#!/usr/bin/env bash
set -euo pipefail

if [ $# -lt 1 ]; then
  echo "Usage: $0 <audio_root_dir>"
  exit 1
fi

ROOT="$1"

find "$ROOT" -type f \( -iname "*.wav" -o -iname "*.mp3" -o -iname "*.m4a" -o -iname "*.mp4" \) | while IFS= read -r f; do
  [ -e "$f" ] || continue
  outf="${f%.*}.16k.wav"
  if [ -f "$outf" ]; then
    continue
  fi
  ffmpeg -hide_banner -loglevel error -y -i "$f" -ac 1 -ar 16000 -af loudnorm "$outf" || {
    echo "Failed to normalize: $f" >&2
  }
done

echo "Normalization complete."