Surround Sound On A Computer (1 Viewer)

[Allen Marshall]

It occured to me that I didnt know the answers to these questions. I'm working on a film that we plan to mix in 5.1 and I have a few questions reguarding surround sound on a comp.

Take a 5.1 soundcard and 5.1 comp speakers, does it work or do you need something else also? I remember seeing some sort of external dolby digital decoder box for computers thats why I ask.

will 5.1 comp speakers convert stereo into something like pro logic or will it leave all the other speakers out of it?

5.1 video on a 2.1 comp system, what does it do downmix it to Stereo? IF so, will this sound worse or awkward opposed to an original Stereo source?

That's a general question I've been asking myself today. Do DVDs that only give you a 5.1 option and no stereo still have a stereo mix in there that they keep for people without surround sound or does it always take the Dolby Digital track and downmix it to Stereo? And once again, does this sound...weird compared to an original Stereo source?

Thanks for any help.

 

[Ken Chan]

Last question first: if there's only a 5.1 track, then the DVD player (set-top or computer) is responsible for doing a downmix. The .1 track is discarded and the 5 main channels are matrix-encoded into 2, so you still get surround. So that's why the .1 should only be used to enhance the bass; there should be bass in the mains. It obviously won't sound as good, but it should sound OK. You can listen for yourself. Depending on the DVD player, you should be able to tell it that you want 2.0 output, then choose a 5.1 track, and it will downmix, even if there is a 2.0 track on the disc. They're supposed to play the track you ask for (although I suppose you could sell that as a feature, that it will automatically choose a 2.0 track flagged in the same language in that situation).

As for the computer, it depends If the speakers are each hooked up separately (or in pairs) to the soundcard, then it should work without a decoder. You would need a program that is capable of doing 5.1 of course, and it would drive those channels directly. Surround audio in games works the same way; they don't encode into Dolby Digital first.

Some computer speakers are hooked up to a receiver of sorts, but they also have a proprietary multi-channel digital connection to the soundcard. That's effectively the same as before.

Some motherboards, like nForce ones, can dynamically encode any 5.1 audio into Dolby Digital. So instead of a proprietary solution, you can use any DD decoder and have 5.1 digital sound using only one cable.

Otherwise, if the motherboard doesn't have an encoder, then the digital connection can only play already-encoded 5.1 audio (like DD or even DTS from a DVD) or any 2-channel audio (like regular stereo for music or 2.0 DD from a DVD).

 

[Allen Marshall]

Thank you Ken, you've been very helpful.