A simple script I use in order to generate a video from audio

audeo.sh

#!/bin/bash

# Generate video from audio and a cover image

if (( $# < 3 )); then
	echo "Usage: audeo.sh <img_file> <audio_file> <dest-video-file>"
else
	ffmpeg -i $2 -loop 1 -i $1 -loop 1 -filter_complex "[0:a]showwaves=s=1920x200:mode=cline:colors=0xFFFFFF|0x333333[fg];[1:v]scale=1920:-1[bg];[bg][fg]overlay=shortest=1:820:format=auto,format=yuv420p[v]" -map "[v]" -map 0:a -c:v libx264 -c:a copy -shortest $3
fi