Splitting audio files in the terminal

I have recently played with AudioStellar, a great tool for “sound object”-based exploration and musicking. It reminds me of CataRT, a great tool for concatenative synthesis. I used CataRT quite a lot previously, for example, in the piece Transformation. However, after I switched to Ubuntu and PD instead of OSX and Max, CataRT was no longer an option. So I got very excited when I discovered AudioStellar some weeks ago. It is lightweight and cross-platform and has some novel features that I would like to explore more in the coming weeks....

March 18, 2021 · 4 min · 795 words · ARJ

Flatten file names in the terminal

I am often dealing with folders with lots of files with weird file names. Spaces, capital letters, and so on, often cause problems. Instead of manually fixing such file names, here is a quick one-liner (found here) that can be run in the terminal (at least on Ubuntu) to solve the problem: rename 'tr/ A-Z/-a-z/' -- * It is based on a simple regular expression, replacing any spaces with hyphens, and changing any capital letters to lower case....

March 1, 2021 · 1 min · 78 words · ARJ

Create timelapse video from images with FFmpeg

I take a lot of timelapse shots with a GoPro camera. Usually, I do this with the camera’s photo setting instead of the video setting. That is because I find it easier to delete unwanted pictures from the series that way. It also simplifies selecting individual photos when I want that. But then I need a way to create a timelapse video from the photos easily. Here is an FFmpeg one-liner that does the job:...

January 2, 2021 · 1 min · 127 words · ARJ

Shell script for compressing PDF files on Ubuntu

I have previously written about a shell script) for compressing PDF files in Ubuntu. Here are some variants of the script. Low, mid, and high resolution Low resolution for screen: gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.6 -dPDFSETTINGS=/screen -dNOPAUSE -dQUIET -dBATCH -sOutputFile=out.pdf in.pdf I prefer the “ebook” mode, which has slightly higher resolution: gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.6 -dPDFSETTINGS=/printer -dNOPAUSE -dQUIET -dBATCH -sOutputFile=out.pdf in.pdf And then there is the high resolution for printing: gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.6 -dPDFSETTINGS=/printer -dNOPAUSE -dQUIET -dBATCH -sOutputFile=out....

August 23, 2020 · 1 min · 175 words · ARJ

Flattening Ricoh Theta 360-degree videos using FFmpeg

I am continuing my explorations of the great terminal-based video tool FFmpeg. Now I wanted to see if I could “flatten” a 360-degree video recorded with a Ricoh Theta camera. These cameras contain two fisheye lenses, capturing two 180-degree videos next to each other. This results in video files like the one I show a screenshot of below. These files are not very useful to watch or work with, so we need to somehow “flatten” them into a more meaningful video file....

March 15, 2020 · 2 min · 223 words · ARJ

Creating image masks from video file

As part of my exploration in creating multi-exposure keyframe image displays with FFmpeg and ImageMagick, I tried out a number of things that did not help solve the initial problem but still could be interesting for other things. Most interesting was the automagic creation of image masks from a video file. I will use a contemporary dance video from the AIST Dance Video Database as an example: The first step is to extract keyframes from the video file using this one-liner ffmpeg command:...

February 21, 2020 · 3 min · 510 words · ARJ

Creating multi-exposure keyframe image displays with FFmpeg and ImageMagick

While I was testing visualization of some videos from the AIST database earlier today, I wanted to also create some “keyframe image displays”. This can be seen as a way of doing multi-exposure photography, and should be quite straightforward to do. Still it took me quite some time to figure out exactly how to implement it. It may be that I was searching for the wrong things, but in case anyone else is looking for the same, here is a quick write up....

February 21, 2020 · 2 min · 419 words · ARJ

Creating individual image files from presentation slides

How do you create full-screen images from each of the slides of a Google Docs presentation without too much manual work? For the previous blog post on my Munin keynote, I wanted to include some pictures from my 90-slide presentation. There is probably a point and click solution to this problem, but it is even more fun to use some command line tools to help out. These commands have been tested on Ubuntu 19....

November 29, 2019 · 1 min · 191 words · ARJ

Installing Ubuntu on a HP Pavilion laptop

So I decided to install Ubuntu on my daughter’s new laptop, more specifically an HP Pavilion. The choice of this particular laptop was because it looked nice, and had good specs for the money. It was first after the purchase I read all the complaints people have about the weird UEFI implementation on HP laptops. So I started the install process with some worries. Reading on various forums, people seemed to have been doing all sorts of strange things to be able to install Ubuntu on HP laptops, including modifying the UEFI setup, changing the BIOS, and so on....

September 28, 2019 · 2 min · 252 words · ARJ

Which Linux version to choose for a 9-year old?

My 9-year old daughter is getting her first laptop. But which OS should she get started with? I have been using various versions of Ubuntu as my main OS for around 5 years now, currently using Ubuntu Studio on my main laptop. This distro is based on XFCE, a very lightweight yet versatile OS. The reason for choosing Ubuntu Studio over the regular XUbuntu was to get a bunch of music apps by default....

September 28, 2019 · 2 min · 302 words · ARJ