flac2opus.py

#!/bin/python3

"""
Converts flac files to opus, preserving audio quality but with smaller file size.

    1. search recursively for *.flac files in the given path
    2. convert the file in-place (using ffmpeg)
    3. backup the original file into a backup directory

Dependencies:
    - ffmpeg
    - python3

Generally they are both pre-installed on most linux distros.

Possible improvements:
    1. parallelization

Example:

./flac2opus.py ~/my-album/  # the given path will be scanned recursively for *.flac files
before:
    ~/my-album/song1.flac
    ~/my-album/song2.flac
    ~/my-album/extra/extra-song.flac
after:
    ~/my-album/song1.opus
    ~/my-album/song1.opus
    ~/my-album/extra/extra-song.opus
    ~/my-album/backup/song1.flac
    ~/my-album/backup/song2.flac
    ~/my-album/backup/extra-song.flac
"""

import subprocess
import argparse

from sys import exit
from os import getcwd
from shutil import move
from pathlib import Path

# get arguments from CLI
parser = argparse.ArgumentParser(
    description="Convert all the flac files in the specified path."
)
parser.add_argument('path', type=Path)
parser.add_argument('--bitrate', type=int, help="Output bitrate in kbps", default=180)
parser.add_argument('--backup-dir', type=Path, help="Backup directory")
args = parser.parse_args()

# set backup dir
if args.backup_dir:
    BACKUP_DIR = args.backup_dir
else:
    BACKUP_DIR = args.path / 'backup'

# get all flac files
files = args.path.glob("**/*.flac") # gets an iterator
files = list(files) # iterator to list

# quit if no flac file is found
if len(files) == 0:
    print("Quitting...")
    print("No flac file found in {}".format(getcwd()))
    exit()

# list the files that will be converted
print("The following files are going to be converted:")
file_count = 0
for i, f in enumerate(files):
    print(' {index} - {filename}'.format(index = i + 1, filename = f))
    file_count = i + 1

# tell user about the backup folder
print("A backup will be available at {}".format(BACKUP_DIR))

# prompt
ans = input("Do you want to continue? [y/n]")
if ans.lower() != "y":
    exit()

# make sure backup dir exists
BACKUP_DIR.mkdir(exist_ok=True)

# start converting files
print("Converting...")
# for each flac file
for idx, f in enumerate(files):
    file_dir = f.parents[0] # absolute path to current file
    output_filename = f.stem + ".opus"
    # show progress to user
    print("  [{current} / {total}] - {track}".format(current=idx + 1, total=file_count, track = file_dir/output_filename))
    # convert track with ffmpeg
    subprocess.run(["ffmpeg", "-i", f, "-b:a", "{}k".format(args.bitrate), file_dir/output_filename, '-loglevel',  'quiet'])
    # move original file to backup folder
    move(f, BACKUP_DIR / f.name)

print("Done. Enjoy your music!")