Arch Linux

t_wrex

Member

Registered: 2020-03-27

Posts: 30

Audio delay script works with Pulseaudio, fails badly with Pipewire

I have a script that someone helpfully provided on Superuser https://superuser.com/questions/526651/ … ime-amount that deliberately introduces a variable amount of delay to the audio. I don't really understand how it works but the end result is that there are X number of 2000ms delays added in a chain in the Pulseaudio. If you delay past a certain amount of time, you have to increase the open file limit of the Pulseaudio process using prlimit. This has been working fine.

I recently reinstalled my Arch system and am trying to use Pipewire. I have installed and enabled pipewire-pulse. I increase the file limits of both the pipewire and pipewire-pulse processes to 4096, the same that I use for Pulse. Immediately after running the script the journal is filled with the same error over and over: pw.context: exceeded hops (64). I have no idea what that means, and if you put "pw.context: exceeded hops" into Google you get literally zero results.

Worse than the error, my speakers also start making this absolutely horrendous screeching noise. I seriously thought they were going to be damaged. It was scary....

So is there any way for this script to work with Pipewire? I have had bad experiences with Pipewire before so am comfortable just using Pulse if I have to. Thanks. I have posted the script below:

#! /bin/bash

sudo prlimit --pid $(pidof pipewire) --nofile=4096:4096
sudo prlimit --pid $(pidof pipewire-pulse) --nofile=4096:4096
#sudo prlimit --pid $(pidof pulseaudio) --nofile=4096:4096

delay_msec="$1"
if [[ ! $delay_msec =~ ^[0-9]+$ ]]; then
    echo "Usage: $( basename "$0" ) delay_milliseconds" >&2
    exit 2
fi
max_loopback_delay=2000

list_delay_loopback_modules() {
    pactl list modules short | grep -P '\tmodule-loopback\t(.*\s)?source=Delay[1-9][0-9]*[.]monitor(\s|$)' | cut -f1
}

list_delay_null_modules() {
    pactl list modules short | grep -P '\tmodule-null-sink\t(.*\s)?sink_name=Delay[1-9][0-9]*(\s|$)' | cut -f1
}

build_module_array() {
    local object_type="$1"
    local array="$( echo "$1" | sed 's/-/_/g' )"
    typeset -n array
    local object_list="$( 
        pactl list "$object_type" |
        perl -00 -p -e ' chomp; s{\s*\n\s*}{|}mg; s{$}{\n}; ' |
        sed -En -e 's/^[a-zA-Z ]* #([0-9]+)[|].*[|]Owner Module: ([0-9]+)[|].*/\1:\2/p'
    )"
    while IFS=: read object module; do
        array[$module]=$object
    done <<<"$object_list"
}

for module in $( list_delay_loopback_modules ); do
    pactl unload-module "$module"
done
for module in $( list_delay_null_modules ); do
    pactl unload-module "$module"
done

last_loopback_delay=$(( (delay_msec + max_loopback_delay - 1) % max_loopback_delay + 1 ))
loops=$(( (delay_msec - last_loopback_delay) / max_loopback_delay + 1 ))
(( loops > 0 )) || exit 0

nbsp="$( echo -e '\u00a0' )"
narrownbsp="$( echo -e '\u202f' )"
i=1
module="$( pactl load-module module-null-sink sink_name="Delay$i" sink_properties="device.description=\"Delay:${nbsp}${delay_msec}${narrownbsp}ms\"" )"
while (( ++i <= loops )); do
    module="$( pactl load-module module-null-sink sink_name="Delay$i" sink_properties="device.description=\"Delay:${nbsp}$(( delay_msec - (i - 1) * max_loopback_delay ))${narrownbsp}ms\"" )"
done
i=$loops
module="$( pactl load-module module-loopback source="Delay$i.monitor" latency_msec=$last_loopback_delay )"
last_loopback_module=$module
while (( --i > 0 )); do
    module="$( pactl load-module module-loopback source="Delay$i.monitor" sink=Delay$(( i + 1 )) latency_msec=$max_loopback_delay )"
done

build_module_array sinks
build_module_array sources
build_module_array sink-inputs
build_module_array source-outputs

for module in $( list_delay_null_modules ); do
    pactl set-source-volume ${sources[$module]} '100%'
    pactl set-sink-volume   ${sinks[$module]}   '100%'
done
for module in $( list_delay_loopback_modules ); do
    pactl set-source-output-volume ${source_outputs[$module]} '100%'
    test "$module" == "$last_loopback_module" && continue
    pactl set-sink-input-volume    ${sink_inputs[$module]}    '100%'
done