flac-alac-converter.sh

#!/bin/zsh
#
# flac-alac-converter.sh — Convert FLAC albums to Apple Lossless (ALAC/m4a)
#
# Usage:
#   ./flac-alac-converter.sh                       Convert all subdirs containing FLAC files
#   ./flac-alac-converter.sh --dry-run             Preview what would happen, no files written
#   ./flac-alac-converter.sh -n                    Same as --dry-run
#   ./flac-alac-converter.sh file.flac             Convert a single FLAC file (output next to source)
#   ./flac-alac-converter.sh --dry-run file.flac   Dry-run a single file
#   ./flac-alac-converter.sh /path/to/album        Convert a specific album directory
#
# Requirements:
#   ffmpeg  (brew install ffmpeg)
#
# For each album directory, a sibling directory is created with " ALA" appended,
# e.g. "AlbumName ALA". FLAC files are converted to ALAC; jpg and cue
# files are copied as-is. Embedded cover art is preserved.

DRY_RUN=0
SINGLE_FILE=""
TARGET_DIR=""

for arg in "$@"; do
  case "$arg" in
    --dry-run|-n) DRY_RUN=1 ;;
    *.flac) SINGLE_FILE="$arg" ;;
    *)
      if [[ -d "$arg" ]]; then
        TARGET_DIR="$arg"
      else
        echo "Unknown argument: $arg"; exit 1
      fi
      ;;
  esac
done

command -v ffmpeg >/dev/null || { echo "ffmpeg not found"; exit 1; }

(( DRY_RUN )) && echo "[dry-run — no files will be written]"

run() {
  if (( DRY_RUN )); then
    echo "    >> $*"
  else
    "$@"
  fi
}

convert_album() {
  local dir="$1"
  local new_dir="${dir} ALA"

  echo ""
  echo "==> $dir"
  run mkdir -p "$new_dir"

  for ext in jpg cue; do
    for f in "$dir"/*.$ext; do
      [ -f "$f" ] || continue
      echo "  copy  ${f##*/}"
      run cp "$f" "$new_dir/"
    done
  done

  local total=0
  for flac in "$dir"/*.flac; do
    [ -f "$flac" ] && (( total++ )) || true
  done

  local i=0
  for flac in "$dir"/*.flac; do
    [ -f "$flac" ] || continue
    (( i++ )) || true
    local m4a="$new_dir/${flac##*/}"
    m4a="${m4a%.flac}.m4a"
    echo "  [$i/$total] ${flac##*/} -> ${m4a##*/}"
    run ffmpeg -loglevel error -i "$flac" -c:a alac -c:v copy -y "$m4a"
  done

  echo "  done ($i track(s))"
}

# Single-file mode
if [[ -n "$SINGLE_FILE" ]]; then
  [[ -f "$SINGLE_FILE" ]] || { echo "File not found: $SINGLE_FILE"; exit 1; }
  local m4a="${SINGLE_FILE%.flac}.m4a"
  echo "Converting: ${SINGLE_FILE##*/} -> ${m4a##*/}"
  run ffmpeg -loglevel error -i "$SINGLE_FILE" -c:a alac -c:v copy -y "$m4a"
  echo "Done."
  exit 0
fi

# Single-directory mode
if [[ -n "$TARGET_DIR" ]]; then
  convert_album "$TARGET_DIR"
  echo ""
  echo "Done."
  exit 0
fi

# Batch mode: discover all subdirectories that contain FLAC files
found=0
for dir in */; do
  dir="${dir%/}"
  # Skip directories we already created
  [[ "$dir" == *" ALA" ]] && continue
  # Only process dirs that contain at least one FLAC file
  local has_flac=0
  for f in "$dir"/*.flac; do
    [ -f "$f" ] && has_flac=1 && break
  done
  (( has_flac )) || continue
  convert_album "$dir"
  (( found++ )) || true
done

if (( found == 0 )); then
  echo "No directories with FLAC files found in the current directory."
  exit 1
fi

echo ""
echo "All albums converted!"