[mythtv-users] ALSA and real AC3 passthrough

Richard Shaw rshaw2 at midsouth.rr.com
Thu Dec 29 15:19:09 EST 2005

Sorry about top posting but my question is along the same lines but a 
little bit tangent. How do you get simultaneous analog and digital 
sound? I could do it in Windows XP on my nForce2 but everthing I've read 
online for alsa assumes you want one or the other, not both. I want 
analog going to the TV while digital goes to the receiver.


Petr Stehlik wrote:

>Hi all,
>yesterday I switched my myth box from analog to digital sound output
>(Asus K8V SE motherboard with its onboard sound). I got it working
>relatively quickly with "ALSA:digital" driver (also "ALSA:default"
>worked) but couldn't get the "AC3 passthrough" working correctly - on
>AC3 DVB-S channels I heard only a noise. At last I managed to get the
>AC3 passthrough (DVB-S ASTRA HD AC3 5.1 sound) working by setting
>"ALSA:spdif" in myth. But that broke analog sound (analog TV capture to
>32000 Hz MP3). Some analog sounds sometime work for a while if they are
>44.1 kHz and the receiver is in a good mood (but it probably plays it a
>bit faster since 44.1 is replayed as 48 kHz).
>So basically I can get everything but real DVB-S AC3 passthrough working
>with "ALSA:digital" or I can get everything but analog sound with
>I copied the .asoundrc from the Digital Sound Howto.
>Xine works properly with MP3 and AC3 sound.
>My question is whether it's possible to set up the .asoundrc in a way
>that it handles both DVB-S AC3 real passthrough and also analog->digital
>conversion plus 32kHz->48kHz resampling.
>I currently think that it's not easily possible and that myth should
>allow me to enter a different sound device for the passthrough. But
>since xine handles it somehow then it might be possible. Please advise. 
>mythtv-users mailing list
>mythtv-users at mythtv.org

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