vidgif.sh

#!/bin/sh

youtube-dl -o "_%(id)s.%(ext)s" $1

infile=$(ls | head -n1)

palette="/tmp/palette.png"

filters="fps=12,scale=500:-1:flags=lanczos"

ffmpeg -v warning -ss $2 -t $3 -i $infile -vf "$filters,palettegen=stats_mode=diff" -y $palette
ffmpeg -v warning -ss $2 -t $3 -i $infile -i $palette -lavfi "$filters [x]; [x][1:v] paletteuse=dither=none" -y anim.gif

rm $infile

to run:
save vidgif.sh
from directory containing vidgif.sh:
bash vidgif.sh youtube_url start_time gif_length
where start time is MM:SS, gif length is time in whole seconds

script downloads youtube video, creates color palette then gif with that palette to ensure highest quality via ffmpeg, writes output to anim.gif, deletes video file

bastardized version of script here: http://blog.pkh.me/p/21-high-quality-gif-with-ffmpeg.html

other adjustable params (hard-coded, sry):

• fps: frames per second, value directly correlated with gif quality
• scale: width, in pixels, will scale gif proportionally

you gotta pip install youtube-dl also