video2gif.sh

#!/bin/bash
# Script to convert video files to GIFs using ffmpeg

FFMPEG_PATH=$(which ffmpeg)
if [[ -z FFMPEG_PATH ]]; then
    echo "FATAL: ffmpeg was not found in your path - please install beforehand"
	exit 1
fi

FPS=10
SCALE=1
CUTOFF=0
FULLPATH=

function usage() {
	echo "Usage: $0 [-f|--fps <fps>] [-s|--scale <scale>] file"
	echo
	echo "Arguments:"
	echo "      file        	File to convert to GIF"
	echo "Options:"
	echo "      -h|--help   	Print this help"
	echo "      -f|--fps    	Framerate (FPS) to use for GIF (default: 10)"
	echo "      -s|--scale  	Scale ratio to use during conversion - will be used as 1/x,"
	echo "                  	i.e. a scale of 2 will result in half the size (default: 1)"
	echo "      -c|--cutoff		Number of seconds to cut off at the end (default: 0)"
	exit $1
}

while [[ $# -gt 0 ]]; do
	KEY=$1

	case $KEY in
		-h | --help)
			usage 0
			;;
		-f | --fps)
			FPS=$2
			shift
			;;
		-s | --scale)
			SCALE=$2
			shift
			;;
		-c | --cutoff)
			CUTOFF=$2
			shift
			;;
		*)
			if [[ $# -eq 1 ]]; then
				FULLPATH=$KEY
				shift
			else
				echo "ERROR: Unknown option: $KEY"
				echo
				usage 1
			fi
			;;
	esac

	shift
done

if [[ -z $FULLPATH ]]; then
	echo "Required argument file is missing"
	echo
	usage 1
fi
if [[ ! -e $FULLPATH ]]; then
	echo "File $FULLPATH does not exist"
	echo
	usage 1
fi

FILENAME=${FULLPATH%%.*}
GIF="${FILENAME}.gif"
PALETTE="${FILENAME}-palette.png"

echo "Converting $FULLPATH to $GIF..."

FILTERS="fps=$FPS,scale=iw/$SCALE:ih/$SCALE:flags=lanczos"

if [[ $CUTOFF -gt 0 ]]; then
	DURATION=$(ffprobe -loglevel quiet -of compact=p=0:nk=1 -show_entries format=duration -i "$FULLPATH")
	DURATION_DIFF=$(echo "$DURATION - $CUTOFF" | bc -l)

	ffmpeg -v warning -i $FULLPATH -vf "$FILTERS,palettegen" -t $DURATION_DIFF -y $PALETTE

	ffmpeg -v warning -i $FULLPATH -i $PALETTE -t $DURATION_DIFF -lavfi "$FILTERS [x]; [x][1:v] paletteuse" -y $GIF
else
	ffmpeg -v warning -i $FULLPATH -vf "$FILTERS,palettegen" -y $PALETTE

	ffmpeg -v warning -i $FULLPATH -i $PALETTE -lavfi "$FILTERS [x]; [x][1:v] paletteuse" -y $GIF
fi

rm $PALETTE

echo "Done - see output $GIF"