why pipewire and not pulseaudio
Short answer: Because you have no other choice if you want to share your screen in a video conferencing tool, like BigBlueButton under a wayland session compositor, like e.g. sway.
list default recording device
I could not find a simple method to determine the default sink and source yet, but at least the following two command lines work for now:
pw-dump | jq -r ".[$(pw-cat -r --list-targets | egrep -o '^\*\s[0-9]+' | cut -f2)].info.props.\"node.description\""
pw-cat -r --list-targets | egrep '^\*\s[0-9]+' | grep -o "\".*\"" | tr -d "\""
list default playback device
The only nice thing about both commands is, that changing one character is enough to display either the default recording or playback device.
pw-dump | jq -r ".[$(pw-cat -p --list-targets | egrep -o '^\*\s[0-9]+' | cut -f2)].info.props.\"node.description\""
pw-cat -p --list-targets | egrep '^\*\s[0-9]+' | grep -o "\".*\"" | tr -d "\""
Is default sink or default source muted?
pw-dump | jq -r ".[$(pw-cat -r --list-targets | egrep -o '^\*\s[0-9]+' | cut -f2)].info.params.Props|.[].mute"
pw-dump | jq -r ".[$(pw-cat -p --list-targets | egrep -o '^\*\s[0-9]+' | cut -f2)].info.params.Props|.[].mute"
volume of the default input and output device
This is getting insane, but do not know the number of channels. It could be a
surround system or a stereo microphone. I am also not sure if this calculation
is correct. It uses channelVolumes as input, but that differs (a little) from
what pavucontrol for values different than 0% or 100%.
pw-dump | jq -r ".[$(pw-cat -r --list-targets | egrep -o '^\*\s[0-9]+' | cut -f2)].info.params.Props|.[].channelVolumes|select(.)|[.[] * 100|floor|tostring + \"%\"]|join(\" \")"
pw-dump | jq -r ".[$(pw-cat -p --list-targets | egrep -o '^\*\s[0-9]+' | cut -f2)].info.params.Props|.[].channelVolumes|select(.)|[.[] * 100|floor|tostring + \"%\"]|join(\" \")"