Angif.sh

#!/bin/bash
# Angif.sh
: '
Copyright (C) 2020 Antoine Hugounet

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see <https://www.gnu.org/licenses/>.
'

# help message
# to echo bold, see 
# https://stackoverflow.com/questions/2924697/how-does-one-output-bold-text-in-bash
bold=$(tput bold)
normal=$(tput sgr0)
help_message_begining="${bold}Angif${normal}
Given a YouTube video url, a starting time and a duration, Angif creates a gif of the video from the starting time and of the duration you gave it. Default parameters are 10 fps (or native video frame rate if it is less than that) and 800 px width (or native video width if it is less than that). See options below.

${bold}Usage${normal}
angif [-h/--help]
angif <url> <starting time> <extract duration> [options]\n"

help_message_options="-h/--help	display this message
-d/--directory <dir>	create the gif in the specified <dir> directory
-f/--fps <val>	choose the number of fps in the gif, default is minimum of video frame rate and 10 fps
-w/--width <val>	choose the width (in px) of the gif, default is minimum of video width and 800 px\n"

help_message_end="${bold}Examples${normal}
$ angif \"https://www.youtube.com/watch?v=dQw4w9WgXcQ\" 0:43 8
This creates an 8 seconds gif from 0:43 seconds in the video, where the script is.
$ angif \"https://www.youtube.com/watch?v=dQw4w9WgXcQ\" 0:43 8 --dir ~/Downloads
This does the same, except that the gif is created in ~/Downloads.

${bold}Warning${normal}
Depending on your OS, you may need to remove the quotes for the YouTube url. They are required on macOS but some friends had to remove them on Linux systems.

Made by Antoine Hugounet. This project is licensed under the GNU General Public License v3.0 - see the LICENSE.md file in the repository (https://github.com/kryzar/stupid-serguei-scripts) for details. If you encounter any bug, please let me know. If you wish to contribute or help anyhow, please contact me or send a pull request: https://github.com/kryzar/stupid-serguei-scripts."

function print_help_message () {
	echo $help_message_begining
	echo ${bold}Options${normal}
	echo $help_message_options | column -ts $'\t'
	echo
	echo $help_message_end
}

# default parameters
fps=10		# default is 10 fps but can be changed with -f/--fps
width=800	# default is 800 px but can be changed with -w/--width

# parsing options (thanks to Florian)
if [[ $# == 0 || $1 == "-h" || $1 == "--help" ]] ; then
	print_help_message
else
	while [ $# -ge 1 ] ; do
		case $1 in
			# boolean options
			-h|--help)
				print_help_message 
				shift
				;;
			# options with arguments
			-d|--directory)
				if [ -n $2 ] && [ ${2:0:1} != "-" ] ; then
					cd $2
					shift 2
				else
					echo "Error: argument for $1 is missing." >&2
					exit 1
				fi
				;;
			-f|--fps)
				if [ -n $2 ] && [ ${2:0:1} != "-" ] ; then
					fps=$2
					shift 2
				else
					echo "Error: argument for $1 is missing." >&2
					exit 1
				fi
				;;
			-w|--width)
				if [ -n $2 ] && [ ${2:0:1} != "-" ] ; then
					width=$2
					shift 2
				else
					echo "Error: argument for $1 is missing." >&2
					exit 1
				fi
				;;
			# 
			-*|--*=) # unsupported flags
				echo "Error: unsupported option $1." >&2
				exit 1
				;;
			*) # preserve positional arguments
				mandatory_args+=($1)
				shift
				;;
		esac
	done

	# get mandatory positional arguments
	link_youtube=$mandatory_args[1]
	starting_time=$mandatory_args[2]
	duration=$mandatory_args[3]

	# get video name and prepare various output file names
	video_name=$(youtube-dl --get-filename $link_youtube)
	extension="${video_name##*.}"
	outfile_name_root="${video_name%.*}-${starting_time}-${duration}"
	outfile_video="${outfile_name_root}.${extension}"
	outfile_gif="${outfile_name_root}.gif"

	# this is where the fun begins
	# instead of downloading the full video and cropping it after,
	# we use youtube-dl --get-url to create a download url understable by FFmpeg
	# we give it to FFmpeg in -i $url and thanks to -ss and -t,
	# FFmpeg is then able to download only the desired extract of the video
	# for more information, see JaySandhu's comment from 2015 December 06
	# https://github.com/ytdl-org/youtube-dl/issues/622
	#
	# -an is to get rid of the audio, see
	# https://superuser.com/questions/268985/remove-audio-from-video-file-with-ffmpeg
	# -y is to avoid FFmpeg asking us override a file already existing
	url=$(youtube-dl --format bestvideo/best --get-url $link_youtube)
	ffmpeg -ss $starting_time -i $url -t $duration -an -y -c:v copy $outfile_video
	# to convert a video to a gif using FFmpeg, see
	# https://superuser.com/questions/556029/how-do-i-convert-a-video-to-gif-using-ffmpeg-with-reasonable-quality
	# the width is the minimum of the video width and 800 px, see
	# https://askubuntu.com/questions/772377/how-to-set-maximum-video-width-in-ffmpeg
	# -vsync vfr -r ${fps} is to limit fps, see Gyan's answer to rogerdpack
	# https://stackoverflow.com/questions/38987396/how-can-i-limit-maximum-fps-with-ffmpeg
	# previous version was -vf "fps=${fps}" and it crashed the script
	# when the user asked for gigantic frame rates
	# this ensures that we don't end with such crashes
	ffmpeg -i $outfile_video -vsync vfr -r ${fps} -vf "scale='min(${width},iw)':-1" $outfile_gif -y

	# remove video
	if [ -f $outfile_video ] ; then
		rm $outfile_video
	fi
fi