Diary – February 2018

Håkon Robbestad Gylterud

This is my public diary — mostly interesting to myself and people who know me.

2018–02–01, Thursday

The standard of truth in mathematics is proof. This means that a mathematician will accept a statement as true only when he seen a convincing proof of the statement. However, mistakes happen, and not only in proofs! Sometimes, a statement appears which is never proven, but simply adopted as truth by the mathematical community.

The problem with these unproven truths is that correcting the record is difficult. If one does prove the statement, the community will say “Oh, we knew that already. That’s not a new result”. So very likely such a proof will not be published. Often this problem is “solved” by giving it to a student. They will include it in their thesis, and thus there is a written record of the proof. But this is unfair for the student, because they also will get little credit for proving a “known” result.

2018–02–02, Friday

Playing around with the configurations for my work computer. Set up XMonad, updated Xresources and tested fontsrv for plan9port.

My .Xresources file now includes the following options for XTerm font:

Xft*antialias:      true
Xft*autohint:       true
XTerm*background:   white
XTerm*foreground:   black
XTerm*cursorColor:  grey
XTerm*saveLines:    10000
XTerm*scrollBar:    false
XTerm*faceName:     Monospace
XTerm*faceSize:     12
XTerm*toolBar:      off

For some reason, fontsrv does not have the font “Monospace”, so now I use FreeMono for Acme:

EDITOR="rc -c 'plumb $*; read'"
acme -F '/mnt/font/FreeMono/14/font'\
     -f '/mnt/font/FreeMono/14a/font'

2018–02–03, Saturday

Today was no computer day at home — which meant we got a lot of cleaning done. And I got around to fixing the TV bench (with the rest of the family as interested helpers). So all we need now is a comfy sofa.


Learning to use PulseAudio. This is something I have attempted several times, but since I now am “performing live” every Wednesday I have some motivation to learn it more properly.

My biggest success so far has been to use LADSPA filters to clear up my microphone sound for Mumble. In short, what I had do do was:

The main problem with this, as admitted by the documentation is that testing is a bit cumbersome, since the control parameters for a filter cannot be changed after the module is loaded.

I used Audacity to play around with LADSPA filters first to find good control parameters. Then I wrote all the commands for filter-loading into a script, and tested the setup by recording from ‘voice.monitor’. Then I could quickly: unload the first module (the null-sink) — which makes all the filters also go away, change the parameters and rerun the script to be ready for another test.

Actually, as I writing this, it occurs to me that I can optimise the testing by creating a test recording first, without filters, and then run the test through the filters, and loop ‘voice.monitor’ back to my headset.


Sofa-day! Our new furniture arrived today. This included our new sofa.

The evening was spent putting together the sofa and arranging the furniture in the living room.


My mother visited us this weekend, which everyone were happy about. She also brought pillowcases she had sewed for our sofa, and a wonderful jacket she knitted for Inna.


For the first time in six years we have a traditional TV-setup. We rarely watch TV, but since the cables and decoder were already present in the apartment, we decided we might as well connect it. So now we have three boxes (netbook, SNES and decoder) competing for two HDMI inputs.


Lately, I have been playing around with JACK. Comparing it with PulseAudio, which I now have some experience with, JACK is more flexible, and has friendler graphical user interfaces — qjackctl especially.1.

After all this playing around with sounds, I was able to record a little track which uses WhySynth and QSynth for the two instruments. You can download the track here.


What is JACK, and how to use it? JACK organises audio (and MIDI) inputs and outputs and lets you connect them the way you want (these connections are called patches). For instance, I run an on-screen (musical) keyboard2 which outputs MIDI to a synthesiser3, which in turn outputs audio to the speakers (which PulseAudio is holding hostage):

The JACK connections as seen in patchage
The JACK connections as seen in patchage

You can see the resulting graphical user interface here.

If I want an equaliser or another filter applied to the stream I can just add it between the synth and the speakers. Here is a short list of JACK related programs I have found useful, with a short description of what I think they do:


D&D session again today! Baern and Kava finally found their way out of the Abyss. Since December the group has been split up, and we have been forced to alternate the sessions between the groups. But next Wednesday, the group will be united, and we can start playing regularly. I hope the players will take the time to tell each others what has happened.

  1. Although, pavucontrol is also quite neat

  2. jack-keyboard

  3. qsynth, or whysynth, a DSSI-plugin running in ghostess

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