nixos-public/deemz.org/pipewire-extra-config.nix
2025-03-04 10:55:48 +01:00

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Nix

{
pipewire = {
"10-downmix-5.1-to-4.0" = {
"context.modules" = [
{
name = "libpipewire-module-filter-chain";
args = {
"node.description" = "5.1 surround downmix";
"media.name" = "5.1 surround downmix";
"filter.graph" = {
nodes = builtins.concatLists [
# FC and LFE connect to multiple nodes, so we need to create a 'copy' node for them
(map (name: { name=name; type="builtin"; label="copy"; })
[ "copyFC" "copyLFE" ])
# Each output (FL, FR, RL, RR) is mixed from:
# In 1: their respective inputs (at original level)
# In 2: the center channel (only for FL and FR)
# In 3: the LFE channel (already amplified to match other channels by the decoder (e.g., 10 dB in Dolby spec) divided by 4)
(map (name: { name=name; type="builtin"; label="mixer"; control={"Gain 1"=1; "Gain 2"=0.5; "Gain 3"=0.25;}; })
[ "mixFL" "mixFR" "mixRL" "mixRR" ])
];
links = [
# FC goes into FL and FR (at half gain)
{ output = "copyFC:Out"; input = "mixFL:In 2"; }
{ output = "copyFC:Out"; input = "mixFR:In 2"; }
# LFE goes into all 4 channels
{ output = "copyLFE:Out"; input = "mixFL:In 3"; }
{ output = "copyLFE:Out"; input = "mixFR:In 3"; }
{ output = "copyLFE:Out"; input = "mixRL:In 3"; }
{ output = "copyLFE:Out"; input = "mixRR:In 3"; }
];
inputs = [ "mixFL:In 1" "mixFR:In 1" "copyFC:In" "copyLFE:In" "mixRL:In 1" "mixRR:In 1" ];
outputs = [ "mixFL:Out" "mixFR:Out" "mixRL:Out" "mixRR:Out" ];
};
"capture.props" = {
"node.name" = "effect_input.downmix-5.1-to-4.0";
"media.class" = "Audio/Sink";
"audio.channels" = 6;
"audio.position" = [ "FL" "FR" "FC" "LFE" "RL" "RR" ];
};
"playback.props" = {
"node.name" = "effect_output.downmix-5.1-to-4.0";
"node.passive" = true;
"audio.channels" = 4;
"audio.position" = [ "FL" "FR" "RL" "RR" ];
};
};
}
];
};
# The following filter is meant for a quadrophonics (4.0) setup with 4 full-range speakers and no dedicated subwoofer.
# It extracts bass from all 4 channels, mixes it, and feeds it back equally to all channels (bass becomes mono).
# The result is more flat bass response in much of the room.
"20-subwoofer-crossover" = let
crossoverFreq = 60;
in {
"context.modules" = [
{
name = "libpipewire-module-filter-chain";
args = {
"node.description" = "Subwoofer crossover";
"media.name" = "Subwoofer crossover";
"filter.graph" = {
nodes = builtins.concatLists [
# Create copy nodes for all our inputs
(map (name: { name=name; type="builtin"; label="copy"; })
[ "copyFL" "copyFR" "copyRL" "copyRR" ])
# Each channel is high-passed
(map (name: { name=name; type="builtin"; label="bq_highpass"; })
[ "highpassFL" "highpassFR" "highpassRL" "highpassRR" ])
# Create our 'LFE' channel
# All channels are mixed before being low-passed (for subwoofer channel)
[
{
name = "mixAll";
type = "builtin";
label = "mixer";
control = { "Gain 1"=0.25; "Gain 2"=0.25; "Gain 3"=0.25; "Gain 4"=0.25; };
}
{
name = "lowpass";
type = "builtin";
label = "bq_lowpass";
control = { Freq = crossoverFreq; };
}
# While we're at it, let's add some extra "oomph"
{
name = "oomph";
type = "builtin";
label = "bq_peaking";
control = { Freq = 28; Q = 1; Gain = 6; };
}
]
# Each of the 4 resulting outputs is mixed from (1) the high-passed channel, (2) the low-passed mix of all 4 channels
(map (name: { name=name; type="builtin"; label="mixer"; })
[ "mixFL" "mixFR" "mixRL" "mixRR" ])
];
links = [
# All 4 channels are mixed to extract subwoofer channel
{ output = "copyFL:Out"; input = "mixAll:In 1"; }
{ output = "copyFR:Out"; input = "mixAll:In 2"; }
{ output = "copyRL:Out"; input = "mixAll:In 3"; }
{ output = "copyRR:Out"; input = "mixAll:In 4"; }
# All 4 channels are high-passed
{ output = "copyFL:Out"; input = "highpassFL:In"; }
{ output = "copyFR:Out"; input = "highpassFR:In"; }
{ output = "copyRL:Out"; input = "highpassRL:In"; }
{ output = "copyRR:Out"; input = "highpassRR:In"; }
# The mixed channel is low-passed
{ output = "mixAll:Out"; input = "lowpass:In"; }
{ output = "lowpass:Out"; input = "oomph:In"; }
# The low-passed signal is mixed into every output channel
{ output = "oomph:Out"; input = "mixFL:In 1"; }
{ output = "oomph:Out"; input = "mixFR:In 1"; }
{ output = "oomph:Out"; input = "mixRL:In 1"; }
{ output = "oomph:Out"; input = "mixRR:In 1"; }
# The high-passed signals are mixed into their respective output channels
{ output = "highpassFL:Out"; input = "mixFL:In 2"; }
{ output = "highpassFR:Out"; input = "mixFR:In 2"; }
{ output = "highpassRL:Out"; input = "mixRL:In 2"; }
{ output = "highpassRR:Out"; input = "mixRR:In 2"; }
];
inputs = [ "copyFL:In" "copyFR:In" "copyRL:In" "copyRR:In" ];
outputs = [ "mixFL:Out" "mixFR:Out" "mixRL:Out" "mixRR:Out" ];
};
"capture.props" = {
"node.name" = "effect_input.subwoofer-crossover";
"media.class" = "Audio/Sink";
"audio.channels" = 4;
"audio.position" = [ "FL" "FR" "RL" "RR" ];
};
"playback.props" = {
"node.name" = "effect_output.subwoofer-crossover";
"node.passive" = true;
"audio.channels" = 4;
"audio.position" = [ "FL" "FR" "RL" "RR" ];
};
};
}
];
};
# Upmixes stereo (2.0) to quadrophonics (4.0).
# The rear speakers get the signal from the front speakers, rotated by 90 degrees, and slightly delayed.
"30-upmix-2.0-to-4.0" = let
#delay = 0.000; # (ms) delay of rear speakers
delay = 0.009; # (ms) delay of rear speakers
in {
"context.modules" = [
{
name = "libpipewire-module-filter-chain";
args = {
"node.description" = "Upmix 2.0 -> 4.0";
"media.name" = "Upmix 2.0 -> 4.0";
"filter.graph" = {
nodes = builtins.concatLists [
(map (name: { name=name; type="builtin"; label="copy"; })
[ "copyFL" "copyFR" "outFL" "outFR" ])
(map (name: { name=name; type="builtin"; label="convolver"; config={filename="/hilbert";}; })
[ "rotateL" "rotateR" ])
(map (name: { name=name; type="builtin"; label="delay"; control={"Delay (s)"=delay;}; config={max-delay=delay;}; })
[ "delayL" "delayR" ])
];
links = [
# Front channels
{ output = "copyFL:Out"; input = "outFL:In"; }
{ output = "copyFR:Out"; input = "outFR:In"; }
# Rear channels
{ output = "copyFL:Out"; input = "rotateL:In"; }
{ output = "copyFR:Out"; input = "rotateR:In"; }
{ output = "rotateL:Out"; input = "delayL:In"; }
{ output = "rotateR:Out"; input = "delayR:In"; }
];
inputs = [ "copyFL:In" "copyFR:In" ];
outputs = [ "outFL:Out" "outFR:Out" "delayL:Out" "delayR:Out" ];
};
"capture.props" = {
"node.name" = "effect_input.upmix-2.0-to-4.0";
"media.class" = "Audio/Sink";
"audio.channels" = 2;
"audio.position" = [ "FL" "FR" ];
};
"playback.props" = {
"node.name" = "effect_output.upmix-2.0-to-4.0";
"node.passive" = true;
"audio.channels" = 4;
"audio.position" = [ "FL" "FR" "RL" "RR" ];
};
};
}
];
};
};
}