From 5b017e0b7729ae4b06f758e5c4ed580183043882 Mon Sep 17 00:00:00 2001
From: Michael Jumper <zhangmaike@users.sourceforge.net>
Date: Tue, 13 Nov 2012 12:17:14 -0800
Subject: [PATCH] Use high-resolution timestamps if available.

---
 .../src/main/resources/audio.js               | 34 ++++++++++++++-----
 1 file changed, 26 insertions(+), 8 deletions(-)

diff --git a/guacamole-common-js/src/main/resources/audio.js b/guacamole-common-js/src/main/resources/audio.js
index 463bb5a14..2ac3287ed 100644
--- a/guacamole-common-js/src/main/resources/audio.js
+++ b/guacamole-common-js/src/main/resources/audio.js
@@ -73,15 +73,11 @@ Guacamole.AudioChannel = function() {
         var packet =
             new Guacamole.AudioChannel.Packet(mimetype, data);
 
-        var now;
-        if (Guacamole.AudioChannel.context)
-            now = Guacamole.AudioChannel.context.currentTime * 1000;
-        else
-            now = new Date().getTime();
+        var now = Guacamole.AudioChannel.getTimestamp();
 
-        // If underflow is detected, delay start
+        // If underflow is detected, reschedule new packets relative to now.
         if (next_packet_time < now)
-            next_packet_time = now + 50;
+            next_packet_time = now;
 
         // Schedule next packet
         packet.play(next_packet_time);
@@ -96,6 +92,28 @@ if (window.webkitAudioContext) {
     Guacamole.AudioChannel.context = new webkitAudioContext();
 }
 
+Guacamole.AudioChannel.getTimestamp = function() {
+
+    // If we have an audio context, use its timestamp
+    if (Guacamole.AudioChannel.context)
+        return Guacamole.AudioChannel.context.currentTime * 1000;
+
+    // If we have high-resolution timers, use those
+    if (window.performance) {
+
+        if (window.performance.now)
+            return window.peformance.now();
+
+        if (window.performance.webkitNow)
+            return window.performance.webkitNow();
+        
+    }
+
+    // Fallback to millisecond-resolution system time
+    return new Date().getTime();
+
+};
+
 /**
  * Abstract representation of an audio packet.
  * 
@@ -173,7 +191,7 @@ Guacamole.AudioChannel.Packet = function(mimetype, data) {
         this.play = function(when) {
             
             // Calculate time until play
-            var now = new Date().getTime();
+            var now = Guacamole.AudioChannel.getTimestamp();
             var delay = when - now;
             
             // Play now if too late