addChaptersTrack work in append mode, Expected?

[WINOFFRG]

Have you read the Tutorials?
Yes

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

What version of Shaka Player are you using?
v4.3.0 (uncompiled)

Please ask your question
On a running stream if we call player.addChaptersTrack it appends the newly parsed chapters to the existing one, Is this an expected behavior? Shouldn't we have a comparator that sorts the chapters based on time? This way we could handle many edge cases like:

1. Removing duplicate chapters based on id or timestamp.
2. Adding another argument to either sort and append or overwrite chapters.
3. warning on overlapping chapter tracks.
4. warning on chapters that are out of timeline range.

In case this could be considered a fix, I can work on it.

[joeyparrish]

@avelad, do I recall correctly that you wrote the chapters code? Is this a bug?

[joeyparrish]

If this is wrong, @WINOFFRG is willing to work on a fix.

[avelad]

It’s not a bug, it’s designed to work on append mode, but we need filter duplicates…

[joeyparrish]

OK. @WINOFFRG, your PR would be welcome!

[WINOFFRG]

Hi! While I was working on the fix for this, I found another issue. @avelad Can you please check and confirm this?

How are we actually handling multiple chapter tracks with same language?

shaka-player/lib/player.js

Lines 5004 to 5006 in 76f96b9

	const chaptersTrack = chaptersTracks.find((t) => {
	return t.language == language;
	});

If you check the above function, this will always return the first track of that language. Essentially the function addChaptersTrack should return that track which has been added. Say, I am adding another track of same language i.e en because of this, It will always return the first matching track.

A solution that comes to my mind is whenever we create a trackElement we must also pass an id= for the HTMLElement to that function and then instead of verifying the track existence via language we can check for that id= and return that one.

How does this look to you?

[avelad]

For me, it’s ok!