Shaka 3.0.1 is not raising DASH timed metadata correctly on a DAI stream

[TheSouryaRoy]

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

What version of Shaka Player are you using?
3.0.1 (issue is not present in Shaka 2.5)

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?
Own custom app (link below)

If custom app, can you reproduce the issue using our demo app?
Could not extract timed metadata from the demo app

What browser and OS are you using?
Chrome 83, MacOS 10.15.5

What issue are you facing?
We are playing a DAI stream on Shaka Player 3.0.1 with IMA SDK. Instead of incrementally raising the timed metadata events as they are encountered, Shaka Player is raising a bunch of them all at once. As a result, our ad measurement pings are being fired incorrectly.

We tried to reproduce the issue on Shaka 2.5, but were unsuccessful. This seems to us a Shaka 3.x-only issue.

What did you do?

1. Went to demo app: https://storage.googleapis.com/gvabox/sanils/h5/dai/shaka_test/dai_shaka_3.0.1.html
2. Used Asset Key: 0ndl1dJcRmKDUPxTRjvdog
3. Hit "Request Live"

For reference, here is the manifest link: https://dai.google.com/linear/dash/pa/event/0ndl1dJcRmKDUPxTRjvdog/stream/4a68c85b-002d-4a69-b1d6-6eadcbbf32d4:ATL/manifest.mpd

What did you expect to happen?
Timed metadata events are being raised as they are encountered in the stream.

What actually happened?
Timed metadata events are not being raised as they are encountered in the stream, and instead are being raised all at once after some delay.

[TheSouryaRoy]

Quick addition: This is only observed after you have the stream running for 20-30 mins.

[ismena]

Just to confirm:

• when you mention 2.5 doesn't have the issue, do you mean that it's working correctly?
• in 3.0.1, does it work as expected for the first 20-30 minutes?

[karlandersson]

Yes, for 2.5 it looks to be working correctly while for 3.0.1 it works in the beginning but stops working after a an amount of time.

[joeyparrish]

Does that time roughly correspond to the period boundaries (ad boundaries?) in the content?

[karlandersson]

Yes, we believe so

[ismena]

Ok, we made some changes to how we handle periods in 3.0+, sounds like it might've screwed up our timed event parsing/raising. We'll investigate.

[ismena]

@TheSouryaRoy @karlandersson
Starting to look into this! This might be a bit far fetched, but please let us know if you have a piece of content with shorter periods where the issue can be reproduced. We can (and will) definitely work with this one, but a repro cycle of 20-30 minutes means a bit of a long iteration.
I'll try to come up with a test to repro the issue in the meantime, now that we have some idea where the problem might lie.

[joeyparrish]

What if we start playback at a time right before the first period transition? Would that still reproduce the issue, but faster?

[ismena]

@joeyparrish It's a live stream with a limited seek window! :)
There's a fair amount of luck involved in what you get when you load :)
I'll sync with you offline though, for more ideas on how to possibly speed this up.

[TheSouryaRoy]

Thanks @ismena and @joeyparrish for looking into this. We'll try to see if we can reproduce during a shorter time period and get back.

On a related note, we have observed Shaka 2.5 to drop some of the metadata at period boundaries, but interestingly that is not happening on Shaka 3.0.1 (more details: #2723).

[TheSouryaRoy]

Haven't been able to find a way to speed things up, still taking 20-30 mins for the stream to run before the issue appears. Also, we have period transitions (ads) in the stream every 30 or so seconds, so even if you move right before the period transition, it would not be of much help.

Will keep on trying and update the thread if I have luck in reproducing this faster.

[ismena]

SG @TheSouryaRoy. We are also trying to repro it in a test to figure out what exactly might be going on.

I've seen the repro on your demo page, trying to get one on my local build now with added logging.

[ismena]

This (Murphy's law!) doesn't seem to repro on my local build (the latest master). Trying the stable 3.0.1 to check if the problem happened to be fixed with one of the latest changes in master.