- Update ion-sfu to v1.20.14
- Enable `abs-send-time` for video tracks
Reference: ion-sfu PR - https://github.com/livekit/ion-sfu/pull/12
Testing:
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- Look at SDP offer in subscriber PC and ensure that abs-send-time is negotiated.
- Ensure that downstream packets have `abs-send-time` extension for video packets.
TODO:
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- Not yet setting this for audio tracks. Eventually we want to move
to TWCC. This is just a step along the way.
* protobuf updates to support new protocol
* use dedicated publish & subscribe peerconnections
* update client to work with dedicated PCs
* fix Go client negotiation, reduced length of UUID
