After more than a week of tinkering with the RPi 3 and an Odroid C2, I am about to give up on multichannel via HDMI:
Apparently, the standard RPi kernel does not support more than 2 channels of PCM output via HDMI. I’ve tried running DietPi with a custom kernel, containing a patched version of bcm2835-pcm.c that raises the number of supported channels to 8, but that didn’t have the expected effect. So I decided to have a look at another SBC that I had flying around…
Running DietPi on the Odroid C2 looked much better - initially. Roon was showing 5.1 and 7.1 in addition to the 2.0 output. While stereo output did produce some audio, both 5.1 and 7.1 were only producing errors, with the RAATServer log file showing:
failed to snd_pcm_hw_params_set_channels exactly. trying to set max channels instead: Invalid argument (-22)
I tried different kinds of bit depth and sampling rates as well, but to no avail.
So here I am, looking for someone who was successful getting this to run…
Interesting. I’m about to give up on multichannel altogether. I guess Roon supports it, but I’ve yet to find any Roon-ready hardware that does. Apparently you can’t even build your own! Good luck - I hope you figure something out!
I just noticed that the latest firmware update for my Oppo UDP-203 disc player supports Roon. The UDP-203 is a multichannel device, but the version for audiophiles is the UDP-205. I decided not to get the UDP-205 beause I send audio output from my UDP-203, including multichannel music, in bitstream format to my multichannel audio processor. Does this mean that I should be able to use Roon for multichannel music?
It does not look like multichannel works on the Roon Bridge running on the 205. I am getting multichannel working by using HDMI from a Roon Intel server. I was unable to get it working from a Raspberry Pi.