Archive:Remap HDMI audio on Gen 1 ION - Linux

HDMI audio output requires several steps to configure properly. My requirements were passthrough, non-passthrough and menu sounds all coming over HDMI to my receiver (fairly common). Some challenges were that the Gen 1 ION had incorrect channel mappings (e.g. Center came out of Left Rear) and menu sounds do not default to HDMI.

MythBuntu 11.10 XBMC Eden Beta 2 Linux 3.0.0

Remapping Surround Channels

I first noticed the audio channels were mismapped while watching a movie - all the voices were coming out of the left rear channel, not center. To verify this, I ran the following command:

speaker-test -D hdmi -c 6

To correct the output, I created the following channel mapping in ~/.asoundrc (.asoundrc is a file which will override the default alsa settings for a user.)

pcm.hdmi-remap {
	type route
	slave.pcm hdmi
	ttable.0.0 1
	ttable.1.1 1
	ttable.2.4 1
	ttable.3.5 1
	ttable.4.2 1
	ttable.5.3 1
	ttable.6.6 1 
	ttable.7.7 1 
}

Note: There is intentionally no slave.channels line in my .asoundrc file since it seems to corrupt the digital stream and prevented proper DTS and DD passthrough to my receiver. If you hear static when using passthrough, this might be the reason why!

To test our new configuration, we can run:

speaker-test -D hdmi-remap -c 6

Hopefully the channels will now be mapped correctly.

Menu Sounds

To configure menu sounds, I told alsa to use the hdmi-remap device as default. I did this by adding the following section to my ~/.asoundrc file:

pcm.!default {
	type plug
	slave.pcm hdmi-remap
}

XBMC Configuration

Within Settings -> System -> Audio Output, I set the following values:

• Audio Output : HDMI
• Speaker Configuration : 7.1
• Boost volume level on downmix : No
• Dolby Digitla (AC3) capable receiver : Yes
• DTS capable receiver : Yes
• Audio output device : Custom
• Custom audio device : hdmi-remap
• Passthrough output device : hdmi(ALSA)

After a reboot, sound was working as expected. Please let me know if you have a similar experience!