iOS: unmuting audio triggers unmute -> mute -> unmute in rapid succession

[mfairley]

I'm finding that when you mute via

room.localParticipant.setMicrophoneEnabled(false)

and then later unmute via

room.localParticipant.setMicrophoneEnabled(true)

iOS registers unmute -> mute -> unmute in rapid succession. The final result is still unmute but rapidly firing these actions may cause problems and makes the mute state flicker. I know this is happening because I am using a custom native module to enable CallKit and I added logging whenever a mute action takes place. If I unmute using the CallKit UI then I see only one event so I know it's related to webrtc/LiveKit.

This might be related to livekit/client-sdk-react-native#287

@livekit/react-native@2.9.6
@livekit/react-native-expo-plugin@1.0.1
@livekit/react-native-webrtc@137.0.2

[mfairley]

This should probably be transferred to https://github.com/livekit/client-sdk-react-native or https://github.com/livekit/client-sdk-js/. I did further testing and found that the following does not trigger the issue, suggesting it is related to the way muting is tracked in the React Native SDK.

 const track = room.localParticipant.getTrackPublication(
      Track.Source.Microphone
    )
const mediaStreamTrack = track?.track?.mediaStreamTrack
mediaStreamTrack.enabled = enabled

[mfairley]

I think figured out the bug. When LiveKit unmutes a track, it checks if deviceHasChanged here https://github.com/livekit/client-sdk-js/blob/main/src/room/track/LocalAudioTrack.ts#L77 and compares {ideal: "default"} against audio (which is what the deviceId is for iOS) and so LiveKit restarts the audio track every time it unmutes even though the device hasn't actually changed. The restart triggers an unmute but then isMuted is still set to true so here https://github.com/livekit/client-sdk-js/blob/main/src/room/track/LocalTrack.ts#L205 the track is muted before being unmuted again here https://github.com/livekit/client-sdk-js/blob/main/src/room/track/LocalAudioTrack.ts#L90