I have previously written about how to export each of the pages of a PDF file as an image. That works well for, for example, presentation slides that should go on a web page. But sometimes there is a need to export only the images within a page. This can be achieved with a small command line tool called pdfimages.
One way of using it is:
pdfimages -p -png file.pdf image
This will export all images in file.pdf and label them with something like image-001-010.png, where the first number refers to the page and the second is a count of images.
Sometimes I just take a screenshot if I want to grab something from a PDF. But this is a more robust method if you want to grab several different images from a PDF file.
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:
ffmpeg -r 10 -pattern_type glob -i "*.JPG" -s 1920x1440 -vcodec libx264 output.mp4
To break down the different parameters a little:
-r 10″: the framerate (fps)
- “-pattern_type glob”: to allow for selecting all JPGs using “*.JPG”
- “-s 1920×1440”: downscales the images to a pseudo-like HD format
- “-vcodec libx264”: force to use this codec
We have a bunch of Canon XF105 at RITMO, a camera that records MXF files. This is not a particularly useful file format (unless for further processing). Since many of our recordings are just for documentation purposes, we often see the need to convert to MP4. Here I present two solutions for converting MXF files to MP4, both as individual files and a combined file from a folder. These are shell scripts based on the handy FFmpeg.
Convert individual MXF files to individual MP4 files
The first solution is based on converting a bunch of MXF files to individual MP4 files. This is practical if there are multiple, single shots.
Save the script above as mxf2mp4.sh, make it executable, with a command like:
chmod u+x mxf2mp4.sh
and run the file:
Convert a folder of MXF files to one MP4 file
The second solution is when we have made one long recording, which is split into individual MXF files of 1.9 GB size (the maximum size of FAT32-formatted drives) in the camera. Then the aim is to merge all of these to one MP4 file. This script will do the trick:
Do the same as above to run the script.
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. I recall that on my Lenovo laptop I had to work quite a bit to turn off all the fancy auto-Windows-stuff.
I am not sure if HP has changed something recently or not, but the final procedure was super-easy: I just hit the F9 button on startup and got a regular “old-school” boot selector. Here I chose the USB drive, and the Ubuntu installer fired up.
I have installed Linux (primarily various Ubuntu versions) on several laptops over the years, and it is very seldom that I get into problems with drivers. Also this time, things went smoothly; everything worked perfectly right after the install. I think it is crucial to continue repeating this message because I still hear people saying that it is tricky to get Ubuntu to play with different hardware. True, there used to be driver issues some years ago, but I haven’t experienced that in five years or so.
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. I haven’t been able to explore these as much as I wanted to, unfortunately, primarily due to everything happening at our new centre (RITMO) and master’s programme (MCT).
Even though I like Ubuntu Studio myself, it is not a distro I would install on my daughter’s machine. Buying a new computer with Windows 10 pre-installed, one could argue that it would be best to leave her with that. This may also help her to be more familiar with the computers they are using at school, which run Windows 7 at the moment. But the question in the store about whether I wanted to buy some antivirus-software with the new laptop, was enough to ensure me that a Linux distro would be a better choice.
I have heard that some people like distros such as Edubuntu for kids, but it does not seem to be maintained? After thinking about it for a little while, I have concluded that it is probably useful for a kid to learn to use a normal OS. If you compare how things were a decade or two ago, most modern-day OSes are comparably easy to use anyways.
Finally I decided to make it simple, and installed the regular Ubuntu distro based on GNOME. It looks “modern”, has large icons, and is fairly easy to navigate due to the streamlining of menus, and so on.