spellbook

Notes for things I find myself searching for over and over. I know they’re faster to find here than somewhere else.

ffmpeg

• convert a bunch of stils into a webm file

ffmpeg -framerate 30 -i name%4d.webp -c:v libvpx-vp9 -pix_fmt yuva420p -lossless 1 out.webm

• reverse

ffmpeg -i input.webm -vf reverse reverse.webm

• stitch two files together

> cat input.txt
file 'one.webm'
file 'two.webm'

ffmpeg -f concat -i input.txt -c copy output.webm

imagemagick

• see tkacz.pro also
• rotate

convert INPUT_FILE -rotate "+90" OUTPUT_FILE

• resize

convert INPUT_FILE -resize 70% OUTPUT_FILE
convert INPUT_FILE -resize 640x480 OUTPUT_FILE

use mogrify for processing multiple files at once generally

• invert colors

convert INPUT -channel RGB -negate OUTPUT

• make transparent

convert INPUT -transparent white OUTPUT

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