Rebroadcast does not support 2-way audio

[fredck]

Describe the bug
I've tried to use the rebroadcast RTSP url of a G4 Doorbell Pro device in a WebRTC Camera card in Home Assistant. All works except that audio is not sent from the microphone to the device.

To Reproduce
Steps to reproduce the behavior:

1. In Home Assistant, have the WebRTC Camera addon installed in HACS.
2. In Scrypted, have a G4 Doorbell Pro doorbell using the Unifi Protect plugin.
3. In Scrypted, copy the rebroadcast RTSP url for that camera.
4. In Home Assistant, create a WebRTC Camera card in any dashboard.
   • Set the url property to the RTSP url copied from Scrypted.
   • Set the media property to video,audio,microphone to enable 2-way audio.
5. Save the card. The camera will show up. If in a Chrome browser, note that the microphone is in use in the browser tab title (red recording icon).
6. Unmute the camera.
7. Speak.

Nothing will be heard at the device.

In fact, the device display changes to "Talk" when 2-way audio is active, which doesn't happen in the above case.

Expected behavior
Audio should be sent from the microphone and heard at the device.

Server (please complete the following information):

• OS: HassOS
• Installation Method: Home Assistant Addon

Hardware Model (please complete the following information):

• Device: G4 Doorbell Pro but maybe with other 2-way audio devices

Client (please complete the following information, if applicable):

• Software: Chrome browser on MacOS