+ # extracted from account/account_menu ep
+ # XXX: These are the supported YouTube UI and API languages,
+ # which is slightly different from languages supported for translation in YouTube studio
+ _SUPPORTED_LANG_CODES = [
+ 'af', 'az', 'id', 'ms', 'bs', 'ca', 'cs', 'da', 'de', 'et', 'en-IN', 'en-GB', 'en', 'es',
+ 'es-419', 'es-US', 'eu', 'fil', 'fr', 'fr-CA', 'gl', 'hr', 'zu', 'is', 'it', 'sw', 'lv',
+ 'lt', 'hu', 'nl', 'no', 'uz', 'pl', 'pt-PT', 'pt', 'ro', 'sq', 'sk', 'sl', 'sr-Latn', 'fi',
+ 'sv', 'vi', 'tr', 'be', 'bg', 'ky', 'kk', 'mk', 'mn', 'ru', 'sr', 'uk', 'el', 'hy', 'iw',
+ 'ur', 'ar', 'fa', 'ne', 'mr', 'hi', 'as', 'bn', 'pa', 'gu', 'or', 'ta', 'te', 'kn', 'ml',
+ 'si', 'th', 'lo', 'my', 'ka', 'am', 'km', 'zh-CN', 'zh-TW', 'zh-HK', 'ja', 'ko'
+ ]
+
+ @functools.cached_property
+ def _preferred_lang(self):
+ """
+ Returns a language code supported by YouTube for the user preferred language.
+ Returns None if no preferred language set.
+ """
+ preferred_lang = self._configuration_arg('lang', ie_key='Youtube', casesense=True, default=[''])[0]
+ if not preferred_lang:
+ return
+ if preferred_lang not in self._SUPPORTED_LANG_CODES:
+ raise ExtractorError(
+ f'Unsupported language code: {preferred_lang}. Supported language codes (case-sensitive): {join_nonempty(*self._SUPPORTED_LANG_CODES, delim=", ")}.',
+ expected=True)
+ elif preferred_lang != 'en':
+ self.report_warning(
+ f'Preferring "{preferred_lang}" translated fields. Note that some metadata extraction may fail or be incorrect.')
+ return preferred_lang
+