[BUG][Android] When in conference, upon switching cameras , the user can notice a small delay in the process

[bogdanmunteanu]

Describe the bug When a user is in conference and changes camera , there is a small delay in the process( 2-3 seconds )

**To Reproduce
**

1. Host a Teams conference

2. Join with an Android device with Calling 1.3.0-beta.1
3. Change participant camera
4. Notice a small delay in the process

Code Snippet

private fun checkCameraFacingSwitch() {
        consultationViewModel.cameraEnabledLiveData.value?.let { isCameraEnabled->
            if(isCameraEnabled){
                when (localVideoStream?.source?.cameraFacing?.name?.toLowerCase(Locale.getDefault())) {
                    FACING_BACK_CAMERA -> consultationViewModel.setCameraFacingFront(true)
                    FACING_FRONT_CAMERA -> consultationViewModel.setCameraFacingFront(false)
                }
            }else{
                showToast(getString(R.string.virtual_consultation_camera_off_toast))
                call?.stopVideo(context, localVideoStream)
                disposeLocalVideoStream()
                onLocalCameraNotConnected()
            }
        }?: run {
            showToast(getString(R.string.virtual_consultation_camera_off_toast))
            call?.stopVideo(context, localVideoStream)
            disposeLocalVideoStream()
            onLocalCameraNotConnected()
        }

    }

We are using a viewmodel because we want to know at anytime what the state of the camera is. The observer for the livedata is below :

        val cameraFacingObserver = Observer<Boolean> { cameraFacingFront ->
            Timber.d("cameraFacingObserver: $cameraFacingFront")
            call?.stopVideo(context, localVideoStream)
            if (cameraFacingFront) {
                fetchLocalVideoStream(FACING_FRONT_CAMERA, false)
            } else {
                fetchLocalVideoStream(FACING_BACK_CAMERA, false)
            }
        }

And the method

private fun fetchLocalVideoStream(cameraFacing: String, joinCall: Boolean) {
       val deviceManager = callClient.getDeviceManager(context).get()
       deviceManager.cameras.forEach {
           val cameraFacingName = it.cameraFacing.name
           if (cameraFacingName.equals(cameraFacing, ignoreCase = true)) {
               Timber.e("local video stream found")
               localVideoStream = LocalVideoStream(it, context)

               if (joinCall) {
                   joinCall()
               } else {
                   call?.startVideo(context, localVideoStream)

                   if (consultationViewModel.waitingRoomState.value == true) {
                       loadWaitingRoomState(localVideoStream)
                   } else {
                       loadConsultationState(localVideoStream, true)
                   }
               }
               return
           }
       }
   }

Expected behavior Camera should be changed instatly.

Screenshots If applicable, add screenshots to help explain your problem.

Setup (please complete the following information):

• OS: Android 10 (Huawei P30 Pro)
• Version of the Library used: Calling 1.3.0-beta.1