I am trying to get surround sound working on my HD front end. It's an abit ai7, and I've tried the onboard ICH5 audio, and an SBlive (06).

My objective is to get 6 channel audio to my receiver's 6 channel input for HD/AC3 5.1 programming, with the fronts also going to the TV for old fasioned stereo SD shows. This mimics the config I used when I ran this HTPC on windows.

Plan B would be stereo/AC3 downmix to the TV, with AC3 to the receiver. This is probably the better config in the long run.

From the user's (wife's) perspective, stereo sound always comes out of the TV, and surround sound comes out of the receiver when available.

The alsa speaker-test works on all 6 channels, but mythtv only uses 2 channels. I've tried ALSA:surround51 and ALSA:plug:surround51:0 audio devices. ALSA:default gives me either 2 channel analog or SPDIF on all channels depending on the ac3 passthrough flag.

I don't know if this is a Myth issue or an Alsa issue, but I could use some pointers. If nothing else, I could use a solid primer on ALSA

I remember reading on the MythTV listing that when you try and use one of the ALSA:plug... it didn't work. It has been fixed in version 0.20 from what I understand.

I have tried a similar thing with my Analog outputs and this was the result of my research.

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Girkers

With the onboard audio, ALSA:plug gave me no audio. With the PCI SBLive it gives me 2 channel audio. Seems to be the same as ASLA:default

I don't think Myth can play AC3 in full surround, only pass it through on the digital ports.

As for a solid primer on ALSA, good luck. Everything I've seen on it seems to assume you're familiar with the internals.

Well, I've reverted to ALSA:spdif with passthrough enabled, and that has Live TV and watch recordings working through my receiver for both HD/AC3 and SD/Mpeg audio. TV speakers are dead for now. I don't think that will work as I bring the other modules online, esp the music player, but it'll buy me some time to study ALSA.

I spent some time going through the Alsa docs to find a way to get simultaneous output to both analog (TV) and digital (receiver) with no luck (or even automatic switching). The best I was able to do was similar to what you have (ALSA:spdif + passthrough). If anyone figures this out, I think a lot of people would be happy.

As for music, there is a separate setting for the output device in the music setup, so this isn't really a problem.

Allen

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ASUS AT3N7A-I (Atom 330)
TBS 8922 PCI (DVB-S2)

I just discovered that Myth 0.20 allows a separate passthrough device. It will automatically switch devices depending on what format the sound track is in.

Sound still won't go to both at once, but after playing with this method, I think I like it better. If I am too lazy to turn on the receiver, I can just switch to a non-AC3/DTS souldtrack to output to the TV.

Definitely a very nice improvement!

Allen

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ASUS AT3N7A-I (Atom 330)
TBS 8922 PCI (DVB-S2)

I have found that ALSA:plug:surround51 works with MythTV 0.20.

The only problem I have now is that when I do:
the Front Left and and Rear Left are on the right hand side of the TV when I am facing the TV. And the opposite for the right hand side obviously. Is this right?

That does sound pretty cool... though it would still be nice to get both at once somehow. My receiver has multiple 'zones', and I have some wireless headphones on one of the zones. The only problem with zones is that they don't process digital signals... so they need analog input.

So, when watching TV with headphones, I need to feed it analog. When watching TV with speakers, I'd of course want digital with surround.

I still have to pick up a sound card to do the optical one of these days and see if I can get it going.

Do I understand correctly though, that you can just pick AC3/DTS or non with the remote while watching TV? I currently don't have HDTV yet either... so I guess I've never noticed this (I'm planning on getting one of the HDHomeRun units soon as well.)

Just trying to do some reading and get my ducks in a row...

Thanks,

-Steve

If there are multiple sound tracks available, there is a menu item while watching a recording or LiveTV to select which one to play.

Allen

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ASUS AT3N7A-I (Atom 330)
TBS 8922 PCI (DVB-S2)

Thanks Allen, I'll look for that.

-Steve