[Photopuppet]

I can confirm the 4k HDR video on an SDR TV lagging and failure seems to be some kind of Kodi bug as when you cast a 4K HDR file via VLC (for example), it plays and gets tonemapped completely fine on the SDR TV. It seems the CCWGTV hardware is perfectly capable of doing the HDR->SDR realtime tonemapping conversion...

Would this one be worth filing on the Kodi bug tracker?

The same problem happens in VLC too so I'm guessing it is unfortunately some kind of bug in Google's video API that needs fixing by them. :/

I don't think it is a Kodi issue nor Android. I have the same behavior on my Android TV box (Broadcom SoC). Basically, there is no HDR->SDR tonemapping implemented. In any case, this is typically something done at SoC level and not directly an Android TV feature just like upscaling.

I believe casting from VLC works because the device casting is the one doing the tone mapping.

Do you mean VLC on my Android phone is pulling the file from the network drive, tonemapping it and then sending it via cast to the CCwGTV?