Video to GIF shell script using ffmpeg

This is an old post that I copied from my old blog.

I like to capture my Xbox One gaming moments to share with friends and have been working on a shell script to quickly convert videos to animated GIFs, I've put together this fairly simple little shell script that takes an input video and uses ffmpeg to convert to an animated GIF.

The GIF file format has a colour limitation of 256 colours, so optimisation needs to be done to ensure a good quality output. The script utilises ffmpegs palettegen options to generate a palette of colours to use in the second pass using the bayer dither option. This is what the palette PNG file looks like (upscaled from 16x16):

The resulting animated GIF turns out quite nice, this was captured from my Xbox One in the Battlefield 1 beta, the file is 480x260 and 4.3MB at 15 frames per second:

The script is available as a gist on my github or it can be copied and pasted from below. First download the script and set it as executable, the simplest method is wget:

$ wget https://gist.githubusercontent.com/mplinuxgeek/dcbc3a4d0f51f2b445608e3da832ebb5/raw/vid2gif.sh
$ chmod +x vid2gif.sh

To use this script just execute it with the filename of a video appended, the script defaults to a width of 480 pixels and frame rate of 15fps:

$ ./vid2gif.sh video.mp4

To change the width and fps of the gif add -w and -f arguments to the script:

$ ./vid2gif.sh -w 320 -f 10 video.mp4

UPDATE: I've recently done some testing with different bayer dithering levels, results are below, I've also added a dithering argument to the script.

To specify a different dithering level use the -d argument:

$ ./vid2gif.sh -w 320 -f 10 -d 5 video.mp4

Dither	Size	Notes
0	3.91MB	Largest file, worst image quality,
1	3.33MB	Noticeable vertical lines
2	3.19MB	Vertical lines still visible but better than 1
3	3.05MB	Vertical lines gone, very good image quality
4	2.90MB	Hard to pick a difference from 3
5	2.82MB	Hard to notice a difference from 4 but some colour banding evident

Bonus: if you want to be able to run the script from anywhere without specifying the full path or ./ simply copy it to /usr/local/bin:

$ sudo cp vid2gif.sh /usr/local/bin/

The script can now be run from any directory:

$ vid2gif.sh

Script:

	#!/bin/bash
	# rev 4 - changes suggested by KownBash https://www.reddit.com/r/bash/comments/5cxfqw/i_wrote_a_simple_video_to_gif_bash_script_thought/da19gjz/
	# rev 5 - made the script more verbose
	# rev 6 - fixed an issue with a variable not displaying correctly
	# rev 7 - added option to change dither level
	# rev 8 - rewrote usage function
	# Usage function, displays valid arguments
	usage() {
	echo "Usage: $(basename ${0}) [arguments] inputfile" 1>&2
	echo " -f fps, defaults to 15" 1>&2
	echo " -w width, defaults to 480" 1>&2
	echo " -d dither level, value between 0 and 5, defaults to 5" 1>&2
	echo " 0 is no dithering and large file" 1>&2
	echo " 5 is maximum dithering and smaller file" 1>&2
	echo -e "\nExample: $(basename ${0}) -w 320 -f 10 -d 1" 1>&2
	exit 1
	}
	# Default variables
	fps=15
	width=480
	dither=5
	# getopts to process the command line arguments
	while getopts ":f:w:d:" opt; do
	case "${opt}" in
	f) fps=${OPTARG};;
	w) width=${OPTARG};;
	d) dither=${OPTARG};;
	*) usage;;
	esac
	done
	# shift out the arguments already processed with getopts
	shift "$((OPTIND - 1))"
	if (( $# == 0 )); then
	printf >&2 'Missing input file\n'
	usage >&2
	fi
	# set input variable to the first option after the arguments
	input="$1"
	# Extract filename from input file without the extension
	filename=$(basename "${input}")
	#extension="${filename##*.}"
	filename="${filename%.*}.gif"
	# Debug display to show what the script is using as inputs
	echo "Input: ${1}"
	echo "Output: ${filename}"
	echo "FPS: ${fps}"
	echo "Width: ${width}"
	echo "Dither Level: ${dither}"
	# temporary file to store the first pass pallete
	palette="/tmp/palette.png"
	# options to pass to ffmpeg
	filters="fps=${fps},scale=${width}:-1:flags=lanczos"
	# ffmpeg first pass
	echo -ne "\nffmpeg 1st pass... "
	ffmpeg -v warning -i "${input}" -vf "${filters},palettegen=stats_mode=diff" -y "${palette}" && echo "done"
	# ffmpeg second pass
	echo -ne "ffmpeg 2nd pass... "
	ffmpeg -v warning -i "${input}" -i "${palette}" -lavfi "${filters} [x]; [x][1:v] paletteuse=dither=bayer:bayer_scale=${dither}" -y "${filename}" && echo "done"
	# display output file size
	filesize=$(du -h "${filename}" | cut -f1)
	echo -e "\nOutput File Name: ${filename}"
	echo "Output File Size: ${filesize}"

view raw vid2gif.sh hosted with ❤ by GitHub

More information on GIF optimisation and bayer dithering can be found here, this was also the basis of my original script:
http://blog.pkh.me/p/21-high-quality-gif-with-ffmpeg.html

Just a warning, keep the input videos short, GIFs can get very large very quickly.