Flatpak multichannel audio over HDMI

I've recently started using the LE13 nighties on an intel NUC. All the HDMI audio works great in Kodi but apps/add-ons running via Flatpak are limited to stereo and i'm trying to use Moonlight with 5.1 surround.

I've tried tweaking the custom audio device setting in "External programs helper" but i don't think that's where the problem is.

I've added some Pulseaudio daemon config with "default-sample-channels = 6" which did make it start outputting 5.1 but the channel map is all mixed up with audio coming from the wrong speaker. Changing "default-channel-map" in the same config doesn't help.

Anyone have any ideas? it would be really good if this could be streamlined / automatically configured based of the Kodi audio output settings in future.

Interesting thanks, speaker-test works correctly, lists the expected channels and the tones play from the expected speaker.

LibreELEC:~ # speaker-test -Dhdmi:CARD=PCH,DEV=0 -c6

speaker-test 1.2.16

Playback device is hdmi:CARD=PCH,DEV=0
Stream parameters are 48000Hz, S16_LE, 6 channels
Using 16 octaves of pink noise
Rate set to 48000Hz (requested 48000Hz)
Buffer size range from 22 to 349525
Period size range from 11 to 174762
Periods = 4
was set period_size = 12000
was set buffer_size = 48000
 0 - Front Left
 4 - Front Center
 1 - Front Right
 3 - Rear Right
 2 - Rear Left
 5 - LFE

But when I config the pulseaudio to with "default-sample-channels = 6" i get:

LibreELEC:~/.config/pulse-daemon.conf.d # pactl info
Server String: /var/run/pulse/native
Library Protocol Version: 35
Server Protocol Version: 35
Is Local: yes
Client Index: 0
Tile Size: 65472
User Name: root
Host Name: LibreELEC
Server Name: pulseaudio
Server Version: 17.0
Default Sample Specification: s16le 6ch 44100Hz
Default Channel Map: front-left,front-left-of-center,front-center,front-right,front-right-of-center,rear-center
Default Sink: auto_null
Default Source: auto_null.monitor
Cookie: b3b3:64ec

I know pulse is used for Bluetooth audio and that's limited to stereo, maybe some existing config for is getting in the way.

I tried a "default-channel-map" like you suggested in the daemon config, same place I set "default-sample-channels = 6" but it had no effect.

Most other suggestions online talk about editing /etc/pulse/default.pa which is read only for us.

Ok i made some progress hacking stuff around until it worked.

I had to add channels=6 to https://github.com/LibreELEC/Libr…run-wrapper#L42 the created sink then has the correct channel count and mapping.

The next issue was by default it now upmixes stereo output to all the channels, for this the daemon config did work so i created a file as:

enable-remixing = no

So would be really nice if the flatpak-run-wrapper could be properly updated to honour your Kodi channel count, as for the remixing at least that is already fixable via user config.