Problem with presentationTimeOffset and mediaPresentationDuration when the playing period crosses more than 1 segment

[ctt828]

Have you read the FAQ and checked for duplicate open issues?
yes

What version of Shaka Player are you using?
v2.5.11

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

Can you reproduce the issue with the latest code from master?
yes

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

What browser and OS are you using?
Chrome on macOS

What are the manifest and license server URIs?
Sent via email

What did you do?

• Original manifest : Total Segments : 2, Segment duration : PT1M0S.
• Use presentationTimeOffset to skip the first segment for 50 seconds, and let the playing period start from there.
• Set the mediaPresentationDuration to PT0M30S

What did you expect to happen?
A 30 seconds of play duration which starts from the first segment with 50 seconds skipped.

What actually happened?

• Only the rear part of the first segment (10 Seconds) is played if "PT0M11S <= mediaPresentationDuration <= PT1M0S"
• It works if "mediaPresentationDuration >= PT1M1S"
• It works with DASH.js reference client 3.1.0

[TheModMaker]

So I think this is a bug in our presentationTimeOffset handling. I remember a lot of confusion about how this is handled with segment times and we've had a bunch of bugs with this property and startNumber in the past.

The segment's presentation time should use the PTO to adjust the S@t value; right now we ignore it for calculation of presentation time.