archive

comms/webRTC-over-websockets/js/bandwidth.js

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+//http://stackoverflow.com/questions/4583395/calculate-speed-using-javascript
+/*
+  this is only download estimation, obviously, in peer2peer default deployment, you will
+  have full mesh, n*times both upstream and donwstream stream comming to you (which is bad, 
+  but unless you have a server in between this is what it is). Remark: simetrical upstream/downstream
+  is not common in DSL deplyoment, where downstream bandwith is much higher.  
+*/
+var BANDWITDH = (function(){
+  var imageAddr;
+  var size;
+  var startTime, endTime;
+  var downloadSize;
+  var download = new Image();
+
+  return {
+      /*
+        don't forget to change the address every time you make a request to avoid browser caching.
+        For a demo, I will be using the same as in the stackoverflow example
+      */
+      init: function(callback, address, size){
+          imageAddr = address !== undefined ? address : "http://www.tranquilmusic.ca/images/cats/Cat2.JPG" + "?n=" + Math.random(); 
+          downloadSize = size !== undefined ? size : 5616998; 
+          startTime = (new Date()).getTime();
+          download.src = imageAddr;
+          download.onload = function() {
+            endTime = (new Date()).getTime();
+            var duration = (endTime - startTime) / 1000;
+            var bitsLoaded = downloadSize * 8;
+            var speedBps = (bitsLoaded / duration).toFixed(2);
+            var speedKbps = (speedBps / 1024).toFixed(2);
+            var speedMbps = (speedKbps / 1024).toFixed(2);
+            callback(speedMbps);
+         }
+      },
+    } 
+})();