brute-force ID3 encoding fix

fix-mp3-tags.py

from argparse import ArgumentParser
from os import path, walk
from typing import Iterable
import sys

from chardet import detect
from mutagen.id3 import Encoding, ID3, TextFrame

TARGET_FIELDS = {'TALB', 'TCOM', 'TIT2', 'TPE1', 'TPE2'}


def collect_files(root_dir: str) -> Iterable[str]:
    for parent, _, names in walk(root_dir):
        yield from (path.join(parent, f) for f in names if f.endswith('.mp3'))


def is_fake_ascii(text: str) -> bool:
    try:
        return detect(text.encode('ascii'))['confidence'] != 1.0
    except UnicodeEncodeError:
        return True


def is_suspect(meta: ID3) -> bool:
    for key in TARGET_FIELDS:
        if key not in meta:
            continue

        value = meta[key]

        if value.encoding == Encoding.LATIN1 and is_fake_ascii(value.text[0]):
            return True
        
    return False


def fix_frame_encoding(frame: TextFrame) -> TextFrame:
    if frame.encoding != Encoding.LATIN1:
        return frame

    # can I copy & update instead of doing it in-place?
    frame.text = [frame.text[0].encode('latin1').decode('gbk')]
    frame.encoding = Encoding.UTF16
    return frame


def main(args):
    for f in collect_files(path.abspath(args.dir)):
        meta = ID3(f)

        if is_suspect(meta):
            fields = []

            for key in TARGET_FIELDS:
                frame = meta.get(key)
                if not frame:
                    continue

                orig = str(meta[key])
                fixed = str(fix_frame_encoding(meta[key]))

                if fixed != orig:
                    fields.append(f'{key}: {orig} -> {fixed}')

            if fields:
                meta.save()

            print('; '.join(fields))


if __name__ == '__main__':
    parser = ArgumentParser()
    parser.add_argument('dir')
    main(parser.parse_args(sys.argv[1:]))