#!/bin/bash

FLAC="$1"
OUT_DIR="mp3"
# get filename without extension
FILENAME="${FLAC##*/}"
# make filename with .mp3 extension
MP3="./${OUT_DIR}/${FILENAME%.flac}.mp3"

mkdir -p "$OUT_DIR"
if [[ ! -f "$MP3" ]]; then
    ffmpeg -i "$FLAC" -c:a libmp3lame -b:a 320K -map a:0 "$MP3"
fi