Single PC solution - Use of 2 USB sound cards as crossovers using PAX Rack

[Tfive]

FYI: Last week we did an experiment and fused two USB cards on the ALSA level. After loading the module-alsa-sink with the given multi-device the card showed up in the output configuration dialog of PaXoverRack with all of its channels.

[Tromperie]

Tfive,
You have no idea how happy that makes me.

I did receive a PM from RAndyB who gave me some assistance but I've been too busy with house repairs to do anything about it (replacing weatherboards that were put up badly and incorrectly is an 'interesting' and perplexing exercise).

Would you be so kind as to post the code and I will adapt to my situation, hopefully with some luck and success? I am trying to install Logitech Media Server on my FreeNAS and if that works, I will use a RaPi as a Squeezelite client with PaXover Rack installed on it as well. One less big box, less energy used, more WAF, and centralised control.

[Tfive]

Well, everything has already been posted here. As far as I remember you have the ALSA side of things setup and the multi-device is working, right?

[RAndyB]

For anyone reading this thread and wondering:

Here is the thread that I started when exploring ALSA to replace MiniDSP:

asoundrc and ladspa

There is now enough information on the web to get started, as Tromperie has shown in his original post. It's difficult to work through the ALSA documentation: even the syntax of asoundrc file seems inconsistent, which adds to the frustration. As I have said before; great software, shame about the user manual.

Tromperie: It's the equivalent of Britain's January with you, if I calculate correctly? Just checked the weather in Melbourne - looks ideal for the outside work, unlike January here.

Andy

PS after a decade or so, I realised that the User Manual was the starting point for software projects. Actual people with cheque books focusses the mind in that direction.

[Tfive]

That's why besides linking two soundcards at the ALSA layer (did it way back when with two M-Audio Delta 1010s in our home studio to have 16 tracks) I have never tinkered with .asoundrc and ALSA before. It's like using assembler compared to python if that makes sense, ALSA is completely at the hardware level.

Tromperie has to do it though as he has a kind of a special case setup with one soundcard delivering all the left channel audio and one soundcard all the right channel audio. As he succeeded in creating a multi-device though everything else should now be handled one layer up, eg. by pulseaudio.

In the end all the fussing about with config files by hand is not user friendly at all and that's why i created this wonderful piece of software - Pulseaudio Crossover Rack. A little bit of self-praisal can never hurt, can it? Let's get serious again, at the end of the day I'm not a coder but a user too and I want things to "just work (TM)".

[Tromperie]

Tfive,
The problem is that I have NOT succeeded in getting my proposal working.

Please post your config files. As I said in the OP, your software solves so many problems and is a fantastic solution.

[Tfive]

Let's go more metholodical here. Please first confirm that your multi-device is working right now with speaker-test.

[Tromperie]

Speaker test works. See post 30.

I understand better by seeing the whole picture and working my way through it. Piecemeal drives me nuts.

[Tfive]

Do you have the original, unmodified version of /etc/pulse/default.pa in place? If not, grab a backup or reinstall the original version first. If not yet done, make a backup. Then, comment the following section:

### Automatically load driver modules depending on the hardware available
.ifexists module-udev-detect.so
load-module module-udev-detect
.else
### Use the static hardware detection module (for systems that lack udev support)
load-module module-detect
.endif

Then uncomment and modifiy the line containing "load-module module-alsa-sink" to read:

load-module module-alsa-sink device=multidev

After that, restart pulseaudio by issueing "pulseaudio -k" from a console. Then pulseaudio should now come up with only one device with 12 channels.

If it doesn't, well, then we have to investigate further. Pro tip: always go step by step, even if you think this is piecemeal. But this is good practice and the basis to debugging a problem. And if you change multiple things at once, how should we know exactly what is the state of your system and how to fix it? So if you want people to help you, you should heed their advice

[Tromperie]

Hello,
I'm back at after several hectic months.

My .pa file is modified. Where can I get an unmodified copy?
Edit: Just found one. Does this look right?

~$ cat /etc/pulse/default.pa
#!/usr/bin/pulseaudio -nF
#
# This file is part of PulseAudio.
#
# PulseAudio is free software; you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# PulseAudio is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with PulseAudio; if not, see <http://www.gnu.org/licenses/>.

# This startup script is used only if PulseAudio is started per-user
# (i.e. not in system mode)

.fail

### Automatically restore the volume of streams and devices
load-module module-device-restore
load-module module-stream-restore
load-module module-card-restore

### Automatically augment property information from .desktop files
### stored in /usr/share/application
load-module module-augment-properties

### Should be after module-*-restore but before module-*-detect
load-module module-switch-on-port-available

### Use hot-plugged devices like Bluetooth or USB automatically (LP: #1702794)
.ifexists module-switch-on-connect.so
load-module module-switch-on-connect
.endif

### Load audio drivers statically
### (it's probably better to not load these drivers manually, but instead
### use module-udev-detect -- see below -- for doing this automatically)
#load-module module-alsa-sink
#load-module module-alsa-source device=hw:1,0
#load-module module-oss device="/dev/dsp" sink_name=output source_name=input
#load-module module-oss-mmap device="/dev/dsp" sink_name=output source_name=input
#load-module module-null-sink
#load-module module-pipe-sink

### Automatically load driver modules depending on the hardware available
.ifexists module-udev-detect.so
load-module module-udev-detect
.else
### Use the static hardware detection module (for systems that lack udev support)
load-module module-detect
.endif

### Automatically connect sink and source if JACK server is present
.ifexists module-jackdbus-detect.so
.nofail
load-module module-jackdbus-detect channels=2
.fail
.endif

### Automatically load driver modules for Bluetooth hardware
.ifexists module-bluetooth-policy.so
load-module module-bluetooth-policy
.endif

.ifexists module-bluetooth-discover.so
load-module module-bluetooth-discover
.endif

### Load several protocols
.ifexists module-esound-protocol-unix.so
load-module module-esound-protocol-unix
.endif
load-module module-native-protocol-unix

### Network access (may be configured with paprefs, so leave this commented
### here if you plan to use paprefs)
#load-module module-esound-protocol-tcp
#load-module module-native-protocol-tcp
#load-module module-zeroconf-publish

### Load the RTP receiver module (also configured via paprefs, see above)
#load-module module-rtp-recv

### Load the RTP sender module (also configured via paprefs, see above)
#load-module module-null-sink sink_name=rtp format=s16be channels=2 rate=44100 sink_properties="device.description='RTP Multicast Sink'"
#load-module module-rtp-send source=rtp.monitor

### Load additional modules from GConf settings. This can be configured with the paprefs tool.
### Please keep in mind that the modules configured by paprefs might conflict with manually
### loaded modules.
.ifexists module-gconf.so
.nofail
load-module module-gconf
.fail
.endif

### Automatically restore the default sink/source when changed by the user
### during runtime
### NOTE: This should be loaded as early as possible so that subsequent modules
### that look up the default sink/source get the right value
load-module module-default-device-restore

### Automatically move streams to the default sink if the sink they are
### connected to dies, similar for sources
load-module module-rescue-streams

### Make sure we always have a sink around, even if it is a null sink.
load-module module-always-sink

### Honour intended role device property
load-module module-intended-roles

### Automatically suspend sinks/sources that become idle for too long
load-module module-suspend-on-idle

### If autoexit on idle is enabled we want to make sure we only quit
### when no local session needs us anymore.
.ifexists module-console-kit.so
load-module module-console-kit
.endif
.ifexists module-systemd-login.so
load-module module-systemd-login
.endif

### Enable positioned event sounds
load-module module-position-event-sounds

### Cork music/video streams when a phone stream is active
load-module module-role-cork

### Modules to allow autoloading of filters (such as echo cancellation)
### on demand. module-filter-heuristics tries to determine what filters
### make sense, and module-filter-apply does the heavy-lifting of
### loading modules and rerouting streams.
load-module module-filter-heuristics
load-module module-filter-apply

### Make some devices default
#set-default-sink output
#set-default-source input