[mythtv-users] Raspberry Pi - Audio Passthrough

[rob e]

ok, it's working ... both AC3 and DTS pass through beautifully and no 
impact to video
my receiver reports 5.1 sound and video is no longer impacted in any way

based on these
https://github.com/raspberrypi/linux/issues/997
https://gist.githubusercontent.com/julianscheel/9094131/raw/af99299b11d32693abb07481698b1f963a423076/bcm2835.conf

add a new file
/usr/share/alsa/cards/bcm2835.conf
with the content above (second link)

reboot

then select the new IEC958 option in Audio setup, no mixer ... and Bob's 
your uncle

aplay -L   # Note the new iec958 option at the end of the list
null
     Discard all samples (playback) or generate zero samples (capture)
sysdefault:CARD=ALSA
     bcm2835 ALSA, bcm2835 ALSA
     Default Audio Device
dmix:CARD=ALSA,DEV=0
     bcm2835 ALSA, bcm2835 ALSA
     Direct sample mixing device
dmix:CARD=ALSA,DEV=1
     bcm2835 ALSA, bcm2835 IEC958/HDMI
     Direct sample mixing device
dsnoop:CARD=ALSA,DEV=0
     bcm2835 ALSA, bcm2835 ALSA
     Direct sample snooping device
dsnoop:CARD=ALSA,DEV=1
     bcm2835 ALSA, bcm2835 IEC958/HDMI
     Direct sample snooping device
hw:CARD=ALSA,DEV=0
     bcm2835 ALSA, bcm2835 ALSA
     Direct hardware device without any conversions
hw:CARD=ALSA,DEV=1
     bcm2835 ALSA, bcm2835 IEC958/HDMI
     Direct hardware device without any conversions
plughw:CARD=ALSA,DEV=0
     bcm2835 ALSA, bcm2835 ALSA
     Hardware device with all software conversions
plughw:CARD=ALSA,DEV=1
     bcm2835 ALSA, bcm2835 IEC958/HDMI
     Hardware device with all software conversions
iec958:CARD=ALSA,DEV=0
     bcm2835 ALSA, bcm2835 IEC958/HDMI
     IEC958 (S/PDIF) Digital Audio Output