period@start time is missing in presentationTimesUs calculation of EventStream

Version

Media3 main branch

More version details

We have encountered with an issue with the Event@presentationTime calculation in Exo Player. Based on the Exo Player logic, the event’s presentation time is calculated as:
Event@presentationTime - EventStream@presentationTimeOffset

Here is the manifest for reference:

<Period id="173" start="PT14H17M58S">
  <EventStream schemeIdUri="metadata-update" timescale="1000" presentationTimeOffset="51478000">
    <Event presentationTime="11211" id="2054">...</Event>
...

This results in a presentation time of -51466789, which is way before the Period's start time and this appears incorrect.

Referencing the MPD events timing model in the DASH spec, The formula for the event start:

The ST of an MPD event, relative to period start time of Period containing the Event, can be calculated using values in its EventStream and Event elements:
ST = PST + (PT - PTO)/TS
where:
— PST is the Period start time of the Period containing the event stream.
— PTO is the presentation time offset of the Event Stream provided by EventStream@presentationTimeoffset.
— TS is the value of EventStream@timescale.
— PT is the value of EventStream@presentationTime.

Which is:
PST = PT14H17M58S = 51478S
PT = 11211
PTO = 51478000
TS = 1000
Based on the given formula:
ST = PST + (PT - PTO) / TS
The calculated Event Start Time is 11.211 seconds.

However, ExoPlayer provides a presentation time of -51466789, which indicates that ExoPlayer does not appear to follow the latest DASH specification (Edition 5).

Dash Spec: https://standards.iso.org/ittf/PubliclyAvailableStandards/c083314_ISO_IEC%2023009-1_2022(en).zip

I checked the Exo Player code and found that parseEvent() API of DashManifestParser, It calculates the presentationTime time as below:

    long presentationTimesUs =
        Util.scaleLargeTimestamp(
            presentationTime - presentationTimeOffset, C.MICROS_PER_SECOND, timescale);

Which does not follows the latest Dash Spec(Edition 5).

Reference:

Devices that reproduce the issue

Any Android Device

Devices that do not reproduce the issue

No response

Reproducible in the demo app?

Yes

Reproduction steps

Play a live event which has the EventStream with EventStream@presentationTimeOffset and EventStream@presentationTime.
When we get the EventStream.presentationTimesUs it returns the incorrect PT time.

Expected result

While creating the EventStream instance, We should also add the period@start time in presentationTimesUs to follow the DASH specification.

Actual result

While creating the EventStream instance, We are not adding the period@start time in presentationTimesUs.

Media

NA

Bug Report

• You will email the zip file produced by adb bugreport to android-media-github@google.com after filing this issue.