Convert series of images to .webm video file with transparent background using ffmpeg

commandline

// Convert all images in directory
ffmpeg -framerate 30 -pattern_type glob -i '*.png'  -pix_fmt yuva420p _export.webm

// For image names frame-1.png, frame-2.png, frame-3.png, etc.
ffmpeg -framerate 30 -i frame-%d.png -pix_fmt yuva420p _export.webm

// For image names frame-00001.png, frame-00002.png, frame-00003.png, etc. (5 apparently stand for the length of the number)
ffmpeg -framerate 30 -i frame-%05d.png  -pix_fmt yuva420p _export.webm

generate-conversion-commands.bash

#!/bin/bash
# Note: I did not figure out why executing the commands did not work. But it logs to the terminal, so you can copy and paste it and it works
#echo $PWD/*
for dir in $PWD/*
do
	if [[ -d $dir ]]; then
		#echo $dir
		for subdir in $dir/*
		do
			
			if [[ -d $dir ]]; then
				#echo $subdir
				filename="$(basename $subdir)"

				cmd="ffmpeg -framerate 30 -pattern_type glob -i '${subdir}/*.png'  -pix_fmt yuva420p $PWD/${filename}.webm"
				echo $cmd";"
				#$cmd
			fi
		done
	fi
done