Tests on the Amlogic S905X3 (Odroid C4) got the device to boot from the image, however the resolution is stuck at 1080p due to some GUI and scaling issues. Switching to 1280x720p60hz yields a distorted, almost thick interlaced image squashed in the vertical axis on the top 1/5th of the screen. It is nearly intelligible to navigate. Switching the resolution to 3840x2160p60hz will usually yield a black screen, followed by the device automatically backing down to 1080p. The displays detect 2160p30hz before the signal resets. You can add an advancedsettings.xml to the storage/.kodi/userdata folder through an SSH connection into the odroid to force 2160p60hz by adding the following lines of code. Adding an advancedsettings.xml file will override the guisettings.xml and will grey out the associated line in the openpht menu.
Upon adding these lines that will force it into 2160p60hz, it will launch into black screen after boot. If you blindly use the remote to navigate to a 4K HDR file, the file will play, and the screen will show an image in 2160p24hz and the display will switch to HDR, but the video will only play in the top left quadrant of the screen (a 1920x1080 size image). There is also no GUI.
Testing the Odroid C4 on the same hardware using a normal Coreelec C4 package displays the GUI/files in their proper formats and resolutions.
I'm at the end of what I'm able to learn and understand from this process. Maybe someone else knows what is going wrong. If you're just looking for a 1080p box that can tonemap HDR to SDR, then OpenPHT on the C4 will work pretty well. The tonemapping is slightly blue/aqua compared to a proper HDR image, but the image doesn't show any macroblocking artifacts. Otherwise, it may be better to go with a different box. I don't know how if the N2 also has this problem or not, but I've heard its tonemapping isn't as good as the C4.
Tests on the Amlogic S905X3 (Odroid C4) got the device to boot from the image, however the resolution is stuck at 1080p due to some GUI and scaling issues. Switching to 1280x720p60hz yields a distorted, almost thick interlaced image squashed in the vertical axis on the top 1/5th of the screen. It is nearly intelligible to navigate. Switching the resolution to 3840x2160p60hz will usually yield a black screen, followed by the device automatically backing down to 1080p. The displays detect 2160p30hz before the signal resets. You can add an advancedsettings.xml to the storage/.kodi/userdata folder through an SSH connection into the odroid to force 2160p60hz by adding the following lines of code. Adding an advancedsettings.xml file will override the guisettings.xml and will grey out the associated line in the openpht menu.
Upon adding these lines that will force it into 2160p60hz, it will launch into black screen after boot. If you blindly use the remote to navigate to a 4K HDR file, the file will play, and the screen will show an image in 2160p24hz and the display will switch to HDR, but the video will only play in the top left quadrant of the screen (a 1920x1080 size image). There is also no GUI.
Testing the Odroid C4 on the same hardware using a normal Coreelec C4 package displays the GUI/files in their proper formats and resolutions.
I'm at the end of what I'm able to learn and understand from this process. Maybe someone else knows what is going wrong. If you're just looking for a 1080p box that can tonemap HDR to SDR, then OpenPHT on the C4 will work pretty well. The tonemapping is slightly blue/aqua compared to a proper HDR image, but the image doesn't show any macroblocking artifacts. Otherwise, it may be better to go with a different box. I don't know how if the N2 also has this problem or not, but I've heard its tonemapping isn't as good as the C4.