I have just upgraded to the latest Firmware 1.05.18 for the WD TV Live (2011) and found that the decoding for the audio in MP4 files is now output as 7 Channel PCM vs the 2 Channel PCM is was beforehand.
While the support of surround is welcome it appears to be incorrect in it’s function. The new firmware seems to force output as 7.0 Channel (even if in the settings I have set my output to 6 Channel) and is missing the Centre channel - ie there is no sound _ at all _ from the Centre channel and it appears that the Centre is partially mixed into left and right.
As I mentioned, the support os surrond is welcome, but, in my opinion i’d rather have 2 channel as my amp can can simulate 5.1 correctly where as the current ouput of 7 Channel sound sounds awful and with the missing Centre Channel is nothing short of horrible to listen to.
To rule out it was an encoding issue I was able to play the _ exact _ same file via my PS3 which was able to output the sound correctly as a 6 channel (5.1) PCM downmix with a distinct Centre Channel. In fact while testing this I noticed that some sound effects were completely missing via the WD Live where as the PS3 was ouputing them correctly to the Centre Channel. I also happen to have the same file in a MKV format with Dolby Digital 5.1 (AC3) and thankfully Dolby 5.1 is still being passed through correctly and sounds fantastic. At this point is appears that the downmixing is be broken and as many amp’s do not support AAC, the ideal solution is to downix the AAC to PCM in the equvalent channels correctly.I suspect it may be a channel matrix issue Channel Order (as far as I am aware) :
Reference: Channel 1 C hannel 2 Channel 3 Channel 4 Channel 5 Channel 6
5.1 AC3 front left channel front center channel front right channel rear left channel rear right channel LFE
5.1 DTS front center channel front left channel front right channel rear left channel rear right channel LFE
5.1 AAC front center channel front left channel front right channel rear left channel rear right channel LFE