[fluid-dev] Distorted Sound with FluidSynth + Alsa on a SBC

[Etienne Besançon]

Hi!

 

I'm running FluidSynth on a Single Board Computer, a Hardkernel Odroid C1+ that is actually stacked with a audio board integrating a high-end DAC. The aim is to turn this into a MIDI expander. Long story short, that actually runs pretty good on my desktop computer but got a very distorted sound on the SBC.

 

The MIDI instrument is well discovered:

    odroid@odroid:~$ lsusb 

    Bus 001 Device 005: ID 2341:8037 Arduino SA 

 

Fluidsynth is configured as follow:

    odroid@odroid:~$ fluidsynth -C0 -R0 -r 44100 -v -d -a alsa -o audio.alsa.device=hw:1 -o synth.polyphony=64 -m alsa_seq /home/odroid/Documents/Bandoneon.sf2 

    FluidSynth version 1.1.6

    Copyright (C) 2000-2012 Peter Hanappe and others.

    Distributed under the LGPL license.

    SoundFont(R) is a registered trademark of E-mu Systems, Inc.

    

    fluidsynth: warning: Failed to pin the sample data to RAM; swapping is possible.

    fluidsynth: prog 0 0 0

    fluidsynth: prog 1 0 0

    fluidsynth: prog 2 0 0

    fluidsynth: prog 3 0 0

    fluidsynth: prog 4 0 0

    fluidsynth: prog 5 0 0

    fluidsynth: prog 6 0 0

    fluidsynth: prog 7 0 0

    fluidsynth: prog 8 0 0

    fluidsynth: prog 9 128 0

    fluidsynth: warning: No preset found on channel 9 [bank=128 prog=0]

    fluidsynth: prog 10 0 0

    fluidsynth: prog 11 0 0

    fluidsynth: prog 12 0 0

    fluidsynth: prog 13 0 0

    fluidsynth: prog 14 0 0

    fluidsynth: prog 15 0 0

    Type 'help' for help topics.

    

    event_pre_noteon 0 60 106

    event_post_noteon 0 60 106

    fluidsynth: noteon 0 60 106 00000 36.312 3.550 0.000 0

    event_pre_noteoff 0 60 106

    event_post_noteoff 0 60 106

    fluidsynth: noteoff 0 60 0 00000 3.574 1

    event_pre_noteon 0 60 106

    event_post_noteon 0 60 106

    fluidsynth: noteon 0 60 106 00001 39.626 3.876 0.000 0

    event_pre_noteoff 0 60 106

    ^C

 

The instrument well connected:

    odroid@odroid:~$ aconnect -io

    client 0: 'System' [type=kernel]

        0 'Timer           '

        1 'Announce        '

    client 24: 'Arduino Micro' [type=kernel]

        0 'Arduino Micro MIDI 1'

    client 128: 'FLUID Synth (3113)' [type=user]

        0 'Synth input port (3113:0)'

    odroid@odroid:~$ aconnect 24 128

 

Well, everything looks fine but the sound I get when playing the midi instrument is very distorted, noisy. Changing the rate did not improved, playing with the buffer a little bit. Weirdly enough, switching output to pulse audio ("fluidsynth -a pulseaudio...") gives expected sounds but with a 2~3 seconds latency.

 

Any clue about this? How can I get more details regarding what going on?

 

Thanks!

HLB