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BJsgoodlife
Asked: 2013-09-02 13:34:52 +0800 CST

Zynaddsubfx fails to initialize with error message "Default I/O did not initialize."

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I am tying to use zynaddsubfx with qjackctl and MIDI. I have it connected, and the configurations are set. This is what I see when I open zynaddsubfx:

Default I/O did not initialize. Defaulting to NULL backend.

What does this mean and how do I fix this?

default

4 Answers

  1. Best Answer

    I got this problem fixed by working with jack. Once I got jackctl set up, the problem disappeared. One of the biggest helps I found with qjackctl is this one here Ubuntu wiki How to JACK Configuration.

    I think this had to do with the Frames/Period. Basically this is the buffer for qjackctl as explained on the wiki. Working with the settings on this and a few other settings helped tremendously.

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  2. I can't comment due to low rep. I had the exact same message "zynaddsubfx default io did not initialize defaulting to NULL backend." right after before installing Qjackctl, when executing zynaddsubfx. So it is not neccesary to have qjackctl installed to have the bug. But there is a "jack" thing that controls midi that probably is that what you are talking about (sorry for being imprecise, midi in linux is difficult)

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  3. Ubuntu 20.04

    I tried a bunch of random things from the web on my Ubuntu 20.04 ZynAddSubFX 3.0.5, one of them worked and I get sounds out of the virtual keyboard, I'm just not sure which:

    • run as:

      zynaddsubfx -O alsa -I alsa

      Without -O alsa, I don't get any sounds still, so that option at least is crucial.

    • sudo apt install qjackctl
sudo usermod -a -G audio $USER

      and log out and log in.

      After taking those actions, the error message does not show up anymore even without -O alsa -I alsa. But I get no sound without -O alsa.

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  4. The message "default I/O did not initialize" is about default audio hardware initialization. It happens in three major cases:

    • device absent
    • access to device blocked
    • device capabilities limited

    You should check system current default audio hardware by

    cat /proc/asound/cards

    The first list item is your system default (if any). You can set default device manually in /etc/asound.conf:

    defaults.pcm.card 1
defaults.ctl.card 1

    Corresponding to list item number discussed upper.

    In my case it was enough to disconnect usb midi-keyboard and restart alsa. Because somehow midi-keyboard became default audio.

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