload === opusPayload) {
+          var fmtpLineIndex = i;
+          break;
+        }
+      }
+    }
+    // No fmtp line found.
+    if (fmtpLineIndex === null)
+      return sdp;
+
+    // append stereo=1 to fmtp line.
+    sdpLines[fmtpLineIndex] = sdpLines[fmtpLineIndex].concat(' stereo=1');
+
+    sdp = sdpLines.join('\r\n');
+    return sdp;
+  }
+
   function extractSdp(sdpLine, pattern) {
     var result = sdpLine.match(pattern);
     return (result && result.length == 2)? result[1]: null;