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Old 07-26-2006, 01:44 PM   #1
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Registered: Jun 2004
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ALSA - How to?: Two sound sources, but just listen to one?


first I want to say that I dont like the ALSA-Wiki Doc Homepage. I'm working with linux about 5 years and after reading ALSA's Wiki's and Howto's I still don't understand the whole ALSA-thing.

Ok. Here we go:
This will be a "sound routing pc":
I'm planning to buy a soundcard which has 2 Inputs: a stereo (Line-in) and another (say a digital In) which is capable of > 4.0 .
The sound card must have one output (say a digital - spdif) which is connected to my Panasonic Receiver.
I want to write a program which just switches between the two input sources. I don't need a GUI or shell like. I just want to use the ALSA-API. (It's OK when the sound stops for 1 sec. when switching)The stereo signal can be upmixed to a 4.0 signal so I can use all of my 4 speakers.
(Maybe someone can point me to such a device with support for ALSA/Linux)

Here's my question:
How can I realize this?
I've read days about .asoundrc and this would be the first place where I would start.

Creating 2 pcm's:
#1 for upmixing stereo input and routing to spdif out.
#2 for routing input to spdif out

But I didn't find out how to link a input to some pcm's and so on... (As I pointed out: I am confused by the whole ALSA-Wiki-Doc Homepage).

Please, can someone enlighten me?


Old 07-27-2006, 05:26 AM   #2
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Registered: Jun 2004
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There are sound cards that have a digital input and digital output. And they have four analog outputs and a Line-In. So, the hardware is not the problem.

I just don't know where to look for hints.

Maybe I should link the two inputs with a mixer and mute just one of them. This "simulates" Switching. Could this work?

What about the digital input. What if there is a stream with just 2 channels (stereo). Will there be an Error (like unknown channels 3)?




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