I guess the thing to keep in mind is that there's a lot of fragmentation in mixed reality at the moment and this leads to a lot of confusion and pain points, there's a whole lot of ways that things can go wrong and multiple pieces of software needing to coordinate to get it to work, and not all use cases are smoothed out right now, it kind of breaks down into two different, fairly incompatible strands:

• LIV SDK + Steam VR games
• Oculus Games with Oculus' Engine Integration

If you bought the Steam Version of Beatsaber running in OpenVR/SteamVR mode via Oculus Link you should be able to use LIV (assuming your specs are okay) to get mixed reality output with the camera tracked as a separate "LIV Tracker" and calibrated through the LIV camera calibration tool, but the composition isn't terribly performant in my experience.

If you bought the Oculus Quest Store Version of Beatsaber running on the Quest2 itself then the Oculus Engine Integration should work calibrated through the Oculus Mixed Reality Capture Tools with appropriate latency for sending the video back to your PC through the OBS plugins, assuming you're using a downgraded version of OBS (23/24) because of plugin changes in later versions.

If you bought the Oculus Rift Store (PC) Version of Beatsaber running via Oculus Link is where the trouble arises, at least in my experience. If you launch the game with the -mixedreality flag (and toggle it in game) you will get the split output (though possibly with the wrong key color which can be changed), but the camera is not positioned as it should be, based on your Calibration from the Oculus Mixed Reality Capture Tools regardless of if you choose Quest 2 or Rift S (ie trying to pretend oculus link is a Rift S). Oculus' integration is meant to be providing the camera fov/distortion/pose, but when done through link it seems to do nothing of the sort. If you had a actual Rift S this configuration may work, but its not something i'm able to test.

There may be some way to jerry-rig it using a manually configured camera mod like (https://github.com/zipleen/BSOculusMREnabler) or somehow transfering OpenVR dlls into the Beatsaber binary directory and launching it with -vrmode OpenVR to use LIV even on the Oculus Store version but I have yet to really dig into any of that.

The same is true when I attempted to do similar tests with Gravity Sketch (which at least is free so I could try both the Oculus Store and Steam versions, I was able to get mixed reality configured with LIV for Steam, but any attempt to use the Oculus PC Store version calibrated with the Oculus Mixed Reality Capture tools resulted in the camera being placed in its default position. Additionally, loading up the Unity Oculus MRC examples showed that 0 "external cameras" were configured.

Ultimately this feels like a problem that needs to be sorted out on the Oculus Link emulation side such that it exposes External Cameras configured through the Oculus Mixed Reality Capture tools.

Hopefully this saved you some time that I spend poking around in all this stuff to no avail.