cfra/pulseaudio-u44.md

## pulseaudio-u44.md

      
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              pulseaudio-u44.md
            
          
    Zoom U-44 PulseAudio Setup

Problem Statement

The Zoom U-44
works out of the box with recent Linux versions.
By default, PulseAudio will register it as a single sink with 4 output channels. As the U-44 is organized to have
two stereo pairs for outputs, there are situations where it is more useful to have 2 separate sinks available, each
playing back to one of the two stereo pairs.
A similar situation holds true for the inputs. They are all controlled separately, so it is useful to have a source for each one of the single inputs.
Solution

This can be implemented using module-remap-sink. The full command to achieve this remapping looks like this:
pactl load-module module-remap-sink \
      sink_name=u44_output_12 \
      "sink_properties=device.description='U-44\ 1/2'" \
      remix=no \
      master=alsa_output.usb-ZOOM_Corporation_U-44-00.analog-surround-40 \
      master_channel_map=front-left,front-right \
      channel_map=front-left,front-right
pactl load-module module-remap-sink \
      sink_name=u44_output_34 \
      "sink_properties=device.description='U-44\ 3/4'" \
      remix=no \
      master=alsa_output.usb-ZOOM_Corporation_U-44-00.analog-surround-40 \
      master_channel_map=rear-left,rear-right \
      channel_map=front-left,front-right
pactl load-module module-remap-source \
      source_name=u44_input_1 \
      "source_properties=device.description='U-44\ 1'" \
      master=alsa_input.usb-ZOOM_Corporation_U-44-00.multichannel-input \
      master_channel_map=front-left \
      channel_map=front-left
pactl load-module module-remap-source \
      source_name=u44_input_2 \
      "source_properties=device.description='U-44\ 2'" \
      master=alsa_input.usb-ZOOM_Corporation_U-44-00.multichannel-input \
      master_channel_map=front-right \
      channel_map=front-left
pactl load-module module-remap-source \
      source_name=u44_input_3 \
      "source_properties=device.description='U-44\ 3'" \
      master=alsa_input.usb-ZOOM_Corporation_U-44-00.multichannel-input \
      master_channel_map=rear-left \
      channel_map=front-left
pactl load-module module-remap-source \
      source_name=u44_input_4 \
      "source_properties=device.description='U-44\ 4'" \
      master=alsa_input.usb-ZOOM_Corporation_U-44-00.multichannel-input \
      master_channel_map=rear-right \
      channel_map=front-left      
Outlook

It would be nice to make this remapping permanent and not rely on shell commands to set it up.
This doesn't seem completely straightforward though, since we need to trigger this from a hot plug event,
because the U-44 might not always be available. This can possibly be achieved by some form of udev rule.