feat: add a live sync panic mode

[gkatsev]

This PR introduces a live sync panic mode (streaming.liveSyncPanicMode) which sets the player into the streaming.liveSyncMinPlaybackRate while we're within the streaming.liveSyncPanicThreshold. This should help reduce the change of subsequent rebuffering events by moving further away from the live edge.

Part 1 of potentially 3 of #6131.

[avelad]

Just one question, have you tested that this code works well in src=? (e.g. HLS in Safari)
Otherwise, LGTM!

[gkatsev]

I did not test this extensively, yet.

[gkatsev]

Seems to be working. I was thinking that it wasn't kicking in enough and then I realized I needed to convert the threshold into ms.

Also, when playing back live HLS in chrome, it basically always stopped here:

shaka-player/lib/player.js

Lines 5657 to 5661 in 35b8fb1

	const currentTime = this.video_.currentTime;
	if (currentTime < seekRange.start) {
	// Bad stream?
	return;
	}

But otherwise, seems to be working as expected for DASH and for live hls on safari.

[avelad]

Seems to be working. I was thinking that it wasn't kicking in enough and then I realized I needed to convert the threshold into ms.

Also, when playing back live HLS in chrome, it basically always stopped here:

shaka-player/lib/player.js

Lines 5657 to 5661 in 35b8fb1

	const currentTime = this.video_.currentTime;
	if (currentTime < seekRange.start) {
	// Bad stream?
	return;
	}

But otherwise, seems to be working as expected for DASH and for live hls on safari.

For it to work in HLS Live in Chorme you need to useSafariBehaviorForLive = false. I have tried and with this it works correctly.

[gkatsev]

For it to work in HLS Live in Chorme you need to useSafariBehaviorForLive = false. I have tried and with this it works correctly.

Ah, Ok, I was missing something 🙂.

Thanks!