movie2gif

#!/bin/sh
# movie2gif
# Convert a video file into an animated GIF file.

VERSION='1.0.1'

movie2gif_main() {
	scriptpath="$( realpath "$0" )"
	scriptname="$( basename "$scriptpath" )"

	e_args=16
	e_file=17

	DRYRUN=0
	VERBOSE=0

	OPTIND=

	while getopts "a:c:d:f:hm:no:p:r:s:t:vVw:" opt
	do
		case "$opt" in
			a) scale="$OPTARG" ;;
			c) colors="$OPTARG" ;;
			d) duration="$OPTARG" ;;
			f) filters="$OPTARG" ;;
			h) movie2gif_help && return ;;
			m) more="$OPTARG" ;;
			n) DRYRUN=1 ;;
			o) crop="$OPTARG" ;;
			p) palette="$OPTARG" ;;
			r) fps="$OPTARG" ;;
			s) start="$OPTARG" ;;
			t) height="$OPTARG" ;;
			v) movie2gif_version && return ;;
			V) VERBOSE=1 ;;
			w) width="$OPTARG" ;;
			*) _invalid_opt ;;
		esac
	done

	shift "$(( OPTIND - 1 ))"

	[ -z "$cmd" ] && cmd="convert"

	case "$cmd" in
		convert|help) "movie2gif_$cmd" "$@" ;;
		*) _invalid_cmd ;;
	esac

	return $?
}

movie2gif_convert() {
	shift "$(( OPTIND - 1 ))"

	[ -z "$colors" ] && colors=32
	[ -z "$fps" ] && fps=10
	[ -z "$height" ] && height=-1
	[ -z "$width" ] && width=720

	args=
	preargs=

	if _is_verbose
	then
		_add_prearg '-loglevel info'
	else
		_add_prearg '-hide_banner'
		_add_prearg '-nostats'
		_add_prearg '-loglevel fatal'
	fi

	if [ -z "$filters" ]
	then
		filters=

		[ -n "$crop" ] && _add_filter "crop=$crop"
		[ -n "$scale" ] && _add_filter "setpts=$scale*PTS"

		_add_filter "fps=$fps,scale=$width:$height:flags=lanczos"

		[ -n "$more" ] && _add_filter "$more"
	fi

	[ -n "$start" ] && _add_prearg "-ss $start"
	[ -n "$duration" ] && _add_prearg "-t $duration"

	[ $# -lt 1 ] && _error "Must set input filename." && return $e_args

	input="$1"
	shift

	output="$1"
	shift

	args="$args $*"
	
	medial="$input"

	if [ -z "$palette" ]
	then
		template="$( mktemp "$medial-palette-$colors.XXXXXX" )"
		rm "$template"
		palette="$( mktemp "$template.png" )"
		tmppalette=1
	else
		tmppalette=0
	fi

	[ -z "$output" ] && output="$( echo "$input" | sed 's/\.[^\.]*$//g' ).gif"

	if _file_absent "$input"
	then
		_error "File not found: $input"
		return $e_file
	fi

	_echo "$input => $output"
	"${scriptname}_file" "$input"

	if _is_verbose
	then
		_echo "ffmpeg filters: $filters"
		_echo "ffmpeg preargs: $preargs"
		_echo "ffmpeg args: $args"
	fi

	_convert

	"${scriptname}_file" "$output"

	[ $tmppalette -eq 1 ] && rm "$palette"
}

movie2gif_file() {
	OPTIND=

	while getopts "s" OPTION
	do
		case "$OPTION" in
			s) format='%f %W %H %b' ;;
			*) _invalid_opt "$OPTION" ;;
		esac
	done

	shift $(( OPTIND - 1 ))

	[ -z "$format" ] && format='%f: %Wx%Hpx (%b)'

	[ $# -lt 1 ] && _error "Must set input filename." && return "$ERR_ARG"

	format="$format\n"
	input="$1"
	shift

	if _file_absent "$input"
	then
		_error "File not found: $input"
		return "$ERR_FILE"
	fi

	identify -format "$format" "$input"[0] 2>/dev/null

	result=$?

	if [ $result -gt 0 ]
	then
		_error "Not an image or not a format ImageMagick can recognise."
	fi

	return $?
}

movie2gif_help() {
cat <<HELP
$scriptname $VERSION

USAGE: $scriptname [<options>] <input> [<output>]

Convert a video file into an animated GIF file.

OPTIONS:

	-a   Time scale. Less than 1 to speed up, more to slow down. (Default: 1)
	-c   Number of colours in palette. (Default: 32)
	-d   Duration in seconds. (Default: all)
	-f   Override all filters with specified ffmpeg filters.
	-h   Show this help screen.
	-m   Append specified ffmpeg filters.
	-n   Dry run. Don't write to any file.
	-o   Crop image (out_w:out_h:x:y). (Default: no crop)
	-r   Number of frames per second (FPS). (Default: 10)
	-s   Start time in seconds. (Default: 0)
	-t   Image height of output. (Default: -1, keeping ratio with width)
	-v   Show version.
	-V   Make console output verbose.
	-w   Image width of output. (Default: 720)

HELP
}

movie2gif_version() {
	echo "$scriptname $VERSION"
}

_add_prearg() {
	[ -n "$preargs" ] && preargs="$preargs "
	preargs="${preargs}$*"
}

_add_arg() {
	[ -n "$args" ] && args="$args "
	args="${args}$*"
}

_add_filter() {
	[ -n "$filters" ] && filters="$filters,"
	filters="${filters}$*"
}

_check_palette() {
	_file_exists "$palette" && return

	_error "Palette file not found: $palette"
	return "$ERR_FILE"
}

_convert() {
	# http://blog.pkh.me/p/21-high-quality-gif-with-ffmpeg.html

	if [ "$tmppalette" -eq 1 ] || ! _file_exists "$palette"
	then
		_run "ffmpeg $preargs -i \"$input\" -vf \"$filters,palettegen\"" \
			"-y $args \"$palette\""
	fi

	_check_palette || return $?

	_run "mogrify +dither -colors $colors \"$palette\""

	_run "ffmpeg $preargs -i \"$medial\" -i \"$palette\"" \
		"-lavfi \"$filters [x]; [x][1:v] paletteuse\" -y $args \"$output\""

	image_optim="$( which image_optim 2>/dev/null )"
	[ -n "$image_optim" ] && $image_optim "$output" 1>/dev/null 2>&1
}

_echo() {
	echo "$@"
}

_error() {
	_echo "$@" >&2
}

_fatal() {
	exit_code="$1"
	shift
	_error "$@"
	exit "$exit_code"
}

_file_absent() {
	_is_dryrun && return 1
	[ ! -f "$1" ]
}

_file_exists() {
	_is_dryrun && return
	[ -f "$1" ]
}

_invalid_cmd() {
	_error "Invalid command: $cmd"
	_echo
	movie2gif_help
	exit $e_args
}

_invalid_opt() {
	_error "Invalid option: $opt"
	_echo
	movie2gif_help
	exit $e_args
}

_is_dryrun() {
	[ $DRYRUN -gt 0 ]
}

_is_verbose() {
	[ $VERBOSE -gt 0 ]
}

_run() {
	_is_verbose && _echo "> $*"
	_is_dryrun && return
	eval "$*"
}

movie2gif_main "$@"