Live start time tweaks

Moving live start time calculation earlier in the code flow to
eliminate a race condition, repeating it on first play to create a
smooth experience, and making sure currentTime is updated to match
these changes.

@@ -66,7 +66,7 @@
          width="600"
          controls>
     <source
-       src="http://solutions.brightcove.com/jwhisenant/hls/apple/bipbop/bipbopall.m3u8"
+       src="http://10.1.12.182:9090/event/adaptive-streaming/brightcove/play/event-master.m3u8?init=3"
        type="application/x-mpegURL">
   </video>
   <script>

@@ -164,6 +164,16 @@ videojs.Hls.prototype.src = function(src) {
       });
     }
 
+    // Start live playlists 30 seconds before the current time
+    // This is done using the old playlist because of a race condition
+    // where the playlist selected below may not be loaded quickly
+    // enough to have its segments available for review. When we receive
+    // a loadedplaylist event, we will call translateMediaIndex and
+    // maintain our position at the live point.
+    if (this.duration() === Infinity && this.mediaIndex === 0) {
+      this.mediaIndex = videojs.Hls.getMediaIndexForLive(oldMediaPlaylist);
+    }
+
     selectedPlaylist = this.selectPlaylist();
     oldBitrate = oldMediaPlaylist.attributes &&
                  oldMediaPlaylist.attributes.BANDWIDTH || 0;
@@ -179,11 +189,6 @@ videojs.Hls.prototype.src = function(src) {
       segmentDlTime = Infinity;
     }
 
-    // start live playlists 30 seconds before the current time
-    if (this.duration() === Infinity && this.mediaIndex === 0 && selectedPlaylist.segments) {
-      this.mediaIndex = videojs.Hls.setMediaIndexForLive(selectedPlaylist);
-    }
-
     // this threshold is to account for having a high latency on the manifest
     // request which is a somewhat small file.
     threshold = 10;
@@ -239,7 +244,10 @@ videojs.Hls.prototype.src = function(src) {
   });
 };
 
-videojs.Hls.setMediaIndexForLive = function(selectedPlaylist) {
+/* Returns the media index for the live point in the current playlist, and updates
+   the current time to go along with it.
+ */
+videojs.Hls.getMediaIndexForLive = function(selectedPlaylist) {
   var tailIterator = selectedPlaylist.segments.length,
       tailDuration = 0,
       targetTail = (selectedPlaylist.targetDuration || 10) * 3;
@@ -279,6 +287,11 @@ videojs.Hls.prototype.play = function() {
     this.mediaIndex = 0;
   }
 
+  if (this.playlists.media() && !this.el().classList.contains('vjs-has-started')) {
+    this.mediaIndex = videojs.Hls.getMediaIndexForLive(this.playlists.media());
+    this.setCurrentTime(this.setCurrentTimeByMediaIndex(this.playlists.media(), this.mediaIndex));
+  }
+
   // delegate back to the Flash implementation
   return videojs.Flash.prototype.play.apply(this, arguments);
 };
@@ -936,7 +949,7 @@ videojs.Hls.translateMediaIndex = function(mediaIndex, original, update) {
 
   if (translatedMediaIndex >= update.segments.length || translatedMediaIndex < 0) {
     // recalculate the live point if the streams are too far out of sync
-    return videojs.Hls.setMediaIndexForLive(update) + 1;
+    return videojs.Hls.getMediaIndexForLive(update) + 1;
   }
 
   // sync on media sequence
@@ -973,6 +986,20 @@ videojs.Hls.getMediaIndexByTime = function(playlist, time) {
   return -1;
 };
 
+videojs.Hls.prototype.setCurrentTimeByMediaIndex = function(playlist, mediaIndex) {
+  var index, time = 0;
+
+  if (!playlist.segments || mediaIndex === 0) {
+    return 0;
+  }
+
+  for (index = 0; index < mediaIndex - 1; index++) {
+    time += playlist.segments[index].duration;
+  }
+
+  return time;
+};
+
 /**
  * A comparator function to sort two playlist object by bandwidth.
  * @param left {object} a media playlist object

@@ -1249,6 +1249,21 @@ test('live playlist starts 30s before live', function() {
   strictEqual(player.hls.mediaIndex, 6, 'mediaIndex is updated after the reload');
 });
 
+test('live playlist starts with correct currentTime value', 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');
+  player.hls.play();
+
+  strictEqual(player.currentTime(), 60, 'currentTime is updated at playback');
+});
+
 test('mediaIndex is zero before the first segment loads', function() {
   window.manifests['first-seg-load'] =
     '#EXTM3U\n' +