Little problem with 5.1 sound through HDMI

Hi there!

I´m using the last Kodi/OSMC version for Raspberry Pi B+ and I´ve been testing the new feature that allows to get surround sound through HDMI (Support 8 channel DTS HD audio decoding) and I have a little question. I´m using wireless surround headphones (connected to the TV via optical toslink cable) that has lights to indicate the kind of surround playing (DTS, Dolby…). When I use mi Hifiberry Digi+ soundcard (connecting the toslink directly to it instead of the TV) this lights are on when playing 5.1, but with HDMI passthrough they do nothing. I think I get the same sound quality with both methods, but I would like to know if it´s normal that my headphones are´nt detecting the sound type or I should setup something.

Thanks a lot and best regards!

Many TV’s don’t support passthrough from HDMI to optical for AC3.
Almost none support passthrough from HDMI to optical for DTS.

Only ones I know of that can passthrough dts and ac3 to optical out are LG TVs.

I have a Panasonic TV. I can’t get 5.1 on my Pi with it then??

Thanks for the reply!

Probably not when you pass it through the tv.
You will need the hifiberry option or a pi2 that is able to decode 5.1 to pcm on the fly.

Oh, so with a Pi 2 I would be able to connect it via HDMI to the TV, then the TV via toslink to the headphones, and get 5.1 without the Hifiberry? That would be pretty convenient, because I would be able to use the gpio ports for another things.

Thank you very much!

Well, I think so. Don’t take my word for it.
Didn’t try that myself.
The pi 2 can decode 7.1 audio streams and send them to the TV as pcm. So it should be able to do it with 5.1, too I guess.

But you have to read the manual of your TV.!
Some even just output 2 channel audio over toslink.

I have an LG television (32LB561V) and that one does pass through AC3 (i.e. Dolby Digital) but no DTS unfortunately.

Mine is a lm640s. It does both.

Enable AC3 passthrough, disable DTS passthrough and enabled AC3 transcode.
You can then output multichannel DTS (and other formats like AAC, PCM, FLAC) as AC3.