Why do I have to enable screen & audio recording on MacOS?

Docks, Hubs, Display Adapters
1

I just received my StarTech USB-C Triple 4K Monitor dock and installed the driver software on my Mac Book Pro M3 system with running MacOS Sonoma 14.2.1. While I understand that the M3 system claims to support only one external monitor, I was very happy to hear that the docking station allowed multiple monitors. However, I don’t understand why I have to enable the DisplayLink Manager to record screen and audio on my system. When I disable that setting, my 2nd monitor goes black and only comes back when I turn it back on.

I would like to know what this setting has to do with making the 2nd monitor work and what is actually being recorded. Is there any way to get the 2nd monitor to working without opening this hole in my privacy and security settings?

I’m thinking others might be interested in this as well given that the setting is recommended for all Mac installations.

Thanks,
Debbie

2

Hello @debbie and thank you for your interest in our Community.

Since macOS Catalina, your system requires the user to permit “Screen Recording” for DisplayLink driver to work properly. Approving it enables the DisplayLink to access the pixels it needs to render a mirrored or extended screen and send the pixels over USB from your computer to the DisplayLink display. It does not send any data or pixels back to DisplayLink. It is simply how Apple named this permission which rather refers to accessing and controlling your display, which is needed in order to generate such display.

We certainly do understand the confusion around the permission’s name. You can read more about it no DisplayLink’s Knowledgebase article here.

I hope this helps! Please let us know if there is anything else we could do to help.

Emmanuel B.

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4

To add some extra context, when installing a USB graphics device such as a USB display adapter, or a Triple 4K dock as in your case, you are installing a virtual display that is only present when the appropriate hardware is connected.

Now, why is this a virtual display? Simply put, because it’s over USB. Normal graphics in a computer are connected either directly to the CPU, the main chip of the computer, or via PCIe which is a special type of internal connection. As this connection isn’t over PCIe which is what operating systems expect for graphics output, they just don’t/can’t output directly to the port on the USB device. This is where the driver you installed, and the chip in the USB device come in. Together they:

  1. Create a virtual display
  2. Tell the operating system (Windows, macOS, etc) that the virtual display exists and you can send video to it
  3. Output video to that virtual display
  4. Record that virtual display, and only that virtual display
  5. Redirect that recorded footage directly to the chip in the USB adapter which then sends it out to the video port(s) on the USB graphics solution

As @EmmanuelB advised, in macOS 10.15.x Catalina Apple added a setting relating to your screen being recorded which catches this process and flags it for your attention, because that is what is happening with the virtual display. No other screen is recorded, and no data is sent anywhere external to the computer as Emmanuel mentioned as well, and as DisplayLink advises on their site.

This is also why if you disable that screen recording permission, you don’t see anything from some ports on the dock. That virtual display isn’t being recorded and so there is no video to be redirected, so you just get no signal.

Justin Weaver (He/Him)
Technical Lead, Customer Support Operations

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