Add autoLowLatencyMode config

[avelad]

It is not always known if a stream is low latency or not (for example, when adding streams from multiple providers). To avoid having to use a responseFilter, a configuration is added to enable low latency automatically.

Related to #1525

[avelad]

@michellezhuogg This is related to your work in low latency, can you review?

[michellezhuogg]

Hello @avelad ,

Thank you! What are the scenarios to use this config? How would it interact with lowLatencyMode config?

[avelad]

@michellezhuogg
Use a default config with:

• lowLatencyMode = false
• rebufferingGoal = 2
• inaccurateManifestTolerance = 0
• autoLowLatencyMode = true

In a Live TV app with a mix of providers and mix of low latency
Stream A (low latency), Stream B, Stream C, Stream D (low latency)

• set default config
• load Stream A
• set default config
• load Stream B
• set default config
• load Stream C
• set default config
• load Stream D

In stream A and D the player automatically chooses the low latency mode, in stream B and C the player takes the conservative values ​​of not low latency

Note: the application does not know which of the previous streams is low latency, but in the streams in which it is available it activates it by default.

[joeyparrish]

@avelad, low latency mode would inhibit response filters for media segments (but not for manifests or license responses), would require the accurate manifests (inaccurateManifestTolerance=0), and would use a low startup/rebuffering goal (rebufferingGoal=0.001) to allow playback to start with less than one segment of content.

Which of these things is a problem for your scenario? If some of your content is low-latency, could you not just turn on low latency mode?

In fact, for DASH, and even for VOD, lowLatencyMode=true could result in faster startup times even without low-latency features in the manifest. So the main reason to avoid it is if you need segment response filters.

[avelad]

@joeyparrish
Speaking of LIVE streams.

The scenario is not knowing if the stream is low latency or not.

I always use inaccurateManifestTolerance = 0 by default, but using rebufferingGoal = 0.001 by default on non-low latency streams can be a problem in my case.

For VOD I have no problem.

[avelad]

Any news?

[michellezhuogg]

Hello @avelad ,

Sorry for the late reply.

1. Would you please help us understand better your case and the problem with using rebufferingGoal = 0.001 by default on non-low latency streams?
2. What will enableLowLatencyMode do?
3. What happens when:
   lowLatencyMode = true && autoLowLatencyMode = false?
   lowLatencyMode = true && autoLowLatencyMode = true?

Thank you!

[avelad]

HI @michellezhuogg,

1. In many cases I need a rebufferingGoal = 1.5 * segmentLenght to avoid new rebuffering
2. enableLowLatencyMode activate the lowLatencyMode flag if the stream loaded is a low latency stream.
3. lowLatencyMode always takes precedence, so if the lowLatencyMode value is activated autoLowLatencyMode has no effect

I have been carefully studying the need for this, and the alternative is to use filters to determine if the manifest is low latency and change the rebufferingGoal setting.

Thanks,

[michellezhuogg]

Makes sense to me, and we need better document or comments to explain how lowLatencyMode / autoLowLatencyMode work for other developers.
Thank you!

[michellezhuogg]

Please add comments here to explain how lowLatencyMode & autoLowLatencyMode works.

[avelad]

Done!

[michellezhuogg]

Please add more comment here to clarify how autoLowLatencyMode interacts with lowLatencyMode.

[avelad]

Done!

[shaka-bot]

All tests passed!

[avelad]

@michellezhuogg Is there anything else I can do so this PR can be merged?