Script created with LLM to convert tons of audio files to another format, recursively, using a network attached disk on Windows

transcode_opus-ogg_to_aac-m4a.sh

#!/bin/bash
set -euo pipefail

# MUST CONFIGURE THIS PATH
NAS_MOUNT="/mnt/z/Audio"       # Windows/WSL: /mnt/z/...
# OR for Linux: "/mnt/nas_audio"

# Configuration Options
DRY_RUN=true
OVERWRITE=false
THREADS=$(nproc)  # Uses all cores
OUTPUT_EXT="m4a"  # Universally compatible AAC format

# Validate mount point
if [[ ! -d "$NAS_MOUNT" ]]; then
  echo "ERROR: NAS mount point not found: $NAS_MOUNT"
  echo "1. Confirm NAS is mounted"
  echo "2. Update NAS_MOUNT path in script"
  exit 1
fi

# Check dependencies
command -v ffmpeg >/dev/null || { echo "Install ffmpeg: sudo apt install ffmpeg"; exit 1; }
command -v parallel >/dev/null || { echo "Install parallel: sudo apt install parallel"; exit 1; }

# Find all opus files
echo "Scanning OPUS files in $NAS_MOUNT..."
mapfile -d '' opus_files < <(find "$NAS_MOUNT" -type f \( -iname "*.opus" -o -iname "*.ogg" \) -print0 2>/dev/null)

if [[ ${#opus_files[@]} -eq 0 ]]; then
  echo "No OPUS files found"
  exit 0
fi

# Dry-run mode
dry_run() {
  echo "--- DRY RUN ($THREADS THREADS) ---"
  echo "Found ${#opus_files[@]} OPUS files"
  for file in "${opus_files[@]}"; do
    output="${file%.*}.$OUTPUT_EXT"
    if [[ -f "$output" && "$OVERWRITE" != "true" ]]; then
      echo "[SKIP] Exists: $output"
    else
      echo "[CONVERT] $file ➔ $output"
    fi
  done

  read -rp "Execute conversion? (y/n): " choice
  [[ "$choice" == "y" ]] || exit 0
}

# Conversion function using native AAC encoder
convert_file() {
  local input="$1"
  local output="${input%.*}.$OUTPUT_EXT"
  
  [[ -f "$output" && "$OVERWRITE" != "true" ]] && return
  
  # Using native AAC encoder with highest quality VBR
  ffmpeg -v error -nostdin -i "$input" -c:a aac -q:a 1 -vn -y "$output"
  echo "✓ $output"
}

export -f convert_file
export OUTPUT_EXT OVERWRITE

# Execution flow
[[ "$DRY_RUN" == "true" ]] && dry_run

echo "Starting conversion with $THREADS threads..."
printf "%s\0" "${opus_files[@]}" | parallel -0 -j "$THREADS" convert_file

# Post-conversion cleanup (manual)
echo -e "\nSuccess! To remove originals safely:"
echo "find \"$NAS_MOUNT\" -type f \( -name \"*.opus\" -o -name \"*.ogg\" \) -exec echo rm {} \;"
echo "# REMOVE 'echo' AFTER VERIFYING FILE LIST"