Fix PTO for SegmentBase

In DASH SegmentBase, we were not dividing presentationTimeOffset by
the timescale.  In all other instances of presentationTimeOffset in
DASH, we were handling it correctly.

This bug was present in all v2 releases until now.

The solution is not only to divide by timescale, but to rename all
internal uses of presentationTimeOffset to either unscaled or scaled,
to differentiate between those in timescale units and those in
seconds.  I believe inconsistent naming and units were a contributing
factor to the creation of the bug.

Closes #1099

Change-Id: Id561f8eb1f5bc011c606e1925c12f0d8183fd51a

externs/shaka/offline.js

@@ -170,7 +170,7 @@ shakaExtern.PeriodDB;
  * @property {boolean} primary
  *   Whether the stream set was primary.
  * @property {number} presentationTimeOffset
- *   The presentation time offset of the stream.
+ *   The presentation time offset of the stream, in seconds.
  * @property {string} contentType
  *   The type of the stream, 'audio', 'text', or 'video'.
  * @property {string} mimeType

lib/dash/dash_parser.js

@@ -285,7 +285,7 @@ shaka.dash.DashParser.SegmentIndexFunctions;
  *   findSegmentPosition: shakaExtern.FindSegmentPositionFunction,
  *   getSegmentReference: shakaExtern.GetSegmentReferenceFunction,
  *   initSegmentReference: shaka.media.InitSegmentReference,
- *   presentationTimeOffset: (number|undefined)
+ *   scaledPresentationTimeOffset: number
  * }}
  *
  * @description
@@ -300,8 +300,8 @@ shaka.dash.DashParser.SegmentIndexFunctions;
  *   The getSegmentReference function for the stream.
  * @property {shaka.media.InitSegmentReference} initSegmentReference
  *   The init segment for the stream.
- * @property {(number|undefined)} presentationTimeOffset
- *   The presentationTimeOffset for the stream.
+ * @property {number} scaledPresentationTimeOffset
+ *   The presentation time offset for the stream, in seconds.
  */
 shaka.dash.DashParser.StreamInfo;
 
@@ -1106,7 +1106,7 @@ shaka.dash.DashParser.prototype.parseRepresentation_ = function(
                 1, 0, duration, function() { return baseUris; }, 0, null);
           },
       initSegmentReference: null,
-      presentationTimeOffset: 0
+      scaledPresentationTimeOffset: 0
     };
   }
 
@@ -1121,7 +1121,7 @@ shaka.dash.DashParser.prototype.parseRepresentation_ = function(
     findSegmentPosition: streamInfo.findSegmentPosition,
     getSegmentReference: streamInfo.getSegmentReference,
     initSegmentReference: streamInfo.initSegmentReference,
-    presentationTimeOffset: streamInfo.presentationTimeOffset,
+    presentationTimeOffset: streamInfo.scaledPresentationTimeOffset,
     mimeType: context.representation.mimeType,
     codecs: context.representation.codecs,
     frameRate: context.representation.frameRate,

lib/dash/mpd_utils.js

@@ -57,7 +57,7 @@ shaka.dash.MpdUtils.TimeRange;
  *   timescale: number,
  *   segmentDuration: ?number,
  *   startNumber: number,
- *   presentationTimeOffset: number,
+ *   scaledPresentationTimeOffset: number,
  *   unscaledPresentationTimeOffset: number,
  *   timeline: Array.<shaka.dash.MpdUtils.TimeRange>
  * }}
@@ -71,10 +71,10 @@ shaka.dash.MpdUtils.TimeRange;
  *   The duration of the segments in seconds, if given.
  * @property {number} startNumber
  *   The start number of the segments; 1 or greater.
- * @property {number} presentationTimeOffset
- *   The presentationTimeOffset of the representation, in seconds.
+ * @property {number} scaledPresentationTimeOffset
+ *   The presentation time offset of the representation, in seconds.
  * @property {number} unscaledPresentationTimeOffset
- *   The presentationTimeOffset of the representation, in timescale units.
+ *   The presentation time offset of the representation, in timescale units.
  * @property {Array.<shaka.dash.MpdUtils.TimeRange>} timeline
  *   The timeline of the representation, if given.  Times in seconds.
  */
@@ -155,13 +155,14 @@ shaka.dash.MpdUtils.fillUriTemplate = function(
  *
  * @param {!Element} segmentTimeline
  * @param {number} timescale
- * @param {number} presentationTimeOffset
+ * @param {number} unscaledPresentationTimeOffset
  * @param {number} periodDuration The Period's duration in seconds.
  *   Infinity indicates that the Period continues indefinitely.
  * @return {!Array.<shaka.dash.MpdUtils.TimeRange>}
  */
-shaka.dash.MpdUtils.createTimeline = function(
-    segmentTimeline, timescale, presentationTimeOffset, periodDuration) {
+shaka.dash.MpdUtils.createTimeline =
+    function(segmentTimeline, timescale, unscaledPresentationTimeOffset,
+             periodDuration) {
   goog.asserts.assert(
       timescale > 0 && timescale < Infinity,
       'timescale must be a positive, finite integer');
@@ -185,7 +186,7 @@ shaka.dash.MpdUtils.createTimeline = function(
 
     // Adjust start considering the presentation time offset
     if (t != null)
-      t -= presentationTimeOffset;
+      t -= unscaledPresentationTimeOffset;
 
     if (!d) {
       shaka.log.warning(
@@ -311,8 +312,9 @@ shaka.dash.MpdUtils.parseSegmentInfo = function(context, callback) {
 
   var startNumberStr =
       MpdUtils.inheritAttribute(context, callback, 'startNumber');
-  var presentationTimeOffset =
-      MpdUtils.inheritAttribute(context, callback, 'presentationTimeOffset');
+  var unscaledPresentationTimeOffset =
+      Number(MpdUtils.inheritAttribute(context, callback,
+                                       'presentationTimeOffset')) || 0;
   var startNumber = XmlUtils.parseNonNegativeInt(startNumberStr || '');
   if (startNumberStr == null || startNumber == null)
     startNumber = 1;
@@ -323,17 +325,18 @@ shaka.dash.MpdUtils.parseSegmentInfo = function(context, callback) {
   var timeline = null;
   if (timelineNode) {
     timeline = MpdUtils.createTimeline(
-        timelineNode, timescale, Number(presentationTimeOffset),
+        timelineNode, timescale, unscaledPresentationTimeOffset,
         context.periodInfo.duration || Infinity);
   }
 
-  var pto = (Number(presentationTimeOffset) / timescale) || 0;
+  var scaledPresentationTimeOffset =
+      (unscaledPresentationTimeOffset / timescale) || 0;
   return {
     timescale: timescale,
     segmentDuration: segmentDuration,
     startNumber: startNumber,
-    presentationTimeOffset: pto,
-    unscaledPresentationTimeOffset: Number(presentationTimeOffset),
+    scaledPresentationTimeOffset: scaledPresentationTimeOffset,
+    unscaledPresentationTimeOffset: unscaledPresentationTimeOffset,
     timeline: timeline
   };
 };

lib/dash/segment_base.js

@@ -87,21 +87,32 @@ shaka.dash.SegmentBase.createStream = function(context, requestInitSegment) {
   // the initial parse.
   var MpdUtils = shaka.dash.MpdUtils;
   var SegmentBase = shaka.dash.SegmentBase;
+  var XmlUtils = shaka.util.XmlUtils;
+
+  var unscaledPresentationTimeOffset = Number(MpdUtils.inheritAttribute(
+      context, SegmentBase.fromInheritance_, 'presentationTimeOffset')) || 0;
+
+  var timescaleStr = MpdUtils.inheritAttribute(
+      context, SegmentBase.fromInheritance_, 'timescale');
+  var timescale = 1;
+  if (timescaleStr) {
+    timescale = XmlUtils.parsePositiveInt(timescaleStr) || 1;
+  }
 
-  var presentationTimeOffset = MpdUtils.inheritAttribute(
-      context, SegmentBase.fromInheritance_, 'presentationTimeOffset');
+  var scaledPresentationTimeOffset =
+      (unscaledPresentationTimeOffset / timescale) || 0;
 
   var init =
       SegmentBase.createInitSegment(context, SegmentBase.fromInheritance_);
   var index = SegmentBase.createSegmentIndex_(
-      context, requestInitSegment, init, Number(presentationTimeOffset));
+      context, requestInitSegment, init, unscaledPresentationTimeOffset);
 
   return {
     createSegmentIndex: index.createSegmentIndex,
     findSegmentPosition: index.findSegmentPosition,
     getSegmentReference: index.getSegmentReference,
     initSegmentReference: init,
-    presentationTimeOffset: Number(presentationTimeOffset) || 0
+    scaledPresentationTimeOffset: scaledPresentationTimeOffset
   };
 };
 
@@ -116,12 +127,12 @@ shaka.dash.SegmentBase.createStream = function(context, requestInitSegment) {
  * @param {number} startByte
  * @param {?number} endByte
  * @param {string} containerType
- * @param {number} presentationTimeOffset
+ * @param {number} unscaledPresentationTimeOffset
  * @return {shaka.dash.DashParser.SegmentIndexFunctions}
  */
 shaka.dash.SegmentBase.createSegmentIndexFromUris = function(
     context, requestInitSegment, init, uris,
-    startByte, endByte, containerType, presentationTimeOffset) {
+    startByte, endByte, containerType, unscaledPresentationTimeOffset) {
   var presentationTimeline = context.presentationTimeline;
   var fitLast = !context.dynamic || !context.periodInfo.isLastPeriod;
   var periodStartTime = context.periodInfo.start;
@@ -146,12 +157,12 @@ shaka.dash.SegmentBase.createSegmentIndexFromUris = function(
 
       if (containerType == 'mp4') {
         references = shaka.media.Mp4SegmentIndexParser(
-            indexData, startByte, uris, presentationTimeOffset);
+            indexData, startByte, uris, unscaledPresentationTimeOffset);
       } else {
         goog.asserts.assert(initData, 'WebM requires init data');
         var parser = new shaka.media.WebmSegmentIndexParser();
         references = parser.parse(indexData, initData, uris,
-            presentationTimeOffset);
+            unscaledPresentationTimeOffset);
       }
 
       presentationTimeline.notifySegments(periodStartTime, references);
@@ -199,13 +210,13 @@ shaka.dash.SegmentBase.fromInheritance_ = function(frame) {
  * @param {shaka.dash.DashParser.Context} context
  * @param {shaka.dash.DashParser.RequestInitSegmentCallback} requestInitSegment
  * @param {shaka.media.InitSegmentReference} init
- * @param {number} presentationTimeOffset
+ * @param {number} unscaledPresentationTimeOffset
  * @return {shaka.dash.DashParser.SegmentIndexFunctions}
  * @throws shaka.util.Error When there is a parsing error.
  * @private
  */
 shaka.dash.SegmentBase.createSegmentIndex_ = function(
-    context, requestInitSegment, init, presentationTimeOffset) {
+    context, requestInitSegment, init, unscaledPresentationTimeOffset) {
   var MpdUtils = shaka.dash.MpdUtils;
   var SegmentBase = shaka.dash.SegmentBase;
   var XmlUtils = shaka.util.XmlUtils;
@@ -269,5 +280,5 @@ shaka.dash.SegmentBase.createSegmentIndex_ = function(
 
   return shaka.dash.SegmentBase.createSegmentIndexFromUris(
       context, requestInitSegment, init, indexUris, indexRange.start,
-      indexRange.end, containerType, presentationTimeOffset);
+      indexRange.end, containerType, unscaledPresentationTimeOffset);
 };

lib/dash/segment_list.js

@@ -86,7 +86,7 @@ shaka.dash.SegmentList.createStream = function(context, segmentIndexMap) {
     findSegmentPosition: segmentIndex.find.bind(segmentIndex),
     getSegmentReference: segmentIndex.get.bind(segmentIndex),
     initSegmentReference: init,
-    presentationTimeOffset: info.presentationTimeOffset
+    scaledPresentationTimeOffset: info.scaledPresentationTimeOffset
   };
 };
 
@@ -113,7 +113,7 @@ shaka.dash.SegmentList.MediaSegment;
  *   segmentDuration: ?number,
  *   startTime: number,
  *   startNumber: number,
- *   presentationTimeOffset: number,
+ *   scaledPresentationTimeOffset: number,
  *   timeline: Array.<shaka.dash.MpdUtils.TimeRange>,
  *   mediaSegments: !Array.<shaka.dash.SegmentList.MediaSegment>
  * }}
@@ -128,8 +128,8 @@ shaka.dash.SegmentList.MediaSegment;
  *   The start time of the first segment, in seconds.
  * @property {number} startNumber
  *   The start number of the segments; 1 or greater.
- * @property {number} presentationTimeOffset
- *   The presentationTimeOffset of the representation, in seconds.
+ * @property {number} scaledPresentationTimeOffset
+ *   The scaledPresentationTimeOffset of the representation, in seconds.
  * @property {Array.<shaka.dash.MpdUtils.TimeRange>} timeline
  *   The timeline of the representation, if given.  Times in seconds.
  * @property {!Array.<shaka.dash.SegmentList.MediaSegment>} mediaSegments
@@ -183,7 +183,7 @@ shaka.dash.SegmentList.parseSegmentListInfo_ = function(context) {
     segmentDuration: segmentInfo.segmentDuration,
     startTime: startTime,
     startNumber: startNumber,
-    presentationTimeOffset: segmentInfo.presentationTimeOffset,
+    scaledPresentationTimeOffset: segmentInfo.scaledPresentationTimeOffset,
     timeline: segmentInfo.timeline,
     mediaSegments: mediaSegments
   };

lib/dash/segment_template.js

@@ -105,7 +105,7 @@ shaka.dash.SegmentTemplate.createStream = function(
     findSegmentPosition: segmentIndexFunctions.findSegmentPosition,
     getSegmentReference: segmentIndexFunctions.getSegmentReference,
     initSegmentReference: init,
-    presentationTimeOffset: info.presentationTimeOffset
+    scaledPresentationTimeOffset: info.scaledPresentationTimeOffset
   };
 };
 
@@ -115,7 +115,7 @@ shaka.dash.SegmentTemplate.createStream = function(
  *   timescale: number,
  *   segmentDuration: ?number,
  *   startNumber: number,
- *   presentationTimeOffset: number,
+ *   scaledPresentationTimeOffset: number,
  *   unscaledPresentationTimeOffset: number,
  *   timeline: Array.<shaka.dash.MpdUtils.TimeRange>,
  *   mediaTemplate: ?string,
@@ -132,10 +132,10 @@ shaka.dash.SegmentTemplate.createStream = function(
  *   The duration of the segments in seconds, if given.
  * @property {number} startNumber
  *   The start number of the segments; 1 or greater.
- * @property {number} presentationTimeOffset
- *   The presentationTimeOffset of the representation, in seconds.
+ * @property {number} scaledPresentationTimeOffset
+ *   The presentation time offset of the representation, in seconds.
  * @property {number} unscaledPresentationTimeOffset
- *   The presentationTimeOffset of the representation, in timescale units.
+ *   The presentation time offset of the representation, in timescale units.
  * @property {Array.<shaka.dash.MpdUtils.TimeRange>} timeline
  *   The timeline of the representation, if given.  Times in seconds.
  * @property {?string} mediaTemplate
@@ -178,7 +178,7 @@ shaka.dash.SegmentTemplate.parseSegmentTemplateInfo_ = function(context) {
     segmentDuration: segmentInfo.segmentDuration,
     timescale: segmentInfo.timescale,
     startNumber: segmentInfo.startNumber,
-    presentationTimeOffset: segmentInfo.presentationTimeOffset,
+    scaledPresentationTimeOffset: segmentInfo.scaledPresentationTimeOffset,
     unscaledPresentationTimeOffset: segmentInfo.unscaledPresentationTimeOffset,
     timeline: segmentInfo.timeline,
     mediaTemplate: media,
@@ -291,7 +291,7 @@ shaka.dash.SegmentTemplate.createFromIndexTemplate_ = function(
 
   return shaka.dash.SegmentBase.createSegmentIndexFromUris(
       context, requestInitSegment, init, resolvedUris, 0, null, containerType,
-      info.presentationTimeOffset);
+      info.scaledPresentationTimeOffset);
 };
 
 

lib/media/mp4_segment_index_parser.js

@@ -31,12 +31,12 @@ goog.require('shaka.util.Mp4Parser');
  *   the MP4 container.
  * @param {!Array.<string>} uris The possible locations of the MP4 file that
  *   contains the segments.
- * @param {number} presentationTimeOffset
+ * @param {number} unscaledPresentationTimeOffset
  * @return {!Array.<!shaka.media.SegmentReference>}
  * @throws {shaka.util.Error}
  */
 shaka.media.Mp4SegmentIndexParser = function(
-    sidxData, sidxOffset, uris, presentationTimeOffset) {
+    sidxData, sidxOffset, uris, unscaledPresentationTimeOffset) {
 
   var Mp4SegmentIndexParser = shaka.media.Mp4SegmentIndexParser;
 
@@ -46,7 +46,7 @@ shaka.media.Mp4SegmentIndexParser = function(
       .fullBox('sidx', function(box) {
         references = Mp4SegmentIndexParser.parseSIDX_(
             sidxOffset,
-            presentationTimeOffset,
+            unscaledPresentationTimeOffset,
             uris,
             box);
       });
@@ -71,7 +71,7 @@ shaka.media.Mp4SegmentIndexParser = function(
  * Parse a SIDX box from the given reader.
  *
  * @param {number} sidxOffset
- * @param {number} presentationTimeOffset
+ * @param {number} unscaledPresentationTimeOffset
  * @param {!Array.<string>} uris The possible locations of the MP4 file that
  *   contains the segments.
  * @param {!shaka.util.Mp4Parser.ParsedBox} box
@@ -80,7 +80,7 @@ shaka.media.Mp4SegmentIndexParser = function(
  */
 shaka.media.Mp4SegmentIndexParser.parseSIDX_ = function(
     sidxOffset,
-    presentationTimeOffset,
+    unscaledPresentationTimeOffset,
     uris,
     box) {
 
@@ -121,8 +121,9 @@ shaka.media.Mp4SegmentIndexParser.parseSIDX_ = function(
   // Add references.
   var referenceCount = box.reader.readUint16();
 
-  // Substract the presentationTimeOffset
-  var unscaledStartTime = earliestPresentationTime - presentationTimeOffset;
+  // Substract the presentation time offset
+  var unscaledStartTime =
+      earliestPresentationTime - unscaledPresentationTimeOffset;
   var startByte = sidxOffset + box.size + firstOffset;
 
   for (var i = 0; i < referenceCount; i++) {