ULL
Scribe: Will Law
ULL - why not use multicast? Does not provide a solution to the congestion problem, compared to HTTP caches. Most congestion occurs in last 10 meters.
Buffer bloat is a problem. In Brazil, got 10% more watch time by turning on BBR as CC algo.
L4S? addresses buffer bloat specifically. ECN also exists.
What is latency from origin to edge? Most accrues in the client. CDN has little latency.
Pierre-Anthony - why not push to edge when content is not cached?
Luke - that is MOQ. We push groups, that are independent of one another, we also prioritize between tracks. RTT is not the source of latency. Buffer bloat is mostly cause of congestion, as well as loss.
FF study - network was faster than local (spinning) disk.
Bursting on the network helps compared to frame-by-frame. That is why chunks of 200ms might send faster than individual frames.
Player has 15s latency - that is not caused by RTT. Mostly caused by queuing, loss and retransmission. Most players have a large buffer, that is there to protect the player from throughput variations.
LL streaming - boundary is how fast you can switch away from content you can’t consume.
Some use RTP with FEC, assumes packet loss is the cause of congestion. Solution is to drain queue and scale down data that is being sent. Report that mobile networks will queue up to 60s.
Depends who are you optimizing for.
First and last mile are the problems. Nice if there is one protocol for both.
Old ISPs? are some of the worst offenders. Also want money for better peering.
Routing is cheapest path, not best performing path.
Not much middle ground between HLS/DASH and WebRTC?.
Some using LL-HLS for more stable but not necessarily lower latency.
Some consider LL-DASH less well known than LL-HLS.
IETF SCONE-PRO helps communicate throughput levels.
CC algos optimizes for throughput or latency.
MOQ allows you to prioritize different tracks against each other.
We ran a speed test using fast.com between different devices at the same table. Huge range in results from 20Mbps - 340Mbps.
Action items:
Promote MoQ?, get involved.
Promote prioritization of H3 with segmented media.