localParticipant.publish(videoTrack:) does not have sound until microphone is turned on

[lucasfischer]

Describe the bug
For the macOS app I am building I want to stream the systems's audio or app's audio to other participants in the room. Currently this only seems to work when I also enable the microphone via localParticipant.setMicrophone(enabled: true).

This creates some issues for me because users should be able to use my app without giving microphone permissions.

To have at least some working solution I used the following code to mute the user's microphone and only play the app audio via screen sharing.

AudioManager.shared.mixer.micVolume = 0
AudioManager.shared.mixer.appVolume = 1.0

But this always shows the microphone indicator and means that macOS automatically ducks/turns down the system volume, which is unwanted behavior for my app.

SDK Version
2.6.0

iOS/macOS Version
macOS 15.5

Xcode Version
Xcode 16.4 w/ Swift 6.1.2

Steps to Reproduce

let track = LocalVideoTrack.createMacOSScreenShareTrack(
    source: screenShareSource,
    options: ScreenShareCaptureOptions(dimensions: .zero, fps: 0, appAudio: true)
)
screenShareTrack = try await room.localParticipant.publish(videoTrack: track)

Expected behavior
I expect to be able to stream the audio of a display or window to other participants without having to activate the microphone.

Thank you for your work on this SDK. It's very simple to use and got me up and running really fast. I acknowledge that this library seems to be more optimized for conferencing and my use-case is live-streaming. I would be thankful for your help.

[hiroshihorie]

Unfortunately this is a limitation that custom audio frames are just mixed with mic audio. So mic track needs to be published.

[lucasfischer]

Is that a limitation, which potentially could get lifted in the future?

[lucasfischer]

Currently trying to find ways around this limitation to make this SDK work for us.

Is there a way to not duck the system audio while mic audio is published?