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Kianouch · (This post was last modified: 2014-10-26, 22:52 by Kianouch.)

Hi,

I have the infamous Logitech Z5450 kit, with both rear Bluetooth speakers dead. (same as everyone who bought this crappy kit)

Therefore I have only 2 possibilities :

- Stereo sound : missing DD & DTS altogether and not using my central speaker
- Passthrough : DD & DTS 5.1 working but I miss all the rear sound which is routed to non existant speakers

I would really like to have Dolby Digital and DTS sound, using my 2 front + central speakers.

Would anyone know if there is a way for me to do so, without losing all the read sound ? I would suppose they could be routed to the front speakers...
The thing really bothering my when I use stereo is my central front speaker is not used.

Thanks !

**DaVu** · 2014-10-26, 23:33

Well...I dont know if it is possible to map those channels to the Front speakers, but I suppose it will "feel" (listen) like shit (tbh). If the rear sound came from the Front the speakers its not "movie-like" anymore. If I would loose my rear speakers, I would only listen to stereo and save some money to buy a better system. What you are trying to achive isnt surround anymore and it wouldnt listen like that.

Greetings

**fritsch** · 2014-10-27, 08:19

Quote:I would really like to have Dolby Digital and DTS sound, using my 2 front + central speakers.

Passthrough is untouched.

**Memphiz** · 2014-10-27, 12:05

You would need to disable passthrough and set the speakerconfig in XBMC to 3.0 (which is left center right). This should do what you want (mixing down the rear speakers into the front speakers and using the center ...)

**fritsch** · 2014-10-27, 17:31

Nope - he has Optical out only - therefore he is limited to 2 pcm channels.

All the surround is done by AC3 or DTS. AC3 Transcode will also encode 5.1 and won't help him.

**Memphiz** · 2014-10-27, 20:18

then out of luck - repair the rears.

Kianouch · (This post was last modified: 2014-11-01, 23:42 by Kianouch.)

(2014-10-27, 12:05)Memphiz Wrote: You would need to disable passthrough and set the speakerconfig in XBMC to 3.0 (which is left center right). This should do what you want (mixing down the rear speakers into the front speakers and using the center ...)

Of course ! I will try that, thanks.

Edit : but where would that be ? I cant find this settings under the System/Audio menu where you configure pass-through or other audio settings.

(2014-10-27, 17:31)fritsch Wrote: Nope - he has Optical out only - therefore he is limited to 2 pcm channels.

All the surround is done by AC3 or DTS. AC3 Transcode will also encode 5.1 and won't help him.

There is a solution : switching the computer to Dolby Digital Live and doing what Memphis said Blush

**fritsch** · (This post was last modified: 2014-11-01, 23:37 by fritsch.)

Na, that's something different you now do. You only output 2 channels right now and your AVR upmixes to 5.1 and you only hear 3.0 as the rears are broken.

Edit: Post a Debug Log I can show you.

Kianouch · 2014-11-04, 17:31

I actually don't understand where the option to downmix from 5.1 do 3.1 is.

That is what I would like to do. If I can find this option it will work perfectly.

**fritsch** · 2014-11-04, 17:40

No, it won't - that's the issue here.

You are using a SPDIF out (Optical). This can only output 2 pcm channels. To get 5.1 output, you need to use a 5.1 AC3 signal which is "encoded over this _2_" pcm channels.

The solution for you would be:
Decode and downmix your input and afterwards encode that to AC3 again while only sending 3.1 - which is not possible with xbmc

Kianouch · 2014-11-04, 18:42

(2014-11-04, 17:40)fritsch Wrote: You are using a SPDIF out (Optical). This can only output 2 pcm channels. To get 5.1 output, you need to use a 5.1 AC3 signal which is "encoded over this _2_" pcm channels.

The solution for you would be:
Decode and downmix your input and afterwards encode that to AC3 again while only sending 3.1 - which is not possible with xbmc

Can't I use some DirectSound/Wave output while using Dolby Digital Live on the driver ? This way XBMC outputs whatever I want and the audio driver does the magic ? Technically, nothing would be blocking that, I think.

Kianouch · 2014-11-04, 20:37

(2014-11-04, 17:40)fritsch Wrote: Audio Engine: SPDIF has only 2 pcm channels. DTS, AC3 are encoded via those 2 channels. It's obviously clear that you are not able to change Speaker Layout when running via SPDIF.

I was gonna ask what if I replace my optical SPDIF with coaxial, but I think it would just be the same.
Therefore I guess my only way out would be to perhaps use a triple analog jack ouput ? No - it would be Dolby Pro Logic at best.

OK then, I guess there's no way out.

S/PDIF can carry two channels of uncompressed PCM audio or compressed 5.1/7.1 surround sound

Would it not be possible to downmix to 3.1 sound and send the 2 rear speakers an almost empty signal ? I would mean remixing the sound to the 3.1 front and pretending there is a rear sound so the sound system would work. Don't know if I'm clear.

**DaVu** · 2014-11-04, 20:52

coax would be the same as s/pdif.

Like fritsch said, what you are trying to achieve is not possible with XBMC/Kodi. Fritsch explained, that you have to decode your audio stream and then reencode it to AC3 by only using 4 channels (3.1), which is not possible, as he said. So you have to do this manually. It doesn´t work on the fly, if I understand correctly. But then I think this won´t sound very well. Imagine you have a car coming from the back to the front...it will sound as it comes from the front to the front...that wouldn´t be my way.

So, it´s like I said in my first posting...If I would loose my rears, I would give stereo a chance or (like you said) let the AVR do Dolby ProLogic 2x, which can be achieved by using 2 analog channels, which are available ootb I suppose. Depending which kind of HTPC hardware you use.