5.1 sound not playing through rear speakers

Anytime i try to play a .mkv that has 5.1 sound it only plays through the front 3 speakers and the sub.  I have a Pioneer Elite VSX-94 TXH receiver that can decode both DD-TrueHD and DTS-HD Master.  I have the WD TV Live connected to the Pioneer using a 1.3b compliant HDMI cable.  I used the Mediainfo tool like i read in some other posts and this is what i get (so i know it’s a 6 channel source)

Format                           : DTS
Format/Info                      : Digital Theater Systems
Codec ID                         : A_DTS
Duration                         : 1h 57mn
Bit rate mode                    : Constant
Bit rate                         : 1536 Kbps
Channel(s)                       : 6 channels
Channel positions                : Front: L C R, Surround: L R, LFE
Sampling rate                    : 48.0 KHz
Resolution                       : 24 bits
Language                         : English

I even tried converting the DTS signal in this particular file to DD and i have the same problem. (using the HeartWear MKV Audio Converter like i read in other posts) I should also say that when the receiver gets the signal all 6 speakers light up on the front display.  it’s really confusing, i have my blu-ray player connected exactly the same way and i have no problems playing any kind of sound through it wether it’s a dvd that has DD5.1 to a bluray with 7.1 DTS-HD Master.

oh one thing i should mention i guess, is that i am using the latest firmware and playing the media files a WD external USB HD connected to the WD TV Live and the audio settings are configured for Digital, not stereo.

Any help would be greatly appreciated

The Live will not correctly pass through DTS-HD, so forget that.  It will also not do True-HD unless it’s in a TS container (and only a TS container) so unless that’s what you’re using forget that as well.

If you have regular 5.1 DTS or AC3 it should play through correctly – mine does – so either your file format is incorrect (which I suspect) or your cabling is (for sure try the optical out to eliminate this possibility).

If optical out gives you the same problems, then it’s your file.  Using an original file with DTS-HD or True-HD, run it through Handbrake using the High Profile preset but change the output to MKV and in the audio tracks do a passthrough of either the DTS or AC3 (highlight the audio track, choose the first track in the file, and then choose AC3 or DTS passthrough depending on the type of track it is).  This should work properly.  If so, then you at least have a starting point to know what works for you and can track back from there to find the issues with your other files.

Is there an actual audio signal going to the rear speakers?  At times, an audio file is encoded for 5.1 but with no actual audio going to a channel.  If there is an actual signal, did you check the individual level/volume on the rear channels via the receiver in case the actual level is very low?

EDIT:  OPPPS, did not notice the encoding.  Thought it was DTS or AC3.

Excellent, thank you very much mkelley, that worked perfectly.  Took 3.5 hours to convert the file, but was totally worth it.