TIP Send audio from one card to the other

From Gentoo Linux Wiki

This article is part of the Tips & Tricks series.

Terminals / Shells • Network • X Window System • Portage • System • Filesystems • Kernel • Other

Contents 1 Introduction 2 Requirements 3 Main course 4 Supplements

[edit] Introduction

I have an onboard sound card and an external usb sound card (well its actually more like a thumb drive). I have the speaker connected to the onboard sound card (card0) and the headphones to the external card (card 2). I also have a TV card which audio out is connected with a wire to the onboard line-in. As the audio goes in to the card that is connected to the speakers, I can unmute line-in and hear TV. Here is how to have the audio delivered to the headphones which are connected to the other sound card.

Please fix the title as you see fit

[edit] Requirements

Please follow How to Jack to setup Jack.

[edit] Main course

You need to run jackd for each sound card, then you may use jack_diplomat. But you may also use two different cards like this:

jackd --realtime --driver=alsa -P hw:2 -C hw:0 &

Then use qjackctl to test the conections

I use this script:

#!/bin/bash
jackd --realtime --driver=alsa -P hw:2 -C hw:0 &
wait 10
jack_connect alsa_pcm:capture_1 alsa_pcm:playback_1
jack_connect alsa_pcm:capture_1 alsa_pcm:playback_2

[edit] Supplements

Peter over the Jackit ML advised that one can use alsa to see sevrel sound cards as one using the .asoundrc file like here: Multiple ICE1712 Sound Cards I may try that approch and add that file.