Rotate lots of image on Ubuntu

I often find myself with a bunch of images that are not properly rotated. Many cameras write the rotation information to the EXIF header of the image file, but the file itself is not actually rotated. Some photo editors do this automagically when you import the files, but I prefer to copy files manually to my drive.

I therefore have a little one-liner that can rotate all the files in a folder:

find . *.jpg -exec jhead -autorot {} \;

It works recursively, and is very quick!

Trim video files using FFmpeg

This is a note to self, and hopefully to others, about how to easily and quickly trim videos without recompressing the file.

I often have long video recordings that I want to split or trim (side note: sometimes people call this “cropping”, but in my world cropping is to cut out parts of the image, that is, a spatial transformation. Splitting and trimming are temporal transformations).

You can split and trim files in most video editing software, but these will typically also recompress the file on export. This reduces the quality of the video, and it also takes a long time. A much better solution is to perform “lossless” trimming, and fortunately there is a way to do this with the wonder-tool FFmpeg. Being a command line utility (available on most platforms) it has a ton of different options, and I never remember these. So here it goes, this is what I use (on Ubuntu) to trim out parts of a long video file:

ffmpeg -i input.mp4 -ss 01:19:27 -to 02:18:51 -c:v copy -c:a copy output.mp4

This will cut out the section from about 1h19min to 2h18min, and will only take a few seconds to run. If you instead want to specify a fixed duration, you can use:

ffmpeg -i input.mp4 -ss 00:01:10 -t 00:01:05 -c:v copy -c:a copy output.mp4

This will extract 1min5sec starting from 1min10sec in the file.

Remove standard bookmarks in Nautilus

Yet another note to self on how to fix things in Ubuntu after a fresh install, found at askubuntu, this time to remove the standard bookmarks in the Nautilus file browser. I use a different setup of folders, and don’t really need these unused bookmarks. I wish it could have been easier to just right-click and delete to remove them (like for your own bookmarks), but it turns out to be a bit more tricky.

The default bookmarks are actually built from ~/.config/user-dirs.dirs, and this file is rebuilt on login from /etc/xdg/user-dirs.defaults. So it is necessary to modify both of the files, which may most easily be done with:

nano ~/.config/user-dirs.dirs

sudo nano /etc/xdg/user-dirs.defaults

In the nano editor you should comment out the ones that you don’t want.

And after a login the bookmarks are gone.

Move windows between screens on Ubuntu

As part of the fun of reinstalling an OS, you need to set up all the small things again (and you also get rid of all the small things you had set up and that you don’t need any longer…). This message is mainly a note to self about how to move windows between screens on Ubuntu with a key combination, found at stackexchange:

  1. Install CompizConfig Settings Manager:  sudo apt install compizconfig-settings-manager compiz-plugins-extra
  2. Run Compiz from the dash
  3. Click Window Management
  4. Enable the Put plug-in (select the check-box)
  5. Click on Put
  6. Configure the shortcut for Put to next Output (click enable). I like to use <super-less>, since that key combination is very convenient on a Norwegian keyboard
  7. Log out and back in to make changes take effect