[mythtv-users] spdif with simultaneous analog out (alsa)?

[Richard Woelk]

Misty P wrote:
> Richard Woelk wrote:
>   
>>> Misty,
>>>    It took me a lot of searching to find this asound.conf (attached)
>>> but it is working on my folks' Mythtv. I think most of it is
>>> overkill,
>>> but it works for me so I haven't tried to clean it up. They are
>>> using a nForce2 based shuttle board with onboard audio. It uses the
>>> snd_intel8x0 module
>>>
>>> In the mythtv settings page, you have to set the audio output to
>>> ALSA:default.
>>> Make sure that AC3 & DTS passthrough are checked and the passthrough
>>> device to ALSA:iec958:{ AES0 0x02 }
>>>
>>> Recordings from the PVR-250 and mythmusic work simultaneously from
>>> analog and digital outputs.
>>> AC3 and DTS tracks from mythdvd (or digital recordings.) are sent
>>> directly out the SPDIF output and the analog is muted
>>>       
>
> Ahh, thanks for that!
>
> It doesn't quite work for me, though...  Things with PCM audio wind up going 
> out the analog, and it's *trying* to go out through the SPDIF but something 
> is amiss.  (The SPDIF light keeps coming on and going out on the receiver.) 
> AC3 does work exactly as you describe.
>
> Unfortunately, since I'm all ATSC OTA, 80% or better of my content has AC3 
> on it.  (Or worse, is AC3 except for the commercials...  yuck!)
>
> I guess what I'm trying to do just isn't possible under linux.  (Which seems 
> insane, because I do it under windows!)  Thanks for the help, though.
>
>
>   
Misty,
    If you uncheck the passthrough boxes in the mythfrontend setup 
screens, then Mythtv won't pass AC3 to the SPDIF, the stream will be 
decoded  internally and output as 2 channel PCM.

I'm not sure why the PCM isn't working correctly, it sounds like its 
trying.

on Line 164, you have to change device 2 to device 1 (judging from your 
.asoundrc that you posted)

you can also try this.
at line 54, you can configure what is default. Maybe try changing that 
to digital-hw instead of dmix-analog
It will prevent other sounds from interfering. You can also use these 4 
device names directly in mythtv

analog
mixed-analog
digital
mixed-digital

It is impossible, as far as I've seen, in windows, to output AC3 over 
SPDIF and decode to analog simultaneously.

- Richard



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