Author: Sebastian

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New features in WAV Builder

Since I’ve been using it quite a bit lately and it’s the top result on Google for “WAV Builder”, I’ve added some new features to WAV Builder, which are:

  • selectable bit depth: you can now create WAV files with a bit depth of 8 bit, 16 bit, 24 bit or 32 bit floating point
  • more examples: “Sine sweep with phase accumulator” and “Logarithmic sine sweep”
  • better accessibility
  • “var” variables in examples replaced with “const” and “let” variables

In the process I learned about some curiosities of the WAVE file format, like the fact that 8 bit samples are saved as unsigned bytes, whereas 16bit and 24 bit samples are saved as signed integers. (Source: http://soundfile.sapp.org/doc/WaveFormat/ )

Link to WAV Builder: https://webaudiotech.com/sites/wav-builder/

‍

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Radial Vector Image Processing in JavaScript

I’m a noob when it comes to image processing algorithms. But when I tried to do something in GIMP that I could not find the right button for, I decided to create an image processing algorithm myself. Maybe there is a much simpler solution to this and maybe you can do it with one click in Photoshop or GIMP, but I just could not find out how.

Continue reading “Radial Vector Image Processing in JavaScript”
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audiophile HDCD

HDCD – Some info and resources

HDCD

This post is to collect some web resources on HDCD. See bottom of post for the resource list.

Why?

In short, HDCD is a technology to encode a 20 bit audio signal to a CD-compatible 16 bit audio signal. While ripping some old audio CDs of mine, I stumbled across two records with the HDCD logo:

  • The B-52’s – Time Capsule – Songs for a Future Generation
  • Dire Straits – Sultans of Swing – The Very Best of Dire Straits
Continue reading “HDCD – Some info and resources”
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DSP Headphones Loudness Sound Personalization

I like my mids … or why sound personalization isn’t that personal

Sound Personalization App Screenshot

I recently bought the new Beyerdynamic Lagoon ANC headphones. They come with MOSAYC sound personalization. This feature is advertised as follows:

Our sense of hearing is unique and changes over the course of our lives. Like a mosaic, some pieces of the sound picture get lost or they fade. The unique MOSAYC sound personalization by Mimi Defined™ compensates exactly this development and adjusts itself precisely to your hearing ability. With individual sound personalization, the missing tiles of the mosaic are restored. And you can enjoy the full sound picture in all its colourful splendour.

https://north-america.beyerdynamic.com/mosayc

Although I really like speakers and headphones with absolutely no sound “enhancements” turned on (DELL and HP laptops, anyone?), I was intrigued by the idea of getting my very own personal sound, so I gave this feature a try and this post is about what I have found out.

Please bear in mind that this post is NEITHER about the quality of the headphones themselves nor its Active Noise Cancellation (ANC) feature. I personally think they are both great. This post is only about the sound personalization feature.

Continue reading “I like my mids … or why sound personalization isn’t that personal”
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Luhmann? Zettelkasten? Digitalisierung?

Heute wäre der bekannte deutsche Soziologe Niklas Luhmann 90 Jahre geworden. Entsprechend ist das Medienecho zurzeit groß: https://www.welt.de/kultur/literarischewelt/article171257947/Das-hoelzerne-Privatinternet-von-Niklas-Luhmann.html http://www.tagesspiegel.de/wissen/niklas-luhmann-zum-90-er-dachte-mit-dem-zettelkasten/20683794.html https://www.nzz.ch/feuilleton/das-genie-der-gesellschaftstheorie-ld.1335385 In den Artikeln ist auch von der zur Zeit stattfindenden Digitalisierung seines berühmten Zettelkastens die Rede. Ich betreue seit gut zwei Jahren am Cologne Center for eHumanities das technische Zusammenspiel dieser Digitalisierung, entwickle die Software zur Erschließung, Transkription und Online-Präsentation der Zettel, und versuche aus dem Datenbestand Wissen und Visualisierungen zu erstellen. Die „Welt“ spricht im oben verlinkten Artikel vom „hölzernen Privatinternet Niklas Luhmanns“, und das trifft es ziemlich gut. Denn Luhmann hat auf seinen mehr als 90.000 handbeschrieben Zetteln jede Menge Verweise („Links“) zu anderen Zetteln hergestellt. Nur einige der Verweise („Links“) des ersten Auszugs des Zettelkastens Auch wie Luhmann die Zettel in den Kasten einsortiert hat, ist spannend: Jeder Zettel hat eine eigene Nummer zur Identifikation, beginnend mit 1. Wenn er dann später einen Zettel zwischen zwei anderen hinzufügen wollte, benannte er diesen bspw. 1a und stellte ihn zwischen 1 und 2, um nicht die ursprüngliche Nummerierung in Frage zu stellen. So entstanden sehr tiefe Hierarchien und lange Zettelnummern wie „28-10l5c3d16-1a“ oder „57-4e7b1-59d2a“. Außerdem entstanden thematische Zettel-Stränge, die voneinander abzweigen, sodass es vielerlei Lesewege durch den Kasten gibt. Luhmann selbst hat dazu gesagt: „Ich denke ja nicht alles allein, sondern das geschieht weitgehend im Zettelkasten … Der Zettelkasten kostet mich mehr Zeit als Bücherschreiben.“ Wir wollen also eine Beschreibung der Struktur des Kastens entwickeln und darauf basierende Vermutungen, wie er funktioniert hat, anstellen. Ein winziger Ausschnitt aus der Struktur des Zettelkastens: Jeder Knoten ist ein Zettel Der Zettelkasten ist wie für das Medium Internet geschaffen:  Mit den digitalen Möglichkeiten erreicht er eine grundlegend neue Nutzbarkeit. Möchte man Verweisen zu anderen Zetteln nachgehen, so muss man im analogen Zettelkasten lange suchen und blättern, in der digitalen Rekonstruktion reicht ein Klick auf den Link. Außerdem enthält die digitale Nachbildung des Kastens erweiterte und praktische Recherchemöglichkeiten wie z. B. ein Schlagwortregister, ein bibliographisches Verzeichnis und eine thematische Inhaltsübersicht, damit man stets den Kasten (Wald) vor lauter Zetteln (Bäume) noch sieht. Natürlich kann bei mehr als 90.000 analogen Zetteln nicht alles konsistent sein, so hat Luhmann ab und zu Zettelnummern doppelt vergeben. Und immer wenn wir glauben, dass unser digitales Modell des Kastens das analoge Original akkurat repräsentiert, taucht auf irgendeinem Zettel ein neuer Sonderfall auf, den wir bisher nicht berücksichtigt hatten. Schließlich ist der Zettelkasten nur ein Teil des Projekts. Daneben gibt es (z. T. unveröffentlichte) Manuskripte Luhmanns und Audio- und Videodokumente (Vorträge, Vorlesungen, Radio- und Fernsehinterviews), die es noch zu erschließen gilt. Die Arbeit bleibt also spannend.

Nächstes Jahr wird das neue Online-Portal des Niklas Luhmann-Archivs an den Start gehen.

 

Weiterführende Links

http://www.uni-bielefeld.de/soz/luhmann-archiv/ http://cceh.uni-koeln.de/luhmann-theorie-als-passion/  
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SEven – A Science Fiction Event Graph Generator

Marty McFly's Timeline

Create relativistic and non-linear timelines of Science Fiction stories. The web editor supports time travels, time dilation and alternate realities.

Science fiction narrations often incorporate non-linear and relativistic timelines that occur because of phenomena such as

  • Time Travel
  • Time Dilation
  • Alternate realities/parallel universes
  • Opposite direction of time flux relative to a reference system (Anti-Time)

Such actions and phenomena are enabled via different fictive technologies like time machines, engine systems and (fictive or real) astronomical anomalies such as wormholes, black holes and parallel universes.

To meaningfully visualize time spans and events of such non-linear fashion, one needs at least two temporal reference frames which can be visualized as axes on a two-dimensional plane (let’s call this a “Zimmer Diagram”).  The X axis of a Zimmer Diagram then represents a non-linear timeline as experienced by a subject of interest. The Y axis represents a timeline of an intertial frame of reference observing this. For example, if the first timeline features the events perceived by a person travelling through time, then the second timeline features the events as perceived by an inert observer with a conventional, linear and continuous world line.

Zimmer diagram

In addition, a third dimension can be used to represent several alternate realities (e. g. parallel universes or alternative timelines). Since events in different universes can be completely independent from each other, and a person entering a universe can enter it at any time, this could be visualized by another plane with the same X axis scale as the first plane, but with its own Y axis scale.

A sequence of events within a continuous or non-continuous reference frame (such as a time travelling person), that is observed as non-linear from the second reference frame, can be defined by assigning the sequence a start date and end date on the scale of the second reference frame, as well as a time dilation factor (in special relativity called the Lorentz factor) that defines the travel speed of reference frame A through the time of reference frame B. The duration of the sequence in reference frame A (TA) then can be calculated by dividing the duration of the path in reference frame B (TB) through the time dilation factor γ:

TA = TB / γ

The X-axes of all universes have the same scale to emphasize that there is only a single timeline of reference frame A, even when switching the universe. The Y-axis of a particular universe goes from the earliest entry point to the latest exit point of reference frame A in B.

Marty McFly's TimelineMarty McFly’s time travelling in the Back to the Future trilogy (with the simplification that everything takes place in one timeline/universe)

Examples of Science Fiction works that feature non-linear timelines

Interstellar (USA, UK 2014)

The protagonist Cooper lands with his spaceship on a planet with high proximity to a super-massive black hole. Time on that planet is severely dilated, one hour on the planet equals approximately seven years of time on Earth.

Back To The Future Trilogy (USA 1985-1990)

Starting out in the year 1985, the protagonist Marty McFly commits several time travels to past and future.

Star Trek Voyager: Blink of an Eye (USA 2000)

The “tachyon core” of a planet has created a “differential in space-time”, meaning that time passes much more quickly on the planet than in the rest of space. For an observer from outer space, one day on the planet is 1.03 seconds long.

Star Trek (USA 2009)

Spock travels 100 years into the past of a parallel universe.

Star Trek – The Next Generation: All Good Things (USA 1994)

This work features a „multiphasic temporal convergence in the space-time continuum, an eruption of anti-time“. Its time flows into the opposite direction than the rest of spacetime.

SEven – A webapp to create non-linear timelines

The author has created a web-based editor that allows creating non-linear timelines being able to cross several universes.

seven app screenshot

Screenshot of “SEven”

Things to improve

  • Not everyone measures time like we do. The start-time/end-time input forms could provide a more general approach than HTML’s “datetime-local” input type
  • Time dilation is not constant but does increase/decrease with more/less speed/gravity. Paths should allow to create time dilation curves.

Things to know

  • A lot of times, you can argue if you enter an alternate reality every you commit a time travel. A lot of fictional works also don’t provide exact points in time or exact time dilation factors. So there is some editorial freedom/arbitrariness on how to model the time travelling. Here’s a good rundown by MinutePhysics on how time travel in science fiction usually works: https://www.youtube.com/watch?v=d3zTfXvYZ9s
  • A spatial dimension is deliberately omitted to not make things more complicated

Take me to the SEven app

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Stopping a Web Audio oscillator at cycle completion (or zero-crossing)

When calling osc.stop(), a running oscillator is stopped immediately, which can result in a nasty click. This is because the oscillator is stopped right in the middle of a cycle.

Here’s a nice tutorial on how to get rid of the click, using automation curves for smooth gain fade-outs: http://alemangui.github.io/blog//2015/12/26/ramp-to-value.html

But there’s another way: When stopping the oscillator, we could just wait for cycle completion before actually stopping it.

Continue reading “Stopping a Web Audio oscillator at cycle completion (or zero-crossing)”
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A piano sustain pedal to MIDI USB adapter

I like my MIDI USB keyboard. But unfortunately, it does not have a sustain pedal jack. That is why I built an adapter, which translates the pedal input into MIDI messages.

All it took was an Arduino Leonardo (Pro Micro module with ATmega32U4), a breadboard, a 7-segment LED display, two resistors, 2 toothsticks, a 6,3mm mono jack socket and some jumper wires. The LED display with its two resistors are optional, of course.

Arduino Code


#include "MIDIUSB.h"

bool isPedalPressed = false;
int pedalPin = 3;

void setup() {
	pinMode(pedalPin, INPUT);

	// turn on pullup resistor as described in http://electronics.stackexchange.com/questions/83133/arduino-digitalread-reading-wrong
	digitalWrite(pedalPin, HIGH);
	
}


void loop() {
	//Pedal pin is by default HIGH, because of pullup resistor
	//When pedal is pushed down, pin should be connected with GND, so that it gets LOW

    if ((digitalRead(pedalPin) == LOW) && (isPedalPressed == false)){

        //channel 1, CC 64 (Sustain), Value 127
        controlChange(0x00, 0x40, 0x7F);
        MidiUSB.flush();
        isPedalPressed = true;
        ledDisplayOne();  //optional
        return;

    }
    
    if ((digitalRead(pedalPin) == HIGH) && (isPedalPressed == true)){
        
        //channel 1, CC 63 (Sustain), Value 0
        controlChange(0x00, 0x40, 0x00);
        MidiUSB.flush();
        isPedalPressed = false;
        digitalWrite(LED_BUILTIN, LOW); 
        ledDisplayZero();  //optional
        return;
        
    }

}

// First parameter is the event type (0x0B = control change).
// Second parameter is the event type, combined with the channel.
// Third parameter is the control number number (0-119).
// Fourth parameter is the control value (0-127).
void controlChange(byte channel, byte control, byte value) {
	midiEventPacket_t event = {0x0B, 0xB0 | channel, control, value};
	MidiUSB.sendMIDI(event);
}
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Martina Gödel, Johannes Schmidt, Sebastian Zimmer – Niklas Luhmanns Zettelkasten: ein “preadaptive advance” digitaler Datenbanken?

On September 26, the Luhmann team and me will be talking at Basis Zwei in Hannover about the challenges of creating the Niklas Luhmann Archive.

Please find more details here: http://basiszwei.tumblr.com/post/148837338530/die-verfl%C3%BCssigung-der-archive

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JavaScript Service Worker Web

Two Service Worker & Push Notification GOTCHAs

I have spent my day diving into Service Workers and Push Notifications since I wanted my webapp STQ (a German Star Trek trivia quiz app) to send out push messages to users. This has probably been the most wanted feature ever since.

Addy Osmani’s guide on PWAs and this codelab by Sam Dutton on implementing push notifications are a great start. But since the technology is still cutting edge, there were a two gotchas along my way, which I want to share.

Continue reading “Two Service Worker & Push Notification GOTCHAs”