I figure this would be the place to ask about a thing like this.
I have a 5.1 Creative speaker system hooked up to my PC (Via the analog 3x 3.5mm plugs). I also have one Xbox 360 that has an optical out jack. Using my Soundblaster X-fi soundcard, how could I take that stream of digital audio from the Xbox 360, and decode it for output to the 5.1 surround sound speakers? I have the audio from the Xbox going to the Optical In port of my sound-card, but It doesn't seem to be doing anything.
Xbox has a weird way of doing things.
Using your computer as a middle man, is probably confusing the sound card inside.
Try asking a friend to look at his 5.1 system I have mine going into an HDMI input on a receiver, into a 5.1
I also have a 003 that runs 5.1 in my apartment so i can mix in 5.1 as well...
damn i have a lot of speakers.
if that fails, call xbox support.
It may not be the xbox per se. Optical connections can use one of two formats (warning: Geek Talk).
The most common format is straight digital called I2S format. This is a variable length (16, 24 or 32 bits/sample, L-R or L-R:F-B:A) simple sampling format. Oldest is 16 bits/sample, 44,100 samples/sec, Left / Right format with a few framing bits. Newest is 48,000 samples/sec 5.1 format, 32 bits.
Look in your XBox and see if you can set the output format to one of these. Same for the X-Fi card. If either one does not support 5.1 (and I doubt that), then use a fallback of simple stereo.
The worst format is the second kind I alluded to and that's an ISO format with DRM. This follows the same format as digital audio & video in an HDMI cable. But this format should only be triggered by playback of a blu-ray disc or DRM protected iTunes or WMV format movie.
Sadly the Xbox is only showing Stereo, 5.1 and WMA for audio options. The big problem is I have no way of knowing if any data is coming through. How would I 'monitor' the output coming from the Xbox? I can see 'Digital-In' In on windows Recording Devices (There is also a 'Digital Input Device (SPDIF)', but it's properties show a yellow jack and say nothing about Optical). Its not grayed out, and says working, but I'm not seeing any movement on the volume bar.
If I pull one end of the cable out of the PC, and data IS being sent, would I be able to see any fluctuation in the brightness, or is it too fast? Right now it's solid red.
Even if it was working, wouldn't it then act like a Mic? How would I be able to get it running back through the PC speakers?
An oscilloscope should show if any audio is getting through.