Captions not working after a period transition on live DASH streams

[caridley]

Have you read the FAQ and checked for duplicate open issues?
Yes i do not see a duplicate

What version of Shaka Player are you using?
3.1.2

Can you reproduce the issue with our latest release version?
I am certain the problem is present but I cannot reproduce because CEA 608 captions don't work at all because of this issue
#3782

Can you reproduce the issue with the latest code from master?
No because CEA 608 captions are not working at all

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

If custom app, can you reproduce the issue using our demo app?
No because CEA 608 captions are not working at all

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

For embedded devices (smart TVs, etc.), what model and firmware version are you using?

What are the manifest and license server URIs?
We will share stream information if necessary

What configuration are you using? What is the output of player.getConfiguration()?
We will share the configuration information if necessary

What did you do?
Play a multi-period live stream with CEA 608 captions embedded and that text track selected.

What did you expect to happen?
We expect to see captions in all periods that contain captions data.

What actually happened?
Captions disappear when we transition to a new period.
Note that this problem does not occur with VOD streams

We have isolate the problem to this code in lib/text/text_engine.js storeAndAppendClosedCaptions()

if (id == this.selectedClosedCaptionId_) {
   this.displayer_.append([cue]);
}

At this point id is "CC1" and this.selectionCloseCaptionId_ is "CC1,,,," with the number of commas varying,

if we change this condition to this.selectedClosedCaptionId_.contains(id) captions work as expected.

[caridley]

I'm going to submit a pull request to fix this.