5.1 surround mixing via s/pdif output?

[miklogik]

I don't think this is possible, but I'd like a confirmation from people smarter than me

S/PDIF can send uncompressed 2 channel audio, or compressed AC3 encoded audio that can be recognized by home theatre receivers.

I'd like to send the multichannel audio from Reaper to S/PDIF, but of course it needs to be encoded/compressed to AC3 first. AC3Filter (Direct Show filter) can encode on the fly and send out via the S/PDIF.

DAW AUDIO OUT -> AC3FILTER -> S/PDIF

Is there any way to send 5 channel audio from Reaper to AC3Filter (or any DirectShow filter)? AC3Filter seems to only work with prerecorded files in media players, rather than live streaming audio. Maybe with virtual audio routing?

[Evan]

I tried this in the past, can't remember the host, can't remember the setup... but it was s/pdif and ac3filter I think... there was additional latency for the ac3 conversion which annoyed me at the time.

Other than that, ac3 is a lossy consumer format. Doesn't your receiver have discreet inputs (6 of them for 5.1)?

[miklogik]

Originally Posted by Evan

I tried this in the past, can't remember the host, can't remember the setup... but it was s/pdif and ac3filter I think... there was additional latency for the ac3 conversion which annoyed me at the time.

Other than that, ac3 is a lossy consumer format. Doesn't your receiver have discreet inputs (6 of them for 5.1)?

I'd be really grateful if you could remember how... the latency wouldn't bother me too much, I'd only use it for mixing the surround, not recording. Ditto on the "lossy" quality, just for mixing not final output, although DolbyDigital and DTS sound pretty good to me.

[Evan]

Mik, I'm afraid it's not possible to remember how I did it. It was in a very different setup than mine, long time ago, and it probably wasn't even with Reaper.

If I remember any details I will let you know.

[jm duchenne]

Hi,
There is this one : http://www.driverheaven.net/general-...3-encoder.html
But I haven't tested it...

[miklogik]

Originally Posted by jm duchenne

Hi,
There is this one : http://www.driverheaven.net/general-...3-encoder.html
But I haven't tested it...

Thanks jm, I did have a look at that, unfortunately my soundcard is unsupported, but it does look like a good method.

Here's something that I've been trying:

Reaper audio > Virtual Audio Cable (VAC) > Graphedit > AC3Filter (within Graphedit) > Soundcard/Spdif

I've made this work with a stereo stream, but not with multiple channels (5.1) as yet. Of course I can already send a stereo stream to S/PDIF, so not too useful unless I can make it work with multichannel.

I remember my old Nforce2 motherboard had AC3 encoding built into the Soundstorm (had pretty low latency ASIO too), worked like a charm (automatically too, without user tweaking) - too bad it didn't catch on...

[miklogik]

Success! After having another look at the redocneKx, I picked up a used Audigy. It works perfectly. When redocneKx is running, any audio sent to it using the Creative ASIO drivers is converted to AC3 and sent through the Audigy SPDIF (make sure the soundcard is set to send digital out only, in it's control panel). As soon as I run redocneKx, my receiver switches into Dolby Digital 5.1 mode. It's very slick and runs with very low latencies.

redocneKx only works with Creative ASIO drivers (only on Audigy or later cards I believe) or kX drivers. The kX drivers work with older cards, but only certain models are supported for SPDIF passthru. I can tell you from finding out the hard way that the Live! 5.1 card doesn't have passthru in the kX drivers (I think this applies to all cards using the 10k1 chip).

More info here on redocneXk (as jm recommended): http://www.driverheaven.net/general-...3-encoder.html
and for the kX drivers: http://kxproject.lugosoft.com/


It seems like there might be a way to do it with the older Creative Live cards, if you have another device that also has SPDIF out, but I had already bought my Audigy, so haven't tried it:
http://wiki.otaking.se/wiki/RedocneXk


Also, thanks jm duchenne for the great surround plugins, especially the new ones specifically for reaper, SpatReap 66 and SpatReap 66 Mod!
http://acousmodules.free.fr/acousmodules_s_en.htm

[Fergo]

That's nice! What exactly the kX drivers do? They get all the sounds, encode them in AC3 and send through SPDIF? Will it convert the 5.1 discrete signals sent by games (for example), encode in AC3 and send through digital out?

Another thing, can you post a picture of the diagram you made in GraphEdit? I'm trying to do something similar, but to use with games.

Thanks,
Fergo

[gofer]

Originally Posted by miklogik

Also, thanks jm duchenne for the great surround plugins, especially the new ones specifically for reaper, SpatReap 66 and SpatReap 66 Mod!
http://acousmodules.free.fr/acousmodules_s_en.htm

Wow, what a great site! I gotta shove me some spare time to redust/reactivate my surround monitoring stuff. I've given up with surround after a while (on some other daws) because it felt not quite worth all the fiddling, but it seems as if things are much easier now.

I'm very inspirated, thanks

[miklogik]

Originally Posted by Fergo

That's nice! What exactly the kX drivers do? They get all the sounds, encode them in AC3 and send through SPDIF? Will it convert the 5.1 discrete signals sent by games (for example), encode in AC3 and send through digital out?

The kX drivers don't encode to AC3. But they can send to SPDIF (not on 10k1 based cards). You need redocneXk to do the encoding. But it will encode 5.1 sent to it and send it through SPDIF properly to your receiver.

Another thing, can you post a picture of the diagram you made in GraphEdit? I'm trying to do something similar, but to use with games.

For the method that worked for me, I don't need graphedit, just the Creative drivers with ASIO and redocneXk. It will also work with the kX drivers.

I had tried graphedit earlier, as I mentioned in my previous post, but was only able to get two channels. For that I needed to install Virtual Audio Cable and AC3Filter. In Reaper I selected VAC as my output device in Reaper. From within the filters in Graphedit (Graphstudio actually), I chose the Virtual Audio Cable from the Audio Capture Sources filters, and connected this to the AC3Filter from the DirectShow filters, and then connected this to the soundcard output filter. I wasn't able to get it to output the five channels and the lag/latency was large.

By comparison, the redocneXk method works easily (the setup is done once, it's always ready to go) and the latency is very low.