Merge pull request #260 from videojs/preciseDuration

Use presentation time stamp to calculate playlist duration

@@ -712,11 +712,11 @@ videojs.Hls.prototype.drainBuffer = function(event) {
     tags,
     bytes,
     segment,
+    durationOffset,
     decrypter,
     segIv,
-
     ptsTime,
-    segmentOffset,
+    segmentOffset = 0,
     segmentBuffer = this.segmentBuffer_;
 
   if (!segmentBuffer.length || !this.sourceBuffer) {
@@ -773,10 +773,32 @@ videojs.Hls.prototype.drainBuffer = function(event) {
   this.segmentParser_.flushTags();
 
   tags = [];
+
   while (this.segmentParser_.tagsAvailable()) {
     tags.push(this.segmentParser_.getNextTag());
   }
 
+  // This block of code uses the presentation timestamp of the ts segment to calculate its exact duration, since this
+  // may differ by fractions of a second from what is reported. Using the exact, calculated 'preciseDuration' allows
+  // for smoother seeking and calculation of the total playlist duration, which previously (especially in short videos)
+  // was reported erroneously and made the play head overrun the end of the progress bar.
+  if (tags.length > 0) {
+    segment.preciseTimestamp = tags[tags.length - 1].pts;
+
+    if (playlist.segments[mediaIndex - 1]) {
+      if (playlist.segments[mediaIndex - 1].preciseTimestamp) {
+        durationOffset = playlist.segments[mediaIndex - 1].preciseTimestamp;
+      } else {
+        durationOffset = (playlist.targetDuration * (mediaIndex - 1) + playlist.segments[mediaIndex - 1].duration) * 1000;
+      }
+      segment.preciseDuration = (segment.preciseTimestamp - durationOffset) / 1000;
+    } else if (mediaIndex === 0) {
+      segment.preciseDuration = segment.preciseTimestamp / 1000;
+    }
+  }
+
+  this.updateDuration(this.playlists.media());
+
   // if we're refilling the buffer after a seek, scan through the muxed
   // FLV tags until we find the one that is closest to the desired
   // playback time
@@ -948,7 +970,7 @@ videojs.Hls.getPlaylistDuration = function(playlist, startIndex, endIndex) {
 
   for (; i >= startIndex; i--) {
     segment = playlist.segments[i];
-    dur += (segment.duration !== undefined ? segment.duration : playlist.targetDuration) || 0;
+    dur += segment.preciseDuration || segment.duration || playlist.targetDuration || 0;
   }
 
   return dur;

@@ -269,7 +269,7 @@ test('sets the duration if one is available on the playlist', function() {
   standardXHRResponse(requests[0]);
   strictEqual(calls, 1, 'duration is set');
   standardXHRResponse(requests[1]);
-  strictEqual(calls, 1, 'duration is set');
+  strictEqual(calls, 2, 'duration is set');
 });
 
 test('calculates the duration if needed', function() {
@@ -1063,6 +1063,37 @@ test('flushes the parser after each segment', function() {
   strictEqual(flushes, 1, 'tags are flushed at the end of a segment');
 });
 
+test('calculates preciseTimestamp and preciseDuration for a new segment', function() {
+  // mock out the segment parser
+  videojs.Hls.SegmentParser = function() {
+    var tagsAvailable = true,
+        tag = { pts : 200000 };
+    this.getFlvHeader = function() {
+      return [];
+    };
+    this.parseSegmentBinaryData = function() {};
+    this.flushTags = function() {};
+    this.tagsAvailable = function() { return tagsAvailable; };
+    this.getNextTag = function() { tagsAvailable = false; return tag; };
+    this.metadataStream = {
+      on: Function.prototype
+    };
+  };
+
+  player.src({
+    src: 'manifest/media.m3u8',
+    type: 'application/vnd.apple.mpegurl'
+  });
+  openMediaSource(player);
+
+  standardXHRResponse(requests[0]);
+  strictEqual(player.duration(), 40, 'player duration is read from playlist on load');
+  standardXHRResponse(requests[1]);
+  strictEqual(player.hls.playlists.media().segments[0].preciseTimestamp, 200000, 'preciseTimestamp is calculated and stored');
+  strictEqual(player.hls.playlists.media().segments[0].preciseDuration, 200, 'preciseDuration is calculated and stored');
+  strictEqual(player.duration(), 230, 'player duration is calculated using preciseDuration');
+});
+
 test('exposes in-band metadata events as cues', function() {
   var track;
   player.src({