Fix seeks between segments. Improve duration calculation. Closes #339

@@ -2,7 +2,7 @@ CHANGELOG
 =========
 
 ## HEAD (Unreleased)
-_(none)_
+* Fix seeks between segments. Improve duration calculation. ([view](https://github.com/videojs/videojs-contrib-hls/pull/339))
 
 --------------------
 

@@ -375,7 +375,8 @@
 
     // the manifest is empty until the parse stream begins delivering data
     this.manifest = {
-      allowCache: true
+      allowCache: true,
+      discontinuityStarts: []
     };
 
     // update the manifest with the m3u8 entry from the parse stream
@@ -513,6 +514,7 @@
             },
             'discontinuity': function() {
               currentUri.discontinuity = true;
+              this.manifest.discontinuityStarts.push(uris.length);
             },
             'targetduration': function() {
               if (!isFinite(entry.duration) || entry.duration < 0) {

@@ -431,11 +431,12 @@
     for (i = 0; i < this.media_.segments.length; i++) {
       time -= Playlist.duration(this.media_,
                                 this.media_.mediaSequence + i,
-                                this.media_.mediaSequence + i + 1);
+                                this.media_.mediaSequence + i + 1,
+                                false);
 
       // HLS version 3 and lower round segment durations to the
       // nearest decimal integer. When the correct media index is
-      // ambiguous, prefer the lower one.
+      // ambiguous, prefer the higher one.
       if (time <= 0) {
         return i;
       }

@@ -5,7 +5,130 @@
   'use strict';
 
   var DEFAULT_TARGET_DURATION = 10;
-  var duration, seekable, segmentsDuration;
+  var accumulateDuration, ascendingNumeric, duration, intervalDuration, rangeDuration, seekable;
+
+  // Array.sort comparator to sort numbers in ascending order
+  ascendingNumeric = function(left, right) {
+    return left - right;
+  };
+
+  /**
+   * Returns the media duration for the segments between a start and
+   * exclusive end index. The start and end parameters are interpreted
+   * as indices into the currently available segments. This method
+   * does not calculate durations for segments that have expired.
+   * @param playlist {object} a media playlist object
+   * @param start {number} an inclusive lower boundary for the
+   * segments to examine.
+   * @param end {number} an exclusive upper boundary for the segments
+   * to examine.
+   * @param includeTrailingTime {boolean} if false, the interval between
+   * the final segment and the subsequent segment will not be included
+   * in the result
+   * @return {number} the duration between the start index and end
+   * index in seconds.
+   */
+  accumulateDuration = function(playlist, start, end, includeTrailingTime) {
+    var
+      ranges = [],
+      rangeEnds = (playlist.discontinuityStarts || []).concat(end),
+      result = 0,
+      i;
+
+    // short circuit if start and end don't specify a non-empty range
+    // of segments
+    if (start >= end) {
+      return 0;
+    }
+
+    // create a range object for each discontinuity sequence
+    rangeEnds.sort(ascendingNumeric);
+    for (i = 0; i < rangeEnds.length; i++) {
+      if (rangeEnds[i] > start) {
+        ranges.push({ start: start, end: rangeEnds[i] });
+        i++;
+        break;
+      }
+    }
+    for (; i < rangeEnds.length; i++) {
+      // ignore times ranges later than end
+      if (rangeEnds[i] >= end) {
+        ranges.push({ start: rangeEnds[i - 1], end: end });
+        break;
+      }
+      ranges.push({ start: ranges[ranges.length - 1].end, end: rangeEnds[i] });
+    }
+
+    // add up the durations for each of the ranges
+    for (i = 0; i < ranges.length; i++) {
+      result += rangeDuration(playlist,
+                              ranges[i],
+                              i === ranges.length - 1 && includeTrailingTime);
+    }
+
+    return result;
+  };
+
+  /**
+   * Returns the duration of the specified range of segments. The
+   * range *must not* cross a discontinuity.
+   * @param playlist {object} a media playlist object
+   * @param range {object} an object that specifies a starting and
+   * ending index into the available segments.
+   * @param includeTrailingTime {boolean} if false, the interval between
+   * the final segment and the subsequent segment will not be included
+   * in the result
+   * @return {number} the duration of the range in seconds.
+   */
+  rangeDuration = function(playlist, range, includeTrailingTime) {
+    var
+      result = 0,
+      targetDuration = playlist.targetDuration || DEFAULT_TARGET_DURATION,
+      segment,
+      left, right;
+
+    // accumulate while searching for the earliest segment with
+    // available PTS information
+    for (left = range.start; left < range.end; left++) {
+      segment = playlist.segments[left];
+      if (segment.minVideoPts !== undefined) {
+        break;
+      }
+      result += segment.duration || targetDuration;
+    }
+
+    // see if there's enough information to include the trailing time
+    if (includeTrailingTime) {
+      segment = playlist.segments[range.end];
+      if (segment && segment.minVideoPts !== undefined) {
+        result += 0.001 *
+          (Math.min(segment.minVideoPts, segment.minAudioPts) -
+           Math.min(playlist.segments[left].minVideoPts,
+                    playlist.segments[left].minAudioPts));
+        return result;
+      }
+    }
+
+    // do the same thing while finding the latest segment
+    for (right = range.end - 1; right >= left; right--) {
+      segment = playlist.segments[right];
+      if (segment.maxVideoPts !== undefined) {
+        break;
+      }
+      result += segment.duration || targetDuration;
+    }
+
+    // add in the PTS interval in seconds between them
+    if (right >= left) {
+      result += 0.001 *
+        (Math.max(playlist.segments[right].maxVideoPts,
+                  playlist.segments[right].maxAudioPts) -
+         Math.min(playlist.segments[left].minVideoPts,
+                  playlist.segments[left].minAudioPts));
+    }
+
+    return result;
+  };
 
   /**
    * Calculate the media duration from the segments associated with a
@@ -17,47 +140,28 @@
    * boundary for the playlist.  Defaults to 0.
    * @param endSequence {number} (optional) an exclusive upper boundary
    * for the playlist.  Defaults to playlist length.
+   * @param includeTrailingTime {boolean} if false, the interval between
+   * the final segment and the subsequent segment will not be included
+   * in the result
    * @return {number} the duration between the start index and end
    * index.
    */
-  segmentsDuration = function(playlist, startSequence, endSequence) {
-    var targetDuration, i, j, segment, endSegment, expiredSegmentCount, result = 0;
+  intervalDuration = function(playlist, startSequence, endSequence, includeTrailingTime) {
+    var result = 0, targetDuration, expiredSegmentCount;
 
     startSequence = startSequence || 0;
-    i = startSequence;
     endSequence = endSequence !== undefined ? endSequence : (playlist.segments || []).length;
     targetDuration = playlist.targetDuration || DEFAULT_TARGET_DURATION;
 
     // estimate expired segment duration using the target duration
     expiredSegmentCount = Math.max(playlist.mediaSequence - startSequence, 0);
     result += expiredSegmentCount * targetDuration;
-    i += expiredSegmentCount;
 
     // accumulate the segment durations into the result
-    for (; i < endSequence; i++) {
-      segment = playlist.segments[i - playlist.mediaSequence];
-
-      // when PTS values aren't available, use information from the playlist
-      if (segment.minVideoPts === undefined) {
-        result += segment.duration ||
-                  targetDuration;
-        continue;
-      }
-
-      // find the last segment with PTS info and use that to calculate
-      // the interval duration
-      for(j = i; j < endSequence - 1; j++) {
-        endSegment = playlist.segments[j - playlist.mediaSequence + 1];
-        if (endSegment.maxVideoPts === undefined ||
-            endSegment.discontinuity) {
-          break;
-        }
-      }
-      endSegment = playlist.segments[j - playlist.mediaSequence];
-      result += (Math.max(endSegment.maxVideoPts, endSegment.maxAudioPts) -
-                 Math.min(segment.minVideoPts, segment.minAudioPts)) * 0.001;
-      i = j;
-    }
+    result += accumulateDuration(playlist,
+                                 startSequence + expiredSegmentCount - playlist.mediaSequence,
+                                 endSequence - playlist.mediaSequence,
+                                 includeTrailingTime);
 
     return result;
   };
@@ -72,14 +176,21 @@
    * boundary for the playlist.  Defaults to 0.
    * @param endSequence {number} (optional) an exclusive upper boundary
    * for the playlist.  Defaults to playlist length.
+   * @param includeTrailingTime {boolean} (optional) if false, the interval between
+   * the final segment and the subsequent segment will not be included
+   * in the result
    * @return {number} the duration between the start index and end
    * index.
    */
-  duration = function(playlist, startSequence, endSequence) {
+  duration = function(playlist, startSequence, endSequence, includeTrailingTime) {
     if (!playlist) {
       return 0;
     }
 
+    if (includeTrailingTime === undefined) {
+      includeTrailingTime = true;
+    }
+
     // if a slice of the total duration is not requested, use
     // playlist-level duration indicators when they're present
     if (startSequence === undefined && endSequence === undefined) {
@@ -95,9 +206,10 @@
     }
 
     // calculate the total duration based on the segment durations
-    return segmentsDuration(playlist,
+    return intervalDuration(playlist,
                             startSequence,
-                            endSequence);
+                            endSequence,
+                            includeTrailingTime);
   };
 
   /**
@@ -119,8 +231,8 @@
       return videojs.createTimeRange(0, duration(playlist));
     }
 
-    start = segmentsDuration(playlist, 0, playlist.mediaSequence);
-    end = start + segmentsDuration(playlist,
+    start = intervalDuration(playlist, 0, playlist.mediaSequence);
+    end = start + intervalDuration(playlist,
                                    playlist.mediaSequence,
                                    playlist.mediaSequence + playlist.segments.length);
     targetDuration = playlist.targetDuration || DEFAULT_TARGET_DURATION;

@@ -31,15 +31,6 @@
     // allow in-band metadata to be observed
     self.metadataStream = new MetadataStream();
 
-    this.mediaTimelineOffset = null;
-
-    // The first timestamp value encountered during parsing. This
-    // value can be used to determine the relative timing between
-    // frames and the start of the current timestamp sequence. It
-    // should be reset to null before parsing a segment with
-    // discontinuous timestamp values from previous segments.
-    self.timestampOffset = null;
-
     // For information on the FLV format, see
     // http://download.macromedia.com/f4v/video_file_format_spec_v10_1.pdf.
     // Technically, this function returns the header and a metadata FLV tag
@@ -360,13 +351,6 @@
           // Skip past "optional" portion of PTS header
           offset += pesHeaderLength;
 
-          // keep track of the earliest encounted PTS value so
-          // external parties can align timestamps across
-          // discontinuities
-          if (self.timestampOffset === null) {
-            self.timestampOffset = pts;
-          }
-
           if (pid === self.stream.programMapTable[STREAM_TYPES.h264]) {
             h264Stream.setNextTimeStamp(pts,
                                         dts,

@@ -260,7 +260,7 @@ videojs.Hls.prototype.setupMetadataCueTranslation_ = function() {
   // add a metadata cue whenever a metadata event is triggered during
   // segment parsing
   metadataStream.on('data', function(metadata) {
-    var i, cue, frame, time, media, segmentOffset, hexDigit;
+    var i, hexDigit;
 
     // create the metadata track if this is the first ID3 tag we've
     // seen
@@ -276,19 +276,11 @@ videojs.Hls.prototype.setupMetadataCueTranslation_ = function() {
       }
     }
 
-    // calculate the start time for the segment that is currently being parsed
-    media = tech.playlists.media();
-    segmentOffset = tech.playlists.expiredPreDiscontinuity_ + tech.playlists.expiredPostDiscontinuity_;
-    segmentOffset += videojs.Hls.Playlist.duration(media, media.mediaSequence, media.mediaSequence + tech.mediaIndex);
-
-    // create cue points for all the ID3 frames in this metadata event
-    for (i = 0; i < metadata.frames.length; i++) {
-      frame = metadata.frames[i];
-      time = tech.segmentParser_.mediaTimelineOffset + ((metadata.pts - tech.segmentParser_.timestampOffset) * 0.001);
-      cue = new window.VTTCue(time, time, frame.value || frame.url || '');
-      cue.frame = frame;
-      textTrack.addCue(cue);
-    }
+    // store this event for processing once the muxing has finished
+    tech.segmentBuffer_[0].pendingMetadata.push({
+      textTrack: textTrack,
+      metadata: metadata
+    });
   });
 
   // when seeking, clear out all cues ahead of the earliest position
@@ -312,6 +304,30 @@ videojs.Hls.prototype.setupMetadataCueTranslation_ = function() {
   });
 };
 
+videojs.Hls.prototype.addCuesForMetadata_ = function(segmentInfo) {
+  var i, cue, frame, metadata, minPts, segment, segmentOffset, textTrack, time;
+  segmentOffset = videojs.Hls.Playlist.duration(segmentInfo.playlist,
+                                                segmentInfo.playlist.mediaSequence,
+                                                segmentInfo.playlist.mediaSequence + segmentInfo.mediaIndex);
+  segment = segmentInfo.playlist.segments[segmentInfo.mediaIndex];
+  minPts = Math.min(segment.minVideoPts, segment.minAudioPts);
+
+  while (segmentInfo.pendingMetadata.length) {
+    metadata = segmentInfo.pendingMetadata[0].metadata;
+    textTrack = segmentInfo.pendingMetadata[0].textTrack;
+
+    // create cue points for all the ID3 frames in this metadata event
+    for (i = 0; i < metadata.frames.length; i++) {
+      frame = metadata.frames[i];
+      time = segmentOffset + ((metadata.pts - minPts) * 0.001);
+      cue = new window.VTTCue(time, time, frame.value || frame.url || '');
+      cue.frame = frame;
+      textTrack.addCue(cue);
+    }
+    segmentInfo.pendingMetadata.shift();
+  }
+};
+
 /**
  * Reset the mediaIndex if play() is called after the video has
  * ended.
@@ -780,7 +796,10 @@ videojs.Hls.prototype.loadSegment = function(segmentUri, offset) {
       // when a key is defined for this segment, the encrypted bytes
       encryptedBytes: null,
       // optionally, the decrypter that is unencrypting the segment
-      decrypter: null
+      decrypter: null,
+      // metadata events discovered during muxing that need to be
+      // translated into cue points
+      pendingMetadata: []
     };
     if (segmentInfo.playlist.segments[segmentInfo.mediaIndex].key) {
       segmentInfo.encryptedBytes = new Uint8Array(this.response);
@@ -870,20 +889,6 @@ videojs.Hls.prototype.drainBuffer = function(event) {
   }
 
   event = event || {};
-  segmentOffset = this.playlists.expiredPreDiscontinuity_;
-  segmentOffset += this.playlists.expiredPostDiscontinuity_;
-  segmentOffset += videojs.Hls.Playlist.duration(playlist, playlist.mediaSequence, playlist.mediaSequence + mediaIndex);
-  segmentOffset *= 1000;
-
-  // if this segment starts is the start of a new discontinuity
-  // sequence, the segment parser's timestamp offset must be
-  // re-calculated
-  if (segment.discontinuity) {
-    this.segmentParser_.mediaTimelineOffset = segmentOffset * 0.001;
-    this.segmentParser_.timestampOffset = null;
-  } else if (this.segmentParser_.mediaTimelineOffset === null) {
-    this.segmentParser_.mediaTimelineOffset = segmentOffset * 0.001;
-  }
 
   // transmux the segment data from MP2T to FLV
   this.segmentParser_.parseSegmentBinaryData(bytes);
@@ -904,20 +909,27 @@ videojs.Hls.prototype.drainBuffer = function(event) {
     tags.push(this.segmentParser_.getNextTag());
   }
 
+  this.addCuesForMetadata_(segmentInfo);
   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
   if (typeof offset === 'number') {
-    ptsTime = offset - segmentOffset + tags[0].pts;
-
-    while (tags[i].pts < ptsTime) {
+    // determine the offset within this segment we're seeking to
+    segmentOffset = this.playlists.expiredPostDiscontinuity_ + this.playlists.expiredPreDiscontinuity_;
+    segmentOffset += videojs.Hls.Playlist.duration(playlist,
+                                                   playlist.mediaSequence,
+                                                   playlist.mediaSequence + mediaIndex);
+    segmentOffset = offset - (segmentOffset * 1000);
+    ptsTime = segmentOffset + tags[0].pts;
+
+    while (tags[i + 1] && tags[i].pts < ptsTime) {
       i++;
     }
 
-    // tell the SWF where we will be seeking to
-    this.el().vjs_setProperty('currentTime', (tags[i].pts - tags[0].pts + segmentOffset) * 0.001);
+    // tell the SWF the media position of the first tag we'll be delivering
+    this.el().vjs_setProperty('currentTime', ((tags[i].pts - ptsTime + offset) * 0.001));
 
     tags = tags.slice(i);
 
@@ -1139,29 +1151,6 @@ videojs.Hls.getMediaIndexByTime = function() {
 };
 
 /**
- * Determine the current time in seconds in one playlist by a media index. This
- * function iterates through the segments of a playlist up to the specified index
- * and then returns the time up to that point.
- *
- * @param playlist {object} The playlist of the segments being searched.
- * @param mediaIndex {number} The index of the target segment in the playlist.
- * @returns {number} The current time to that point, or 0 if none appropriate.
- */
-videojs.Hls.prototype.getCurrentTimeByMediaIndex_ = function(playlist, mediaIndex) {
-  var index, time = 0;
-
-  if (!playlist.segments || mediaIndex === 0) {
-    return 0;
-  }
-
-  for (index = 0; index < mediaIndex; 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
  * @param right {object} a media playlist object

@@ -22,5 +22,6 @@
   ],
   "targetDuration": 10,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -142,5 +142,6 @@
   ],
   "targetDuration": 10,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -14,5 +14,6 @@
   ],
   "targetDuration": 10,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -41,5 +41,6 @@
       },
       "uri": "http://c.brightcove.com/services/mobile/streaming/index/rendition.m3u8?assetId=1824687660001&videoId=1824650741001"
     }
-  ]
+  ],
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -138,5 +138,6 @@
   ],
   "targetDuration": 10,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -14,5 +14,6 @@
   ],
   "targetDuration": 10,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -22,5 +22,6 @@
     }
   ],
   "targetDuration": 19,
-  "endList": true
+  "endList": true,
+  "discontinuityStarts": [2]
 }

@@ -44,5 +44,6 @@
     }
   ],
   "targetDuration": 19,
-  "endList": true
+  "endList": true,
+  "discontinuityStarts": [2, 4, 7]
 }

@@ -22,5 +22,6 @@
   ],
   "targetDuration": 10,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -14,5 +14,6 @@
   ],
   "targetDuration": 10,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -22,5 +22,6 @@
   ],
   "targetDuration": 8,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -29,5 +29,6 @@
   ],
   "targetDuration": 10,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -41,5 +41,6 @@
       },
       "uri": "http://c.brightcove.com/services/mobile/streaming/index/rendition.m3u8?assetId=1824687660001&videoId=1824650741001"
     }
-  ]
+  ],
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -2,6 +2,7 @@
   "allowCache": true,
   "mediaSequence": 7794,
   "discontinuitySequence": 0,
+  "discontinuityStarts": [],
   "segments": [
     {
       "duration": 2.833,

@@ -30,5 +30,6 @@
   ],
   "targetDuration": 10,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -9,5 +9,6 @@
   ],
   "targetDuration": 8,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -142,5 +142,6 @@
   ],
   "targetDuration": 10,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -14,5 +14,6 @@
   ],
   "targetDuration": 10,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -22,5 +22,6 @@
   ],
   "targetDuration": 8,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -29,5 +29,6 @@
   ],
   "targetDuration": 10,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -141,5 +141,6 @@
     }
   ],
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -17,5 +17,6 @@
     }
   ],
   "targetDuration": 8,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -40,5 +40,6 @@
     }
   ],
   "targetDuration": 10,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -8,5 +8,6 @@
     }
   ],
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -25,5 +25,6 @@
   ],
   "targetDuration": 10,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -9,5 +9,6 @@
   ],
   "targetDuration": 10,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -41,5 +41,6 @@
       },
       "uri": "media3.m3u8"
     }
-  ]
+  ],
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -22,5 +22,6 @@
   ],
   "targetDuration": 10,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -22,5 +22,6 @@
   ],
   "targetDuration": 8,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -12,5 +12,6 @@
     }
   ],
   "targetDuration": 10,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -18,5 +18,6 @@
   ],
   "targetDuration": 10,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -22,5 +22,6 @@
   ],
   "targetDuration": 8,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -22,5 +22,6 @@
   ],
   "targetDuration": 8,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -19,5 +19,6 @@
       "duration": 10
     }
   ],
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -22,5 +22,6 @@
   ],
   "targetDuration": 8,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -142,5 +142,6 @@
   ],
   "targetDuration": 10,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -10,5 +10,6 @@
   ],
   "targetDuration": 8,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -10,5 +10,6 @@
     {
       "uri": "media1.m3u8"
     }
-  ]
+  ],
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -22,5 +22,6 @@
   ],
   "targetDuration": 8,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -10,5 +10,6 @@
   ],
   "targetDuration": 10,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -22,5 +22,6 @@
   ],
   "targetDuration": 10,
   "endList": true,
-  "discontinuitySequence": 0
+  "discontinuitySequence": 0,
+  "discontinuityStarts": []
 }
\ No newline at end of file

@@ -3,7 +3,7 @@
   'use strict';
   var Playlist = videojs.Hls.Playlist;
 
-  module('Playlist Utilities');
+  module('Playlist Duration');
 
   test('total duration for live playlists is Infinity', function() {
     var duration = Playlist.duration({
@@ -16,7 +16,9 @@
     equal(duration, Infinity, 'duration is infinity');
   });
 
-  test('interval duration accounts for media sequences', function() {
+  module('Playlist Interval Duration');
+
+  test('accounts for media sequences', function() {
     var duration = Playlist.duration({
       mediaSequence: 10,
       endList: true,
@@ -38,7 +40,7 @@
     equal(duration, 14 * 10, 'duration includes dropped segments');
   });
 
-  test('interval duration uses PTS values when available', function() {
+  test('uses PTS values when available', function() {
     var duration = Playlist.duration({
       mediaSequence: 0,
       endList: true,
@@ -67,52 +69,244 @@
     equal(duration, ((4 * 10 * 1000 + 2) - 1) * 0.001, 'used PTS values');
   });
 
-  test('interval duration works when partial PTS information is available', function() {
-    var firstInterval, secondInterval, duration = Playlist.duration({
+  test('works when partial PTS information is available', function() {
+    var duration = Playlist.duration({
       mediaSequence: 0,
       endList: true,
       segments: [{
         minVideoPts: 1,
         minAudioPts: 2,
-        maxVideoPts: 1 * 10 * 1000 + 1,
+        maxVideoPts: 10 * 1000 + 1,
 
         // intentionally less duration than video
         // the max stream duration should be used
-        maxAudioPts: 1 * 10 * 1000 + 1,
+        maxAudioPts: 10 * 1000 + 1,
+        uri: '0.ts'
+      }, {
+        duration: 9,
+        uri: '1.ts'
+      }, {
+        duration: 10,
+        uri: '2.ts'
+      }, {
+        duration: 10,
+        minVideoPts: 30 * 1000 + 7,
+        minAudioPts: 30 * 1000 + 10,
+        maxVideoPts: 40 * 1000 + 1,
+        maxAudioPts: 40 * 1000 + 2,
+        uri: '3.ts'
+      }, {
+        duration: 10,
+        maxVideoPts: 50 * 1000 + 1,
+        maxAudioPts: 50 * 1000 + 2,
+        uri: '4.ts'
+      }]
+    }, 0, 5);
+
+    equal(duration,
+          ((50 * 1000 + 2) - 1) * 0.001,
+          'calculated with mixed intervals');
+  });
+
+  test('ignores segments before the start', function() {
+    var duration = Playlist.duration({
+      mediaSequence: 0,
+      segments: [{
+        duration: 10,
         uri: '0.ts'
       }, {
         duration: 10,
         uri: '1.ts'
       }, {
         duration: 10,
-        minVideoPts: 2 * 10 * 1000 + 7,
-        minAudioPts: 2 * 10 * 1000 + 10,
-        maxVideoPts: 3 * 10 * 1000 + 1,
-        maxAudioPts: 3 * 10 * 1000 + 2,
+        uri: '2.ts'
+      }]
+    }, 1, 3);
+
+    equal(duration, 10 + 10, 'ignored the first segment');
+  });
+
+  test('ignores discontinuity sequences earlier than the start', function() {
+    var duration = Playlist.duration({
+      mediaSequence: 0,
+      discontinuityStarts: [1, 3],
+      segments: [{
+        minVideoPts: 0,
+        minAudioPts: 0,
+        maxVideoPts: 10 * 1000,
+        maxAudioPts: 10 * 1000,
+        uri: '0.ts'
+      }, {
+        discontinuity: true,
+        duration: 9,
+        uri: '1.ts'
+      }, {
+        duration: 10,
         uri: '2.ts'
       }, {
+        discontinuity: true,
         duration: 10,
-        maxVideoPts: 4 * 10 * 1000 + 1,
-        maxAudioPts: 4 * 10 * 1000 + 2,
         uri: '3.ts'
       }]
-    }, 0, 4);
+    }, 2, 4);
+
+    equal(duration, 10 + 10, 'excluded the earlier segments');
+  });
 
-    firstInterval = (1 * 10 * 1000 + 1) - 1;
-    firstInterval *= 0.001;
-    secondInterval = (4 * 10 * 1000 + 2) - (2 * 10 * 1000 + 7);
-    secondInterval *= 0.001;
+  test('ignores discontinuity sequences later than the end', function() {
+    var duration = Playlist.duration({
+      mediaSequence: 0,
+      discontinuityStarts: [1, 3],
+      segments: [{
+        minVideoPts: 0,
+        minAudioPts: 0,
+        maxVideoPts: 10 * 1000,
+        maxAudioPts: 10 * 1000,
+        uri: '0.ts'
+      }, {
+        discontinuity: true,
+        duration: 9,
+        uri: '1.ts'
+      }, {
+        duration: 10,
+        uri: '2.ts'
+      }, {
+        discontinuity: true,
+        duration: 10,
+        uri: '3.ts'
+      }]
+    }, 0, 2);
 
-    equal(duration, firstInterval + 10 + secondInterval, 'calculated with mixed intervals');
+    equal(duration, 19, 'excluded the later segments');
   });
 
-  test('interval duration accounts for discontinuities', function() {
+  test('handles trailing segments without PTS information', function() {
     var duration = Playlist.duration({
       mediaSequence: 0,
       endList: true,
       segments: [{
         minVideoPts: 0,
         minAudioPts: 0,
+        maxVideoPts: 10 * 1000,
+        maxAudioPts: 10 * 1000,
+        uri: '0.ts'
+      }, {
+        duration: 9,
+        uri: '1.ts'
+      }, {
+        duration: 10,
+        uri: '2.ts'
+      }, {
+        minVideoPts: 29.5 * 1000,
+        minAudioPts: 29.5 * 1000,
+        maxVideoPts: 39.5 * 1000,
+        maxAudioPts: 39.5 * 1000,
+        uri: '3.ts'
+      }]
+    }, 0, 3);
+
+    equal(duration, 29.5, 'calculated duration');
+  });
+
+  test('uses PTS intervals when the start and end segment have them', function() {
+    var playlist, duration;
+    playlist = {
+      mediaSequence: 0,
+      segments: [{
+        minVideoPts: 0,
+        minAudioPts: 0,
+        maxVideoPts: 10 * 1000,
+        maxAudioPts: 10 * 1000,
+        uri: '0.ts'
+      }, {
+        duration: 9,
+        uri: '1.ts'
+      },{
+        minVideoPts: 20 * 1000 + 100,
+        minAudioPts: 20 * 1000 + 100,
+        maxVideoPts: 30 * 1000 + 100,
+        maxAudioPts: 30 * 1000 + 100,
+        duration: 10,
+        uri: '2.ts'
+      }]
+    };
+    duration = Playlist.duration(playlist, 0, 2);
+
+    equal(duration, 20.1, 'used the PTS-based interval');
+
+    duration = Playlist.duration(playlist, 0, 3);
+    equal(duration, 30.1, 'used the PTS-based interval');
+  });
+
+  test('uses the largest continuous available PTS ranges', function() {
+    var playlist = {
+      mediaSequence: 0,
+      segments: [{
+        minVideoPts: 0,
+        minAudioPts: 0,
+        maxVideoPts: 10 * 1000,
+        maxAudioPts: 10 * 1000,
+        uri: '0.ts'
+      }, {
+        duration: 10,
+        uri: '1.ts'
+      }, {
+        // starts 0.5s earlier than the previous segment indicates
+        minVideoPts: 19.5 * 1000,
+        minAudioPts: 19.5 * 1000,
+        maxVideoPts: 29.5 * 1000,
+        maxAudioPts: 29.5 * 1000,
+        uri: '2.ts'
+      }, {
+        duration: 10,
+        uri: '3.ts'
+      }, {
+        // ... but by the last segment, there is actual 0.5s more
+        // content than duration indicates
+        minVideoPts: 40.5 * 1000,
+        minAudioPts: 40.5 * 1000,
+        maxVideoPts: 50.5 * 1000,
+        maxAudioPts: 50.5 * 1000,
+        uri: '4.ts'
+      }]
+    };
+
+    equal(Playlist.duration(playlist, 0, 5),
+          50.5,
+          'calculated across the larger PTS interval');
+  });
+
+  test('counts the time between segments as part of the earlier segment\'s duration', function() {
+    var duration = Playlist.duration({
+      mediaSequence: 0,
+      endList: true,
+      segments: [{
+        minVideoPts: 0,
+        minAudioPts: 0,
+        maxVideoPts: 1 * 10 * 1000,
+        maxAudioPts: 1 * 10 * 1000,
+        uri: '0.ts'
+      }, {
+        minVideoPts: 1 * 10 * 1000 + 100,
+        minAudioPts: 1 * 10 * 1000 + 100,
+        maxVideoPts: 2 * 10 * 1000 + 100,
+        maxAudioPts: 2 * 10 * 1000 + 100,
+        duration: 10,
+        uri: '1.ts'
+      }]
+    }, 0, 1);
+
+    equal(duration, (1 * 10 * 1000 + 100) * 0.001, 'included the segment gap');
+  });
+
+  test('accounts for discontinuities', function() {
+    var duration = Playlist.duration({
+      mediaSequence: 0,
+      endList: true,
+      discontinuityStarts: [1],
+      segments: [{
+        minVideoPts: 0,
+        minAudioPts: 0,
         maxVideoPts: 1 * 10 * 1000,
         maxAudioPts: 1 * 10 * 1000,
         uri: '0.ts'
@@ -130,6 +324,76 @@
     equal(duration, 10 + 10, 'handles discontinuities');
   });
 
+  test('does not count ending segment gaps across a discontinuity', function() {
+    var duration = Playlist.duration({
+      mediaSequence: 0,
+      discontinuityStarts: [1],
+      endList: true,
+      segments: [{
+        minVideoPts: 0,
+        minAudioPts: 0,
+        maxVideoPts: 1 * 10 * 1000,
+        maxAudioPts: 1 * 10 * 1000,
+        uri: '0.ts'
+      }, {
+        discontinuity: true,
+        minVideoPts: 1 * 10 * 1000 + 100,
+        minAudioPts: 1 * 10 * 1000 + 100,
+        maxVideoPts: 2 * 10 * 1000 + 100,
+        maxAudioPts: 2 * 10 * 1000 + 100,
+        duration: 10,
+        uri: '1.ts'
+      }]
+    }, 0, 1);
+
+    equal(duration, (1 * 10 * 1000) * 0.001, 'did not include the segment gap');
+  });
+
+  test('trailing duration on the final segment can be excluded', function() {
+    var duration = Playlist.duration({
+      mediaSequence: 0,
+      endList: true,
+      segments: [{
+        minVideoPts: 0,
+        minAudioPts: 0,
+        maxVideoPts: 1 * 10 * 1000,
+        maxAudioPts: 1 * 10 * 1000,
+        uri: '0.ts'
+      }, {
+        minVideoPts: 1 * 10 * 1000 + 100,
+        minAudioPts: 1 * 10 * 1000 + 100,
+        maxVideoPts: 2 * 10 * 1000 + 100,
+        maxAudioPts: 2 * 10 * 1000 + 100,
+        duration: 10,
+        uri: '1.ts'
+      }]
+    }, 0, 1, false);
+
+    equal(duration, (1 * 10 * 1000) * 0.001, 'did not include the segment gap');
+  });
+
+  test('a non-positive length interval has zero duration', function() {
+    var playlist = {
+      mediaSequence: 0,
+      discontinuityStarts: [1],
+      segments: [{
+        duration: 10,
+        uri: '0.ts'
+      }, {
+        discontinuity: true,
+        duration: 10,
+        uri: '1.ts'
+      }]
+    };
+
+    equal(Playlist.duration(playlist, 0, 0), 0, 'zero-length duration is zero');
+    equal(Playlist.duration(playlist, 0, 0, false), 0, 'zero-length duration is zero');
+    equal(Playlist.duration(playlist, 0, -1), 0, 'negative length duration is zero');
+    equal(Playlist.duration(playlist, 2, 1, false), 0, 'negative length duration is zero');
+  });
+
+  module('Playlist Seekable');
+
   test('calculates seekable time ranges from the available segments', function() {
     var playlist = {
       mediaSequence: 0,

@@ -97,15 +97,13 @@ var
     var MockSegmentParser;
 
     if (tags === undefined) {
-      tags = [];
+      tags = [{ pts: 0, bytes: new Uint8Array(1) }];
     }
     MockSegmentParser = function() {
       this.getFlvHeader = function() {
         return 'flv';
       };
       this.parseSegmentBinaryData = function() {};
-      this.timestampOffset = 0;
-      this.mediaTimelineOffset = 0;
       this.flushTags = function() {};
       this.tagsAvailable = function() {
         return tags.length;
@@ -1287,30 +1285,32 @@ test('clears in-band cues ahead of current time on seek', function() {
 
   player.hls.segmentParser_.parseSegmentBinaryData = function() {
     // trigger a metadata event
-    if (events.length) {
+    while (events.length) {
       player.hls.segmentParser_.metadataStream.trigger('data', events.shift());
     }
   };
   standardXHRResponse(requests.shift()); // media
-  tags.push({ pts: 10 * 1000, bytes: new Uint8Array(1) });
+  tags.push({ pts: 0, bytes: new Uint8Array(1) },
+            { pts: 10 * 1000, bytes: new Uint8Array(1) });
   events.push({
-      pts: 20 * 1000,
+      pts: 9.9 * 1000,
       data: new Uint8Array([]),
       frames: [{
         id: 'TXXX',
-        value: 'cue 3'
+        value: 'cue 1'
       }]
   });
   events.push({
-      pts: 9.9 * 1000,
+      pts: 20 * 1000,
       data: new Uint8Array([]),
       frames: [{
         id: 'TXXX',
-        value: 'cue 1'
+        value: 'cue 3'
       }]
   });
   standardXHRResponse(requests.shift()); // segment 0
-  tags.push({ pts: 20 * 1000, bytes: new Uint8Array(1) });
+  tags.push({ pts: 10 * 1000 + 1, bytes: new Uint8Array(1) },
+            { pts: 20 * 1000, bytes: new Uint8Array(1) });
   events.push({
       pts: 19.9 * 1000,
       data: new Uint8Array([]),
@@ -1323,12 +1323,12 @@ test('clears in-band cues ahead of current time on seek', function() {
   standardXHRResponse(requests.shift()); // segment 1
 
   track = player.textTracks()[0];
-  equal(track.cues.length, 2, 'added the cues');
+  equal(track.cues.length, 3, 'added the cues');
 
   // seek into segment 1
   player.currentTime(11);
   player.trigger('seeking');
-  equal(track.cues.length, 1, 'removed a cue');
+  equal(track.cues.length, 1, 'removed later cues');
   equal(track.cues[0].startTime, 9.9, 'retained the earlier cue');
 });
 
@@ -1342,9 +1342,6 @@ test('translates ID3 PTS values to cue media timeline positions', function() {
   openMediaSource(player);
 
   player.hls.segmentParser_.parseSegmentBinaryData = function() {
-    // setup the timestamp offset
-    this.timestampOffset = tags[0].pts;
-
     // trigger a metadata event
     player.hls.segmentParser_.metadataStream.trigger('data', {
       pts: 5 * 1000,
@@ -1373,9 +1370,6 @@ test('translates ID3 PTS values across discontinuities', function() {
   openMediaSource(player);
 
   player.hls.segmentParser_.parseSegmentBinaryData = function() {
-    if (this.timestampOffset === null) {
-      this.timestampOffset = tags[0].pts;
-    }
     // trigger a metadata event
     if (events.length) {
       player.hls.segmentParser_.metadataStream.trigger('data', events.shift());
@@ -1393,7 +1387,6 @@ test('translates ID3 PTS values across discontinuities', function() {
                            '1.ts\n');
 
   // segment 0 starts at PTS 14000 and has a cue point at 15000
-  player.hls.segmentParser_.timestampOffset = 14 * 1000;
   tags.push({ pts: 14 * 1000, bytes: new Uint8Array(1) },
             { pts: 24 * 1000, bytes: new Uint8Array(1) });
   events.push({
@@ -2010,6 +2003,48 @@ test('continues playing after seek to discontinuity', function() {
   strictEqual(aborts, 1, 'cleared the segment buffer on a seek');
 });
 
+test('seeking does not fail when targeted between segments', function() {
+  var tags = [], currentTime, segmentUrl;
+  videojs.Hls.SegmentParser = mockSegmentParser(tags);
+  player.src({
+    src: 'media.m3u8',
+    type: 'application/vnd.apple.mpegurl'
+  });
+  openMediaSource(player);
+
+  // mock out the currentTime callbacks
+  player.hls.el().vjs_setProperty = function(property, value) {
+    if (property === 'currentTime') {
+      currentTime = value;
+    }
+  };
+  player.hls.el().vjs_getProperty = function(property) {
+    if (property === 'currentTime') {
+      return currentTime;
+    }
+  };
+
+  standardXHRResponse(requests.shift()); // media
+  tags.push({ pts: 100, bytes: new Uint8Array(1) },
+            { pts: 9 * 1000 + 100, bytes: new Uint8Array(1) });
+  standardXHRResponse(requests.shift()); // segment 0
+  player.hls.checkBuffer_();
+  tags.push({ pts: 9.5 * 1000 + 100, bytes: new Uint8Array(1) },
+            { pts: 20 * 1000 + 100, bytes: new Uint8Array(1) });
+  segmentUrl = requests[0].url;
+  standardXHRResponse(requests.shift()); // segment 1
+
+  // seek to a time that is greater than the last tag in segment 0 but
+  // less than the first in segment 1
+  player.currentTime(9.4);
+  equal(requests[0].url, segmentUrl, 'requested the later segment');
+
+  tags.push({ pts: 9.5 * 1000 + 100, bytes: new Uint8Array(1) },
+            { pts: 20 * 1000 + 100, bytes: new Uint8Array(1) });
+  standardXHRResponse(requests.shift()); // segment 1
+  equal(player.currentTime(), 9.5, 'seeked to the later time');
+});
+
 test('resets the switching algorithm if a request times out', function() {
   player.src({
     src: 'master.m3u8',
@@ -2666,12 +2701,13 @@ test('treats invalid keys as a key request failure', function() {
   equal(bytes[0], 'flv', 'appended the flv header');
 
   tags.length = 0;
-  tags.push({ pts: 1, bytes: new Uint8Array([1]) });
+  tags.push({ pts: 2833, bytes: new Uint8Array([1]) },
+            { pts: 4833, bytes: new Uint8Array([2]) });
   // second segment request
   standardXHRResponse(requests.shift());
 
   equal(bytes.length, 2, 'appended bytes');
-  deepEqual(new Uint8Array([1]), bytes[1], 'skipped to the second segment');
+  deepEqual(bytes[1], new Uint8Array([1, 2]), 'skipped to the second segment');
 });
 
 test('live stream should not call endOfStream', function(){