Bandwidth limit for 2 users with slow ISP?

My ISP connection provides 7Mbps download / 768kbps upload (on DSL). I can open a Jitsi connection on the main Jitsi demo server at https://meet.jit.si/ and talk to others just fine.

But the camera image freezes if I create a second connection from my house (or someone else here makes a connection.) The connection quality (small colored circle in the thumbnail) is yellow or red, and shows “Nonoptimal” or “Poor” connection.

Looking at [jitsi-users] Recommended bandwidth/perf for a Jitsi Meet server, it appears that each Jitsi client connection requires 4-5 Mbps upload and download capacity.

So is that a complete explanation for this observed behavior? That there’s no way to run two Jitsi sessions on such a slow ISP link? Are there any workarounds? Thanks.

You can enable audio-only mode for both participants and that whould work. But doing video on this link will not work very well.

Update: Firefox Developer version works a lot better on slow internet connections than earlier (stable, released) versions of Firefox. Test conditions:

  • Running Firefox Developer version 76.0b6 on macOS 10.15.3
  • Testing against current meet.jit.si as of 21Apr2020. It’s hard to find what versions are actually being served.
  • Slow ISP link - 7mbps down, 768kbps up (DSL)
  • Monitoring the traffic on my outside link to my ISP
  • All meeting windows allow access to camera and microphone, microphone immediately muted to avoid feedback. (This means no testing of audio.)
  • Manage video quality using default “High Definition” in all sessions.

Starting the experiment:

  • Create a meeting on meet.jit.si. Traffic is nominal (about 1-2% of ISP link) Background traffic dominates the stats.

  • Open a second window to the same meeting. Video quality is usable for talking: slight lag, and you can see heads and mouths moving. Traffic on ISP link grows to about 500-550kbps (65-70% of upload link). Connection status displays Nonoptimal or Poor connection with about 200 kbps down, 220-250kbps up.

  • Open a third window to the meeting. Video quality degrades further, lags more. Traffic on ISP link goes to ~85-90% of capacity. Individual windows show Poor connection, about 200kbps down, 125kbps up.

  • Open a fourth window. A couple other window’s video freezes. Traffic on ISP link stays at 85-90% of capacity. Individual windows show Poor quality, with either 125kbps up, or N/A. Not usable.

Additional experiments that occur to me:

  1. What is the effect of using Standard video quality?
  2. Is it possible to share screen?

TL;DR: Each meeting window creates about 200kbps of traffic up and down on the client machine.

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