Live start time tweaks & tests

Adding a test for live start position and tweaking some of the code

@@ -141,13 +141,14 @@ videojs.Hls.prototype.handleSourceOpen = function() {
       segmentDlTime = Infinity;
     }
 
-    if(this.duration === Infinity && this.mediaIndex === 0 && selectedPlaylist.segments) {
-      var i = selectedPlaylist.segments.length - 1;
-      var tailDuration = 0;
-      while (tailDuration < 30 && i > 0) {
+    // start live playlists 30 seconds before the current time
+    if(this.duration() === Infinity && this.mediaIndex === 0 && selectedPlaylist.segments) {
+      var i = selectedPlaylist.segments.length - 1,
+          tailDuration = 0;
+      do {
         tailDuration += selectedPlaylist.segments[i].duration;
         i--;
-      }
+      } while (tailDuration < 30 && i > 0);
       this.mediaIndex = i;
     }
 

+{
+  "allowCache": true,
+  "mediaSequence": 0,
+  "segments": [
+    {
+      "duration": 10,
+      "uri": "001.ts"
+    },
+    {
+      "duration": 19,
+      "uri": "002.ts"
+    },
+    {
+      "duration": 10,
+      "uri": "003.ts"
+    },
+    {
+      "duration": 11,
+      "uri": "004.ts"
+    },
+    {
+      "duration": 10,
+      "uri": "005.ts"
+    },
+    {
+      "duration": 10,
+      "uri": "006.ts"
+    },
+    {
+      "duration": 10,
+      "uri": "007.ts"
+    },
+    {
+      "duration": 10,
+      "uri": "008.ts"
+    },
+    {
+      "duration": 16,
+      "uri": "009.ts"
+    }
+  ],
+  "targetDuration": 19
+}
\ No newline at end of file

+#EXTM3U
+#EXT-X-MEDIA-SEQUENCE:0
+#EXT-X-ALLOW-CACHE:YES
+#EXT-X-TARGETDURATION:19
+#EXTINF:10,0
+001.ts
+#EXTINF:19,0
+002.ts
+#EXTINF:10,0
+003.ts
+#EXTINF:11,0
+004.ts
+#EXTINF:10,0
+005.ts
+#EXTINF:10,0
+006.ts
+#EXTINF:10,0
+007.ts
+#EXTINF:10,0
+008.ts
+#EXTINF:16,0
+009.ts
\ No newline at end of file

@@ -1054,6 +1054,20 @@ test('updates the media index when a playlist reloads', function() {
   strictEqual(player.hls.mediaIndex, 2, 'mediaIndex is updated after the reload');
 });
 
+test('live playlist starts 30s before live', function() {
+  player.src({
+    src: 'http://example.com/manifest/liveStart30sBefore.m3u8',
+    type: 'application/vnd.apple.mpegurl'
+  });
+  openMediaSource(player);
+
+  standardXHRResponse(requests[0]);
+
+  player.hls.playlists.trigger('loadedmetadata');
+
+  strictEqual(player.hls.mediaIndex, 5, 'mediaIndex is updated after the reload');
+});
+
 test('mediaIndex is zero before the first segment loads', function() {
   window.manifests['first-seg-load'] =
     '#EXTM3U\n' +