Anyone know how to get 7.1 over spdif? (1 Viewer)

[lm]

On my system anyway, the only way I can get mediaportal to play back it's own videos is by setting up some alternative AUDIO codecs to handle the file errors mediaportal puts in the files when it's recording. So while I'm at it anyway, I've been spending wwaaaayyy tooo much time fighting with (and I suppose slowly learning how to use) ffdshow, and all the complexity that goes with the coders, decoders, filters.... it's all very confusing... but anyway...

One of the things I'd wanted to do is make some use of the 7.1 av reciever I bought... I have never heard the back 2 speakers in use. the matrix mixer in ffdshow seemed like the ticket, but I've found that when I set the 'output speakers configuration' to 6 or 7 channels, the spdif stream kicks back to some type of stereo stream (up to 5 chan works as expected). Am I correct in assuming that this is a limitation of the sound card AC3 encoder, even though it's a 7.1 capable card? Before I go analog (go out and buy a bunch of cables to hook the 4 mini jacks on the sound card to the 8 RCA multichannel analog in jacks on the av receiver), I thought I'd ask here if anyone knows of any possible way to configure mediaportal to play any media out to 7.1 using all 8 channels over a digital link?

And while I'm posting, superfluous thanks to all on the dev team!!!

 

[Dubyahjay]

If you are using optical/coaxial SPDIF you sound card doesnt make a lick of difference. Basically, SPDIF is a transport for digital sound that "should" be pure to the original audio track. In the case of AC3/DTS, your reciever will get the digital stream from the SPDIF connection and decode it. If the soundtrack is not 6.1 (which most are only 5.1) you will only recieve 5.1 surround sound. Again, this is only if you are passing unmolested audio through the SPDIF connection. A good utility to do this easily is SPDIFer.

To update, the only transport that can carry 7.1 (8 channel) audio is HDMI 1.1 -1.3. So you will not get discrete 8 channel audio from SPDIF.


Using FFdshow you can do all sorts of matrix upmixing/downmixing/levels/LFE/etc. Only do this if you want to change the original audio stream. To utilize your extra two speakers, your best bet is to use a soundmode that is built into the DSP of your reciever.

Was that clear? Let me know if i can be of more help.

 

[lm]

Thanks for the help. I had a hard time believing that, but I've been researching all morning and yep you are right. I'm surprised there has been no standard laid down for 'beyond 6 channels' over spdif. Fibre seems to me like the natural choice from a physics point of view. Oh well. I've hooked up the 8 analog audio lines and everything seems to be working fine. I suppose I'll have to try to ignore the audiophile in me who is frowning and shaking his head.

Your suggestion of using the recievers built in DSP has its good points, but I want a solution where all the 'processing mode' switching is done automatically based on content, and so since my amp doesn't know how to do that (ie: switch modes based on track count...) I'll just be attempting to set up ffdshow to do that. And it seems well equipped for that purpose.

Again thanks!

 

[Dubyahjay]

No problem

I know it doesnt make much sense, as optical(even coax) has plenty of bandwith to handle the extra channels. The problem is the SPDIF standard. It only supports 6.1.

Just another forced upgrade, we should be use to that by now