Vista - Wierd problems with surround sound

I have a Sony Vaio XL201 with Vista Media Center outputting sound via an SPDIF optical cable to my amp. My Vaio uses the Sigmatel High Definition Audio codec.
I have found that when you go into Control Panel and Sound, I have configured for SPDIF output only, but there is no settings for 5.1 etc. In VMC itself, I have set the speaker settings to 5.1.

My amp shows on the front panel what channels it is receiving.
I play an MP3 and the amp shows sterio.
I play a stored .mkv video file and the amp shows 5.1.
I then play a DVD that has 5.1 sound, but the amp only shows sterio.
I then play that same DVD using Arcsoft Total Media Theatre software and my amp shows 5.1.
And all DVD's with 5.1 sound also do the same in VMC - only sterio.

Can anyone explain this? It is driving me nuts this.

Hi

You don't say what decoder you are using.

You need to set SPDIF on both your decoder and the sound card, with no sound enhancement selected.

Did you make sure that you selected 5.1 on the DVD audio menu?

Regards
UKMedia

Hi UKMedia, thanks for the reply. Any help here is welcome!
I did state that the driver was the Sigmatel one, is that what the decoder is?
If not, how do I find out which decoder I'm using?
And when you say the DVD Audio menu, you mean from the Menu on the DVD? If so, yes, otherwise I presume it would not play as 5.1 through Arcsoft TMT.
Thanks

Please run this:

(http://www.microsoft.com/downloads/d...displaylang=en)

...and let me know what it says.

Sorry, but that link above is invalid.

Sorry try this.

http://www.microsoft.com/downloads/d...displaylang=en

Hi, tried that. It seems to show video decoders only? It shows 4 with the selected one being the MSMPEG2 decoder.
What about the audio decoder?

One other thing I've tested: I played a DVD using WMP and it gave me 5.1 at the amp. I played the same DVD using VMC and I get 2.0. So WMP is OK, Arcsoft TMT is OK but VMC is not OK. This is weird. So is VMC using a different codec to the others?

VMC and WMP should use the same decoder for Audio and Video. I use PowerDVD and I have to set SPDif for the Audio there and on the sound card for it to pass 5.1 through to the amp. This also places an addon within VMC. When playing a DVD within VMC (Don't stop it) navigate to Options, DVD - Do you see an Audio option? (this will only be there when playing a DVD.) If so make sure that the speakers option is set to SPDIF.

I played the DVD in VMC and then went to Settings, DVD, Audio. The settings there were:
----------------------------
......Theater Sound
...*..Auto Volume
----------------------------
Dolby Decoder setting
.......Theater mode
....*..Normal mode
........Night mode
-----------------------------

In the first section, Theater sound was not available to select, but Auto Volume could be ticked.
In the second section, none of the options were available to select, but 'Normal mode' was already set on.
I also noticed that this exact same list of options was available when the DVD was not playing.
Where is it getting the setting for 'Normal mode' and why can't I change it?

I thought the Audio options for the default decoder were set in Media Player - Now Playing - More Options - Audio. I suggest that you download PowerDVD (they offer a 30 day free trial) and then use the decoder utility to ensure it is selected (there will be 4 enabled for PowerDVD, if you go for the BD option). Then in the options for PowerDVD, select SPDIF for the audio output. This should ensure that a native signal from your DVD is passed straight through to your amp.

Regards
UKMedia