I'm interesting in running OpenELEC on a Raspberry PI as it would be a cheap XBMC solution. The OpenELEC Raspberry PI/FAQ notes:
The RPi cannot decode DTS and AC3 because of the overhead, it is recommended that you use a passthrough device with these files.
The OpenELEC XBMC Settings wiki notes:
Passthrough output device
This device you use to play the encoded formats, these are any of the formats checked above in the "capable receiver" options.
I'm still not 100% sure what this means. The screenshot indicates that the Passthrough device would be through HDMI.
So basically I want someone to confirm to me that the Raspberry Pi would be able to play videos on OpenELEC but not decode the AC3/DTS sound itself but it could send it over the HDMI cable to my TV to let my TV decode it. My TV is able to play AC3/DTS over HDMI if I connect my laptop and also plays video's with AC3/DTS from a USB stick so I should be in the clear if I'd enable the passthrough option?