Tuesday, April 4, 2017

Recording screencast with Atom and Firefox

The need

I have recently started work on a video course about VueJS. The major part of it are screen recordings. I went through the original documentation my editor provided and it was just for Win/Mac (no surprise there) so I needed to go and figure it out for myself.

The how

As it turns out recording screen on Linux is quite easy. There are lots of good applications for it. I went with the good old ffmpeg

$ Xephyr :1 -ac -screen 1280x720 -br -reset &
$ sleep 2
$ setxkbmap -display :0 -print | xkbcomp - :1 &> /dev/null
$ DISPLAY=:1 evilwm -snap 50 &
$ DISPLAY=:1 atom &
$ DISPLAY=:1 firefox &

Now that we have all the apps running in a nice enclosure let's record the action:

$ ffmpeg \
    -f pulse -ac 2 -i default \
    -f x11grab -r 25 -s 1270x720 -i :1 -c:v libx264 \
This will create a new file with human readable timestamp each time you run this command encoding the 720p video in h.264 format and audio in AAC putting it all into an MPEG4 container.

Making Atom captures easy to edit

When editing the video in post production, for example using Blender's NLE, it is hard to fit the blinking intervals when cutting parts of the video. For that reason I recommend disabling the blink cursor in Atom. Select "Open your stylesheet" menu item and enter the following snippet

atom-text-editor.editor .is-focused .cursors .cursor {
  opacity: 1

That's it. Now the cursor is solid and editing is easy again

Happy recording!

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