Control Volume while in Passthrough?

Im having quite a hard time getting my audio to do what I want.

Heres how I have things hooked up: Windows Computer -> Yamaha Receiver, via optical SPDIF

Heres what I WANT to happen: I want to have my 5.1 files send the 5.1 audio to my receiver, while XBMC still allows me to control things like Volume

Heres what happens instead: XBMC will PASSTHROUGH my 5.1 audio straight to my receiver, which prevents me from controlling volume (and usually blasting our eardrums, since I have my receiver vol so high)


Obviously, Ive played around in the settings trying to find something that works... no matter what I try, I cant figure this out. I thought AudioEngine was supposed to fix this? (Am I stupid and just dont know how to enable AudioEngine maybe?)



Thanks in advance for any help!

EDIT: Im running a nightly, installed earlier today

The only way I know to control vol in this scenario from the PC is via the spdif volume output in the OS itself.

Or you disable passthrough in audio settings to restore volume control within XBMC but that sounds.. not so good.

Your issue is with the optical output. The only way 5.1 audio can get thru with optical is encoded as AC3 i.e. passed through, which means untouched and no messing with the volume.

You have two choices if you still want 5.1 - passthru or upgrade to HDMI which can do exactly what you're asking.

(2012-08-31 05:51)DDDamian Wrote:  You have two choices if you still want 5.1 - passthru or upgrade to HDMI which can do exactly what you're asking.

I was afraid of that.
Whelp. Looks like its time for a new receiver, i suppose.

Thanks for the quick response

Np - afraid it's a very real limitation of spdif/optical/coax.

With HDMI the signal can be decoded to LPCM, volume adjusted and then all 5.1 (or more) channels sent across it. You can also get DTS-MA/TrueHD over HDMI which you can't over spdif.

To do what you ask over optical we would need to: decode AC3 > convert int to float > adjust volume > convert float to int > transcode back to AC3.

Or you can adjust the volume on the receiver

(2012-08-31 06:26)DDDamian Wrote:  To do what you ask over optical we would need to: decode AC3 > convert int to float > adjust volume > convert float to int > transcode back to AC3.

Just to be sure mate. NO!!!!!

thank you! this is the info I was looking for in relation to passthrough on spdif; no volume control and DTS-MA and TrueHD cannot be passed over. Not trying to hijack the thread, but this brings up a few related questions for me:

-In XBMC audio settings, if both an audio output and passthrough devices are specified, is passthrough the 'default'? If that's correct, then to not use passthrough, I simply select 'none' under the passthrough device?

-If passthrough is not being used, can I still specify spdif for output and have it work? In this case what does XBMC do with the sound before passing on to the receiver? I would assume it just decodes it all to PCM and then sends it to the receiver, as opposed to the receiver decoding, which seems it would end up with the exact same sound quality? But user Ardalista mentioned above that no passthrough would not sound as good. Is there a loss in audio quality when not using passthrough?

EDIT: I'll take this to a new thread

(2012-08-31 06:26)DDDamian Wrote:  Np - afraid it's a very real limitation of spdif/optical/coax.

With HDMI the signal can be decoded to LPCM, volume adjusted and then all 5.1 (or more) channels sent across it. You can also get DTS-MA/TrueHD over HDMI which you can't over spdif.

To do what you ask over optical we would need to: decode AC3 > convert int to float > adjust volume > convert float to int > transcode back to AC3.

Or you can adjust the volume on the receiver

Hi DDamian,

I'm don't agree with your explination. I've got a similar setup as Plasma2002: Windows PC with Optical audio to Receiver, these things happen:

When I start an .AVI file, the volume can be ajusted with my remote (even the nice OSD appears)
When I start an .ISO (DVD-file) file, the message "Passtrough in use" appears

So it seams XBMC is capable of ajusting sound output over Optical SPDIF since it does when I watch a .AVI file, why doesn't it work with an .ISO file?
Hope to hear from you or someone because I would like to fix this issue for a long time. :-)

A happy XBMC 11 Eden user!

Renver

EDIT: I found the solution!
Try turning off the AC3 & DTS capable receiver options in Settings. That will make XBMC do the decoding, but it will let you control the volume, even with Optical SPDIF!

I'm so happy!!

But don't you sacrifice surround sound then?

Are there any benefits to lettings XBMC decode AC3, DTS, etc and sending LPCM to the receiver? Other then controling the volume via XBMC (I don't see this as a benefit). Why would someone want to do this?