Can the virtual camera created by MFCreateVirtualCamera be used simultaneously by multiple applications?

[BingoZha]

I created a virtual camera using VirtualCameraManager_App, but it can only be accessed by one application at a time. Is this due to a configuration issue, or is it a limitation of the MFCreateVirtualCamera function?

[LPBourret]

Hi,
a virtual camera will behave like a real camera; there can only be 1 app/client using a camera source with "Exclusive control" (https://learn.microsoft.com/en-us/uwp/api/windows.media.capture.mediacapturesharingmode?view=winrt-26100), the other apps would need to use this camera in "Shared mode" to access it concurrently to the other "Exclusive Control" app. This is for example something the page in Windows Settings -> Bluetooth & devices -> Cameras -> <your camera name> does so that you can preview from a camera already in use elsewhere.

[BingoZha]

Hi @LPBourret ,
Thank you for your reply. As you mentioned, the preview in Windows Camera can indeed use the camera in "Shared Mode." However, in the following scenario, when you use the Windows Camera app to open the virtual camera from this project, other software, such as OBS or web-based online camera tools, cannot access it simultaneously. On the other hand, a virtual camera from OBS can be opened by multiple applications at the same time.

[LPBourret]

Hi,
Yeah in your case I assume here that web clients and OBS will also attempt to acquire the camera in "Exclusive control" and since Camera App is already running in that mode as well, it prevents others from doing so.
As for the "virtual camera" from OBS, it is a DShow filter (https://learn.microsoft.com/en-us/windows/win32/directshow/directshow-filters) and not an IMFVirtualCamera; DShow is considered legacy technology at this point (not worked on anymore nor encouraged to use v.s. newer MF APIs) and will not register a camera source for all categories that apps are aware of and looking for. Such DShow filter virtual camera for example will not be available in apps like Windows Camera App or Windows Settings page alluded to above.. and the camera driver capability set it can implement are limited (i.e. no extended control, single pin, etc.) compared to IMFVirtualCamera, and can incur issues if modified from 1 client while concurrently used from another. Some apps do still support DShow sources in some capacity such as Teams, Skype, Zoom.

That said.. stay tuned, in 24h2 we have been thinking about a scenario (Multi-App Camera Access) where a user can decide to provision their camera as if all apps are using a "sharing mode", allowing such sharing regardless of the app opening in "exclusive control".

[BingoZha]

Hi @LPBourret ,
Can you recommend any applications (not Windows internal camera) which can set "sharing mode" option so that multiple applications can access it concurrently?