TrueHD Decoding separates?

[evilkat]

Need some advice regarding the new HD format for sound. I just recently bought a receiver (arnd the beginning of this yr), but I just realized that it won't do the decoding for the TrueHD or whatever format HD sound scores come in. I don't feel like buying a new receiver just for that, so I'm wondering if you guys know if there are any components that can do the decoding and pass it through to my speakers via the receiver? I know some of the HD players can do the decoding, but I don't know if it converts the signal to some other format before sending it to the receiver and then to the speakers (I'm pretty ignorant on this subject).

Anyway, any advice/options I have available would be much appreciated. Hopefully I communicated the problem right!!

 

[Seth=L]

The formats are decoded in the HD players and converted to multichannel LPCM. This process is the same if it occurs in a receiver. The bitstream would be sent to the receiver and converted to LPCM then the receiver's DACs would convert it to analog. The only thing that changes is where the bitstream HD audio is converted to LPCM (the player or the receiver). It is arguable that it makes limited to no difference. I would keep the Yamaha until HDMI 1.3 or something higher becomes available for a lower price and is available and usable on all components.

 

[evilkat]

Hey Seth, thanx for the info. So if I get audio out from the HD player and plug it into my reciver, the receiver will do the necessary conversion to analog without meddling with signal format right? So I should essentially see the PCM light come on when I am getting a signal from a successfully decoded HD stream from the player? Hmm but that doesn't sound right because when I get a PCM signal from my computer the receiver does Dolby decoding to get it into 5.1

I guess I'm still a little confused. I just don't want the receiver to do anything if the signal is from the HD player, and simply pass it through to the speakers, unlike my PC digital out signal (comes as PCM and is decoded as Dolby 5.1). I'm sure I'm not understand the process right some place here....

I would rather keep the Yamaha around for a LONG while because I just won't have the $$ to drop on another equivalent receiver

 

[Seth=L]

I am assuming that the computer is connected via SPDIF? What source would you be media source are you using when it says "Dolby (5.1)" on the receiver?

If you are receiving stereo PCM (the highest possible form of PCM that can pass via SPDIF) and you activate Dolby Pro Logic IIx that would make sense. the PC would not be able to output multichannel LPCM via any output unless you have a very expensive video card with HDMI output (assuming the card can indeed output audio via HDMI).

Keep in mind the HD player must be set up correctly to send out multichannel PCM.

 

[evilkat]

You got it. I don't have a DVD player at the moment, so I use my PC to play DVDs. What I do is, i use the SPDIF on my audigy card to output the sound in PCM (i can double check) to my receiver. The receiver shows it's getting 5.1 channels and I believe the Dolby light comes on (I can double check this, once I go home). So I always assumed that 5.1 channels were somehow being encoded in the 'raw' PCM format and sent to the receiver who knew how to decode it.

But it sounds like you're telling me that the PCM is only two channels, not multi, and that the receiver is in fact doing some 'up conversion' to get the other channels? Doesn't seem right though, because whenever I get two channel output from the SPDIF, I always see only two speakers light up, not the 5.1 speakers.

 

[Hi Ho]

I have the same receiver. When I play HD-DVDs with DD+ or TrueHD tracks the display on the receiver shows "SUR DECODE MPCM". The sound is substantially better than plain DD or DTS on standard DVDs.

 

[evilkat]

Thanks HH. I didn't think there'd be a noticeable difference, but it sounds like the receiver will not be doing any decoding and passing it through fine.

I'll have to read up on this PCM business.

 

[Seth=L]

Actually it sounds like the Dolby Digital bitstream is coming through on the SPDIF to the receiver, as it should. I don't think an audio card will convert 5.1 Dolby Digital to PCM.

Pretty much you just have to wait for HDMI.