[SamuelHenderson]

Hi everyone.

I'm running XBMC on Crystalbuntu on my 1st gen Apple TV (with the Broadcom gpu upgrade) and am having problems with my audio setup.

Basically my Apple TV (and other devices like PS3 and Satellite Receiver) connect to my TV (a Sony Bravia XBR) via HDMI and then my TV connects to my surround sound receiver (a Panasonic SA-PT760) via Optical. I've done a bit of research into the audio already and have my Audio Output settings as follows:

Audio Output: HDMI
Speaker Configuration: 5.1
Boost Volume Level on downmix: Yes
Dolby Digital (AC3) Capable Receiver: No(?)
DTS Capable Receiver: Yes
Audio Output Device: Custom
Custom Audio Device: plughw:0,3
Audio Passthrough Device: Custom
Custom Passthrough Device: plughw:0,3

This setup seems to work for non 5.1 movies as the normal XBMC menu sounds are working fine and so are some TV shows that I have ripped. When I try to play some HD content though (1080p, 5.1 Surround Sound) I either hear nothing, all sounds and music except voices (which is really weird).

Can anyone point me in the right direction? Also, does my receiver support AC3? The manual mentions it's capable of DTS 5.1 and Dolby Pro Logic II but it doesn't say anything about AC3 :S

Any advice is welcome

[ruggedoutdoor]

I have done the same build as you. ATV1 with Broadcom GPU (BCM970012 to be exact) and Crystalbuntu internal hard drive install. I run HDMI 5.1 and have set my device custom like you in the setting menu of XBMC. When a 5.1 HD movie starts to play I get a quick half second scratch sound then dead air. Hope this helps the moderator/support folks with either or both of our issues.

UPDATE: My issue looks like a DTS issue causing the quick static then dead air. I can play 5.1 channel AAC streams but with sound and music only like you. Cannot hear the actors. Sounds like we are in a fairly identical situation.

[SamuelHenderson]

Hi ruggedoutdoor

Yeah your issue definitely sounds the same as mine. Since I've posted this I've determined that my receiver definitely supports AC3 and DTS (looked up the specifications online). I've also bought a generic optical switch/splitter that allows me to feed all my optical devices into one input into the receiver. The only downside is that when I want to switch between my ATV1, PS3 and Satellite TV I need to get up and move the switch (so far it's not a big deal though ).

I posted pretty much the same thread over at crystalbuntu users forum: http://forum.stmlabs.com/showthread.php?tid=1998

This is the response I got there:

You'll find a notable number of TV's don't passthrough 5.1 via their optical output: in my case the TV decodes Dolby Digital 5.1 and DTS 5.1 but pushes everything out the optical by two-channel PCM. I understand why a lot of people only hook up their TVs to their home cinema amps - everything that comes out the TV then goes through to the amp without having to change the input on the amp - but in most cases, for trouble free surround sound it's best to connect the optical/co-ax of each device directly to the amp. A good universal remote can be programmed to use macros, so for example if I press the TV button on my URC9760 the TV's input is changed to HDMI1 for the TiVo and the amp is changed to the TiVo input, while if I press the MOVIE button the TV input changes to HDMI2 for the Revo and the amp is changed to HTPC input.

Basically it was this response that convinced me to go the optical switch route (since my receiver only has one optical in) and ditch the TV passthrough.

**I should note however that even when I go optical from my ATV1 to my receiver I still can't get DTS working, however I'm at least able to disable the DTS option in XBMC and still hear sound from all sound channels...**

I'm going to continue doing some research in this area because I *know* that my receiver should have no problem decoding DTS. Perhaps my Bravia TV is downverting my DTS to 2 channel PCM, but my ATV1 direct to receiver via optical should not suffer that problem at all.

[ruggedoutdoor]

This totally makes sense. So easy to fix too. I did not know Optical of TV splits the channel. Swapped with my receiver bound PS3 and viola! Surround sound lives! I never use the PS3 anymore anyway if I do I can live with 2 channels until I get a receiver that can handle 3 or more HDMI inputs. They are much more money. Thank you so much for the simple yet critical piece of info - moving cables around! ;-)