[PATCH] Dual Audio Output support for XBMC (Eden Updated)

(2013-04-11 04:59)GCMX Wrote:  I hope this helps some people. I'm pretty sure my setup and what I'm trying to achieve must be pretty common. I hope its not specific to my hardware.

I have 2 independent zones on my AV receiver. Zone 1 audio is 5.1 from my video card's HDMI port. Zone 2 can only receive analogue and is hooked up to a pair of outdoor stereo speakers. Zone 2 is only used for stereo music, not 5.1 video. The way I use it is if zone 2 is playing then, zone 1 is either muted or is playing the same thing as zone 2. I haven't tried playing something different on zones 1 and 2 using two instances of XBMC or another media program. I can't see why what I describe below wouldn't work for that, but then again I can't really work out why it does work in the first place. This would also work for anyone that wants simultaneous stereo headphones and 5.1 output.

The Windows dual audio build of Eden works fine, however, I find DTS doesn't sound as good as it should and I'd hoped Frodo would improve it. I got sick of waiting for a Frodo build with dual audio so I did a little tinkering.

I've found I can get dual audio in Eden (I haven't tested Frodo yet, but it should work) without using the dual audio options if I plug my front (headphone) audio port into zone 2 using a 3.5mm to stereo RCA adapter cable and set headphones as the default output device in windows (it only shows up if something is plugged in), then go into to XBMC audio settings and set my video card's HDMI and 5.1 as the output device. I'm using WASPI (following the XBMC WASPI audio engine guide) and everything seems to work fine outputting simultaneous stereo to zone 1 and 2. Zone 1 outputs 5.1 surround for movies. For some reason if I unplug the headphone port, the sound on zone 1 becomes garbled, no idea why but I just leave it plugged in and everything is fine.

I'm not sure why this works (all my research tells me it shouldn't). It may be do with the fact that I'm using onboard sound and a separate video card, but I would have thought that was pretty common. My guess is its something to do with the way windows mutes speakers when you plug in headphones and XBMC is overriding it. Not sure if it would work with onboard HDMI video or in linux.

I really hope this helps some people. I'm going to try Frodo this weekend and will post back if something doesn't work or if I have to make some changes.

Addendum: I bought one of those HDMI2HDMI+Audio things mentioned a few pages back off ebay. I couldn't get any sound out of the 3.5mm port and it made windows, XBMC and my AV receiver detect HDMI as stereo only (which might be fine for some people with purely stereo setups but not what I was looking for). So I cannot recommend them for a 5.1 setup.

Edit: spelling

You have exactly the same setup as me, (Onkyo AV Receiver per chance? ). The problem with those HDMI audio extractors is that they are only going to work for 2 channel PCM audio. Unless you get one with full decoding support for DTS etc, it's probably not going to fulfill what we need.

I does seem that the best solution is to have XBMC do it internally as that way it can pass DTS pass-through audio to the digital output and decode and down mix for stereo to the analogue. Anything else I think is just going to be hacky / expensive.

(2013-04-12 15:47)XenoPhoenix Wrote:  You have exactly the same setup as me, (Onkyo AV Receiver per chance? ).

Pioneer

(2013-04-12 15:47)XenoPhoenix Wrote:  The problem with those HDMI audio extractors is that they are only going to work for 2 channel PCM audio. Unless you get one with full decoding support for DTS etc, it's probably not going to fulfill what we need.

Yeah, I know that now, wish I had of known before I bought it. I couldn't find a lot of info about them at the time.

(2013-04-12 15:47)XenoPhoenix Wrote:  I does seem that the best solution is to have XBMC do it internally as that way it can pass DTS pass-through audio to the digital output and decode and down mix for stereo to the analogue. Anything else I think is just going to be hacky / expensive.

I agree that would be ideal but unfortunately it doesn't look like its going to happen officially. In the meantime, the above method works for me.

(2013-04-13 02:39)GCMX Wrote:  I agree that would be ideal but unfortunately it doesn't look like its going to happen officially. In the meantime, the above method works for me.

My setup is using Linux so I suspect that trick will not work for me. With your setup, are you using DTS etc. pass-through or are you having XBMC decode the audio? I presume you must have pass-through disabled for what your doing to work.

(2013-04-15 16:44)XenoPhoenix Wrote:  My setup is using Linux so I suspect that trick will not work for me.

I don't know, it seems unlikely but its easy enough to try it out. It could be a hardware thing related to the onboard sound front headers I suppose.

(2013-04-15 16:44)XenoPhoenix Wrote:  With your setup, are you using DTS etc. pass-through or are you having XBMC decode the audio? I presume you must have pass-through disabled for what your doing to work.

Yeah I'm using pass-through (at least I think its set up properly) and I've now tested in Frodo and all seems to be working fine. As I described above though, I don't use DTS for my zone 2, purely stereo music in mp3, which if I understand correctly isn't affected by pass-through settings. DTS won't work for zone 2 because its an analogue stereo output/input and I don't need it to. DTS works fine on zone 1 though. As far as I can tell XBMC is sending everything normally through HDMI, windows (or possibly but unlikely the onboard sound card) is simultaneously sending anything it is capable of through the headphones jack.