Thank you @sam_nazarko, and thank you @Chillbo particularly for all your patience in helping us work through this.
I think this is also working for me now as well. I’m using the same settings that @james.a.milner posted earlier, with DD+ also enabled, all via ARC. As a result, i’m getting:
DD 5.1 passed through
DD+ 5.1 passed through (I think. It may actually be transcoding to regular DD 5.1)
DTS 5.1 passed through
TrueHD transcoded to DD 5.1
DTS-HD MA transcoded to DTS 5.1
AAC 2.0 output as PCM 2.0
AAC 5.1 transcoded to DD 5.1
All output just fine. The only problem i’m still experiencing is that now John Oliver files are stuttering unwatchably (they were ok before transcoding was switched on), but that looks to be a quirk of a specific encoder because they’re the only files i’ve found with the problem.
I think part of the problem you had in getting this into my head was the fact that setting my speakers to 2.0 seems completely counter-intuitive. I realise now that this doesn’t apply to passthrough, and is a means to enable transcoding, but that isn’t super-obvious in the Kodi GUI. I also struggled with the fact that my AVR supports native TrueHD and DTS-HD MA, so why would I want to transcode them? It all felt completely backwards.
I did read through the Wiki articles you linked, and I think the repeated emphasis that S/PDIF only supports 2-channel LPCM is slightly misleading (especially when I was also setting my speakers to 2.0) because we’re trying to achieve 5.1 output.
Theres also a bit of “If this, then that, except when” involved. For example, my situation matches the section titled “Recommended audio settings when using your AVR/soundbar/TV’s HDMI input” but i’ve ended up using a combination of settings from that section and the following one to get the desired result. I know that is called out in the text, but it becomes a bit of a logic maze to follow.
I honestly don’t know how you could write it up any better though. There are quite a few different technologies and use cases that you need to cover, and you do call out everything the user needs to know, so it should work.
In any case, thank you for your perseverance. I really appreciate it. I now have 4k HDR video and multi-channel surround sound. Its a fantastic result, and you guys are awesome with your support