Dash <eventstream> presentationTimeOffset not taken into account

[wvanhaevre]

What version of Shaka Player are you using?

4.11.1 Demo player on Chrome: link

Can you reproduce the issue with our latest release version?
Yes

Can you reproduce the issue with the latest code from main?
Yes

Are you using the demo app or your own custom app?
The demo page

If custom app, can you reproduce the issue using our demo app?
Yes

What browser and OS are you using?
Mac OS / Chrome

For embedded devices (smart TVs, etc.), what model and firmware version are you using?
Does not apply

What are the manifest and license server URIs?

These cannot be shared as they are proprietary. The issue is however clear from the code: link

What did you do?

Start playing a dash stream containing an eventStream that has the presentationTimeOffset attribute set to a none 0 value. The parsed events get a startTime that does not take into account the presentationTimeOffset of the eventStream. Only the startTime is used in relation to the PeriodStart.

<Period id="21" start="PT1725017471.892S">
		<BaseURL>.../</BaseURL>
		<EventStream presentationTimeOffset="273000000" timescale="1000" schemeIdUri="...">
			<Event presentationTime="273000000" id="249" messageData="..."/>
			<Event presentationTime="273006006" id="250" messageData="..."/>
			<Event presentationTime="273018018" id="251" messageData="..."/>
			...
		</EventStream>
		<AdaptationSet contentType="video" segmentAlignment="true" bitstreamSwitching="true">
			<InbandEventStream schemeIdUri="..." value="0"/>
			<Representation id="video-0" mimeType="video/mp4" codecs="avc1.64001e" bandwidth="400000" width="416" height="234">
				<SegmentList presentationTimeOffset="273000000" timescale="1000" startNumber="44">
					<SegmentTimeline>
						<S d="6006" t="273000000"/>
						<S d="6006" t="273006006"/>
						<S d="6006" t="273012012"/>

This sample should 'enter' the cue with id 249 at the moment the first segment from this period is played. However, the event startTime is not taking into account the presentationTimeOffset="273000000", resulting is a wrong startTime

What did you expect to happen?
There should be a shift in the event timeline equal to the presentationTimeOffset

What actually happened?

presentationTimeOffset was not taken into account.

Are you planning send a PR to fix it?
No