Widescreen Gaming Forum

I thought I'd put this question in Surround Discussion even though this fourm is supposedly intended for surround gaming. I figured those that hang out here probably know surround solutions better.

As the title implies the one thing that's holding up my hardware setup decisions for the HTPC I want to build is how to decode the 5.1 audio from HDTV broadcasts. I don't want to use any external devices other than maybe a TV tuner card. Freeing up one of the PCI slots might actually be necessary anyway if I want the flexibility of going dual GPU. I've not decided yet if I'll go with an HDTV display or monitor.

In my searching I'm finding that none of the sound cards or TV tuners actually decode 5.1. Many support 5.1 decoding but you need software or an external device to do the actual decoding, the latter of which is not preferable to me. This means using a software application such as Nvidia's PureVideo Decoder, which AutumnWave, makers of the OnAir HDTV GT external TV tuner recommend.

The problem is I want to use Vista Home Premium in the HTPC I'm building and Nvidia says their PureVideo Decoder won't work with Vista. Surely there must be some software that decodes the 5.1 audio from HDTV broadcasts? I know some TV tuners come with software or recommend programs such as BeyondTV, but I really don't want to buy into any unecessary services or end up with software that is finicky and problematic to use.

If I go with an HDTV as a dislay I will still need something to decode the 5.1 audio. Even if I use a digital audio cable from the TV to a soundcard that has a digital audio input, there are no internal sound cards made that decode the 5.1. I would assume PureVideo Decoder would suffice there as well as with a TV tuner card IF Vista supported it.

I know MS has gone the way of avoiding hardware acceleration for audio with Vista, so I'm a bit surprised since they seem to want audio to be more software driven for less compatibility issues in games they would not make PureVideo compatible with Vista. The guy at Nvidia I spoke to said Vista doesn't need PureVideo, it has it's own decoders, but then he said those built into Vista won't decode 5.1 though.

BTW, just to give you an idea of an acceptable price range for software 5.1 decoders, Nvidia's Platinum version of PureVideo Decoder runs $50 and it will decode both Dolby 5.1 and DTS 5.1. I'd like to stay within that range and it HAS to be compatible with Vista of course and preferably easy to use and stable. I may luck out and find MS will update Vista with 5.1 decoding capability, but I'm not counting on it.

Not 100% sure if it'll work flawlessly in Vista, but it sounds like AC3Filter would fit your needs perfectly (plus it's free as well).

Thanks, sounds like a cool tool, I might try that. Someone over on the AVS forum told me as long as you have Vista compatible drivers for the TV tuner you use, Vista's built-in decoders will decode the mpeg stream the tuner creates into 5.1. I take it that means a Media Center version of Vista has to be used.

I also found this nice free utility that allows you to separately select alternate installed decoders in Vista for video and audio.
http://mediacenterexpert.blogspot.com/2006/07/vista-media-center-decoder-utility.html

For now I may see if the one you linked to works to turn the stereo signal I'm pulling off my HDTV into 5.1. I only have XP Home on my current rig, so no MCE decoders.

Hi Frag Maniac,
This is Ryan Pertusio from AutumnWave.

I think I saw your post on a different forum. I apologize if I am incorrect.

The nVidia Decoder is compatible with Vista, but Microsoft offers no way to change the decoder from their built-in one. The AC3 Filter is one of the best (free) audio decoders you can find. You might want to take the Media Center Decoder Utility that you found, and select the following:

Video Decoder: nVidia Video Decoder
Audio Decoder: AC3 Filter

You can either buy the nVidia decoder from nVidia, or find a program that bundles it. We (at AutumnWave) have bundled nVidia's "Silver" edition with our OnAir GT tuner. If you're interested in getting an HDTV tuner, it might be a good way to get both.

FYI, Media Center will only pull in Digital TV from Over-The-Air broadcasts. So, if you're interested in connecting to digital cable, Media Center is probably out of the question.

- Ryan Pertusio

AutumnWave Technical Support
OnAir Solution North America
http://www.AutumnWave.com