def sina_download_by_vkey(vkey, title=None, output_dir='.', merge=True, info_only=False):
    """
    """

    url = 'http://video.sina.com/v/flvideo/%s_0.flv' % vkey
    type, ext, size = url_info(url)

    print_info(site_info, title, 'flv', size)
    if not info_only:
        download_urls([url], title, 'flv', size, output_dir = output_dir, merge = merge)