ffmpeg multiple processes directory videos

ffmpeg.sh

#!/bin/bash
set -e

handler(){
    path=$@
    filename=$(basename "${path}")
    basename=${filename%.*}
    dirname=$(dirname "${path}")
    newname=$dirname/$basename.mp4
    ffmpeg -i "$path" "$newname"
}
export -f handler

find $1 -name '*.avi' -exec bash -c 'handler "{}"' \;