I think I'm close to setup audio passthrough through HDMI. I would need someone who can test those passtrough modes. Any volunteer? Please write which modes you can test and which board do you have.

Me。

I have both One and PC, and a home theatre system , I need OpenELEC to support DTS-HD passthrough, AFAP.

Great, do you have any coding skills? It would go much faster... Expect first test image soon after the weekend.

You'd better to create a new git branch.

I created passthrough branch at https://github.com/jernejsk/OpenELEC-OPi2/tree/passthrough

There are two things to consider:
1. kernel drivers treats samples as 24 bit but kodi as 16 bit. Probably 24 bit hack should be removed in kernel.
2. kernel patch linux-93-hdmi-fix-raw-output.patch might be needed, just remove ".disabled" from file extension to test

Please build, test and report