Simultcast - `remoteVideoSourcesDidChange` called with incorrect number of videoSources

What happened and what did you expect to happen?

3rd attempt to enable simulcast in our app.

remoteVideoSourcesDidChange is called with an incorrect number of videoSources

Have you reviewed our existing documentation?

• GitHub issues
• FAQs page
• README page
• Feature-specific guides

Reproduction steps

We haven’t tested to see if this can be reproduced in a simple setup, so it may apply only to our app.

Using:

• DefaultSimulcastUplinkPolicy.
• config.serverSideNetworkAdaption = ServerSideNetworkAdaption.BandwidthProbing

Layout (devices are of no relevance, except for the number of attendees):

• Device A (local)
• Device B (remote)
• Device C (remote)
• all devices have their cameras ON

When Device C hits refresh :

• A will see B as having turned off its camera (also its stream disappears), though B has not taken any action.
• remoteVideoSourcesDidChange is triggered twice; once with the remaining remote video source (B) and the second time with an empty array.
• weirdly enough, we can’t reproduce in less or more than 3 attendees
• cannot reproduce when not using simulcast

Amazon Chime SDK for JavaScript version

3.6.0

What browsers are you seeing the problem on?

any

Browser version

any

Meeting and Attendee ID Information.

No response

Browser console logs

no logs needed

[carlossantos74]

The fix has been released in the latest 3.9.0 version on Sep 21.

This version is already in the changelog, but it is not yet available npmjs, do you have any predictions for when it will be available there?

[xuesichao]

I reproduced the issue without using BandwidthProbing, and observed exact same results as previous test.

I used the same repro steps list below.

Steps:

1. Three attendees (1, 2, 3) join the meeting enabling simulcast, priorityBasedDownlinkPolicy with BandwidthProbing.
2. All of three enable camera.
3. Refresh page in the window of attendee 3.
4. From attendee 1’s window, attendee 3’s video tile disappears, and attendee 2’s video tile disappears shortly and appears.
5. From attendee 2’s window, attendee 3’s video tile disappears, and attendee 1’s video tile disappears shortly and appears.

step 4 and 5 happens at the same time.

I observed three remoteVideoSourcesDidChange events from either attendee 1 or attendee 2’s perspective:

1. videoSources contains the remaining remote attendee. (expected result)
2. videoSources is empty.
3. videoSources contains the remaining remote attendee. (expected result)

The only difference is step1. Three attendees (1, 2, 3) join the meeting enabling simulcast, priorityBasedDownlinkPolicy with Server Side Network Adaption set to None instead of using BandwidthProbing.

Got the same results:

It seems it’s not a BandwidthProbing issue. @hensmi-amazon