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moq-wg / moq-transport

draft-ietf-moq-transport
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No way to keep two subscriptions with identical priority in sync #475

Open ianswett opened 6 days ago

ianswett commented 6 days ago

If two subscriptions have identical priority, the current way to ensure both receive enough data is based on the Object receipt time at the relay.

If one subscription experiences a large delay at any stage, which could even include delay in publication of one track vs another for the same content (ie: transcoding), it would be easy for them to become substantially out of sync, potentially impacting QoE, particularly for very low latency use cases.

Three suggested ways forward include: 1) Decide this is not a problem we care to solve 2) Decide we want to enable syncing, but don't care about actual time 3) Decide we care about actual time for use cases like server-side ABR and include a relative timestamp

afrind commented 6 days ago

Individual comment:

This is a use case I care about, I’d like to see a method of synchronization included in moqt.

I don’t have a strong preference about using time or not.

ianswett commented 6 days ago

As an individual:

I believe using the timestamp enables server side ABR, which I believe is valuable, but there may be other mechanisms that enable that.