Kodi Community Forum

Full Version: Multi-channel audio + DTS Connect card
You're currently viewing a stripped down version of our content. View the full version with proper formatting.
Good day to my favourite Media Center guys.

I've been having a small issue regarding the new Gotham release, which I only realised was a problem about two days ago.

I have an Asus Crossfire V Formula-Z motherboard (details here) which has an SPDIF output that has hardware DTS Encoding (also called DTS Connect).
My receiver is a Sony Muteki STR-KM5000 which supports DTS and Dolby Digital-Ex.
I have an Optoma HD33 projector which is connected in the following configuration: PC -> Receiver -> Projector.
For some reason HDMI audio never worked, and probably never will because of incompatibility with the projector+receiver+pc...

So, I have my receiver connected via the Optical output of the PC, which supports DTS Connect. This works rather well, because the audio device in Windows pretends to be a 5.1 channel PCM device with the ability of SPDIF passthrough. I never use passthrough because I prefer setting the receiver to a predetermined volume and then use the Windows volume control to control the volume, with passthrough you cannot control the volume in software at all. Also, the DTS Connect encoding works very well with games and stuff that isn't surround sound, 2 channel sources go out as the front 2 channels over the DTS 5.1 stream, at which point I tell the receiver to decode the LFE and not mess with the sound any further.

I don't know the exact details of how it works, but it does register as a purely digital SPDIF device in XBMC. When using VLC, I have to tell VLC in the audio output configuration that the device is a 5.1 channel device, and this works fine. In XBMC Frodo I could manually select the amount of channels and have the same results as VLC, true 5.1 channel audio to my receiver. With Gotham however, it seems like the SPDIF output has taken precedence and I can no longer force the output to be true 5.1 channel audio, I only get 2 channels. Passthrough audio works, kinda, BluRay disks do not have audio at all, I don't think my receiver supports DTS-HD.

Just to be absolutely sure my ears weren't deceiving me, I found a channel test video from Dolby's site, with which I then confirmed my suspicions.

I use the "Channel Check" video from the Dolby site: http://www.dolby.com/us/en/consumer/tech...nload.html
This video tests each channel individually, in XBMC Gotham I can hear all channels, but they play over only over the front left and right channels (like it's downmixed)

This is my VLC configuration that works correctly:
Image

Is there a way to override this limitation with a command line option or a config file entry?

PS: I forgot to add that if I use the DirectSound ouput option for my Audio device, the DTS connect takes over and plays in the 2 channel way, but if I switch to WSAPI, my receiver reports that its getting a 2 Channel PCM stream (which effectively overrides the DTS connect).
PPS: Some screenshots of the Audio device's properties in the Windows Control Panel

General:
Image

Image

Image

Image
Hey NeoAcheron,

did you manage to get it working in the end? I have a similar problem here.

Thanks in advance!
Hi ploebb,

I've since switched to a Linux box where I force PulseAudio to re-encode 6 channel audio over SPDIF. XBMC seems to respect that configuration, because I get surround sound without passthrough. However, I would not attempt this without a solid knowledge of ALSA and PulseAudio. There's a bunch of tutorials about this, its called "AC3 encoding through PulseAudio". A word of caution though, this will encode the audio in software (It will use your CPU), and then use he sound card's "passthrough" to stream it to your receiver. On my old Phenom II Quad Core, It pegged a CPU at 25% during audio playback. This could be a bit much for a lower end HTPC, and forget about getting it to run completely silent ever again.

More recently I bought an LG 4K TV that has an optical output, and the HDMI audio can be re-encoded onto the optical output to the audio receiver. For some reason my receiver doesn't have audio support through HDMI, its only a switch to switch between inputs.

This whole marketing thing with the audio card guys is a real mess, because only a select few sound cards can actually output real surround sound over SPDIF. Others have passthrough and stereo PCM only, due to patents and politics. What makes it even worse is that the implementation of the drivers of the cards that do manage to do this, are exceptionally bad and easy to break.

I've given up on Windows... Linux is a superior HTPC platform for video and music entertainment, but somewhat lacking in the gaming front.Undecided