RPI4 Trifecta: VARA, Packet & ARDOP – One Audio Interface

A Short Demonstration

Requirements

Update 2023/04/21 – If you have this system set up already, there is a typo in the .asoundrc, where the string 44000 should instead be 48000. This document has been updated with the correction.

Update 2022/08/15 I have created an image for RPI4 systems, documented here.

This document assumes you have already installed the VARA suite of modems and the companion programs via the Winelink project. If not, now is your chance-

Word of caution: installing wine is disk intensive, if you have not yet got your home directory on a real physical disk instead of the SD Card- now is the time to consider doing that. The SD Card is also incredibly slow for wine applications.

To install Wine and the ARM x86 emulator system, visit the Winelink GitHub page.

Or go wild and run it live from the command line:

curl -O https://raw.githubusercontent.com/WheezyE/Winelink/main/install_winelink.sh && \
     bash install_winelink.sh

VARA: dsnoop & dmix

This part of the document is a breakdown of the .asoundrc config file, for the complete file skip to the Complete Config File, but be mindful that the config file is only a small part of the process as there are also steps to be taken in the Windows registry editor.

Physical audio interface mapping to the virtual sound devices for playback (dsnoop) and recording (dmix), the device shown below- “hw:1,0” refers to the audio interface ID provided by the ‘aplay -l’ command. Yours may differ. E.g. hw:2,0 etc.

pcm.dsnooped0 {
     type dsnoop
     ipc_key 50000
     ipc_key_add_uid false # let multiple users share
     ipc_perm 0666 # IPC permissions for multi-user sharing (octal, default 0600)
     slave {
           pcm "hw:1,0"
           channels 1
           }
}

pcm.dmix0 {
     type dmix
     ipc_key 60000
     ipc_key_add_uid false # let multiple users share
     ipc_perm 0666 # IPC permissions for multi-user sharing (octal, default 0600)
     slave {
           pcm "hw:1,0"
           rate 48000
     } 
}

Both VARA and ARDOP require 48KHz sample rate to be forced (default is 44.1 for system sounds) so two new audio streams are required and this is accomplished using the .asoundrc file configuration.

Below is a snip showing the previously configured dsnoop0 & dmix0 interfaces, we’re going to call them ARDOP2IN and ARDOP2OUT.

pcm.ARDOP2IN {type rate slave {pcm "plug:dsnooped0" rate 48000}}
pcm.ARDOP2OUT {type rate slave {pcm "plug:dmix0" rate 48000}}

Wine (for VARA) requires these 48KHz audio device streams, but in a slightly different presentation to the system. Wine requires asymmetrical streams that we currently do not have, these are provisioned by combining the two previously configured ARDOP streams into a new virtual device “asymwine”.

pcm.asymwine { 
        type asym 
        playback.pcm "ARDOP2OUT" 
        capture.pcm "ARDOP2IN"
} 

pcm.!default { 
        type plug 
        slave.pcm "asymwine" 
} 

pcm.dsp { 
        type plug 
        slave.pcm "asymwine" 
} 

The next bit gets hairy as we are now required to edit the Wine Registry- what happens is that ‘winecfg’ enumerates (gathers) what it can glean from the host operating system about the audio drivers, unfortunately this process does not scrape the .asoundrc file so this particular gotcha requires a couple of new entries in the registry to be made by hand.

Run from the command line:

wine regedit

In the registry editor, navigate to:

HKEY_CURRENT_USER\Software\Wine\Drivers\winealsa.drv

From within winealsa.drv, create a new “Multi-string value”.

Name this key:

ALSAOutputDevices

Hit enter to save, then create another key and title it:

ALSAInputDevices

After adding the keys, double-click each newly created key to open it in data entry mode. Insert the device name previously configured in the .asoundrc file – asymwine, do this for BOTH ALSAOutputDevices and ALSAInputDevices.

Close the registry editor and relax.

Now run “winecfg” again and navigate to the Audio tab, from the list of each input/output it should now be possible to select the newly appearing “asymwine” audio interface. If all things went to plan, be sure to do this action for each of the 4 fields.

Apply, OK and exit winecfg.

Open up VARA HF and navigate to sound settings to select the asymwine interfaces.

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