python script to convert id3 fields to unicode

id3_utf8.py

#!/usr/bin/env python2.6
# -*- coding: utf-8 -*-

# TODO: doesn’t convert to id3v2; eyed3 and mutagen have been fussy
# with non-utf tags

# TODO: prints, prints everywhere

import sys
from ID3 import *
import mutagen.id3
import chardet

def convert(id3_tags, fromenc):
    changed = False
    for k, v in id3_tags.items():
        try:
            uv = v.decode(fromenc).encode('utf-8')
        except UnicodeDecodeError, e:
            print "WARNING: %s = '%s': Error reading input as %s; ignoring illegal characters" % (k, v, fromenc)
            uv = v.decode(fromenc, 'ignore').encode('utf-8')

        if v == uv:
            continue
        else:
            id3_tags[k] = uv
            print "Changing: %s = '%s' → '%s'" % (k, v, uv)
            changed = True

    if changed:
        id3_tags.write()
    return changed

def convert_auto(id3_tags):
    changed=False
    for k, v in id3_tags.items():
        det = chardet.detect(v)
        confidence = det['confidence']
        enc = det['encoding'].lower()

        if (confidence < 0.5):
            print "Not changing: Confidence too low: %s, %s certain" % (enc, confidence)
        else:
            if (enc != 'ascii' and enc != 'utf-8'):
                uv = v.decode(enc).encode('utf-8')
                id3_tags[k] = uv

                print "Changed: %s = '%s' → '%s' (%s, %s certain)" % (k, v, uv, enc, confidence)
                changed=True
    if changed:
        id3_tags.write()
    return changed

def print_detections(id3_tags):
    for k, v in id3_tags.items():
        det = chardet.detect(v)
        confidence = det['confidence']
        enc = det['encoding'].lower()
        print "%s = '%s' (%s, %s certain)" % (k, v, enc, confidence)


    
if __name__ == '__main__':
    from optparse import OptionParser
    p = OptionParser(usage='Usage: %prog [options] <file1.mp3 file2.mp3 ... fileN.mp3>')
    p.add_option('-f', '--from', dest='fromenc', default='auto',
                 help="Convert from this encoding (default: try to guess)")
    p.add_option('-d', '--detect-only', dest='detect',
                 action='store_true', default=False,
                 help="Don't change tags; just print results of detection")

    (options, args) = p.parse_args()

    for fname in args:
        try:
            id3_tags = ID3(fname)
        except (Exception, InvalidTagError), e:
            print "Ignoring file: %s: %s" % (fname, e)
            continue

        if options.detect:
            print_detections(id3_tags)
        elif options.fromenc == 'auto':
            convert_auto(id3_tags)
        else:
            convert(id3_tags, options.fromenc)