def METHOD_NAME(self, img_url, img_name) -> bytes:
    logger.info('extract image from {}'.format(img_url))
    if img_url.endswith('mp3') or img_url.endswith('ogg') or img_url.endswith('wma'):
        from mutagen.mp3 import EasyMP3
        metadata_mp3 = EasyMP3(img_url)
        tags_mp3 = metadata_mp3.tags
        assert tags_mp3 is not None
        content = tags_mp3._EasyID3__id3._DictProxy__dict['APIC:'].data
    elif img_url.endswith('m4a'):
        from mutagen.easymp4 import EasyMP4
        metadata_mp4 = EasyMP4(img_url)
        tags_mp4 = metadata_mp4.tags
        assert tags_mp4 is not None
        content = tags_mp4._EasyMP4Tags__mp4._DictProxy__dict['covr'][0]
    else:
        raise Exception('Unsupported file type')
    return content