Lower FLAC, MP3 -> MP3 to a target bitrate, and replace the files in dir(s) (requires ffmpeg, multiprocess, Python3, *nix only for now)

bitrate_lower.py

import argparse
import hashlib
import logging
import subprocess
from multiprocessing import Pool, log_to_stderr
from os import path, remove, replace, walk

from mutagen.mp3 import MP3

parser = argparse.ArgumentParser(description="Floor bitrate of mp3 (and flac) to mp3 to gain storage space, recursively on DIR")
parser.add_argument('DIR',
                    nargs='+')
parser.add_argument('--target',
                    dest="bitrate",
                    type=int,
                    default=192,
                    choices=[64, 128, 192, 256, 320],
                    help="target kbits/s")

EXTS = ["mp3", "flac", "wav", "m4a"]

logger = log_to_stderr()
logger.setLevel(logging.ERROR)


def work(filepath):
    if filepath.lower().endswith("mp3"):
        f = MP3(filepath)
        bitrate = int(f.info.bitrate / 1000)
        if bitrate <= THRESHOLD:
            logger.info("%s left untouched (%d kbps)", filepath, bitrate)
            return None
        ext = "mp3"
    else:
        ext = filepath.lower().split(".")[-1]

    h = hashlib.sha256(filepath.encode("utf-8")).hexdigest()
    tmp_filepath = "/tmp/%s.mp3" % h

    command = ["ffmpeg",
               "-i",
               filepath,
               "-ab",
               "%dk" % THRESHOLD,
               "-map_metadata",
               "0",
               "-id3v2_version",
               "3",
               tmp_filepath,
               "-y"]

    output = subprocess.run(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    if ext == "mp3":
        replace(tmp_filepath, filepath)
        logger.info("Converted %s !", filepath)
    else:
        new_filepath = path.splitext(filepath)[0] + ".mp3"
        replace(tmp_filepath, new_filepath)
        remove(filepath)  # Remove the original flac file
        logger.info("Converted %s to %s and removed the original !", filepath, new_filepath)
    return (filepath, output)


if __name__ == '__main__':
    args = vars(parser.parse_args())
    THRESHOLD = args['bitrate']
    files_input = []
    for folder in args['DIR']:
        for r, _, files in walk(folder):
            for filename in files:
                if any([filename.lower().endswith(ext) for ext in EXTS]):
                    full_path = path.join(r, filename)
                    files_input.append(full_path)
    original_size = len(files_input)
    i = original_size
    with Pool() as p:
        for result in p.imap_unordered(work, files_input):
            if result:
                filename, result = result
                if result.returncode != 0:
                    logger.error(result.decode("utf-8"))
                else:
                    logger.info("%s treated...", filename)
            i -= 1
            if i > 0:
                logger.info(">> Left to treat %d / %d" % (i, original_size))
    logger.info("Done")