One-frame-per-action GIF recording for optimal quality/size ratio.

See Helm System Packages for examples.

Most Emacs screencasts are done by first recording a video, then converting it to a GIF. It seems like a waste of resources considering the little animation Emacs features.

Most of the time, one user action equals one visual change. By exploiting this fact, this package tailors GIF-screencasting for Emacs and captures one frame per user action. It’s much more efficient than capturing frames even at a frequency as low as 10 per second. You could roughly expect 3 to 10 times smaller files compared to videos of the same quality. (Benchmarks are welcome.)

Conversely, should your Emacs demo feature self-animated content (such as output scrolling in Eshell), no frame will be captured. A workaround consists in hammering some no-op key such as forward-char or end-of-line.

Another neat perk of action-based captures is that it produces editable GIF files: programs such as Gifsicle or The GIMP can be used to edit the delays or rearrange frames.

This is particularly useful to fix mistakes in “post-processing”, without having to record the demo all over again.

• Recordings can be paused and resumed.
• Resulting GIF files are editable, which allows for post-processing / fixing.
• Quality is top notch.
• File-size is optimal.
• The result might feel a tad jittery sometimes.
• It won’t render self-animated content such as auto-scrolling, this is workable however.
• It should be much lighter on memory and CPU than video recording.

Upon start, it adds gid-screencast-capture to pre-command-hook which makes every command (including those called by key presses) take a screenshot. On each screenshot, it records the timestamp.

If paused then resumed, the timestamps are offset by the length of the pause.

When stopped, it compiles the screenshots together into a GIF file using the timestamps to set the appropriate delays for each frame.

You’ll need a screenshot program and a GIF converter. Defaults are:

• gif-screencast-program: scrot
• gif-screencast-convert-program: convert (from the ImageMagick suite)
• Optional: gif-screencast-optimize-program: Gifsicle

You can pass arguments to the screenshot program via git-screencast-args to command it to capture only part of the screen, e.g. you can restrict the capture to the Emacs frame with scrot’s argument --focused

You might want to set some bindings for convenience.

(with-eval-after-load 'gif-screencast
  (define-key gif-screencast-mode-map (kbd "<f8>") 'gif-screencast-toggle-pause)
  (define-key gif-screencast-mode-map (kbd "<f9>") 'gif-screencast-stop))

Start recording with gif-screencast!

macOS requires some additional settings:

(with-eval-after-load 'gif-screencast
  (setq gif-screencast-args '("-x")) ;; To shut up the shutter sound of `screencapture' (see `gif-screencast-command').
  (setq gif-screencast-cropping-program "mogrify") ;; Optional: Used to crop the capture to the Emacs frame.
  (setq gif-screencast-capture-format "ppm") ;; Optional: Required to crop captured images.

mogrify is part of the ImageMagick suite.

The KeyCast package is useful to dispay the pressed keys in the modeline while recording.