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Fix wrong timing calculation for client/server clock drift. #3759

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merged 2 commits into from
Sep 6, 2021
Merged

Fix wrong timing calculation for client/server clock drift. #3759

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110a415
Fix wrong timing calculation for client/server clock drift.
dsilhavy Sep 6, 2021
04d6bfc
Move reference time calculation to SegmentsUtils.js
dsilhavy Sep 6, 2021
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4 changes: 2 additions & 2 deletions src/dash/utils/SegmentsUtils.js
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Original file line number Diff line number Diff line change
Expand Up @@ -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

const refTime = timelineConverter.getAvailabilityWindowAnchorTime();
// 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);
return segment.availabilityStartTime.getTime() <= refTime && (!isFinite(segment.availabilityEndTime) || segment.availabilityEndTime.getTime() >= refTime);
}

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18 changes: 9 additions & 9 deletions src/dash/utils/TimelineConverter.js
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Original file line number Diff line number Diff line change
Expand Up @@ -67,7 +67,7 @@ function TimelineConverter() {
clientServerTimeShift = value;
}

function calcAvailabilityTimeFromPresentationTime(presentationEndTime, representation, isDynamic, calculateAvailabilityEndTime) {
function _calcAvailabilityTimeFromPresentationTime(presentationEndTime, representation, isDynamic, calculateAvailabilityEndTime) {
let availabilityTime;
let mpd = representation.adaptation.period.mpd;
const availabilityStartTime = mpd.availabilityStartTime;
Expand Down Expand Up @@ -99,15 +99,15 @@ function TimelineConverter() {
}

function calcAvailabilityStartTimeFromPresentationTime(presentationEndTime, representation, isDynamic) {
return calcAvailabilityTimeFromPresentationTime.call(this, presentationEndTime, representation, isDynamic);
return _calcAvailabilityTimeFromPresentationTime(presentationEndTime, representation, isDynamic);
}

function calcAvailabilityEndTimeFromPresentationTime(presentationEndTime, representation, isDynamic) {
return calcAvailabilityTimeFromPresentationTime.call(this, presentationEndTime, representation, isDynamic, true);
return _calcAvailabilityTimeFromPresentationTime(presentationEndTime, representation, isDynamic, true);
}

function calcPresentationTimeFromWallTime(wallTime, period) {
return ((wallTime.getTime() - period.mpd.availabilityStartTime.getTime() - clientServerTimeShift * 1000) / 1000);
return ((wallTime.getTime() - period.mpd.availabilityStartTime.getTime() + clientServerTimeShift * 1000) / 1000);
}

function calcPresentationTimeFromMediaTime(mediaTime, representation) {
Expand Down Expand Up @@ -138,10 +138,6 @@ function TimelineConverter() {
return wallTime;
}

function getAvailabilityWindowAnchorTime() {
return Date.now() - ((timelineAnchorAvailabilityOffset + clientServerTimeShift) * 1000);
}

/**
* Calculates the timeshiftbuffer range. This range might overlap multiple periods and is not limited to period boundaries. However, we make sure that the range is potentially covered by period.
* @param {Array} streams
Expand Down Expand Up @@ -272,6 +268,10 @@ function TimelineConverter() {
timelineAnchorAvailabilityOffset = now - range.end;
}

function getTimelineAnchorAvailabilityOffset() {
return timelineAnchorAvailabilityOffset;
}

function _adjustTimeBasedOnPeriodRanges(streams, time, isEndOfDvrWindow = false) {
try {
let i = 0;
Expand Down Expand Up @@ -360,7 +360,7 @@ function TimelineConverter() {
initialize,
getClientTimeOffset,
setClientTimeOffset,
getAvailabilityWindowAnchorTime,
getTimelineAnchorAvailabilityOffset,
calcAvailabilityStartTimeFromPresentationTime,
calcAvailabilityEndTimeFromPresentationTime,
calcPresentationTimeFromWallTime,
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