I have same issue, but I think it is a 8 - byte value.

I find that the Dask provided. by Apple can only be used to verify spc, ckc. If you want to test playback with a FPS Client, request the FPS deployment package.

Did you find a solution for this? We are also looking for a way to encrypt audio with FPS on Linux.

Have you found a way to solve your issue?

Any news on that?