BruteFIR for LibreELEC.tv

This project builds BruteFIR with PulseAudio support as addon for LibreELEC.tv based distributions.

As the patches to BruteFIR are not yet ready for inclusion in the official BruteFIR release, i do NOT use the orignal sources from Anders Torger's homepage for BruteFIR, but my own integration-repository.

The packaged BruteFIR supports the following IO modules:

• pulse for connecting to a PulseAudio-server
• alsa for traditional ALSA support
• file for file-/pipe-support
• eq
• cli

Mixing different input-/output-modules has NOT been tested yet.

Installation

As there is no addon-repository available the addon and its requirements have to be installed via ZIP-file.

Copy resulting zip-file to libreelec-host or some other (USB-)storage-device.

Install addon using the menu Install from ZIP-file.

Prerequisites

FFTW3 has to be available as a shared library. It is provided as two separate addons that have to be installed.

• fftw3
• fftw3f

Configuration

BruteFIR loads its configuration from file /storage/.brutefir_config.

The provided example in brutefir_config.example will be copied in place if no existing config-file is found.

By configuring a PulseAudio device-name the sound-server will auto-connect the sink-inputs and source-outputs to the configured and available sinks and sources.

Configure different application-names via param app_name if you have multiple instances of BruteFIR connecting to the same PulseAudio-server.

Service startup and shutdown

The described audio-setup is provided by script /storage/.kodi/addons/brutefir/usr/share/brutefir/startup.sh, which is executed on service-startup.

The loaded modules are then stored in /storage/.brutefir-pulseaudio.modules.

The modules are unloaded on service-shutdown or -failure by /storage/.kodi/addons/brutefir/usr/share/brutefir/shutdown.sh.

Setup audio-routing via PulseAudio

I've choosen this setup as it gives me a short and constant delay in audio-output when playing media in KODI.

Kernel-module snd-aloop is missing, so the audio-signal is routed through PulseAudio.

By giving a null-sink the name BruteFIR we get a monitoring output named BruteFIR.monitor in PulseAudio. This output will be picked up by BruteFIR's IO-module pulse.

The filtered output from BruteFIR is available as a PulseAudio source-output, which has to be connected to an output for actual sound, e.g. the ALSA-device "default".

Configure PulseAudio to provide null-sink to stream to BruteFIR

Load null-sink to loopback KODI-output to BruteFIRs input-stream

pactl load-module module-null-sink sink_name="BruteFIR"

Activate ALSA soundcard

Provide ALSA-card to PulseAudio by loading module module-alsa-sink. The resulting sink will be named alsa_output.default.

pactl load-module module-alsa-sink device=default

Set default sink

Declare null-sink as default output, BruteFIR will pickup audio from its monitor-out BruteFIR.monitor.

pactl set-default-sink BruteFIR

Reboot

You should hear sounds when reboot is completed.

In KODI settings Settings -> System -> Audio the previously available ALSA-devices should be gone, because the PulseAudio module module-als-sink already uses them.

Set KODI to output audio via PulseAudio

If you don't hear any sounds by now, use the menu Settings -> System -> Audio to switch KODI output to PulseAudio.

Troubleshooting

Plugin fails to install

Sometimes the plugin fails to install. I'm not sure yet what ist causing this. Reboot and try again, it helped most of time. Or try deleting all plugin-files manually.

Commands systemd

A short list of helpful commands for pulseaudio

List input-elements

pactl list sinks
pactl list sources

List output-elements

pactl list sink-inputs
pactl list source-outputs

Start the service

systemctl start brutefir.service

Stop the service

systemctl stop brutefir.service

Restart the service

systemctl restart brutefir.service

Happy filtering :)