+class SoundcloudIE(InfoExtractor):
+       """Information extractor for soundcloud.com
+          To access the media, the uid of the song and a stream token
+          must be extracted from the page source and the script must make
+          a request to media.soundcloud.com/crossdomain.xml. Then
+          the media can be grabbed by requesting from an url composed
+          of the stream token and uid
+        """
+
+       _VALID_URL = r'^(?:https?://)?(?:www\.)?soundcloud\.com/([\w\d-]+)/([\w\d-]+)'
+       IE_NAME = u'soundcloud'
+
+       def __init__(self, downloader=None):
+               InfoExtractor.__init__(self, downloader)
+
+       def report_webpage(self, video_id):
+               """Report information extraction."""
+               self._downloader.to_screen(u'[%s] %s: Downloading webpage' % (self.IE_NAME, video_id))
+
+       def report_extraction(self, video_id):
+               """Report information extraction."""
+               self._downloader.to_screen(u'[%s] %s: Extracting information' % (self.IE_NAME, video_id))
+
+       def _real_extract(self, url):
+               htmlParser = HTMLParser.HTMLParser()
+
+               mobj = re.match(self._VALID_URL, url)
+               if mobj is None:
+                       self._downloader.trouble(u'ERROR: invalid URL: %s' % url)
+                       return
+
+               # extract uploader (which is in the url)
+               uploader = mobj.group(1).decode('utf-8')
+               # extract simple title (uploader + slug of song title)
+               slug_title =  mobj.group(2).decode('utf-8')
+               simple_title = uploader + '-' + slug_title
+
+               self.report_webpage('%s/%s' % (uploader, slug_title))
+
+               request = urllib2.Request('http://soundcloud.com/%s/%s' % (uploader, slug_title))
+               try:
+                       webpage = urllib2.urlopen(request).read()
+               except (urllib2.URLError, httplib.HTTPException, socket.error), err:
+                       self._downloader.trouble(u'ERROR: unable to download video webpage: %s' % str(err))
+                       return
+
+               self.report_extraction('%s/%s' % (uploader, slug_title))
+
+               # extract uid and stream token that soundcloud hands out for access
+               mobj = re.search('"uid":"([\w\d]+?)".*?stream_token=([\w\d]+)', webpage)
+               if mobj:
+                       video_id = mobj.group(1)
+                       stream_token = mobj.group(2)
+
+               # extract unsimplified title
+               mobj = re.search('"title":"(.*?)",', webpage)
+               if mobj:
+                       title = mobj.group(1)
+
+               # construct media url (with uid/token)
+               mediaURL = "http://media.soundcloud.com/stream/%s?stream_token=%s"
+               mediaURL = mediaURL % (video_id, stream_token)
+
+               # description
+               description = u'No description available'
+               mobj = re.search('track-description-value"><p>(.*?)</p>', webpage)
+               if mobj:
+                       description = mobj.group(1)
+               
+               # upload date
+               upload_date = None
+               mobj = re.search("pretty-date'>on ([\w]+ [\d]+, [\d]+ \d+:\d+)</abbr></h2>", webpage)
+               if mobj:
+                       try:
+                               upload_date = datetime.datetime.strptime(mobj.group(1), '%B %d, %Y %H:%M').strftime('%Y%m%d')
+                       except Exception, e:
+                               print str(e)
+
+               # for soundcloud, a request to a cross domain is required for cookies
+               request = urllib2.Request('http://media.soundcloud.com/crossdomain.xml', std_headers)
+
+               try:
+                       self._downloader.process_info({
+                               'id':           video_id.decode('utf-8'),
+                               'url':          mediaURL,
+                               'uploader':     uploader.decode('utf-8'),
+                               'upload_date':  upload_date,
+                               'title':        simple_title.decode('utf-8'),
+                               'stitle':       simple_title.decode('utf-8'),
+                               'ext':          u'mp3',
+                               'format':       u'NA',
+                               'player_url':   None,
+                               'description': description.decode('utf-8')
+                       })
+               except UnavailableVideoError:
+                       self._downloader.trouble(u'\nERROR: unable to download video')
+
+
+class InfoQIE(InfoExtractor):
+       """Information extractor for infoq.com"""
+
+       _VALID_URL = r'^(?:https?://)?(?:www\.)?infoq\.com/[^/]+/[^/]+$'
+       IE_NAME = u'infoq'
+
+       def report_webpage(self, video_id):
+               """Report information extraction."""
+               self._downloader.to_screen(u'[%s] %s: Downloading webpage' % (self.IE_NAME, video_id))
+
+       def report_extraction(self, video_id):
+               """Report information extraction."""
+               self._downloader.to_screen(u'[%s] %s: Extracting information' % (self.IE_NAME, video_id))
+
+       def _real_extract(self, url):
+               htmlParser = HTMLParser.HTMLParser()
+
+               mobj = re.match(self._VALID_URL, url)
+               if mobj is None:
+                       self._downloader.trouble(u'ERROR: invalid URL: %s' % url)
+                       return
+
+               self.report_webpage(url)
+
+               request = urllib2.Request(url)
+               try:
+                       webpage = urllib2.urlopen(request).read()
+               except (urllib2.URLError, httplib.HTTPException, socket.error), err:
+                       self._downloader.trouble(u'ERROR: unable to download video webpage: %s' % str(err))
+                       return
+
+               self.report_extraction(url)
+
+
+               # Extract video URL
+               mobj = re.search(r"jsclassref='([^']*)'", webpage)
+               if mobj is None:
+                       self._downloader.trouble(u'ERROR: unable to extract video url')
+                       return
+               video_url = 'rtmpe://video.infoq.com/cfx/st/' + urllib2.unquote(mobj.group(1).decode('base64'))
+
+
+               # Extract title
+               mobj = re.search(r'contentTitle = "(.*?)";', webpage)
+               if mobj is None:
+                       self._downloader.trouble(u'ERROR: unable to extract video title')
+                       return
+               video_title = mobj.group(1).decode('utf-8')
+
+               # Extract description
+               video_description = u'No description available.'
+               mobj = re.search(r'<meta name="description" content="(.*)"(?:\s*/)?>', webpage)
+               if mobj is not None:
+                       video_description = mobj.group(1).decode('utf-8')
+
+               video_filename = video_url.split('/')[-1]
+               video_id, extension = video_filename.split('.')
+
+               self._downloader.increment_downloads()
+               info = {
+                       'id': video_id,
+                       'url': video_url,
+                       'uploader': None,
+                       'upload_date': None,
+                       'title': video_title,
+                       'stitle': _simplify_title(video_title),
+                       'ext': extension,
+                       'format': extension, # Extension is always(?) mp4, but seems to be flv
+                       'thumbnail': None,
+                       'description': video_description,
+                       'player_url': None,
+               }
+
+               try:
+                       self._downloader.process_info(info)
+               except UnavailableVideoError, err:
+                       self._downloader.trouble(u'\nERROR: unable to download ' + video_url)
+
+class MixcloudIE(InfoExtractor):
+       """Information extractor for www.mixcloud.com"""
+       _VALID_URL = r'^(?:https?://)?(?:www\.)?mixcloud\.com/([\w\d-]+)/([\w\d-]+)'
+       IE_NAME = u'mixcloud'
+
+       def __init__(self, downloader=None):
+               InfoExtractor.__init__(self, downloader)
+
+       def report_download_json(self, file_id):
+               """Report JSON download."""
+               self._downloader.to_screen(u'[%s] Downloading json' % self.IE_NAME)
+
+       def report_extraction(self, file_id):
+               """Report information extraction."""
+               self._downloader.to_screen(u'[%s] %s: Extracting information' % (self.IE_NAME, file_id))
+
+       def get_urls(self, jsonData, fmt, bitrate='best'):
+               """Get urls from 'audio_formats' section in json"""
+               file_url = None
+               try:
+                       bitrate_list = jsonData[fmt]
+                       if bitrate is None or bitrate == 'best' or bitrate not in bitrate_list:
+                               bitrate = max(bitrate_list) # select highest
+
+                       url_list = jsonData[fmt][bitrate]
+               except TypeError: # we have no bitrate info.
+                       url_list = jsonData[fmt]
+                               
+               return url_list
+
+       def check_urls(self, url_list):
+               """Returns 1st active url from list"""
+               for url in url_list:
+                       try:
+                               urllib2.urlopen(url)
+                               return url
+                       except (urllib2.URLError, httplib.HTTPException, socket.error), err:
+                               url = None
+
+               return None
+
+       def _print_formats(self, formats):
+               print 'Available formats:'
+               for fmt in formats.keys():
+                       for b in formats[fmt]:
+                               try:
+                                       ext = formats[fmt][b][0]
+                                       print '%s\t%s\t[%s]' % (fmt, b, ext.split('.')[-1])
+                               except TypeError: # we have no bitrate info
+                                       ext = formats[fmt][0]
+                                       print '%s\t%s\t[%s]' % (fmt, '??', ext.split('.')[-1])
+                                       break
+
+       def _real_extract(self, url):
+               mobj = re.match(self._VALID_URL, url)
+               if mobj is None:
+                       self._downloader.trouble(u'ERROR: invalid URL: %s' % url)
+                       return
+               # extract uploader & filename from url
+               uploader = mobj.group(1).decode('utf-8')
+               file_id = uploader + "-" + mobj.group(2).decode('utf-8')
+
+               # construct API request
+               file_url = 'http://www.mixcloud.com/api/1/cloudcast/' + '/'.join(url.split('/')[-3:-1]) + '.json'
+               # retrieve .json file with links to files
+               request = urllib2.Request(file_url)
+               try:
+                       self.report_download_json(file_url)
+                       jsonData = urllib2.urlopen(request).read()
+               except (urllib2.URLError, httplib.HTTPException, socket.error), err:
+                       self._downloader.trouble(u'ERROR: Unable to retrieve file: %s' % str(err))
+                       return
+
+               # parse JSON
+               json_data = json.loads(jsonData)
+               player_url = json_data['player_swf_url']
+               formats = dict(json_data['audio_formats'])
+
+               req_format = self._downloader.params.get('format', None)
+               bitrate = None
+
+               if self._downloader.params.get('listformats', None):
+                       self._print_formats(formats)
+                       return
+
+               if req_format is None or req_format == 'best':
+                       for format_param in formats.keys():
+                               url_list = self.get_urls(formats, format_param)
+                               # check urls
+                               file_url = self.check_urls(url_list)
+                               if file_url is not None:
+                                       break # got it!
+               else:
+                       if req_format not in formats.keys():
+                               self._downloader.trouble(u'ERROR: format is not available')
+                               return
+
+                       url_list = self.get_urls(formats, req_format)
+                       file_url = self.check_urls(url_list)
+                       format_param = req_format
+
+               # We have audio
+               self._downloader.increment_downloads()
+               try:
+                       # Process file information
+                       self._downloader.process_info({
+                               'id':           file_id.decode('utf-8'),
+                               'url':          file_url.decode('utf-8'),
+                               'uploader':     uploader.decode('utf-8'),
+                               'upload_date':  u'NA',
+                               'title':        json_data['name'],
+                               'stitle':       _simplify_title(json_data['name']),
+                               'ext':          file_url.split('.')[-1].decode('utf-8'),
+                               'format':       (format_param is None and u'NA' or format_param.decode('utf-8')),
+                               'thumbnail':    json_data['thumbnail_url'],
+                               'description':  json_data['description'],
+                               'player_url':   player_url.decode('utf-8'),
+                       })
+               except UnavailableVideoError, err:
+                       self._downloader.trouble(u'ERROR: unable to download file')
+
+class StanfordOpenClassroomIE(InfoExtractor):
+       """Information extractor for Stanford's Open ClassRoom"""
+
+       _VALID_URL = r'^(?:https?://)?openclassroom.stanford.edu(?P<path>/?|(/MainFolder/(?:HomePage|CoursePage|VideoPage)\.php([?]course=(?P<course>[^&]+)(&video=(?P<video>[^&]+))?(&.*)?)?))$'
+       IE_NAME = u'stanfordoc'
+
+       def report_download_webpage(self, objid):
+               """Report information extraction."""
+               self._downloader.to_screen(u'[%s] %s: Downloading webpage' % (self.IE_NAME, objid))
+
+       def report_extraction(self, video_id):
+               """Report information extraction."""
+               self._downloader.to_screen(u'[%s] %s: Extracting information' % (self.IE_NAME, video_id))
+
+       def _real_extract(self, url):
+               mobj = re.match(self._VALID_URL, url)
+               if mobj is None:
+                       self._downloader.trouble(u'ERROR: invalid URL: %s' % url)
+                       return
+
+               if mobj.group('course') and mobj.group('video'): # A specific video
+                       course = mobj.group('course')
+                       video = mobj.group('video')
+                       info = {
+                               'id': _simplify_title(course + '_' + video),
+                       }
+       
+                       self.report_extraction(info['id'])
+                       baseUrl = 'http://openclassroom.stanford.edu/MainFolder/courses/' + course + '/videos/'
+                       xmlUrl = baseUrl + video + '.xml'
+                       try:
+                               metaXml = urllib2.urlopen(xmlUrl).read()
+                       except (urllib2.URLError, httplib.HTTPException, socket.error), err:
+                               self._downloader.trouble(u'ERROR: unable to download video info XML: %s' % unicode(err))
+                               return
+                       mdoc = xml.etree.ElementTree.fromstring(metaXml)
+                       try:
+                               info['title'] = mdoc.findall('./title')[0].text
+                               info['url'] = baseUrl + mdoc.findall('./videoFile')[0].text
+                       except IndexError:
+                               self._downloader.trouble(u'\nERROR: Invalid metadata XML file')
+                               return
+                       info['stitle'] = _simplify_title(info['title'])
+                       info['ext'] = info['url'].rpartition('.')[2]
+                       info['format'] = info['ext']
+                       self._downloader.increment_downloads()
+                       try:
+                               self._downloader.process_info(info)
+                       except UnavailableVideoError, err:
+                               self._downloader.trouble(u'\nERROR: unable to download video')
+               elif mobj.group('course'): # A course page
+                       unescapeHTML = HTMLParser.HTMLParser().unescape
+
+                       course = mobj.group('course')
+                       info = {
+                               'id': _simplify_title(course),
+                               'type': 'playlist',
+                       }
+
+                       self.report_download_webpage(info['id'])
+                       try:
+                               coursepage = urllib2.urlopen(url).read()
+                       except (urllib2.URLError, httplib.HTTPException, socket.error), err:
+                               self._downloader.trouble(u'ERROR: unable to download course info page: ' + unicode(err))
+                               return
+
+                       m = re.search('<h1>([^<]+)</h1>', coursepage)
+                       if m:
+                               info['title'] = unescapeHTML(m.group(1))
+                       else:
+                               info['title'] = info['id']
+                       info['stitle'] = _simplify_title(info['title'])
+
+                       m = re.search('<description>([^<]+)</description>', coursepage)
+                       if m:
+                               info['description'] = unescapeHTML(m.group(1))
+
+                       links = _orderedSet(re.findall('<a href="(VideoPage.php\?[^"]+)">', coursepage))
+                       info['list'] = [
+                               {
+                                       'type': 'reference',
+                                       'url': 'http://openclassroom.stanford.edu/MainFolder/' + unescapeHTML(vpage),
+                               }
+                                       for vpage in links]
+
+                       for entry in info['list']:
+                               assert entry['type'] == 'reference'
+                               self.extract(entry['url'])
+               else: # Root page
+                       unescapeHTML = HTMLParser.HTMLParser().unescape
+
+                       info = {
+                               'id': 'Stanford OpenClassroom',
+                               'type': 'playlist',
+                       }
+
+                       self.report_download_webpage(info['id'])
+                       rootURL = 'http://openclassroom.stanford.edu/MainFolder/HomePage.php'
+                       try:
+                               rootpage = urllib2.urlopen(rootURL).read()
+                       except (urllib2.URLError, httplib.HTTPException, socket.error), err:
+                               self._downloader.trouble(u'ERROR: unable to download course info page: ' + unicode(err))
+                               return
+
+                       info['title'] = info['id']
+                       info['stitle'] = _simplify_title(info['title'])
+
+                       links = _orderedSet(re.findall('<a href="(CoursePage.php\?[^"]+)">', rootpage))
+                       info['list'] = [
+                               {
+                                       'type': 'reference',
+                                       'url': 'http://openclassroom.stanford.edu/MainFolder/' + unescapeHTML(cpage),
+                               }
+                                       for cpage in links]
+
+                       for entry in info['list']:
+                               assert entry['type'] == 'reference'
+                               self.extract(entry['url'])
+
+