Windows Media Center cannot output Dolby Digital/DTS through SPDIF... only PCM stereo is sent

Question：Hi,

I recently purchased an HP Pavilion 5150t desktop with Vista Home Premium (64-bit).  The PC comes with a TV tuner and it works well with Media Center except that it cannot output Dolby Digital (either on-air program that has DD or DVD movies that have DD) to my external A/V receiver.

My desktop has Realtek HD Audio and I have enabled the Digital output (SPDIF) in the Sound program.  I have set the "Properties" of the Digital Output to support *BOTH* DTS and Dolby Digital encoding.  When I press the "Test" button for either of the format, the external A/V receiver properly recognizes the format, so the problem is not with my receiver.

Reading online forums and help notes, I strongly suspect that the default MPEG-2 codec for Windows Media Center is not set up properly to pass through DD or DTS -- it somehow always down-mixes to stereo before sending to SPDIF.  Could you tell me how to check and modify the codec setting?  Thanks!

-- Colin

Answer 1：Hi Chow Ho,
 
This problem occurs because the DirectShow component and the MPEG2 audio decoder in Windows Vista do not correctly support DTS pass-through over S/PDIF or HDMI.
 
To work around this problem, click to select both the DTS Audio check box and the Dolby Digital check box in the SPDIF Out Properties dialog box or in the HDMI Out Properties dialog box.
 
You can also refer the link below for further information:
 
http://support.microsoft.com/kb/940685
 
I hope this information is helpful.
 
Please let us know if you require further help.
 
Regards
Rehman - Microsoft Support

Answer 2：I have the same problem with a very similar hp system.   I have both DTS and Dolby checked in my SPDIF out, but I am still only seeing PCM 2.0.  Did the proposed solution work for you Colin.  

Thanks.

carmine

Answer 3：I just got it working.   I have both DTS and Dolby checked, but that didn't work initially.   I noticed in the advanced tab on my Digital Output properties the "Allow applications to take exclusive control of this device" wasn't checked.  I also checked, "Give exclusive mode applications priority".  I would assume this would be necessary for the player to output the raw signal.  It a non exclusive mode I wouldn't think the receiver would be able to process multiple digital streams.   Not that I know what the heck I'm talking about.

thanks for the posts.

carmine