Added partial support to specify negative r values in SegmentTimeline

Can now specify negative values for the r attribute in SegmentTimeline.
Not supported with live when used on the last element.

Issue #162

Change-Id: I7206e02f7af469a7daf1e4710befb2d102f4f979

lib/dash/list_segment_index_source.js

@@ -103,7 +103,8 @@ shaka.dash.ListSegmentIndexSource.prototype.create = function() {
   var timeline = [];
   if (segmentList.timeline) {
     timeline = shaka.dash.MpdUtils.createTimeline(
-        segmentList.timeline, segmentList.timescale || 1);
+        segmentList.timeline, segmentList.timescale || 1,
+        this.period_.duration || 0);
   }
 
   // Calculate a value to be used as an initial start value.

lib/dash/mpd_parser.js

@@ -1442,7 +1442,7 @@ shaka.dash.mpd.SegmentTimePoint.prototype.parse = function(parent, elem) {
   // Parse attributes.
   this.startTime = mpd.parseAttr_(elem, 't', mpd.parseNonNegativeInt_);
   this.duration = mpd.parseAttr_(elem, 'd', mpd.parseNonNegativeInt_);
-  this.repeat = mpd.parseAttr_(elem, 'r', mpd.parseNonNegativeInt_);
+  this.repeat = mpd.parseAttr_(elem, 'r', mpd.parseInt_);
 };
 
 
@@ -1775,6 +1775,18 @@ shaka.dash.mpd.parseRange_ = function(rangeString) {
 };
 
 
+/**
+ * Parses an integer.
+ * @param {string} intString The integer string.
+ * @return {?number} The parsed integer on success; otherwise, return null.
+ * @private
+ */
+shaka.dash.mpd.parseInt_ = function(intString) {
+  var result = window.parseInt(intString, 10);
+  return (!isNaN(result) ? result : null);
+};
+
+
 /**
  * Parses a positive integer.
  * @param {string} intString The integer string.

lib/dash/mpd_utils.js

@@ -223,12 +223,15 @@ shaka.dash.MpdUtils.fillUrlTemplate = function(
  *
  * @param {shaka.dash.mpd.SegmentTimeline} segmentTimeline
  * @param {number} timescale
+ * @param {number} durationSeconds The duration of the period (in seconds).
  * @return {!Array.<{start: number, end: number}>}
  */
-shaka.dash.MpdUtils.createTimeline = function(segmentTimeline, timescale) {
+shaka.dash.MpdUtils.createTimeline = function(
+    segmentTimeline, timescale, durationSeconds) {
   shaka.asserts.assert(segmentTimeline);
 
   var lastEndTime = 0;
+  var duration = durationSeconds * timescale;
   var timePoints = segmentTimeline.timePoints;
 
   /** @type {!Array.<{start: number, end: number}>} */
@@ -247,36 +250,46 @@ shaka.dash.MpdUtils.createTimeline = function(segmentTimeline, timescale) {
     var startTime = tpStart != null ? tpStart : lastEndTime;
 
     var repeat = timePoints[i].repeat || 0;
-    for (var j = 0; j <= repeat; ++j) {
-      var endTime = startTime + timePoints[i].duration;
+    if (repeat < 0) {
+      var d = timePoints[i].duration;
+      if (i + 1 === timePoints.length) {
+        var delta = timePoints[0].startTime + duration - startTime;
+        repeat = Math.ceil(delta / d) - 1;
+      } else {
+        var next = timePoints[i + 1].startTime;
+        repeat = Math.ceil((next - startTime) / d) - 1;
+      }
+    }
 
-      // The end of the last segment may end before the start of the current
-      // segment (a gap) or may end after the start of the current segment (an
-      // overlap). If there is a gap/overlap then stretch/compress the end of
-      // the last segment to the start of the current segment.
-      //
-      // Note: it is possible to move the start of the current segment to the
-      // end of the last segment, but this would complicate the computation of
-      // the $Time$ placeholder.
-      if ((timeline.length > 0) && (startTime != lastEndTime)) {
-        var delta = startTime - lastEndTime;
+    // The end of the last segment may end before the start of the current
+    // segment (a gap) or may end after the start of the current segment (an
+    // overlap). If there is a gap/overlap then stretch/compress the end of
+    // the last segment to the start of the current segment.
+    //
+    // Note: it is possible to move the start of the current segment to the
+    // end of the last segment, but this would complicate the computation of
+    // the $Time$ placeholder.
+    if ((timeline.length > 0) && (startTime != lastEndTime)) {
+      var delta = startTime - lastEndTime;
 
-        if (Math.abs(delta / timescale) >=
-            shaka.dash.MpdUtils.GAP_OVERLAP_WARN_THRESHOLD) {
-          shaka.log.warning(
-              'SegmentTimeline contains a large gap/overlap.',
-              'The content may have errors in it.',
-              timePoints[i]);
-        }
-
-        timeline[timeline.length - 1].end = startTime;
+      if (Math.abs(delta / timescale) >=
+          shaka.dash.MpdUtils.GAP_OVERLAP_WARN_THRESHOLD) {
+        shaka.log.warning(
+            'SegmentTimeline contains a large gap/overlap.',
+            'The content may have errors in it.',
+            timePoints[i]);
       }
 
+      timeline[timeline.length - 1].end = startTime;
+    }
+
+    for (var j = 0; j <= repeat; ++j) {
+      var endTime = startTime + timePoints[i].duration;
       timeline.push({start: startTime, end: endTime});
 
       startTime = endTime;
       lastEndTime = endTime;
-    }  // for j
+    }
   }
 
   return timeline;

lib/dash/timeline_segment_index_source.js

@@ -95,7 +95,8 @@ shaka.dash.TimelineSegmentIndexSource.prototype.create = function() {
 
   var segmentTemplate = this.representation_.segmentTemplate;
   var timeline = shaka.dash.MpdUtils.createTimeline(
-      segmentTemplate.timeline, segmentTemplate.timescale || 1);
+      segmentTemplate.timeline, segmentTemplate.timescale || 1,
+      this.period_.duration || 0);
 
   /** @type {!Array.<!shaka.media.SegmentReference>} */
   var references = [];

spec/mpd_utils_spec.js

@@ -167,5 +167,92 @@ describe('MpdUtils', function() {
               1, 2, 3, 4)).toBeNull();
     });
   });
+
+  // TODO: Create more unit tests for this.
+  describe('createTimeline', function() {
+    it('supports negative repetitions', function() {
+      var timepoints = [
+        createTimepoint(0, 10, 0),
+        createTimepoint(10, 10, -1),
+        createTimepoint(40, 10, 0)
+      ];
+      var result = [
+        { start: 0, end: 10 },
+        { start: 10, end: 20 },
+        { start: 20, end: 30 },
+        { start: 30, end: 40 },
+        { start: 40, end: 50 }
+      ];
+      checkTimepoints(timepoints, result, 1, 0);
+    });
+
+    it('supports negative repetitions with uneven border', function() {
+      var timepoints = [
+        createTimepoint(0, 10, 0),
+        createTimepoint(10, 10, -1),
+        createTimepoint(45, 5, 0)
+      ];
+      var result = [
+        { start: 0, end: 10 },
+        { start: 10, end: 20 },
+        { start: 20, end: 30 },
+        { start: 30, end: 40 },
+        { start: 40, end: 45 },
+        { start: 45, end: 50 }
+      ];
+      checkTimepoints(timepoints, result, 1, 0);
+    });
+
+    it('supports negative repetitions at end', function() {
+      var timepoints = [
+        createTimepoint(0, 10, 0),
+        createTimepoint(10, 5, -1)
+      ];
+      var result = [
+        { start: 0, end: 10 },
+        { start: 10, end: 15 },
+        { start: 15, end: 20 },
+        { start: 20, end: 25 }
+      ];
+      checkTimepoints(timepoints, result, 1, 25);
+    });
+
+    /**
+     * Creates a new timepoint.
+     *
+     * @param {number} start
+     * @param {number} dur
+     * @param {number} rep
+     */
+    function createTimepoint(start, dur, rep) {
+      var ret = new shaka.dash.mpd.SegmentTimePoint();
+      ret.startTime = start;
+      ret.duration = dur;
+      ret.repeat = rep;
+      return ret;
+    }
+
+    /**
+     * Checks that the createTimeline works with the given timepoints and the
+     * given expected results.
+     *
+     * @param {!Array.<!shaka.dash.mpd.TimePoint>} points
+     * @param {!Array.<{start: number, end: number}} expected
+     * @param {number} scale
+     * @param {number} duration
+     */
+    function checkTimepoints(points, expected, scale, duration) {
+      var timeline = new shaka.dash.mpd.SegmentTimeline();
+      timeline.timePoints = points;
+
+      var data = MpdUtils.createTimeline(timeline, scale, duration);
+      expect(data).toBeTruthy();
+      expect(data.length).toBe(expected.length);
+      for (var i = 0; i < expected.length; i++) {
+        expect(data[i].start).toBe(expected[i].start);
+        expect(data[i].end).toBe(expected[i].end);
+      }
+    }
+  });
 });