I just bought my WD TV Player. The audio does not work on the Blue Ray - MKV movies. The picture looks great, but no voice. All other movies the audio is working. My son has a WD TV Live Player and there is no problem with these same movies - there is audio with this player.
is the audio DTS?
if so then thats probably the problem, just convert the audio to AC3 and then use mkvmerge to mux the AC3 audio in, then it should play fine
how do you do that its just one file
First download MKVtoolnix if you dont already have it ( http://www.videohelp.com/download/mkvtoolnix-unicode-3.3.0-setup.exe)
Then download this ( http://www.videohelp.com/download/MKVExtractGUI-220.127.116.11Wizard-1.2.zip) and copy the contents of the mkvextractGUI folder to where you installed mkvtoolnix
then use mkvextract to extract the DTS audio stream
then download and install this ( http://www.videohelp.com/download/XviD4PSP_18.104.22.168_r132.exe) then open the extracted DTS stream in that program and convert it to AC3
then use mkvmerge to mux the new AC3 audio into the mkv file, if you dont want the DTS stream anymore just untick it when you add the AC3, then save it and it should play
thats what i do, hope that helps and is easy to follow, never been the best at giving step by step instructions