I was interested to see how easy/difficult it is to edit the animated GIF "videos" pico8 produces. My goal was to trim some frames from the beginning and end to make a more succinct recording.

After much trial, error and experimentation here are my findings using Mac OS X.

Animated GIFs can be:

• viewed frame-by-frame using macOS Preview.app
• manipulated using "gifsicle" command line tool
• converted using "ffmpeg" command line tool

Notes

• useful tools need to be installed using "brew" command line tool http://brew.sh

VIEWING

Open the GIF in Preview.app and it will show you all frames.
Preview calls the first frame 1 (one), but other tools usually call it 0 (zero).

original/source animated GIF:

TRIMMING

required: gifsicle

brew install gifsicle

then this is how you trim

gifsicle anim.gif "#212-238" > trimmed.gif

note: this makes a copy of the GIF and keep frames 213 to 239 (gifsicle uses zero based frame count)

RESIZING

if you want to double size of the image:

gifsicle --scale 2 trimmed.gif > resized.gif

CAPTIONING

if you want to add an overlay to caption the animation

required: imagemagick

brew install imagemagick

then use this bash script:

#!/bin/bash
source=$1
caption=$2
: ${1?"Usage: $0 anim.gif overlay.gif [output.gif]"}
: ${2?"Usage: $0 anim.gif overlay.gif [output.gif]"}

fnsource=$(basename "$source" .gif)
fncaption=$(basename "$caption" .gif)

output=${3:-"$fnsource-$fncaption.gif"}

gifsicle -E $source
for f in *.gif.*; do composite $caption $f $f; done
gifsicle --loopcount *.gif.* > $output
rm *.gif.*

how to run the command

./caption.sh anim.gif overlay.gif [output.gif]

note: if you do not specify an output name, it will be named using original filenames, eg. anim-overlay.gif

caption.gif

CONVERT TO VIDEO

required: ffmpeg

brew install ffmpeg

to convert the GIF to MP4:

ffmpeg -i trimmed.gif video.mp4

video uploaded to YouTube:

EASY?

If there is enough demand I will create a trimming tool that does not require you load terminal every time.

Resize command now done using gifsicle rather than ffmpeg for sharper results

Added example animations, images and video.

Hey there, thanks for writing this up. I just wanted to add to this that you can also tell gifsicle to super-optimise your GIFs by adding the option -O3 on the command line. This removes redundant frames, and also only leaves parts of frames where the image has changed. I also recommend using the --careful flag with this, to do it in a way that makes the GIFs more compatible across different viewers.

So you could do this using a command like:

gifsicle -O3 --careful input.gif > output.gif

Good point!

If you do use optimise, -O, and you want to edit the GIF further then be sure to use -U to unoptimise it otherwise the editing commands won't work as expected. This is the reason I left it out.

If in doubt, optimise a copy of your animation.