Recoding Dolby Digital 5.1 bitstream from Xbox360

[Seraphic-]

I've been doing extensive research trying to find a way to record Dolby Digital 5.1 from Xbox 360 over Toslink or HDMI.
At first I was looking for hardware that would be able to decode Dolby Digital 5.1 to LPCM 5.1 over HDMI.
Found a few devices as seen below (but can't confirm if they would be able to do the decoding):

http://www.gefen.com/gefentv/gtvproduct.jsp?prod_id=5277
http://www.lektropacks.com/view_product_standard.php?product=1001185&sub1=&show=
http://www.tmfsolutions.co.uk/Octava_HDMIto71.htm

Since I haven't been able to get confirmation on the above hardware, I next moved on to researching direct Dolby Digital 5.1 recoding over Toslink or Coax. Found several interesting reads:

https://www.videohelp.com/forum/archive/how-to-capture-ac3-t347474.html
http://forum.doom9.org/showthread.php?t=70024
http://forum.doom9.org/showthread.php?s=&threadid=25650
http://forum.doom9.org/showthread.php?s=&threadid=65549
http://forum.doom9.org/showthread.php?t=56795

From what I can gather, you need a few things to do this.
1. A soundcard with Toslink or Coax input
2. Bit-matched recording
3. 48khz - 16bit recoding option
4. BeSplit software
5. Even with all of the above, some soundcards still might not work

My Auzentech Prelude 7.1 (not sure it it works) soundcard supports one through three and using BeSplit I've done a several tests.

Set Xbox 360 to output Dolby Digital 5.1
Started up a game and let it run
Set soundcard software to record Digita-In (toslink) bitmatched




Viewing the above topics I'm told you should have a wave
that has white noise. Below is what I see viewed with Adobe Audition (peaked out).



Next using BeSplit I ran the following script. It runs, but does not read any track time during creation and creates an .ac3 file with no file size.

BeSplit -core( -input live.wav -prefix e:\track -type ac3 -fix )

The following script runs, reads track time and creates file with a file size. But doesn't seem to be correct as when you play it, there is no audio.

BeSplit -core( -input live.wav -prefix e:\track -type ddwav -fix )

I also learned that this could be done doing capture with VirtualDub, but I haven't had much luck since I have no bit-matched option when recording the audio.

Is anyone able to offer some more thoughts? Thanks

[jman98]

It's my understanding that it is currently IMPOSSIBLE to record ANYTHING over HDMI. HDMI has been out for a few years now and nobody has broken it as far as I know.

I've heard of Toslink captures, but I have no experience with such and little interest in it. I simply know that I've read about it being done. The only purpose of my post is to get you away from HDMI capturing which is currently just a waste of time.

May I ask why you want to do this? The reason is that almost everybody who wants to record stuff from a game system is doing so to post it on YouTube and YouTube won't support AC3 audio anyway, so why bother? If you simply like a soundtrack on a game, some game soundtracks are available for sale and honestly just buying the soundtrack might be a better use of your time and money than trying to make this work. I'm not a gamer, but I know that some game soundtracks are out of print and ridiculously expensive. However, you figured out how to do a lot (even if it didn't work) and you could put some of that ingenuity to work in figuring out a way to obtain a soundtrack at a significant discount.

I could have told you from looking at your Adobe Audition capture that you have nothing. But why you have nothing, sorry, I don't know.

That Octavia device is simply a device that can transmit HDMI protected audio over analog output. Such output could, in theory, be captured. But it's designed for things like HD-DTS and DD+ and not really for AC3, which is what you apparently have. I didn't look at the others.

[Seraphic-]

The HDMI REPEATER that I linked to from lektropacks.com seems to be it would be the best hope (at least what I have found). As for toslink capture, the problem is almost all the threads I found on this topic are from around 2003 or so. Would be great if I could talk to someone who had done this already and would be able to offer some deeper knowledge on the topic.

[jman98]

I find it very interesting that you do not wish to say WHY you want to do this.

Good luck. Perhaps someone here will respond with some practical experience doing toslink captures.

[Seraphic-]

The reason is because I want to see if it is possible. And I'm not using youtube.
Anyway, thanks for the help. Anyone else have some thoughts?