Pulseaudio.md

pacmd list-sinks to list name or index number of possible sinks

pacmd set-default-sink "SINKNAME" to set the default output sink

pacmd set-default-source "SOURCENAME" to set the default input

Note: Changing the output sink through the command line interface can only take effect if stream target device reading is disabled. This can be done by editing the corresponing line in /etc/pulse/default.pa to:

load-module module-stream-restore restore_device=false

Remapping stereo channel into 2 mono ones

First, get the name of device from pacmd list-sources

...
 * index: 2
name: <alsa_input.usb-BEHRINGER_UMC204HD_192k-00.analog-stereo>
driver: <module-alsa-card.c>
flags: HARDWARE HW_MUTE_CTRL HW_VOLUME_CTRL DECIBEL_VOLUME LATENCY DYNAMIC_LATENCY
state: RUNNING
suspend cause: (none)
priority: 9049
volume: front-left: 65536 / 100% / 0.00 dB,   front-right: 65536 / 100% / 0.00 dB
        balance 0.00
base volume: 65536 / 100% / 0.00 dB
volume steps: 65537
muted: no
current latency: 0.59 ms
max rewind: 0 KiB
sample spec: s32le 2 k 44100 Hz
channel map: front-left,front-right

then look at channel spec and map them to 2 separate mono channels

pacmd load-module module-remap-source source_name=UMC204HD_in1 master=alsa_input.usb-BEHRINGER_UMC204HD_192k-00.analog-stereo channel_map=mono master_channel_map=front-left source_properties="device.description='UMC204HD\ input\ 1'"
pacmd load-module module-remap-source source_name=UMC204HD_in2 master=alsa_input.usb-BEHRINGER_UMC204HD_192k-00.analog-stereo channel_map=mono master_channel_map=front-right source_properties="device.description='UMC204HD\ input\ 2'"
pacmd set-default-source UMC204HD_in1