Error when trying to use PulseAudio's null sink as input/output device

[heather7283]

Describe the bug

Real time conversion in a GUI doesn't work when I'm trying to use PulseAudio's null sinks as input or output devices. The only configuration that works for me is when both input and output devices are set to "default (ALSA)".
My OS is Arch Linux and I'm using pipewire.

To Reproduce

0. Have a Linux machine with pipewire installed
1. Create new null sink with pactl load-module module-null-sink media.class=Audio/Sink sink_name=VirtualAudioDevice1 channel_map=stereo rate=48000 format=s32le
2. Run svcg, select model and config files
3. Select "VirtualAudioDevice1" as output device
4. Click "(Re)Start Voice Changer"
5. Get one of the following errors:
   sounddevice.PortAudioError: Error opening Stream: Illegal combination of I/O [PaErrorCode -9993]
sounddevice.PortAudioError: Error opening Stream: Invalid sample rate [PaErrorCode -9997]

Additional context

pactl info:

Server String: /run/user/1000/pulse/native
Library Protocol Version: 35
Server Protocol Version: 35
Is Local: yes
Client Index: 968
Tile Size: 65472
User Name: heather
Host Name: FA506IH
Server Name: PulseAudio (on PipeWire 0.3.78)
Server Version: 15.0.0
Default Sample Specification: float32le 2ch 48000Hz
Default Channel Map: front-left,front-right
Default Sink: alsa_output.pci-0000_05_00.6.analog-stereo
Default Source: alsa_input.pci-0000_05_00.6.analog-stereo
Cookie: 5077:1ce5

pactl list short sinks:

51      alsa_output.pci-0000_05_00.6.analog-stereo      PipeWire        s32le 2ch 48000Hz       RUNNING
649     VirtualAudioDevice1     PipeWire        s32le 2ch 48000Hz       IDLE

Version

4.1.1

Platform

Arch Linux

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