Remove clientServerTimeShift from _calcAvailabilityTimeFromPresentati…

…onTime and use it in getClientReferenceTime() instead before requesting a segment.
Dash-Industry-Forum · Sep 6, 2021 · 6a0d37c · 6a0d37c
1 parent 66bc8f9
commit 6a0d37c
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Showing 2 changed files with 13 additions and 9 deletions.
diff --git a/src/dash/utils/SegmentsUtils.js b/src/dash/utils/SegmentsUtils.js
@@ -164,8 +164,8 @@ function isSegmentAvailable(timelineConverter, representation, segment, isDynami
         // SAST = Period@start + seg@presentationStartTime + seg@duration
         // ASAST = SAST - ATO
         // SAET = SAST + TSBD + seg@duration
-        // refTime serves as an anchor time to compare the availability time of the segments against. Note that we already compensated for the client/server drift when calculating the availability time of a segment. Thats why we do not subtract clientServerTimeShift here again.
-        const refTime = Date.now() - ((timelineConverter.getTimelineAnchorAvailabilityOffset()) * 1000);
+        // refTime serves as an anchor time to compare the availability time of the segments against.
+        const refTime = timelineConverter.getClientReferenceTime();
         return segment.availabilityStartTime.getTime() <= refTime && (!isFinite(segment.availabilityEndTime) || segment.availabilityEndTime.getTime() >= refTime);
     }
 

diff --git a/src/dash/utils/TimelineConverter.js b/src/dash/utils/TimelineConverter.js
@@ -67,6 +67,14 @@ function TimelineConverter() {
         clientServerTimeShift = value;
     }
 
+    /**
+     * Returns a "now" reference time for the client to compare the availability time of a segment against.
+     * Takes the client/server drift into account
+     */
+    function getClientReferenceTime() {
+        return Date.now() - (timelineAnchorAvailabilityOffset * 1000) + (clientServerTimeShift * 1000);
+    }
+
     function _calcAvailabilityTimeFromPresentationTime(presentationEndTime, representation, isDynamic, calculateAvailabilityEndTime) {
         let availabilityTime;
         let mpd = representation.adaptation.period.mpd;
@@ -78,7 +86,7 @@ function TimelineConverter() {
             // When not present, the value is infinite.
             if (isDynamic && mpd.timeShiftBufferDepth !== Number.POSITIVE_INFINITY) {
                 // SAET = SAST + TSBD + seg@duration
-                availabilityTime = new Date(availabilityStartTime.getTime() + ((presentationEndTime - clientServerTimeShift + mpd.timeShiftBufferDepth) * 1000));
+                availabilityTime = new Date(availabilityStartTime.getTime() + ((presentationEndTime + mpd.timeShiftBufferDepth) * 1000));
             } else {
                 availabilityTime = mpd.availabilityEndTime;
             }
@@ -88,7 +96,7 @@ function TimelineConverter() {
                 // ASAST = SAST - ATO
                 const availabilityTimeOffset = representation.availabilityTimeOffset;
                 // presentationEndTime = Period@start + seg@presentationStartTime + Segment@duration
-                availabilityTime = new Date(availabilityStartTime.getTime() + (presentationEndTime - clientServerTimeShift - availabilityTimeOffset) * 1000);
+                availabilityTime = new Date(availabilityStartTime.getTime() + (presentationEndTime - availabilityTimeOffset) * 1000);
             } else {
                 // in static mpd, all segments are available at the same time
                 availabilityTime = availabilityStartTime;
@@ -268,10 +276,6 @@ function TimelineConverter() {
         timelineAnchorAvailabilityOffset = now - range.end;
     }
 
-    function getTimelineAnchorAvailabilityOffset() {
-        return timelineAnchorAvailabilityOffset;
-    }
-
     function _adjustTimeBasedOnPeriodRanges(streams, time, isEndOfDvrWindow = false) {
         try {
             let i = 0;
@@ -360,7 +364,7 @@ function TimelineConverter() {
         initialize,
         getClientTimeOffset,
         setClientTimeOffset,
-        getTimelineAnchorAvailabilityOffset,
+        getClientReferenceTime,
         calcAvailabilityStartTimeFromPresentationTime,
         calcAvailabilityEndTimeFromPresentationTime,
         calcPresentationTimeFromWallTime,