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Introduction

This tutorial is not a howto on setting up slackware or on installing software... There are pleanty of tutorials out there on that subject so no need to re-design the wheel... I am assuming a certain proficency with a linux system.. I am basing this set up on my own setup which works and is stable..

first things first..

Load the module for the looopback sound card which is already part of the slackware base install.. It is just not loaded by default.You will need to be root to do this task

edit /etc/rc.d/rc.modules and add the following line to the file....

/sbin/modprobe snd-aloop

save and exit

reload alsa with following command.

/etc/rc.d/rc.alsa restart

What we have done here with the loopback soundcard is the groundwork for preparing the alsa to jack loopback bridge which will become very handy later on if we want to play multiple sounds at the same time. There are few ways to set the bridge up but we are going to do the simple setup here for now. Threre is another way to set up the bridge which creates up to 4 virtual soundcards but that is for another tutorial. This basic setup here will achieve everything we need to do for the moment.

software installation

most of the software available from slackbuilds.org

install alsaplugins
install skype
install set_rlimits
install qjackctl and all dependencies
install idjc and all stuff required on the list.

Setup the realtime permissions for jack and alsa in and out

next edit /etc/set_rlimits.conf and add the following lines.

@audio /usr/bin/qjackctl -1 80
@audio /usr/bin/alsa_in -1 80
@audio /usr/bin/alsa_out -1 80


Make sure your user is part of the audio group or these settings added to set_rlimits.conf wont make the slighest bit of difference and you will get an error trying to start jack or use the alsa_in and alsa_out comands.

Configure Soundcard

next create a file in your home directory called .asoundrc and insert the following code into it.

# --- begin ----- # playback PCM device: using loopback subdevice 0,0 pcm.amix { type dmix ipc_key 219345 slave.pcm "hw:Loopback,0,0" } # capture PCM device: using loopback subdevice 0,1 pcm.asnoop { type dsnoop ipc_key 219346 slave.pcm "hw:Loopback,0,1" #slave.pcm "hw:Loopback,1,0" } # duplex device combining our PCM devices defined above pcm.aduplex { type asym playback.pcm "amix" capture.pcm "asnoop" } # ------------------------------------------------------ # for jack alsa_in and alsa_out: looped-back signal at other ends pcm.ploop { type plug slave.pcm "hw:Loopback,1,1" } pcm.cloop { type dsnoop ipc_key 219348 slave.pcm "hw:Loopback,1,0" } # ------------------------------------------------------ # default device pcm.!default { type plug slave.pcm "aduplex" } # VoIP plugin for the IDJC default profile. pcm.idjcvoip { type plug slave.pcm { type jack playback_ports { 0 idjc_default:voip_in_l 1 idjc_default:voip_in_r } capture_ports { 0 idjc_default:voip_out_l 1 idjc_default:voip_out_r } } } #---- end ---------------

now restart alsa again

/etc/rc.d/rc.alsa restart.

What we have done here is configure the loopback sound card and the bridge control which handles all out sound mixing. We can capture these sounds and route them with jack into the idjc aux channels. If we play a flash video or play audio on a player idjc can now hear them. We also have our plug device which skype now can access. That is the idjcvoip plug. The idjcplug also sets up the automatic connection of any call direct into idjc voip input.

Setup some default connections

Create a file called loop2jack or whatever you want and insert the following code

#---------------- start -------------------- #!/bin/sh # script loop2jack, located in /usr/local/bin # start idjc /usr/local/bin/idjc & # give it a chance to start sleep 2 # loop client creation set_rlimits /usr/bin/alsa_out -j ploop -dploop -q 1 2>&1 1> /dev/null & set_rlimits /usr/bin/alsa_in -j cloop -dcloop -q 1 2>&1 1> /dev/null & # The following line is specific to my setup only #but I shall leave it here for refference. # It sets up a jack plug for my USB microphone # in the jack connection manager which i can then # plug into IDJC. you can find the name of your USB # mic by using the command arecord -l. # The name of your mic will be the second field of the # revelent audio device. Mine is called mirophone. #set_rlimits /usr/bin/alsa_in -j Microphone -d hw:Microphone -q 1 2>&1> /dev/null & # give it some time before connection to system ports sleep 1 # cloop ports -> jack -> idjc voip input ports jack_connect cloop:capture_1 idjc_default:voip_in_l jack_connect cloop:capture_2 idjc_default:voip_in_r #jack_connect Microphone:capture_1 idjc_default:ch_in_1 # done exit 0 #------------ end --------------------

now make that loop2jack script executeable

chmod 744 loop2jack

Testing and finishing setup

We will start qjackctl the following way we can create a command for easy launch later..

set_rlimits /usr/bin/qjackctl

Next we will go to setup on the qjackctl window.
Click on the options tab.
Select execute script after startup
The command you want to start is the loop2jack script we just created.
now quit jack and restart it again the way we did the first time.
now clik the start button
in a moment idjc should start
set the default to open autmatically
start skype
go to options and sound devices and set the mic speaker and ringing to idjc (plug)
clik apply.
in idjc clik the green button
in skype make a test called
all should be working.