youtube_dl/extractor/youtube.py

   1 # coding: utf-8
   2
   3 import json
   4 import netrc
   5 import re
   6 import socket
   7
   8 from .common import InfoExtractor, SearchInfoExtractor
   9 from ..utils import (
  10     compat_http_client,
  11     compat_parse_qs,
  12     compat_urllib_error,
  13     compat_urllib_parse,
  14     compat_urllib_request,
  15     compat_str,
  16
  17     clean_html,
  18     get_element_by_id,
  19     ExtractorError,
  20     unescapeHTML,
  21     unified_strdate,
  22 )
  23
  24
  25 class YoutubeIE(InfoExtractor):
  26     """Information extractor for youtube.com."""
  27
  28     _VALID_URL = r"""^
  29                      (
  30                          (?:https?://)?                                       # http(s):// (optional)
  31                          (?:youtu\.be/|(?:\w+\.)?youtube(?:-nocookie)?\.com/|
  32                             tube\.majestyc\.net/)                             # the various hostnames, with wildcard subdomains
  33                          (?:.*?\#/)?                                          # handle anchor (#/) redirect urls
  34                          (?:                                                  # the various things that can precede the ID:
  35                              (?:(?:v|embed|e)/)                               # v/ or embed/ or e/
  36                              |(?:                                             # or the v= param in all its forms
  37                                  (?:watch(?:_popup)?(?:\.php)?)?              # preceding watch(_popup|.php) or nothing (like /?v=xxxx)
  38                                  (?:\?|\#!?)                                  # the params delimiter ? or # or #!
  39                                  (?:.*?&)?                                    # any other preceding param (like /?s=tuff&v=xxxx)
  40                                  v=
  41                              )
  42                          )?                                                   # optional -> youtube.com/xxxx is OK
  43                      )?                                                       # all until now is optional -> you can pass the naked ID
  44                      ([0-9A-Za-z_-]+)                                         # here is it! the YouTube video ID
  45                      (?(1).+)?                                                # if we found the ID, everything can follow
  46                      $"""
  47     _LANG_URL = r'https://www.youtube.com/?hl=en&persist_hl=1&gl=US&persist_gl=1&opt_out_ackd=1'
  48     _LOGIN_URL = 'https://accounts.google.com/ServiceLogin'
  49     _AGE_URL = 'http://www.youtube.com/verify_age?next_url=/&gl=US&hl=en'
  50     _NEXT_URL_RE = r'[\?&]next_url=([^&]+)'
  51     _NETRC_MACHINE = 'youtube'
  52     # Listed in order of quality
  53     _available_formats = ['38', '37', '46', '22', '45', '35', '44', '34', '18', '43', '6', '5', '17', '13']
  54     _available_formats_prefer_free = ['38', '46', '37', '45', '22', '44', '35', '43', '34', '18', '6', '5', '17', '13']
  55     _video_extensions = {
  56         '13': '3gp',
  57         '17': 'mp4',
  58         '18': 'mp4',
  59         '22': 'mp4',
  60         '37': 'mp4',
  61         '38': 'mp4',
  62         '43': 'webm',
  63         '44': 'webm',
  64         '45': 'webm',
  65         '46': 'webm',
  66     }
  67     _video_dimensions = {
  68         '5': '240x400',
  69         '6': '???',
  70         '13': '???',
  71         '17': '144x176',
  72         '18': '360x640',
  73         '22': '720x1280',
  74         '34': '360x640',
  75         '35': '480x854',
  76         '37': '1080x1920',
  77         '38': '3072x4096',
  78         '43': '360x640',
  79         '44': '480x854',
  80         '45': '720x1280',
  81         '46': '1080x1920',
  82     }
  83     IE_NAME = u'youtube'
  84
  85     @classmethod
  86     def suitable(cls, url):
  87         """Receives a URL and returns True if suitable for this IE."""
  88         if YoutubePlaylistIE.suitable(url): return False
  89         return re.match(cls._VALID_URL, url, re.VERBOSE) is not None
  90
  91     def report_lang(self):
  92         """Report attempt to set language."""
  93         self.to_screen(u'Setting language')
  94
  95     def report_login(self):
  96         """Report attempt to log in."""
  97         self.to_screen(u'Logging in')
  98
  99     def report_video_webpage_download(self, video_id):
 100         """Report attempt to download video webpage."""
 101         self.to_screen(u'%s: Downloading video webpage' % video_id)
 102
 103     def report_video_info_webpage_download(self, video_id):
 104         """Report attempt to download video info webpage."""
 105         self.to_screen(u'%s: Downloading video info webpage' % video_id)
 106
 107     def report_video_subtitles_download(self, video_id):
 108         """Report attempt to download video info webpage."""
 109         self.to_screen(u'%s: Checking available subtitles' % video_id)
 110
 111     def report_video_subtitles_request(self, video_id, sub_lang, format):
 112         """Report attempt to download video info webpage."""
 113         self.to_screen(u'%s: Downloading video subtitles for %s.%s' % (video_id, sub_lang, format))
 114
 115     def report_video_subtitles_available(self, video_id, sub_lang_list):
 116         """Report available subtitles."""
 117         sub_lang = ",".join(list(sub_lang_list.keys()))
 118         self.to_screen(u'%s: Available subtitles for video: %s' % (video_id, sub_lang))
 119
 120     def report_information_extraction(self, video_id):
 121         """Report attempt to extract video information."""
 122         self.to_screen(u'%s: Extracting video information' % video_id)
 123
 124     def report_unavailable_format(self, video_id, format):
 125         """Report extracted video URL."""
 126         self.to_screen(u'%s: Format %s not available' % (video_id, format))
 127
 128     def report_rtmp_download(self):
 129         """Indicate the download will use the RTMP protocol."""
 130         self.to_screen(u'RTMP download detected')
 131
 132     def _decrypt_signature(self, s):
 133         """Decrypt the key the two subkeys must have a length of 43"""
 134         (a,b) = s.split('.')
 135         if len(a) != 43 or len(b) != 43:
 136             raise ExtractorError(u'Unable to decrypt signature, subkeys lengths %d.%d not supported; retrying might work' % (len(a), len(b)))
 137         if self._downloader.params.get('verbose'):
 138             self.to_screen('encrypted signature length %d.%d' % (len(a), len(b)))
 139         b = ''.join([b[:8],a[0],b[9:18],b[-4],b[19:39], b[18]])[0:40]
 140         a = a[-40:]
 141         s_dec = '.'.join((a,b))[::-1]
 142         return s_dec
 143
 144     def _get_available_subtitles(self, video_id):
 145         self.report_video_subtitles_download(video_id)
 146         request = compat_urllib_request.Request('http://video.google.com/timedtext?hl=en&type=list&v=%s' % video_id)
 147         try:
 148             sub_list = compat_urllib_request.urlopen(request).read().decode('utf-8')
 149         except (compat_urllib_error.URLError, compat_http_client.HTTPException, socket.error) as err:
 150             return (u'unable to download video subtitles: %s' % compat_str(err), None)
 151         sub_lang_list = re.findall(r'name="([^"]*)"[^>]+lang_code="([\w\-]+)"', sub_list)
 152         sub_lang_list = dict((l[1], l[0]) for l in sub_lang_list)
 153         if not sub_lang_list:
 154             return (u'video doesn\'t have subtitles', None)
 155         return sub_lang_list
 156
 157     def _list_available_subtitles(self, video_id):
 158         sub_lang_list = self._get_available_subtitles(video_id)
 159         self.report_video_subtitles_available(video_id, sub_lang_list)
 160
 161     def _request_subtitle(self, sub_lang, sub_name, video_id, format):
 162         """
 163         Return tuple:
 164         (error_message, sub_lang, sub)
 165         """
 166         self.report_video_subtitles_request(video_id, sub_lang, format)
 167         params = compat_urllib_parse.urlencode({
 168             'lang': sub_lang,
 169             'name': sub_name,
 170             'v': video_id,
 171             'fmt': format,
 172         })
 173         url = 'http://www.youtube.com/api/timedtext?' + params
 174         try:
 175             sub = compat_urllib_request.urlopen(url).read().decode('utf-8')
 176         except (compat_urllib_error.URLError, compat_http_client.HTTPException, socket.error) as err:
 177             return (u'unable to download video subtitles: %s' % compat_str(err), None, None)
 178         if not sub:
 179             return (u'Did not fetch video subtitles', None, None)
 180         return (None, sub_lang, sub)
 181
 182     def _request_automatic_caption(self, video_id, webpage):
 183         """We need the webpage for getting the captions url, pass it as an
 184            argument to speed up the process."""
 185         sub_lang = self._downloader.params.get('subtitleslang') or 'en'
 186         sub_format = self._downloader.params.get('subtitlesformat')
 187         self.to_screen(u'%s: Looking for automatic captions' % video_id)
 188         mobj = re.search(r';ytplayer.config = ({.*?});', webpage)
 189         err_msg = u'Couldn\'t find automatic captions for "%s"' % sub_lang
 190         if mobj is None:
 191             return [(err_msg, None, None)]
 192         player_config = json.loads(mobj.group(1))
 193         try:
 194             args = player_config[u'args']
 195             caption_url = args[u'ttsurl']
 196             timestamp = args[u'timestamp']
 197             params = compat_urllib_parse.urlencode({
 198                 'lang': 'en',
 199                 'tlang': sub_lang,
 200                 'fmt': sub_format,
 201                 'ts': timestamp,
 202                 'kind': 'asr',
 203             })
 204             subtitles_url = caption_url + '&' + params
 205             sub = self._download_webpage(subtitles_url, video_id, u'Downloading automatic captions')
 206             return [(None, sub_lang, sub)]
 207         except KeyError:
 208             return [(err_msg, None, None)]
 209
 210     def _extract_subtitle(self, video_id):
 211         """
 212         Return a list with a tuple:
 213         [(error_message, sub_lang, sub)]
 214         """
 215         sub_lang_list = self._get_available_subtitles(video_id)
 216         sub_format = self._downloader.params.get('subtitlesformat')
 217         if  isinstance(sub_lang_list,tuple): #There was some error, it didn't get the available subtitles
 218             return [(sub_lang_list[0], None, None)]
 219         if self._downloader.params.get('subtitleslang', False):
 220             sub_lang = self._downloader.params.get('subtitleslang')
 221         elif 'en' in sub_lang_list:
 222             sub_lang = 'en'
 223         else:
 224             sub_lang = list(sub_lang_list.keys())[0]
 225         if not sub_lang in sub_lang_list:
 226             return [(u'no closed captions found in the specified language "%s"' % sub_lang, None, None)]
 227
 228         subtitle = self._request_subtitle(sub_lang, sub_lang_list[sub_lang].encode('utf-8'), video_id, sub_format)
 229         return [subtitle]
 230
 231     def _extract_all_subtitles(self, video_id):
 232         sub_lang_list = self._get_available_subtitles(video_id)
 233         sub_format = self._downloader.params.get('subtitlesformat')
 234         if  isinstance(sub_lang_list,tuple): #There was some error, it didn't get the available subtitles
 235             return [(sub_lang_list[0], None, None)]
 236         subtitles = []
 237         for sub_lang in sub_lang_list:
 238             subtitle = self._request_subtitle(sub_lang, sub_lang_list[sub_lang].encode('utf-8'), video_id, sub_format)
 239             subtitles.append(subtitle)
 240         return subtitles
 241
 242     def _print_formats(self, formats):
 243         print('Available formats:')
 244         for x in formats:
 245             print('%s\t:\t%s\t[%s]' %(x, self._video_extensions.get(x, 'flv'), self._video_dimensions.get(x, '???')))
 246
 247     def _real_initialize(self):
 248         if self._downloader is None:
 249             return
 250
 251         username = None
 252         password = None
 253         downloader_params = self._downloader.params
 254
 255         # Attempt to use provided username and password or .netrc data
 256         if downloader_params.get('username', None) is not None:
 257             username = downloader_params['username']
 258             password = downloader_params['password']
 259         elif downloader_params.get('usenetrc', False):
 260             try:
 261                 info = netrc.netrc().authenticators(self._NETRC_MACHINE)
 262                 if info is not None:
 263                     username = info[0]
 264                     password = info[2]
 265                 else:
 266                     raise netrc.NetrcParseError('No authenticators for %s' % self._NETRC_MACHINE)
 267             except (IOError, netrc.NetrcParseError) as err:
 268                 self._downloader.report_warning(u'parsing .netrc: %s' % compat_str(err))
 269                 return
 270
 271         # Set language
 272         request = compat_urllib_request.Request(self._LANG_URL)
 273         try:
 274             self.report_lang()
 275             compat_urllib_request.urlopen(request).read()
 276         except (compat_urllib_error.URLError, compat_http_client.HTTPException, socket.error) as err:
 277             self._downloader.report_warning(u'unable to set language: %s' % compat_str(err))
 278             return
 279
 280         # No authentication to be performed
 281         if username is None:
 282             return
 283
 284         request = compat_urllib_request.Request(self._LOGIN_URL)
 285         try:
 286             login_page = compat_urllib_request.urlopen(request).read().decode('utf-8')
 287         except (compat_urllib_error.URLError, compat_http_client.HTTPException, socket.error) as err:
 288             self._downloader.report_warning(u'unable to fetch login page: %s' % compat_str(err))
 289             return
 290
 291         galx = None
 292         dsh = None
 293         match = re.search(re.compile(r'<input.+?name="GALX".+?value="(.+?)"', re.DOTALL), login_page)
 294         if match:
 295           galx = match.group(1)
 296
 297         match = re.search(re.compile(r'<input.+?name="dsh".+?value="(.+?)"', re.DOTALL), login_page)
 298         if match:
 299           dsh = match.group(1)
 300
 301         # Log in
 302         login_form_strs = {
 303                 u'continue': u'https://www.youtube.com/signin?action_handle_signin=true&feature=sign_in_button&hl=en_US&nomobiletemp=1',
 304                 u'Email': username,
 305                 u'GALX': galx,
 306                 u'Passwd': password,
 307                 u'PersistentCookie': u'yes',
 308                 u'_utf8': u'霱',
 309                 u'bgresponse': u'js_disabled',
 310                 u'checkConnection': u'',
 311                 u'checkedDomains': u'youtube',
 312                 u'dnConn': u'',
 313                 u'dsh': dsh,
 314                 u'pstMsg': u'0',
 315                 u'rmShown': u'1',
 316                 u'secTok': u'',
 317                 u'signIn': u'Sign in',
 318                 u'timeStmp': u'',
 319                 u'service': u'youtube',
 320                 u'uilel': u'3',
 321                 u'hl': u'en_US',
 322         }
 323         # Convert to UTF-8 *before* urlencode because Python 2.x's urlencode
 324         # chokes on unicode
 325         login_form = dict((k.encode('utf-8'), v.encode('utf-8')) for k,v in login_form_strs.items())
 326         login_data = compat_urllib_parse.urlencode(login_form).encode('ascii')
 327         request = compat_urllib_request.Request(self._LOGIN_URL, login_data)
 328         try:
 329             self.report_login()
 330             login_results = compat_urllib_request.urlopen(request).read().decode('utf-8')
 331             if re.search(r'(?i)<form[^>]* id="gaia_loginform"', login_results) is not None:
 332                 self._downloader.report_warning(u'unable to log in: bad username or password')
 333                 return
 334         except (compat_urllib_error.URLError, compat_http_client.HTTPException, socket.error) as err:
 335             self._downloader.report_warning(u'unable to log in: %s' % compat_str(err))
 336             return
 337
 338         # Confirm age
 339         age_form = {
 340                 'next_url':     '/',
 341                 'action_confirm':   'Confirm',
 342                 }
 343         request = compat_urllib_request.Request(self._AGE_URL, compat_urllib_parse.urlencode(age_form))
 344         try:
 345             self.report_age_confirmation()
 346             compat_urllib_request.urlopen(request).read().decode('utf-8')
 347         except (compat_urllib_error.URLError, compat_http_client.HTTPException, socket.error) as err:
 348             raise ExtractorError(u'Unable to confirm age: %s' % compat_str(err))
 349
 350     def _extract_id(self, url):
 351         mobj = re.match(self._VALID_URL, url, re.VERBOSE)
 352         if mobj is None:
 353             raise ExtractorError(u'Invalid URL: %s' % url)
 354         video_id = mobj.group(2)
 355         return video_id
 356
 357     def _real_extract(self, url):
 358         # Extract original video URL from URL with redirection, like age verification, using next_url parameter
 359         mobj = re.search(self._NEXT_URL_RE, url)
 360         if mobj:
 361             url = 'https://www.youtube.com/' + compat_urllib_parse.unquote(mobj.group(1)).lstrip('/')
 362         video_id = self._extract_id(url)
 363
 364         # Get video webpage
 365         self.report_video_webpage_download(video_id)
 366         url = 'https://www.youtube.com/watch?v=%s&gl=US&hl=en&has_verified=1' % video_id
 367         request = compat_urllib_request.Request(url)
 368         try:
 369             video_webpage_bytes = compat_urllib_request.urlopen(request).read()
 370         except (compat_urllib_error.URLError, compat_http_client.HTTPException, socket.error) as err:
 371             raise ExtractorError(u'Unable to download video webpage: %s' % compat_str(err))
 372
 373         video_webpage = video_webpage_bytes.decode('utf-8', 'ignore')
 374
 375         # Attempt to extract SWF player URL
 376         mobj = re.search(r'swfConfig.*?"(http:\\/\\/.*?watch.*?-.*?\.swf)"', video_webpage)
 377         if mobj is not None:
 378             player_url = re.sub(r'\\(.)', r'\1', mobj.group(1))
 379         else:
 380             player_url = None
 381
 382         # Get video info
 383         self.report_video_info_webpage_download(video_id)
 384         for el_type in ['&el=embedded', '&el=detailpage', '&el=vevo', '']:
 385             video_info_url = ('https://www.youtube.com/get_video_info?&video_id=%s%s&ps=default&eurl=&gl=US&hl=en'
 386                     % (video_id, el_type))
 387             video_info_webpage = self._download_webpage(video_info_url, video_id,
 388                                     note=False,
 389                                     errnote='unable to download video info webpage')
 390             video_info = compat_parse_qs(video_info_webpage)
 391             if 'token' in video_info:
 392                 break
 393         if 'token' not in video_info:
 394             if 'reason' in video_info:
 395                 raise ExtractorError(u'YouTube said: %s' % video_info['reason'][0])
 396             else:
 397                 raise ExtractorError(u'"token" parameter not in video info for unknown reason')
 398
 399         # Check for "rental" videos
 400         if 'ypc_video_rental_bar_text' in video_info and 'author' not in video_info:
 401             raise ExtractorError(u'"rental" videos not supported')
 402
 403         # Start extracting information
 404         self.report_information_extraction(video_id)
 405
 406         # uploader
 407         if 'author' not in video_info:
 408             raise ExtractorError(u'Unable to extract uploader name')
 409         video_uploader = compat_urllib_parse.unquote_plus(video_info['author'][0])
 410
 411         # uploader_id
 412         video_uploader_id = None
 413         mobj = re.search(r'<link itemprop="url" href="http://www.youtube.com/(?:user|channel)/([^"]+)">', video_webpage)
 414         if mobj is not None:
 415             video_uploader_id = mobj.group(1)
 416         else:
 417             self._downloader.report_warning(u'unable to extract uploader nickname')
 418
 419         # title
 420         if 'title' not in video_info:
 421             raise ExtractorError(u'Unable to extract video title')
 422         video_title = compat_urllib_parse.unquote_plus(video_info['title'][0])
 423
 424         # thumbnail image
 425         if 'thumbnail_url' not in video_info:
 426             self._downloader.report_warning(u'unable to extract video thumbnail')
 427             video_thumbnail = ''
 428         else:   # don't panic if we can't find it
 429             video_thumbnail = compat_urllib_parse.unquote_plus(video_info['thumbnail_url'][0])
 430
 431         # upload date
 432         upload_date = None
 433         mobj = re.search(r'id="eow-date.*?>(.*?)</span>', video_webpage, re.DOTALL)
 434         if mobj is not None:
 435             upload_date = ' '.join(re.sub(r'[/,-]', r' ', mobj.group(1)).split())
 436             upload_date = unified_strdate(upload_date)
 437
 438         # description
 439         video_description = get_element_by_id("eow-description", video_webpage)
 440         if video_description:
 441             video_description = clean_html(video_description)
 442         else:
 443             fd_mobj = re.search(r'<meta name="description" content="([^"]+)"', video_webpage)
 444             if fd_mobj:
 445                 video_description = unescapeHTML(fd_mobj.group(1))
 446             else:
 447                 video_description = u''
 448
 449         # subtitles
 450         video_subtitles = None
 451
 452         if self._downloader.params.get('writesubtitles', False):
 453             video_subtitles = self._extract_subtitle(video_id)
 454             if video_subtitles:
 455                 (sub_error, sub_lang, sub) = video_subtitles[0]
 456                 if sub_error:
 457                     # We try with the automatic captions
 458                     video_subtitles = self._request_automatic_caption(video_id, video_webpage)
 459                     (sub_error_auto, sub_lang, sub) = video_subtitles[0]
 460                     if sub is not None:
 461                         pass
 462                     else:
 463                         # We report the original error
 464                         self._downloader.report_warning(sub_error)
 465
 466         if self._downloader.params.get('allsubtitles', False):
 467             video_subtitles = self._extract_all_subtitles(video_id)
 468             for video_subtitle in video_subtitles:
 469                 (sub_error, sub_lang, sub) = video_subtitle
 470                 if sub_error:
 471                     self._downloader.report_warning(sub_error)
 472
 473         if self._downloader.params.get('listsubtitles', False):
 474             self._list_available_subtitles(video_id)
 475             return
 476
 477         if 'length_seconds' not in video_info:
 478             self._downloader.report_warning(u'unable to extract video duration')
 479             video_duration = ''
 480         else:
 481             video_duration = compat_urllib_parse.unquote_plus(video_info['length_seconds'][0])
 482
 483         # Decide which formats to download
 484         req_format = self._downloader.params.get('format', None)
 485
 486         try:
 487             mobj = re.search(r';ytplayer.config = ({.*?});', video_webpage)
 488             if not mobj:
 489                 raise ValueError('Could not find vevo ID')
 490             info = json.loads(mobj.group(1))
 491             args = info['args']
 492             # Easy way to know if the 's' value is in url_encoded_fmt_stream_map
 493             # this signatures are encrypted
 494             m_s = re.search(r'[&,]s=', args['url_encoded_fmt_stream_map'])
 495             if m_s is not None:
 496                 self.to_screen(u'%s: Encrypted signatures detected.' % video_id)
 497                 video_info['url_encoded_fmt_stream_map'] = [args['url_encoded_fmt_stream_map']]
 498         except ValueError:
 499             pass
 500
 501         if 'conn' in video_info and video_info['conn'][0].startswith('rtmp'):
 502             self.report_rtmp_download()
 503             video_url_list = [(None, video_info['conn'][0])]
 504         elif 'url_encoded_fmt_stream_map' in video_info and len(video_info['url_encoded_fmt_stream_map']) >= 1:
 505             url_map = {}
 506             for url_data_str in video_info['url_encoded_fmt_stream_map'][0].split(','):
 507                 url_data = compat_parse_qs(url_data_str)
 508                 if 'itag' in url_data and 'url' in url_data:
 509                     url = url_data['url'][0]
 510                     if 'sig' in url_data:
 511                         url += '&signature=' + url_data['sig'][0]
 512                     elif 's' in url_data:
 513                         signature = self._decrypt_signature(url_data['s'][0])
 514                         url += '&signature=' + signature
 515                     if 'ratebypass' not in url:
 516                         url += '&ratebypass=yes'
 517                     url_map[url_data['itag'][0]] = url
 518
 519             format_limit = self._downloader.params.get('format_limit', None)
 520             available_formats = self._available_formats_prefer_free if self._downloader.params.get('prefer_free_formats', False) else self._available_formats
 521             if format_limit is not None and format_limit in available_formats:
 522                 format_list = available_formats[available_formats.index(format_limit):]
 523             else:
 524                 format_list = available_formats
 525             existing_formats = [x for x in format_list if x in url_map]
 526             if len(existing_formats) == 0:
 527                 raise ExtractorError(u'no known formats available for video')
 528             if self._downloader.params.get('listformats', None):
 529                 self._print_formats(existing_formats)
 530                 return
 531             if req_format is None or req_format == 'best':
 532                 video_url_list = [(existing_formats[0], url_map[existing_formats[0]])] # Best quality
 533             elif req_format == 'worst':
 534                 video_url_list = [(existing_formats[len(existing_formats)-1], url_map[existing_formats[len(existing_formats)-1]])] # worst quality
 535             elif req_format in ('-1', 'all'):
 536                 video_url_list = [(f, url_map[f]) for f in existing_formats] # All formats
 537             else:
 538                 # Specific formats. We pick the first in a slash-delimeted sequence.
 539                 # For example, if '1/2/3/4' is requested and '2' and '4' are available, we pick '2'.
 540                 req_formats = req_format.split('/')
 541                 video_url_list = None
 542                 for rf in req_formats:
 543                     if rf in url_map:
 544                         video_url_list = [(rf, url_map[rf])]
 545                         break
 546                 if video_url_list is None:
 547                     raise ExtractorError(u'requested format not available')
 548         else:
 549             raise ExtractorError(u'no conn or url_encoded_fmt_stream_map information found in video info')
 550
 551         results = []
 552         for format_param, video_real_url in video_url_list:
 553             # Extension
 554             video_extension = self._video_extensions.get(format_param, 'flv')
 555
 556             video_format = '{0} - {1}'.format(format_param if format_param else video_extension,
 557                                               self._video_dimensions.get(format_param, '???'))
 558
 559             results.append({
 560                 'id':       video_id,
 561                 'url':      video_real_url,
 562                 'uploader': video_uploader,
 563                 'uploader_id': video_uploader_id,
 564                 'upload_date':  upload_date,
 565                 'title':    video_title,
 566                 'ext':      video_extension,
 567                 'format':   video_format,
 568                 'thumbnail':    video_thumbnail,
 569                 'description':  video_description,
 570                 'player_url':   player_url,
 571                 'subtitles':    video_subtitles,
 572                 'duration':     video_duration
 573             })
 574         return results
 575
 576 class YoutubePlaylistIE(InfoExtractor):
 577     """Information Extractor for YouTube playlists."""
 578
 579     _VALID_URL = r"""(?:
 580                         (?:https?://)?
 581                         (?:\w+\.)?
 582                         youtube\.com/
 583                         (?:
 584                            (?:course|view_play_list|my_playlists|artist|playlist|watch)
 585                            \? (?:.*?&)*? (?:p|a|list)=
 586                         |  p/
 587                         )
 588                         ((?:PL|EC|UU)?[0-9A-Za-z-_]{10,})
 589                         .*
 590                      |
 591                         ((?:PL|EC|UU)[0-9A-Za-z-_]{10,})
 592                      )"""
 593     _TEMPLATE_URL = 'https://gdata.youtube.com/feeds/api/playlists/%s?max-results=%i&start-index=%i&v=2&alt=json&safeSearch=none'
 594     _MAX_RESULTS = 50
 595     IE_NAME = u'youtube:playlist'
 596
 597     @classmethod
 598     def suitable(cls, url):
 599         """Receives a URL and returns True if suitable for this IE."""
 600         return re.match(cls._VALID_URL, url, re.VERBOSE) is not None
 601
 602     def _real_extract(self, url):
 603         # Extract playlist id
 604         mobj = re.match(self._VALID_URL, url, re.VERBOSE)
 605         if mobj is None:
 606             raise ExtractorError(u'Invalid URL: %s' % url)
 607
 608         # Download playlist videos from API
 609         playlist_id = mobj.group(1) or mobj.group(2)
 610         page_num = 1
 611         videos = []
 612
 613         while True:
 614             url = self._TEMPLATE_URL % (playlist_id, self._MAX_RESULTS, self._MAX_RESULTS * (page_num - 1) + 1)
 615             page = self._download_webpage(url, playlist_id, u'Downloading page #%s' % page_num)
 616
 617             try:
 618                 response = json.loads(page)
 619             except ValueError as err:
 620                 raise ExtractorError(u'Invalid JSON in API response: ' + compat_str(err))
 621
 622             if 'feed' not in response:
 623                 raise ExtractorError(u'Got a malformed response from YouTube API')
 624             playlist_title = response['feed']['title']['$t']
 625             if 'entry' not in response['feed']:
 626                 # Number of videos is a multiple of self._MAX_RESULTS
 627                 break
 628
 629             for entry in response['feed']['entry']:
 630                 index = entry['yt$position']['$t']
 631                 if 'media$group' in entry and 'media$player' in entry['media$group']:
 632                     videos.append((index, entry['media$group']['media$player']['url']))
 633
 634             if len(response['feed']['entry']) < self._MAX_RESULTS:
 635                 break
 636             page_num += 1
 637
 638         videos = [v[1] for v in sorted(videos)]
 639
 640         url_results = [self.url_result(url, 'Youtube') for url in videos]
 641         return [self.playlist_result(url_results, playlist_id, playlist_title)]
 642
 643
 644 class YoutubeChannelIE(InfoExtractor):
 645     """Information Extractor for YouTube channels."""
 646
 647     _VALID_URL = r"^(?:https?://)?(?:youtu\.be|(?:\w+\.)?youtube(?:-nocookie)?\.com)/channel/([0-9A-Za-z_-]+)"
 648     _TEMPLATE_URL = 'http://www.youtube.com/channel/%s/videos?sort=da&flow=list&view=0&page=%s&gl=US&hl=en'
 649     _MORE_PAGES_INDICATOR = 'yt-uix-load-more'
 650     _MORE_PAGES_URL = 'http://www.youtube.com/channel_ajax?action_load_more_videos=1&flow=list&paging=%s&view=0&sort=da&channel_id=%s'
 651     IE_NAME = u'youtube:channel'
 652
 653     def extract_videos_from_page(self, page):
 654         ids_in_page = []
 655         for mobj in re.finditer(r'href="/watch\?v=([0-9A-Za-z_-]+)&?', page):
 656             if mobj.group(1) not in ids_in_page:
 657                 ids_in_page.append(mobj.group(1))
 658         return ids_in_page
 659
 660     def _real_extract(self, url):
 661         # Extract channel id
 662         mobj = re.match(self._VALID_URL, url)
 663         if mobj is None:
 664             raise ExtractorError(u'Invalid URL: %s' % url)
 665
 666         # Download channel page
 667         channel_id = mobj.group(1)
 668         video_ids = []
 669         pagenum = 1
 670
 671         url = self._TEMPLATE_URL % (channel_id, pagenum)
 672         page = self._download_webpage(url, channel_id,
 673                                       u'Downloading page #%s' % pagenum)
 674
 675         # Extract video identifiers
 676         ids_in_page = self.extract_videos_from_page(page)
 677         video_ids.extend(ids_in_page)
 678
 679         # Download any subsequent channel pages using the json-based channel_ajax query
 680         if self._MORE_PAGES_INDICATOR in page:
 681             while True:
 682                 pagenum = pagenum + 1
 683
 684                 url = self._MORE_PAGES_URL % (pagenum, channel_id)
 685                 page = self._download_webpage(url, channel_id,
 686                                               u'Downloading page #%s' % pagenum)
 687
 688                 page = json.loads(page)
 689
 690                 ids_in_page = self.extract_videos_from_page(page['content_html'])
 691                 video_ids.extend(ids_in_page)
 692
 693                 if self._MORE_PAGES_INDICATOR  not in page['load_more_widget_html']:
 694                     break
 695
 696         self._downloader.to_screen(u'[youtube] Channel %s: Found %i videos' % (channel_id, len(video_ids)))
 697
 698         urls = ['http://www.youtube.com/watch?v=%s' % id for id in video_ids]
 699         url_entries = [self.url_result(url, 'Youtube') for url in urls]
 700         return [self.playlist_result(url_entries, channel_id)]
 701
 702
 703 class YoutubeUserIE(InfoExtractor):
 704     """Information Extractor for YouTube users."""
 705
 706     _VALID_URL = r'(?:(?:(?:https?://)?(?:\w+\.)?youtube\.com/user/)|ytuser:)([A-Za-z0-9_-]+)'
 707     _TEMPLATE_URL = 'http://gdata.youtube.com/feeds/api/users/%s'
 708     _GDATA_PAGE_SIZE = 50
 709     _GDATA_URL = 'http://gdata.youtube.com/feeds/api/users/%s/uploads?max-results=%d&start-index=%d'
 710     _VIDEO_INDICATOR = r'/watch\?v=(.+?)[\<&]'
 711     IE_NAME = u'youtube:user'
 712
 713     def _real_extract(self, url):
 714         # Extract username
 715         mobj = re.match(self._VALID_URL, url)
 716         if mobj is None:
 717             raise ExtractorError(u'Invalid URL: %s' % url)
 718
 719         username = mobj.group(1)
 720
 721         # Download video ids using YouTube Data API. Result size per
 722         # query is limited (currently to 50 videos) so we need to query
 723         # page by page until there are no video ids - it means we got
 724         # all of them.
 725
 726         video_ids = []
 727         pagenum = 0
 728
 729         while True:
 730             start_index = pagenum * self._GDATA_PAGE_SIZE + 1
 731
 732             gdata_url = self._GDATA_URL % (username, self._GDATA_PAGE_SIZE, start_index)
 733             page = self._download_webpage(gdata_url, username,
 734                                           u'Downloading video ids from %d to %d' % (start_index, start_index + self._GDATA_PAGE_SIZE))
 735
 736             # Extract video identifiers
 737             ids_in_page = []
 738
 739             for mobj in re.finditer(self._VIDEO_INDICATOR, page):
 740                 if mobj.group(1) not in ids_in_page:
 741                     ids_in_page.append(mobj.group(1))
 742
 743             video_ids.extend(ids_in_page)
 744
 745             # A little optimization - if current page is not
 746             # "full", ie. does not contain PAGE_SIZE video ids then
 747             # we can assume that this page is the last one - there
 748             # are no more ids on further pages - no need to query
 749             # again.
 750
 751             if len(ids_in_page) < self._GDATA_PAGE_SIZE:
 752                 break
 753
 754             pagenum += 1
 755
 756         urls = ['http://www.youtube.com/watch?v=%s' % video_id for video_id in video_ids]
 757         url_results = [self.url_result(url, 'Youtube') for url in urls]
 758         return [self.playlist_result(url_results, playlist_title = username)]
 759
 760 class YoutubeSearchIE(SearchInfoExtractor):
 761     """Information Extractor for YouTube search queries."""
 762     _API_URL = 'https://gdata.youtube.com/feeds/api/videos?q=%s&start-index=%i&max-results=50&v=2&alt=jsonc'
 763     _MAX_RESULTS = 1000
 764     IE_NAME = u'youtube:search'
 765     _SEARCH_KEY = 'ytsearch'
 766
 767     def report_download_page(self, query, pagenum):
 768         """Report attempt to download search page with given number."""
 769         self._downloader.to_screen(u'[youtube] query "%s": Downloading page %s' % (query, pagenum))
 770
 771     def _get_n_results(self, query, n):
 772         """Get a specified number of results for a query"""
 773
 774         video_ids = []
 775         pagenum = 0
 776         limit = n
 777
 778         while (50 * pagenum) < limit:
 779             self.report_download_page(query, pagenum+1)
 780             result_url = self._API_URL % (compat_urllib_parse.quote_plus(query), (50*pagenum)+1)
 781             request = compat_urllib_request.Request(result_url)
 782             try:
 783                 data = compat_urllib_request.urlopen(request).read().decode('utf-8')
 784             except (compat_urllib_error.URLError, compat_http_client.HTTPException, socket.error) as err:
 785                 raise ExtractorError(u'Unable to download API page: %s' % compat_str(err))
 786             api_response = json.loads(data)['data']
 787
 788             if not 'items' in api_response:
 789                 raise ExtractorError(u'[youtube] No video results')
 790
 791             new_ids = list(video['id'] for video in api_response['items'])
 792             video_ids += new_ids
 793
 794             limit = min(n, api_response['totalItems'])
 795             pagenum += 1
 796
 797         if len(video_ids) > n:
 798             video_ids = video_ids[:n]
 799         videos = [self.url_result('http://www.youtube.com/watch?v=%s' % id, 'Youtube') for id in video_ids]
 800         return self.playlist_result(videos, query)