FFmpeg batch convert files in recursive directories

ffmpeg-batch-recursive

#!/usr/bin/env bash

# parallel runs in N-process batches
# https://unix.stackexchange.com/a/216475
N=4

# enable globstar, requires bash >=4.0
shopt -s globstar

for f in ../iTunes\ Media/**/*.m4a; do
  ((i=i%N)); ((i++==0)) && wait
  fname="$(basename "$f")"
  ffmpeg -i "$f" -c:a libmp3lame -q:a 0 -n "${fname%.*}.mp3" &
done