[pulseaudio-discuss] how to map equalizer to arbitrary device

[Malte Gell]

Hi there,

I have enabled the pulseaudio EQ, this gives me 2 new output devices:


FFT based equalizer on Internal Audio Analog Stereo

LADSPA Plugin Multiband EQ on Internal Audio Analog Stereo


I would like to use the EQ with my bluetooth headphone, so how do I map
the EQ to the bluetooth device? I would like to have a output device
named like "FFT based equlizer on Philips SHB9100", how do I get it?

And why are there 2 EQ devices, FFT based EQ and LADSPA, what is the
difference between them?

Thanx
Malte

[Alexander E. Patrakov]

Post by Malte Gell
Hi there,
FFT based equalizer on Internal Audio Analog Stereo
LADSPA Plugin Multiband EQ on Internal Audio Analog Stereo
I would like to use the EQ with my bluetooth headphone, so how do I map
the EQ to the bluetooth device? I would like to have a output device
named like "FFT based equlizer on Philips SHB9100", how do I get it?

Please ignore the "FFT based equalizer". Or better, don't load
module-equalizer-sink (the module it comes from). It is too bad, both
from the DSP viewpoint and from the general C coding viewpoint.

The other output device comes from module-ladspa-sink. There are two
ways to deal with it.

1. As you have obviously followed some instruction to get to the stage
where it actually creates a sink, please find the instruction again. It
says either "pacmd load-module module-ladspa-sink lots-of-magic" or "add
the equivalent load-module directive to default.pa". Now, with "pacmd
list-sinks | grep name" find the dotted notation for your bluetooth
device's sink name. Add master=that.dotted.name to the module arguments
in the instruction.

2. Undo everything that you have done to get these sinks. Install
veromix (either in the python3 + gtk3 form, or as a KDE plasmoid). Use
it to attach the equalizer to the bluetooth sink. It will automatically
load module-ladspa-sink with the correct arguments.

Of course, the master=... approach works with module-equalizer-sink too,
but I still recommend that you avoid loading that module.

[Malte Gell]

Post by Alexander E. Patrakov

Post by Malte Gell
I would like to use the EQ with my bluetooth headphone, so how do I map
the EQ to the bluetooth device? I would like to have a output device
named like "FFT based equlizer on Philips SHB9100", how do I get it?

1. As you have obviously followed some instruction to get to the stage
where it actually creates a sink, please find the instruction again. It
says either "pacmd load-module module-ladspa-sink lots-of-magic" or "add
the equivalent load-module directive to default.pa".

Yes, there is a line in ~/.pulse/default.pa:

load-module module-ladspa-sink sink_name=ladspa_output.mbeq_1197.mbeq
master=alsa_output.pci-0000_00_1b.0.analog-stereo plugin=mbeq_1197
label=mbeq
control=-16.0,-16.0,6.5,6.5,6.0,5.5,4.5,1.0,1.0,1.0,-8.0,-10.0,-16.0,-16.0,-20.4

I could change the value for master to my bluetooth sink
bluez_sink.00_23_78_AB_09_A6 but is there no load-module option that
allows to map a module to two sinks at the same time?

Thanks
Malte


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[Daniel Sonck]

Post by Malte Gell

Post by Alexander E. Patrakov

Post by Malte Gell
I would like to use the EQ with my bluetooth headphone, so how do I map
the EQ to the bluetooth device? I would like to have a output device
named like "FFT based equlizer on Philips SHB9100", how do I get it?

1. As you have obviously followed some instruction to get to the stage
where it actually creates a sink, please find the instruction again. It
says either "pacmd load-module module-ladspa-sink lots-of-magic" or "add
the equivalent load-module directive to default.pa".

load-module module-ladspa-sink sink_name=ladspa_output.mbeq_1197.mbeq
master=alsa_output.pci-0000_00_1b.0.analog-stereo plugin=mbeq_1197
label=mbeq
control=-16.0,-16.0,6.5,6.5,6.0,5.5,4.5,1.0,1.0,1.0,-8.0,-10.0,-16.0,-16.0,-
20.4
I could change the value for master to my bluetooth sink
bluez_sink.00_23_78_AB_09_A6 but is there no load-module option that
allows to map a module to two sinks at the same time?
Thanks
Malte

Well you can, but it takes some more configuration. Before doing this, think
about the problem this faces:

You have two different audio devices that work with different buffers, different
timers and probably different audio requirements. This will create a problem
for pulseaudio related to synchronization. One sound card might ask for audio
a little faster each time so you might notice some delays or roughness... This
is the reason that it doesn't support multiple sinks... But if you don't mind
that, then:

Basically you would want a dummy sink for all your audio, you can choose to
add the equalizer to the dummy sink, connect the monitor of the dummy sink to
the two outputs and you're done. You can also add individual equalizers to
each output and connect the dummy sink monitor to the two equalizers. It's a
matter of what you actually want to achieve with the equalizers.

Now, for the basic splitting (you can decide where you want to add the
equalizer(s) to):

You make a null sink for all your audio:
load-module module-null-sink sink_name=AudioOut

And use the loopback module to connect the monitor of the null to the different
soundcards:
load-module module-loopback source=AudioOut.monitor sink=<audiocard_1>
load-module module-loopback source=AudioOut.monitor sink=<audiocard_2>

Daniel Sonck