[youtubedl] / youtube-dl

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Author: Ricardo Garcia Gonzalez
# Author: Danny Colligan
# Author: Benjamin Johnson
# License: Public domain code
import htmlentitydefs
import httplib
import locale
import math
import netrc
import os
import os.path
import re
import socket
import string
import subprocess
import sys
import time
import urllib
import urllib2

# parse_qs was moved from the cgi module to the urlparse module recently.
try:
        from urlparse import parse_qs
except ImportError:
        from cgi import parse_qs

std_headers = {
        'User-Agent': 'Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.6) Gecko/20100627 Firefox/3.6.6',
        'Accept-Charset': 'ISO-8859-1,utf-8;q=0.7,*;q=0.7',
        'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
        'Accept-Language': 'en-us,en;q=0.5',
}

simple_title_chars = string.ascii_letters.decode('ascii') + string.digits.decode('ascii')

def preferredencoding():
        """Get preferred encoding.

        Returns the best encoding scheme for the system, based on
        locale.getpreferredencoding() and some further tweaks.
        """
        def yield_preferredencoding():
                try:
                        pref = locale.getpreferredencoding()
                        u'TEST'.encode(pref)
                except:
                        pref = 'UTF-8'
                while True:
                        yield pref
        return yield_preferredencoding().next()

def htmlentity_transform(matchobj):
        """Transforms an HTML entity to a Unicode character.
        
        This function receives a match object and is intended to be used with
        the re.sub() function.
        """
        entity = matchobj.group(1)

        # Known non-numeric HTML entity
        if entity in htmlentitydefs.name2codepoint:
                return unichr(htmlentitydefs.name2codepoint[entity])

        # Unicode character
        mobj = re.match(ur'(?u)#(x?\d+)', entity)
        if mobj is not None:
                numstr = mobj.group(1)
                if numstr.startswith(u'x'):
                        base = 16
                        numstr = u'0%s' % numstr
                else:
                        base = 10
                return unichr(long(numstr, base))

        # Unknown entity in name, return its literal representation
        return (u'&%s;' % entity)

def sanitize_title(utitle):
        """Sanitizes a video title so it could be used as part of a filename."""
        utitle = re.sub(ur'(?u)&(.+?);', htmlentity_transform, utitle)
        return utitle.replace(unicode(os.sep), u'%')

def sanitize_open(filename, open_mode):
        """Try to open the given filename, and slightly tweak it if this fails.

        Attempts to open the given filename. If this fails, it tries to change
        the filename slightly, step by step, until it's either able to open it
        or it fails and raises a final exception, like the standard open()
        function.

        It returns the tuple (stream, definitive_file_name).
        """
        try:
                if filename == u'-':
                        return (sys.stdout, filename)
                stream = open(filename, open_mode)
                return (stream, filename)
        except (IOError, OSError), err:
                # In case of error, try to remove win32 forbidden chars
                filename = re.sub(ur'[/<>:"\|\?\*]', u'#', filename)

                # An exception here should be caught in the caller
                stream = open(filename, open_mode)
                return (stream, filename)


class DownloadError(Exception):
        """Download Error exception.
        
        This exception may be thrown by FileDownloader objects if they are not
        configured to continue on errors. They will contain the appropriate
        error message.
        """
        pass

class SameFileError(Exception):
        """Same File exception.

        This exception will be thrown by FileDownloader objects if they detect
        multiple files would have to be downloaded to the same file on disk.
        """
        pass

class PostProcessingError(Exception):
        """Post Processing exception.

        This exception may be raised by PostProcessor's .run() method to
        indicate an error in the postprocessing task.
        """
        pass

class UnavailableFormatError(Exception):
        """Unavailable Format exception.

        This exception will be thrown when a video is requested
        in a format that is not available for that video.
        """
        pass

class ContentTooShortError(Exception):
        """Content Too Short exception.

        This exception may be raised by FileDownloader objects when a file they
        download is too small for what the server announced first, indicating
        the connection was probably interrupted.
        """
        # Both in bytes
        downloaded = None
        expected = None

        def __init__(self, downloaded, expected):
                self.downloaded = downloaded
                self.expected = expected

class FileDownloader(object):
        """File Downloader class.

        File downloader objects are the ones responsible of downloading the
        actual video file and writing it to disk if the user has requested
        it, among some other tasks. In most cases there should be one per
        program. As, given a video URL, the downloader doesn't know how to
        extract all the needed information, task that InfoExtractors do, it
        has to pass the URL to one of them.

        For this, file downloader objects have a method that allows
        InfoExtractors to be registered in a given order. When it is passed
        a URL, the file downloader handles it to the first InfoExtractor it
        finds that reports being able to handle it. The InfoExtractor extracts
        all the information about the video or videos the URL refers to, and
        asks the FileDownloader to process the video information, possibly
        downloading the video.

        File downloaders accept a lot of parameters. In order not to saturate
        the object constructor with arguments, it receives a dictionary of
        options instead. These options are available through the params
        attribute for the InfoExtractors to use. The FileDownloader also
        registers itself as the downloader in charge for the InfoExtractors
        that are added to it, so this is a "mutual registration".

        Available options:

        username:       Username for authentication purposes.
        password:       Password for authentication purposes.
        usenetrc:       Use netrc for authentication instead.
        quiet:          Do not print messages to stdout.
        forceurl:       Force printing final URL.
        forcetitle:     Force printing title.
        simulate:       Do not download the video files.
        format:         Video format code.
        format_limit:   Highest quality format to try.
        outtmpl:        Template for output names.
        ignoreerrors:   Do not stop on download errors.
        ratelimit:      Download speed limit, in bytes/sec.
        nooverwrites:   Prevent overwriting files.
        retries:        Number of times to retry for HTTP error 503
        continuedl:     Try to continue downloads if possible.
        noprogress:     Do not print the progress bar.
        """

        params = None
        _ies = []
        _pps = []
        _download_retcode = None
        _num_downloads = None

        def __init__(self, params):
                """Create a FileDownloader object with the given options."""
                self._ies = []
                self._pps = []
                self._download_retcode = 0
                self._num_downloads = 0
                self.params = params
        
        @staticmethod
        def pmkdir(filename):
                """Create directory components in filename. Similar to Unix "mkdir -p"."""
                components = filename.split(os.sep)
                aggregate = [os.sep.join(components[0:x]) for x in xrange(1, len(components))]
                aggregate = ['%s%s' % (x, os.sep) for x in aggregate] # Finish names with separator
                for dir in aggregate:
                        if not os.path.exists(dir):
                                os.mkdir(dir)
        
        @staticmethod
        def format_bytes(bytes):
                if bytes is None:
                        return 'N/A'
                if type(bytes) is str:
                        bytes = float(bytes)
                if bytes == 0.0:
                        exponent = 0
                else:
                        exponent = long(math.log(bytes, 1024.0))
                suffix = 'bkMGTPEZY'[exponent]
                converted = float(bytes) / float(1024**exponent)
                return '%.2f%s' % (converted, suffix)

        @staticmethod
        def calc_percent(byte_counter, data_len):
                if data_len is None:
                        return '---.-%'
                return '%6s' % ('%3.1f%%' % (float(byte_counter) / float(data_len) * 100.0))

        @staticmethod
        def calc_eta(start, now, total, current):
                if total is None:
                        return '--:--'
                dif = now - start
                if current == 0 or dif < 0.001: # One millisecond
                        return '--:--'
                rate = float(current) / dif
                eta = long((float(total) - float(current)) / rate)
                (eta_mins, eta_secs) = divmod(eta, 60)
                if eta_mins > 99:
                        return '--:--'
                return '%02d:%02d' % (eta_mins, eta_secs)

        @staticmethod
        def calc_speed(start, now, bytes):
                dif = now - start
                if bytes == 0 or dif < 0.001: # One millisecond
                        return '%10s' % '---b/s'
                return '%10s' % ('%s/s' % FileDownloader.format_bytes(float(bytes) / dif))

        @staticmethod
        def best_block_size(elapsed_time, bytes):
                new_min = max(bytes / 2.0, 1.0)
                new_max = min(max(bytes * 2.0, 1.0), 4194304) # Do not surpass 4 MB
                if elapsed_time < 0.001:
                        return long(new_max)
                rate = bytes / elapsed_time
                if rate > new_max:
                        return long(new_max)
                if rate < new_min:
                        return long(new_min)
                return long(rate)

        @staticmethod
        def parse_bytes(bytestr):
                """Parse a string indicating a byte quantity into a long integer."""
                matchobj = re.match(r'(?i)^(\d+(?:\.\d+)?)([kMGTPEZY]?)$', bytestr)
                if matchobj is None:
                        return None
                number = float(matchobj.group(1))
                multiplier = 1024.0 ** 'bkmgtpezy'.index(matchobj.group(2).lower())
                return long(round(number * multiplier))

        @staticmethod
        def verify_url(url):
                """Verify a URL is valid and data could be downloaded. Return real data URL."""
                request = urllib2.Request(url, None, std_headers)
                data = urllib2.urlopen(request)
                data.read(1)
                url = data.geturl()
                data.close()
                return url

        def add_info_extractor(self, ie):
                """Add an InfoExtractor object to the end of the list."""
                self._ies.append(ie)
                ie.set_downloader(self)
        
        def add_post_processor(self, pp):
                """Add a PostProcessor object to the end of the chain."""
                self._pps.append(pp)
                pp.set_downloader(self)
        
        def to_stdout(self, message, skip_eol=False, ignore_encoding_errors=False):
                """Print message to stdout if not in quiet mode."""
                try:
                        if not self.params.get('quiet', False):
                                print (u'%s%s' % (message, [u'\n', u''][skip_eol])).encode(preferredencoding()),
                        sys.stdout.flush()
                except (UnicodeEncodeError), err:
                        if not ignore_encoding_errors:
                                raise
        
        def to_stderr(self, message):
                """Print message to stderr."""
                print >>sys.stderr, message.encode(preferredencoding())
        
        def fixed_template(self):
                """Checks if the output template is fixed."""
                return (re.search(ur'(?u)%\(.+?\)s', self.params['outtmpl']) is None)

        def trouble(self, message=None):
                """Determine action to take when a download problem appears.

                Depending on if the downloader has been configured to ignore
                download errors or not, this method may throw an exception or
                not when errors are found, after printing the message.
                """
                if message is not None:
                        self.to_stderr(message)
                if not self.params.get('ignoreerrors', False):
                        raise DownloadError(message)
                self._download_retcode = 1

        def slow_down(self, start_time, byte_counter):
                """Sleep if the download speed is over the rate limit."""
                rate_limit = self.params.get('ratelimit', None)
                if rate_limit is None or byte_counter == 0:
                        return
                now = time.time()
                elapsed = now - start_time
                if elapsed <= 0.0:
                        return
                speed = float(byte_counter) / elapsed
                if speed > rate_limit:
                        time.sleep((byte_counter - rate_limit * (now - start_time)) / rate_limit)

        def report_destination(self, filename):
                """Report destination filename."""
                self.to_stdout(u'[download] Destination: %s' % filename, ignore_encoding_errors=True)
        
        def report_progress(self, percent_str, data_len_str, speed_str, eta_str):
                """Report download progress."""
                if self.params.get('noprogress', False):
                        return
                self.to_stdout(u'\r[download] %s of %s at %s ETA %s' %
                                (percent_str, data_len_str, speed_str, eta_str), skip_eol=True)

        def report_resuming_byte(self, resume_len):
                """Report attemtp to resume at given byte."""
                self.to_stdout(u'[download] Resuming download at byte %s' % resume_len)
        
        def report_retry(self, count, retries):
                """Report retry in case of HTTP error 503"""
                self.to_stdout(u'[download] Got HTTP error 503. Retrying (attempt %d of %d)...' % (count, retries))
        
        def report_file_already_downloaded(self, file_name):
                """Report file has already been fully downloaded."""
                try:
                        self.to_stdout(u'[download] %s has already been downloaded' % file_name)
                except (UnicodeEncodeError), err:
                        self.to_stdout(u'[download] The file has already been downloaded')
        
        def report_unable_to_resume(self):
                """Report it was impossible to resume download."""
                self.to_stdout(u'[download] Unable to resume')
        
        def report_finish(self):
                """Report download finished."""
                if self.params.get('noprogress', False):
                        self.to_stdout(u'[download] Download completed')
                else:
                        self.to_stdout(u'')
        
        def increment_downloads(self):
                """Increment the ordinal that assigns a number to each file."""
                self._num_downloads += 1

        def process_info(self, info_dict):
                """Process a single dictionary returned by an InfoExtractor."""
                # Do nothing else if in simulate mode
                if self.params.get('simulate', False):
                        # Verify URL if it's an HTTP one
                        if info_dict['url'].startswith('http'):
                                try:
                                        self.verify_url(info_dict['url'].encode('utf-8')).decode('utf-8')
                                except (OSError, IOError, urllib2.URLError, httplib.HTTPException, socket.error), err:
                                        raise UnavailableFormatError

                        # Forced printings
                        if self.params.get('forcetitle', False):
                                print info_dict['title'].encode(preferredencoding(), 'xmlcharrefreplace')
                        if self.params.get('forceurl', False):
                                print info_dict['url'].encode(preferredencoding(), 'xmlcharrefreplace')
                        if self.params.get('forcethumbnail', False) and 'thumbnail' in info_dict:
                                print info_dict['thumbnail'].encode(preferredencoding(), 'xmlcharrefreplace')
                        if self.params.get('forcedescription', False) and 'description' in info_dict:
                                print info_dict['description'].encode(preferredencoding(), 'xmlcharrefreplace')

                        return
                        
                try:
                        template_dict = dict(info_dict)
                        template_dict['epoch'] = unicode(long(time.time()))
                        template_dict['ord'] = unicode('%05d' % self._num_downloads)
                        filename = self.params['outtmpl'] % template_dict
                except (ValueError, KeyError), err:
                        self.trouble('ERROR: invalid output template or system charset: %s' % str(err))
                if self.params.get('nooverwrites', False) and os.path.exists(filename):
                        self.to_stderr(u'WARNING: file exists: %s; skipping' % filename)
                        return

                try:
                        self.pmkdir(filename)
                except (OSError, IOError), err:
                        self.trouble('ERROR: unable to create directories: %s' % str(err))
                        return

                try:
                        success = self._do_download(filename, info_dict['url'].encode('utf-8'), info_dict.get('player_url', None))
                except (OSError, IOError), err:
                        raise UnavailableFormatError
                except (urllib2.URLError, httplib.HTTPException, socket.error), err:
                        self.trouble('ERROR: unable to download video data: %s' % str(err))
                        return
                except (ContentTooShortError, ), err:
                        self.trouble('ERROR: content too short (expected %s bytes and served %s)' % (err.expected, err.downloaded))
                        return

                if success:
                        try:
                                self.post_process(filename, info_dict)
                        except (PostProcessingError), err:
                                self.trouble('ERROR: postprocessing: %s' % str(err))
                                return

        def download(self, url_list):
                """Download a given list of URLs."""
                if len(url_list) > 1 and self.fixed_template():
                        raise SameFileError(self.params['outtmpl'])

                for url in url_list:
                        suitable_found = False
                        for ie in self._ies:
                                # Go to next InfoExtractor if not suitable
                                if not ie.suitable(url):
                                        continue

                                # Suitable InfoExtractor found
                                suitable_found = True

                                # Extract information from URL and process it
                                ie.extract(url)

                                # Suitable InfoExtractor had been found; go to next URL
                                break

                        if not suitable_found:
                                self.trouble('ERROR: no suitable InfoExtractor: %s' % url)

                return self._download_retcode

        def post_process(self, filename, ie_info):
                """Run the postprocessing chain on the given file."""
                info = dict(ie_info)
                info['filepath'] = filename
                for pp in self._pps:
                        info = pp.run(info)
                        if info is None:
                                break
        
        def _download_with_rtmpdump(self, filename, url, player_url):
                self.report_destination(filename)

                # Check for rtmpdump first
                try:
                        subprocess.call(['rtmpdump', '-h'], stdout=(file(os.path.devnull, 'w')), stderr=subprocess.STDOUT)
                except (OSError, IOError):
                        self.trouble(u'ERROR: RTMP download detected but "rtmpdump" could not be run')
                        return False

                # Download using rtmpdump. rtmpdump returns exit code 2 when
                # the connection was interrumpted and resuming appears to be
                # possible. This is part of rtmpdump's normal usage, AFAIK.
                basic_args = ['rtmpdump', '-q'] + [[], ['-W', player_url]][player_url is not None] + ['-r', url, '-o', filename]
                retval = subprocess.call(basic_args + [[], ['-e', '-k', '1']][self.params.get('continuedl', False)])
                while retval == 2 or retval == 1:
                        prevsize = os.path.getsize(filename)
                        self.to_stdout(u'\r[rtmpdump] %s bytes' % prevsize, skip_eol=True)
                        time.sleep(5.0) # This seems to be needed
                        retval = subprocess.call(basic_args + ['-e'] + [[], ['-k', '1']][retval == 1])
                        cursize = os.path.getsize(filename)
                        if prevsize == cursize and retval == 1:
                                break
                if retval == 0:
                        self.to_stdout(u'\r[rtmpdump] %s bytes' % os.path.getsize(filename))
                        return True
                else:
                        self.trouble('\nERROR: rtmpdump exited with code %d' % retval)
                        return False

        def _do_download(self, filename, url, player_url):
                # Attempt to download using rtmpdump
                if url.startswith('rtmp'):
                        return self._download_with_rtmpdump(filename, url, player_url)

                stream = None
                open_mode = 'wb'
                basic_request = urllib2.Request(url, None, std_headers)
                request = urllib2.Request(url, None, std_headers)

                # Establish possible resume length
                if os.path.isfile(filename):
                        resume_len = os.path.getsize(filename)
                else:
                        resume_len = 0

                # Request parameters in case of being able to resume
                if self.params.get('continuedl', False) and resume_len != 0:
                        self.report_resuming_byte(resume_len)
                        request.add_header('Range','bytes=%d-' % resume_len)
                        open_mode = 'ab'

                count = 0
                retries = self.params.get('retries', 0)
                while True:
                        # Establish connection
                        try:
                                data = urllib2.urlopen(request)
                                break
                        except (urllib2.HTTPError, ), err:
                                if err.code == 503:
                                        # Retry in case of HTTP error 503
                                        count += 1
                                        if count <= retries:
                                                self.report_retry(count, retries)
                                                continue
                                if err.code != 416: #  416 is 'Requested range not satisfiable'
                                        raise
                                # Unable to resume
                                data = urllib2.urlopen(basic_request)
                                content_length = data.info()['Content-Length']

                                if content_length is not None and long(content_length) == resume_len:
                                        # Because the file had already been fully downloaded
                                        self.report_file_already_downloaded(filename)
                                        return True
                                else:
                                        # Because the server didn't let us
                                        self.report_unable_to_resume()
                                        open_mode = 'wb'

                data_len = data.info().get('Content-length', None)
                data_len_str = self.format_bytes(data_len)
                byte_counter = 0
                block_size = 1024
                start = time.time()
                while True:
                        # Download and write
                        before = time.time()
                        data_block = data.read(block_size)
                        after = time.time()
                        data_block_len = len(data_block)
                        if data_block_len == 0:
                                break
                        byte_counter += data_block_len

                        # Open file just in time
                        if stream is None:
                                try:
                                        (stream, filename) = sanitize_open(filename, open_mode)
                                        self.report_destination(filename)
                                except (OSError, IOError), err:
                                        self.trouble('ERROR: unable to open for writing: %s' % str(err))
                                        return False
                        try:
                                stream.write(data_block)
                        except (IOError, OSError), err:
                                self.trouble('\nERROR: unable to write data: %s' % str(err))
                        block_size = self.best_block_size(after - before, data_block_len)

                        # Progress message
                        percent_str = self.calc_percent(byte_counter, data_len)
                        eta_str = self.calc_eta(start, time.time(), data_len, byte_counter)
                        speed_str = self.calc_speed(start, time.time(), byte_counter)
                        self.report_progress(percent_str, data_len_str, speed_str, eta_str)

                        # Apply rate limit
                        self.slow_down(start, byte_counter)

                self.report_finish()
                if data_len is not None and str(byte_counter) != data_len:
                        raise ContentTooShortError(byte_counter, long(data_len))
                return True

class InfoExtractor(object):
        """Information Extractor class.

        Information extractors are the classes that, given a URL, extract
        information from the video (or videos) the URL refers to. This
        information includes the real video URL, the video title and simplified
        title, author and others. The information is stored in a dictionary
        which is then passed to the FileDownloader. The FileDownloader
        processes this information possibly downloading the video to the file
        system, among other possible outcomes. The dictionaries must include
        the following fields:

        id:             Video identifier.
        url:            Final video URL.
        uploader:       Nickname of the video uploader.
        title:          Literal title.
        stitle:         Simplified title.
        ext:            Video filename extension.
        format:         Video format.
        player_url:     SWF Player URL (may be None).

        The following fields are optional. Their primary purpose is to allow
        youtube-dl to serve as the backend for a video search function, such
        as the one in youtube2mp3.  They are only used when their respective
        forced printing functions are called:

        thumbnail:      Full URL to a video thumbnail image.
        description:    One-line video description.

        Subclasses of this one should re-define the _real_initialize() and
        _real_extract() methods, as well as the suitable() static method.
        Probably, they should also be instantiated and added to the main
        downloader.
        """

        _ready = False
        _downloader = None

        def __init__(self, downloader=None):
                """Constructor. Receives an optional downloader."""
                self._ready = False
                self.set_downloader(downloader)

        @staticmethod
        def suitable(url):
                """Receives a URL and returns True if suitable for this IE."""
                return False

        def initialize(self):
                """Initializes an instance (authentication, etc)."""
                if not self._ready:
                        self._real_initialize()
                        self._ready = True

        def extract(self, url):
                """Extracts URL information and returns it in list of dicts."""
                self.initialize()
                return self._real_extract(url)

        def set_downloader(self, downloader):
                """Sets the downloader for this IE."""
                self._downloader = downloader
        
        def _real_initialize(self):
                """Real initialization process. Redefine in subclasses."""
                pass

        def _real_extract(self, url):
                """Real extraction process. Redefine in subclasses."""
                pass

class YoutubeIE(InfoExtractor):
        """Information extractor for youtube.com."""

        _VALID_URL = r'^((?:http://)?(?:youtu\.be/|(?:\w+\.)?youtube\.com/(?:(?:v/)|(?:(?:watch(?:_popup)?(?:\.php)?)?[\?#](?:.+&)?v=))))?([0-9A-Za-z_-]+)(?(1).+)?$'
        _LANG_URL = r'http://uk.youtube.com/?hl=en&persist_hl=1&gl=US&persist_gl=1&opt_out_ackd=1'
        _LOGIN_URL = 'http://www.youtube.com/signup?next=/&gl=US&hl=en'
        _AGE_URL = 'http://www.youtube.com/verify_age?next_url=/&gl=US&hl=en'
        _NETRC_MACHINE = 'youtube'
        # Listed in order of priority for the -b option
        _available_formats = ['38', '37', '22', '45', '35', '34', '43', '18', '6', '5', '17', '13', None]
        _video_extensions = {
                '13': '3gp',
                '17': 'mp4',
                '18': 'mp4',
                '22': 'mp4',
                '37': 'mp4',
                '38': 'video', # You actually don't know if this will be MOV, AVI or whatever
                '43': 'webm',
                '45': 'webm',
        }

        @staticmethod
        def suitable(url):
                return (re.match(YoutubeIE._VALID_URL, url) is not None)

        def report_lang(self):
                """Report attempt to set language."""
                self._downloader.to_stdout(u'[youtube] Setting language')

        def report_login(self):
                """Report attempt to log in."""
                self._downloader.to_stdout(u'[youtube] Logging in')
        
        def report_age_confirmation(self):
                """Report attempt to confirm age."""
                self._downloader.to_stdout(u'[youtube] Confirming age')
        
        def report_video_webpage_download(self, video_id):
                """Report attempt to download video webpage."""
                self._downloader.to_stdout(u'[youtube] %s: Downloading video webpage' % video_id)
        
        def report_video_info_webpage_download(self, video_id):
                """Report attempt to download video info webpage."""
                self._downloader.to_stdout(u'[youtube] %s: Downloading video info webpage' % video_id)
        
        def report_information_extraction(self, video_id):
                """Report attempt to extract video information."""
                self._downloader.to_stdout(u'[youtube] %s: Extracting video information' % video_id)
        
        def report_unavailable_format(self, video_id, format):
                """Report extracted video URL."""
                self._downloader.to_stdout(u'[youtube] %s: Format %s not available' % (video_id, format))
        
        def report_rtmp_download(self):
                """Indicate the download will use the RTMP protocol."""
                self._downloader.to_stdout(u'[youtube] RTMP download detected')
        
        def _real_initialize(self):
                if self._downloader is None:
                        return

                username = None
                password = None
                downloader_params = self._downloader.params

                # Attempt to use provided username and password or .netrc data
                if downloader_params.get('username', None) is not None:
                        username = downloader_params['username']
                        password = downloader_params['password']
                elif downloader_params.get('usenetrc', False):
                        try:
                                info = netrc.netrc().authenticators(self._NETRC_MACHINE)
                                if info is not None:
                                        username = info[0]
                                        password = info[2]
                                else:
                                        raise netrc.NetrcParseError('No authenticators for %s' % self._NETRC_MACHINE)
                        except (IOError, netrc.NetrcParseError), err:
                                self._downloader.to_stderr(u'WARNING: parsing .netrc: %s' % str(err))
                                return

                # Set language
                request = urllib2.Request(self._LANG_URL, None, std_headers)
                try:
                        self.report_lang()
                        urllib2.urlopen(request).read()
                except (urllib2.URLError, httplib.HTTPException, socket.error), err:
                        self._downloader.to_stderr(u'WARNING: unable to set language: %s' % str(err))
                        return

                # No authentication to be performed
                if username is None:
                        return

                # Log in
                login_form = {
                                'current_form': 'loginForm',
                                'next':         '/',
                                'action_login': 'Log In',
                                'username':     username,
                                'password':     password,
                                }
                request = urllib2.Request(self._LOGIN_URL, urllib.urlencode(login_form), std_headers)
                try:
                        self.report_login()
                        login_results = urllib2.urlopen(request).read()
                        if re.search(r'(?i)<form[^>]* name="loginForm"', login_results) is not None:
                                self._downloader.to_stderr(u'WARNING: unable to log in: bad username or password')
                                return
                except (urllib2.URLError, httplib.HTTPException, socket.error), err:
                        self._downloader.to_stderr(u'WARNING: unable to log in: %s' % str(err))
                        return
        
                # Confirm age
                age_form = {
                                'next_url':             '/',
                                'action_confirm':       'Confirm',
                                }
                request = urllib2.Request(self._AGE_URL, urllib.urlencode(age_form), std_headers)
                try:
                        self.report_age_confirmation()
                        age_results = urllib2.urlopen(request).read()
                except (urllib2.URLError, httplib.HTTPException, socket.error), err:
                        self._downloader.trouble(u'ERROR: unable to confirm age: %s' % str(err))
                        return

        def _real_extract(self, url):
                # Extract video id from URL
                mobj = re.match(self._VALID_URL, url)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: invalid URL: %s' % url)
                        return

                # At this point we have a new video
                if self._downloader is not None:
                        self._downloader.increment_downloads()
                video_id = mobj.group(2)

                # Downloader parameters
                best_quality = False
                all_formats = False
                format_param = None
                quality_index = 0
                if self._downloader is not None:
                        params = self._downloader.params
                        format_param = params.get('format', None)
                        if format_param == '0':
                                format_limit = params.get('format_limit', None)
                                if format_limit is not None:
                                        try:
                                                # Start at a different format if the user has limited the maximum quality
                                                quality_index = self._available_formats.index(format_limit)
                                        except ValueError:
                                                pass
                                format_param = self._available_formats[quality_index]
                                best_quality = True
                        elif format_param == '-1':
                                format_param = self._available_formats[quality_index]
                                all_formats = True

                while True:
                        # Extension
                        video_extension = self._video_extensions.get(format_param, 'flv')

                        # Get video webpage
                        self.report_video_webpage_download(video_id)
                        request = urllib2.Request('http://www.youtube.com/watch?v=%s&gl=US&hl=en' % video_id, None, std_headers)
                        try:
                                video_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

                        # Attempt to extract SWF player URL
                        mobj = re.search(r'swfConfig.*"(http://.*?watch.*?-.*?\.swf)"', video_webpage)
                        if mobj is not None:
                                player_url = mobj.group(1)
                        else:
                                player_url = None

                        # Get video info
                        self.report_video_info_webpage_download(video_id)
                        for el_type in ['&el=embedded', '&el=detailpage', '&el=vevo', '']:
                                video_info_url = ('http://www.youtube.com/get_video_info?&video_id=%s%s&ps=default&eurl=&gl=US&hl=en'
                                                   % (video_id, el_type))
                                request = urllib2.Request(video_info_url, None, std_headers)
                                try:
                                        video_info_webpage = urllib2.urlopen(request).read()
                                        video_info = parse_qs(video_info_webpage)
                                        if 'token' in video_info:
                                                break
                                except (urllib2.URLError, httplib.HTTPException, socket.error), err:
                                        self._downloader.trouble(u'ERROR: unable to download video info webpage: %s' % str(err))
                                        return
                        self.report_information_extraction(video_id)

                        # "t" param
                        if 'token' not in video_info:
                                # Attempt to see if YouTube has issued an error message
                                if 'reason' not in video_info:
                                        self._downloader.trouble(u'ERROR: unable to extract "t" parameter for unknown reason')
                                        stream = open('reportme-ydl-%s.dat' % time.time(), 'wb')
                                        stream.write(video_info_webpage)
                                        stream.close()
                                else:
                                        reason = urllib.unquote_plus(video_info['reason'][0])
                                        self._downloader.trouble(u'ERROR: YouTube said: %s' % reason.decode('utf-8'))
                                return
                        token = urllib.unquote_plus(video_info['token'][0])
                        video_real_url = 'http://www.youtube.com/get_video?video_id=%s&t=%s&eurl=&el=detailpage&ps=default&gl=US&hl=en' % (video_id, token)
                        if format_param is not None:
                                video_real_url = '%s&fmt=%s' % (video_real_url, format_param)

                        # Check possible RTMP download
                        if 'conn' in video_info and video_info['conn'][0].startswith('rtmp'):
                                self.report_rtmp_download()
                                video_real_url = video_info['conn'][0]

                        # uploader
                        if 'author' not in video_info:
                                self._downloader.trouble(u'ERROR: unable to extract uploader nickname')
                                return
                        video_uploader = urllib.unquote_plus(video_info['author'][0])

                        # title
                        if 'title' not in video_info:
                                self._downloader.trouble(u'ERROR: unable to extract video title')
                                return
                        video_title = urllib.unquote_plus(video_info['title'][0])
                        video_title = video_title.decode('utf-8')
                        video_title = sanitize_title(video_title)

                        # simplified title
                        simple_title = re.sub(ur'(?u)([^%s]+)' % simple_title_chars, ur'_', video_title)
                        simple_title = simple_title.strip(ur'_')

                        # thumbnail image
                        if 'thumbnail_url' not in video_info:
                                self._downloader.trouble(u'WARNING: unable to extract video thumbnail')
                                video_thumbnail = ''
                        else:   # don't panic if we can't find it
                                video_thumbnail = urllib.unquote_plus(video_info['thumbnail_url'][0])

                        # description
                        video_description = 'No description available.'
                        if self._downloader.params.get('forcedescription', False):
                                mobj = re.search(r'<meta name="description" content="(.*)"(?:\s*/)?>', video_webpage)
                                if mobj is not None:
                                        video_description = mobj.group(1)

                        try:
                                # Process video information
                                self._downloader.process_info({
                                        'id':           video_id.decode('utf-8'),
                                        'url':          video_real_url.decode('utf-8'),
                                        'uploader':     video_uploader.decode('utf-8'),
                                        'title':        video_title,
                                        'stitle':       simple_title,
                                        'ext':          video_extension.decode('utf-8'),
                                        'format':       (format_param is None and u'NA' or format_param.decode('utf-8')),
                                        'thumbnail':    video_thumbnail.decode('utf-8'),
                                        'description':  video_description.decode('utf-8'),
                                        'player_url':   player_url,
                                })

                                if all_formats:
                                        quality_index += 1
                                        if quality_index == len(self._available_formats):
                                                # None left to get
                                                return
                                        else:
                                                format_param = self._available_formats[quality_index]
                                                continue
                                return

                        except UnavailableFormatError, err:
                                if best_quality or all_formats:
                                        quality_index += 1
                                        if quality_index == len(self._available_formats):
                                                # I don't ever expect this to happen
                                                if not all_formats:
                                                        self._downloader.trouble(u'ERROR: no known formats available for video')
                                                return
                                        else:
                                                self.report_unavailable_format(video_id, format_param)
                                                format_param = self._available_formats[quality_index]
                                                continue
                                else: 
                                        self._downloader.trouble('ERROR: format not available for video')
                                        return


class MetacafeIE(InfoExtractor):
        """Information Extractor for metacafe.com."""

        _VALID_URL = r'(?:http://)?(?:www\.)?metacafe\.com/watch/([^/]+)/([^/]+)/.*'
        _DISCLAIMER = 'http://www.metacafe.com/family_filter/'
        _FILTER_POST = 'http://www.metacafe.com/f/index.php?inputType=filter&controllerGroup=user'
        _youtube_ie = None

        def __init__(self, youtube_ie, downloader=None):
                InfoExtractor.__init__(self, downloader)
                self._youtube_ie = youtube_ie

        @staticmethod
        def suitable(url):
                return (re.match(MetacafeIE._VALID_URL, url) is not None)

        def report_disclaimer(self):
                """Report disclaimer retrieval."""
                self._downloader.to_stdout(u'[metacafe] Retrieving disclaimer')

        def report_age_confirmation(self):
                """Report attempt to confirm age."""
                self._downloader.to_stdout(u'[metacafe] Confirming age')
        
        def report_download_webpage(self, video_id):
                """Report webpage download."""
                self._downloader.to_stdout(u'[metacafe] %s: Downloading webpage' % video_id)
        
        def report_extraction(self, video_id):
                """Report information extraction."""
                self._downloader.to_stdout(u'[metacafe] %s: Extracting information' % video_id)

        def _real_initialize(self):
                # Retrieve disclaimer
                request = urllib2.Request(self._DISCLAIMER, None, std_headers)
                try:
                        self.report_disclaimer()
                        disclaimer = urllib2.urlopen(request).read()
                except (urllib2.URLError, httplib.HTTPException, socket.error), err:
                        self._downloader.trouble(u'ERROR: unable to retrieve disclaimer: %s' % str(err))
                        return

                # Confirm age
                disclaimer_form = {
                        'filters': '0',
                        'submit': "Continue - I'm over 18",
                        }
                request = urllib2.Request(self._FILTER_POST, urllib.urlencode(disclaimer_form), std_headers)
                try:
                        self.report_age_confirmation()
                        disclaimer = urllib2.urlopen(request).read()
                except (urllib2.URLError, httplib.HTTPException, socket.error), err:
                        self._downloader.trouble(u'ERROR: unable to confirm age: %s' % str(err))
                        return
        
        def _real_extract(self, url):
                # Extract id and simplified title from URL
                mobj = re.match(self._VALID_URL, url)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: invalid URL: %s' % url)
                        return

                video_id = mobj.group(1)

                # Check if video comes from YouTube
                mobj2 = re.match(r'^yt-(.*)$', video_id)
                if mobj2 is not None:
                        self._youtube_ie.extract('http://www.youtube.com/watch?v=%s' % mobj2.group(1))
                        return

                # At this point we have a new video
                if self._downloader is not None:
                        self._downloader.increment_downloads()

                simple_title = mobj.group(2).decode('utf-8')
                video_extension = 'flv'

                # Retrieve video webpage to extract further information
                request = urllib2.Request('http://www.metacafe.com/watch/%s/' % video_id)
                try:
                        self.report_download_webpage(video_id)
                        webpage = urllib2.urlopen(request).read()
                except (urllib2.URLError, httplib.HTTPException, socket.error), err:
                        self._downloader.trouble(u'ERROR: unable retrieve video webpage: %s' % str(err))
                        return

                # Extract URL, uploader and title from webpage
                self.report_extraction(video_id)
                mobj = re.search(r'(?m)&mediaURL=([^&]+)', webpage)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: unable to extract media URL')
                        return
                mediaURL = urllib.unquote(mobj.group(1))

                #mobj = re.search(r'(?m)&gdaKey=(.*?)&', webpage)
                #if mobj is None:
                #       self._downloader.trouble(u'ERROR: unable to extract gdaKey')
                #       return
                #gdaKey = mobj.group(1)
                #
                #video_url = '%s?__gda__=%s' % (mediaURL, gdaKey)

                video_url = mediaURL

                mobj = re.search(r'(?im)<title>(.*) - Video</title>', webpage)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: unable to extract title')
                        return
                video_title = mobj.group(1).decode('utf-8')
                video_title = sanitize_title(video_title)

                mobj = re.search(r'(?ms)By:\s*<a .*?>(.+?)<', webpage)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: unable to extract uploader nickname')
                        return
                video_uploader = mobj.group(1)

                try:
                        # Process video information
                        self._downloader.process_info({
                                'id':           video_id.decode('utf-8'),
                                'url':          video_url.decode('utf-8'),
                                'uploader':     video_uploader.decode('utf-8'),
                                'title':        video_title,
                                'stitle':       simple_title,
                                'ext':          video_extension.decode('utf-8'),
                                'format':       u'NA',
                                'player_url':   None,
                        })
                except UnavailableFormatError:
                        self._downloader.trouble(u'ERROR: format not available for video')


class DailymotionIE(InfoExtractor):
        """Information Extractor for Dailymotion"""

        _VALID_URL = r'(?i)(?:https?://)?(?:www\.)?dailymotion\.[a-z]{2,3}/video/([^_/]+)_([^/]+)'

        def __init__(self, downloader=None):
                InfoExtractor.__init__(self, downloader)

        @staticmethod
        def suitable(url):
                return (re.match(DailymotionIE._VALID_URL, url) is not None)

        def report_download_webpage(self, video_id):
                """Report webpage download."""
                self._downloader.to_stdout(u'[dailymotion] %s: Downloading webpage' % video_id)
        
        def report_extraction(self, video_id):
                """Report information extraction."""
                self._downloader.to_stdout(u'[dailymotion] %s: Extracting information' % video_id)

        def _real_initialize(self):
                return

        def _real_extract(self, url):
                # Extract id and simplified title from URL
                mobj = re.match(self._VALID_URL, url)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: invalid URL: %s' % url)
                        return

                # At this point we have a new video
                if self._downloader is not None:
                        self._downloader.increment_downloads()
                video_id = mobj.group(1)

                simple_title = mobj.group(2).decode('utf-8')
                video_extension = 'flv'

                # Retrieve video webpage to extract further information
                request = urllib2.Request(url)
                try:
                        self.report_download_webpage(video_id)
                        webpage = urllib2.urlopen(request).read()
                except (urllib2.URLError, httplib.HTTPException, socket.error), err:
                        self._downloader.trouble(u'ERROR: unable retrieve video webpage: %s' % str(err))
                        return

                # Extract URL, uploader and title from webpage
                self.report_extraction(video_id)
                mobj = re.search(r'(?i)addVariable\(\"video\"\s*,\s*\"([^\"]*)\"\)', webpage)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: unable to extract media URL')
                        return
                mediaURL = urllib.unquote(mobj.group(1))

                # if needed add http://www.dailymotion.com/ if relative URL

                video_url = mediaURL

                # '<meta\s+name="title"\s+content="Dailymotion\s*[:\-]\s*(.*?)"\s*\/\s*>'
                mobj = re.search(r'(?im)<title>Dailymotion\s*[\-:]\s*(.+?)</title>', webpage)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: unable to extract title')
                        return
                video_title = mobj.group(1).decode('utf-8')
                video_title = sanitize_title(video_title)

                mobj = re.search(r'(?im)<div class="dmco_html owner">.*?<a class="name" href="/.+?">(.+?)</a></div>', webpage)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: unable to extract uploader nickname')
                        return
                video_uploader = mobj.group(1)

                try:
                        # Process video information
                        self._downloader.process_info({
                                'id':           video_id.decode('utf-8'),
                                'url':          video_url.decode('utf-8'),
                                'uploader':     video_uploader.decode('utf-8'),
                                'title':        video_title,
                                'stitle':       simple_title,
                                'ext':          video_extension.decode('utf-8'),
                                'format':       u'NA',
                                'player_url':   None,
                        })
                except UnavailableFormatError:
                        self._downloader.trouble(u'ERROR: format not available for video')

class GoogleIE(InfoExtractor):
        """Information extractor for video.google.com."""

        _VALID_URL = r'(?:http://)?video\.google\.(?:com(?:\.au)?|co\.(?:uk|jp|kr|cr)|ca|de|es|fr|it|nl|pl)/videoplay\?docid=([^\&]+).*'

        def __init__(self, downloader=None):
                InfoExtractor.__init__(self, downloader)

        @staticmethod
        def suitable(url):
                return (re.match(GoogleIE._VALID_URL, url) is not None)

        def report_download_webpage(self, video_id):
                """Report webpage download."""
                self._downloader.to_stdout(u'[video.google] %s: Downloading webpage' % video_id)

        def report_extraction(self, video_id):
                """Report information extraction."""
                self._downloader.to_stdout(u'[video.google] %s: Extracting information' % video_id)

        def _real_initialize(self):
                return

        def _real_extract(self, url):
                # Extract id from URL
                mobj = re.match(self._VALID_URL, url)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: Invalid URL: %s' % url)
                        return

                # At this point we have a new video
                if self._downloader is not None:
                        self._downloader.increment_downloads()
                video_id = mobj.group(1)

                video_extension = 'mp4'

                # Retrieve video webpage to extract further information
                request = urllib2.Request('http://video.google.com/videoplay?docid=%s&hl=en&oe=utf-8' % video_id)
                try:
                        self.report_download_webpage(video_id)
                        webpage = urllib2.urlopen(request).read()
                except (urllib2.URLError, httplib.HTTPException, socket.error), err:
                        self._downloader.trouble(u'ERROR: Unable to retrieve video webpage: %s' % str(err))
                        return

                # Extract URL, uploader, and title from webpage
                self.report_extraction(video_id)
                mobj = re.search(r"download_url:'([^']+)'", webpage)
                if mobj is None:
                        video_extension = 'flv'
                        mobj = re.search(r"(?i)videoUrl\\x3d(.+?)\\x26", webpage)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: unable to extract media URL')
                        return
                mediaURL = urllib.unquote(mobj.group(1))
                mediaURL = mediaURL.replace('\\x3d', '\x3d')
                mediaURL = mediaURL.replace('\\x26', '\x26')

                video_url = mediaURL

                mobj = re.search(r'<title>(.*)</title>', webpage)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: unable to extract title')
                        return
                video_title = mobj.group(1).decode('utf-8')
                video_title = sanitize_title(video_title)
                simple_title = re.sub(ur'(?u)([^%s]+)' % simple_title_chars, ur'_', video_title)

                # Extract video description
                mobj = re.search(r'<span id=short-desc-content>([^<]*)</span>', webpage)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: unable to extract video description')
                        return
                video_description = mobj.group(1).decode('utf-8')
                if not video_description:
                        video_description = 'No description available.'

                # Extract video thumbnail
                if self._downloader.params.get('forcethumbnail', False):
                        request = urllib2.Request('http://video.google.com/videosearch?q=%s+site:video.google.com&hl=en' % abs(int(video_id)))
                        try:
                                webpage = urllib2.urlopen(request).read()
                        except (urllib2.URLError, httplib.HTTPException, socket.error), err:
                                self._downloader.trouble(u'ERROR: Unable to retrieve video webpage: %s' % str(err))
                                return
                        mobj = re.search(r'<img class=thumbnail-img (?:.* )?src=(http.*)>', webpage)
                        if mobj is None:
                                self._downloader.trouble(u'ERROR: unable to extract video thumbnail')
                                return
                        video_thumbnail = mobj.group(1)
                else:   # we need something to pass to process_info
                        video_thumbnail = ''


                try:
                        # Process video information
                        self._downloader.process_info({
                                'id':           video_id.decode('utf-8'),
                                'url':          video_url.decode('utf-8'),
                                'uploader':     u'NA',
                                'title':        video_title,
                                'stitle':       simple_title,
                                'ext':          video_extension.decode('utf-8'),
                                'format':       u'NA',
                                'player_url':   None,
                        })
                except UnavailableFormatError:
                        self._downloader.trouble(u'ERROR: format not available for video')


class PhotobucketIE(InfoExtractor):
        """Information extractor for photobucket.com."""

        _VALID_URL = r'(?:http://)?(?:[a-z0-9]+\.)?photobucket\.com/.*[\?\&]current=(.*\.flv)'

        def __init__(self, downloader=None):
                InfoExtractor.__init__(self, downloader)

        @staticmethod
        def suitable(url):
                return (re.match(PhotobucketIE._VALID_URL, url) is not None)

        def report_download_webpage(self, video_id):
                """Report webpage download."""
                self._downloader.to_stdout(u'[photobucket] %s: Downloading webpage' % video_id)

        def report_extraction(self, video_id):
                """Report information extraction."""
                self._downloader.to_stdout(u'[photobucket] %s: Extracting information' % video_id)

        def _real_initialize(self):
                return

        def _real_extract(self, url):
                # Extract id from URL
                mobj = re.match(self._VALID_URL, url)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: Invalid URL: %s' % url)
                        return

                # At this point we have a new video
                if self._downloader is not None:
                        self._downloader.increment_downloads()
                video_id = mobj.group(1)

                video_extension = 'flv'

                # Retrieve video webpage to extract further information
                request = urllib2.Request(url)
                try:
                        self.report_download_webpage(video_id)
                        webpage = urllib2.urlopen(request).read()
                except (urllib2.URLError, httplib.HTTPException, socket.error), err:
                        self._downloader.trouble(u'ERROR: Unable to retrieve video webpage: %s' % str(err))
                        return

                # Extract URL, uploader, and title from webpage
                self.report_extraction(video_id)
                mobj = re.search(r'<link rel="video_src" href=".*\?file=([^"]+)" />', webpage)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: unable to extract media URL')
                        return
                mediaURL = urllib.unquote(mobj.group(1))

                video_url = mediaURL

                mobj = re.search(r'<title>(.*) video by (.*) - Photobucket</title>', webpage)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: unable to extract title')
                        return
                video_title = mobj.group(1).decode('utf-8')
                video_title = sanitize_title(video_title)
                simple_title = re.sub(ur'(?u)([^%s]+)' % simple_title_chars, ur'_', video_title)

                video_uploader = mobj.group(2).decode('utf-8')

                try:
                        # Process video information
                        self._downloader.process_info({
                                'id':           video_id.decode('utf-8'),
                                'url':          video_url.decode('utf-8'),
                                'uploader':     video_uploader,
                                'title':        video_title,
                                'stitle':       simple_title,
                                'ext':          video_extension.decode('utf-8'),
                                'format':       u'NA',
                                'player_url':   None,
                        })
                except UnavailableFormatError:
                        self._downloader.trouble(u'ERROR: format not available for video')


class YahooIE(InfoExtractor):
        """Information extractor for video.yahoo.com."""

        # _VALID_URL matches all Yahoo! Video URLs
        # _VPAGE_URL matches only the extractable '/watch/' URLs
        _VALID_URL = r'(?:http://)?(?:[a-z]+\.)?video\.yahoo\.com/(?:watch|network)/([0-9]+)(?:/|\?v=)([0-9]+)(?:[#\?].*)?'
        _VPAGE_URL = r'(?:http://)?video\.yahoo\.com/watch/([0-9]+)/([0-9]+)(?:[#\?].*)?'

        def __init__(self, downloader=None):
                InfoExtractor.__init__(self, downloader)

        @staticmethod
        def suitable(url):
                return (re.match(YahooIE._VALID_URL, url) is not None)

        def report_download_webpage(self, video_id):
                """Report webpage download."""
                self._downloader.to_stdout(u'[video.yahoo] %s: Downloading webpage' % video_id)

        def report_extraction(self, video_id):
                """Report information extraction."""
                self._downloader.to_stdout(u'[video.yahoo] %s: Extracting information' % video_id)

        def _real_initialize(self):
                return

        def _real_extract(self, url, new_video=True):
                # Extract ID from URL
                mobj = re.match(self._VALID_URL, url)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: Invalid URL: %s' % url)
                        return

                # At this point we have a new video
                if self._downloader is not None and new_video:
                        self._downloader.increment_downloads()
                video_id = mobj.group(2)
                video_extension = 'flv'

                # Rewrite valid but non-extractable URLs as
                # extractable English language /watch/ URLs
                if re.match(self._VPAGE_URL, url) is None:
                        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 retrieve video webpage: %s' % str(err))
                                return

                        mobj = re.search(r'\("id", "([0-9]+)"\);', webpage)
                        if mobj is None:
                                self._downloader.trouble(u'ERROR: Unable to extract id field')
                                return
                        yahoo_id = mobj.group(1)

                        mobj = re.search(r'\("vid", "([0-9]+)"\);', webpage)
                        if mobj is None:
                                self._downloader.trouble(u'ERROR: Unable to extract vid field')
                                return
                        yahoo_vid = mobj.group(1)

                        url = 'http://video.yahoo.com/watch/%s/%s' % (yahoo_vid, yahoo_id)
                        return self._real_extract(url, new_video=False)

                # Retrieve video webpage to extract further information
                request = urllib2.Request(url)
                try:
                        self.report_download_webpage(video_id)
                        webpage = urllib2.urlopen(request).read()
                except (urllib2.URLError, httplib.HTTPException, socket.error), err:
                        self._downloader.trouble(u'ERROR: Unable to retrieve video webpage: %s' % str(err))
                        return

                # Extract uploader and title from webpage
                self.report_extraction(video_id)
                mobj = re.search(r'<meta name="title" content="(.*)" />', webpage)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: unable to extract video title')
                        return
                video_title = mobj.group(1).decode('utf-8')
                simple_title = re.sub(ur'(?u)([^%s]+)' % simple_title_chars, ur'_', video_title)

                mobj = re.search(r'<h2 class="ti-5"><a href="http://video\.yahoo\.com/(people|profile)/[0-9]+" beacon=".*">(.*)</a></h2>', webpage)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: unable to extract video uploader')
                        return
                video_uploader = mobj.group(1).decode('utf-8')

                # Extract video thumbnail
                mobj = re.search(r'<link rel="image_src" href="(.*)" />', webpage)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: unable to extract video thumbnail')
                        return
                video_thumbnail = mobj.group(1).decode('utf-8')

                # Extract video description
                mobj = re.search(r'<meta name="description" content="(.*)" />', webpage)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: unable to extract video description')
                        return
                video_description = mobj.group(1).decode('utf-8')
                if not video_description: video_description = 'No description available.'

                # Extract video height and width
                mobj = re.search(r'<meta name="video_height" content="([0-9]+)" />', webpage)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: unable to extract video height')
                        return
                yv_video_height = mobj.group(1)

                mobj = re.search(r'<meta name="video_width" content="([0-9]+)" />', webpage)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: unable to extract video width')
                        return
                yv_video_width = mobj.group(1)

                # Retrieve video playlist to extract media URL
                # I'm not completely sure what all these options are, but we
                # seem to need most of them, otherwise the server sends a 401.
                yv_lg = 'R0xx6idZnW2zlrKP8xxAIR'  # not sure what this represents
                yv_bitrate = '700'  # according to Wikipedia this is hard-coded
                request = urllib2.Request('http://cosmos.bcst.yahoo.com/up/yep/process/getPlaylistFOP.php?node_id=' + video_id +
                                          '&tech=flash&mode=playlist&lg=' + yv_lg + '&bitrate=' + yv_bitrate + '&vidH=' + yv_video_height +
                                          '&vidW=' + yv_video_width + '&swf=as3&rd=video.yahoo.com&tk=null&adsupported=v1,v2,&eventid=1301797')
                try:
                        self.report_download_webpage(video_id)
                        webpage = urllib2.urlopen(request).read()
                except (urllib2.URLError, httplib.HTTPException, socket.error), err:
                        self._downloader.trouble(u'ERROR: Unable to retrieve video webpage: %s' % str(err))
                        return

                # Extract media URL from playlist XML
                mobj = re.search(r'<STREAM APP="(http://.*)" FULLPATH="/?(/.*\.flv\?[^"]*)"', webpage)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: Unable to extract media URL')
                        return
                video_url = urllib.unquote(mobj.group(1) + mobj.group(2)).decode('utf-8')
                video_url = re.sub(r'(?u)&(.+?);', htmlentity_transform, video_url)

                try:
                        # Process video information
                        self._downloader.process_info({
                                'id':           video_id.decode('utf-8'),
                                'url':          video_url,
                                'uploader':     video_uploader,
                                'title':        video_title,
                                'stitle':       simple_title,
                                'ext':          video_extension.decode('utf-8'),
                                'thumbnail':    video_thumbnail.decode('utf-8'),
                                'description':  video_description,
                                'thumbnail':    video_thumbnail,
                                'description':  video_description,
                                'player_url':   None,
                        })
                except UnavailableFormatError:
                        self._downloader.trouble(u'ERROR: format not available for video')


class GenericIE(InfoExtractor):
        """Generic last-resort information extractor."""

        def __init__(self, downloader=None):
                InfoExtractor.__init__(self, downloader)

        @staticmethod
        def suitable(url):
                return True

        def report_download_webpage(self, video_id):
                """Report webpage download."""
                self._downloader.to_stdout(u'WARNING: Falling back on generic information extractor.')
                self._downloader.to_stdout(u'[generic] %s: Downloading webpage' % video_id)

        def report_extraction(self, video_id):
                """Report information extraction."""
                self._downloader.to_stdout(u'[generic] %s: Extracting information' % video_id)

        def _real_initialize(self):
                return

        def _real_extract(self, url):
                # At this point we have a new video
                if self._downloader is not None:
                        self._downloader.increment_downloads()

                video_id = url.split('/')[-1]
                request = urllib2.Request(url)
                try:
                        self.report_download_webpage(video_id)
                        webpage = urllib2.urlopen(request).read()
                except (urllib2.URLError, httplib.HTTPException, socket.error), err:
                        self._downloader.trouble(u'ERROR: Unable to retrieve video webpage: %s' % str(err))
                        return
                except ValueError, err:
                        # since this is the last-resort InfoExtractor, if
                        # this error is thrown, it'll be thrown here
                        self._downloader.trouble(u'ERROR: Invalid URL: %s' % url)
                        return

                # Start with something easy: JW Player in SWFObject
                mobj = re.search(r'flashvars: [\'"](?:.*&)?file=(http[^\'"&]*)', webpage)
                if mobj is None:
                        # Broaden the search a little bit
                        mobj = re.search(r'[^A-Za-z0-9]?(?:file|source)=(http[^\'"&]*)', webpage)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: Invalid URL: %s' % url)
                        return

                # It's possible that one of the regexes
                # matched, but returned an empty group:
                if mobj.group(1) is None:
                        self._downloader.trouble(u'ERROR: Invalid URL: %s' % url)
                        return

                video_url = urllib.unquote(mobj.group(1))
                video_id  = os.path.basename(video_url)

                # here's a fun little line of code for you:
                video_extension = os.path.splitext(video_id)[1][1:]
                video_id        = os.path.splitext(video_id)[0]

                # it's tempting to parse this further, but you would
                # have to take into account all the variations like
                #   Video Title - Site Name
                #   Site Name | Video Title
                #   Video Title - Tagline | Site Name
                # and so on and so forth; it's just not practical
                mobj = re.search(r'<title>(.*)</title>', webpage)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: unable to extract title')
                        return
                video_title = mobj.group(1).decode('utf-8')
                video_title = sanitize_title(video_title)
                simple_title = re.sub(ur'(?u)([^%s]+)' % simple_title_chars, ur'_', video_title)

                # video uploader is domain name
                mobj = re.match(r'(?:https?://)?([^/]*)/.*', url)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: unable to extract title')
                        return
                video_uploader = mobj.group(1).decode('utf-8')

                try:
                        # Process video information
                        self._downloader.process_info({
                                'id':           video_id.decode('utf-8'),
                                'url':          video_url.decode('utf-8'),
                                'uploader':     video_uploader,
                                'title':        video_title,
                                'stitle':       simple_title,
                                'ext':          video_extension.decode('utf-8'),
                                'format':       u'NA',
                                'player_url':   None,
                        })
                except UnavailableFormatError:
                        self._downloader.trouble(u'ERROR: format not available for video')


class YoutubeSearchIE(InfoExtractor):
        """Information Extractor for YouTube search queries."""
        _VALID_QUERY = r'ytsearch(\d+|all)?:[\s\S]+'
        _TEMPLATE_URL = 'http://www.youtube.com/results?search_query=%s&page=%s&gl=US&hl=en'
        _VIDEO_INDICATOR = r'href="/watch\?v=.+?"'
        _MORE_PAGES_INDICATOR = r'(?m)>\s*Next\s*</a>'
        _youtube_ie = None
        _max_youtube_results = 1000

        def __init__(self, youtube_ie, downloader=None):
                InfoExtractor.__init__(self, downloader)
                self._youtube_ie = youtube_ie
        
        @staticmethod
        def suitable(url):
                return (re.match(YoutubeSearchIE._VALID_QUERY, url) is not None)

        def report_download_page(self, query, pagenum):
                """Report attempt to download playlist page with given number."""
                query = query.decode(preferredencoding())
                self._downloader.to_stdout(u'[youtube] query "%s": Downloading page %s' % (query, pagenum))

        def _real_initialize(self):
                self._youtube_ie.initialize()
        
        def _real_extract(self, query):
                mobj = re.match(self._VALID_QUERY, query)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: invalid search query "%s"' % query)
                        return

                prefix, query = query.split(':')
                prefix = prefix[8:]
                query  = query.encode('utf-8')
                if prefix == '':
                        self._download_n_results(query, 1)
                        return
                elif prefix == 'all':
                        self._download_n_results(query, self._max_youtube_results)
                        return
                else:
                        try:
                                n = long(prefix)
                                if n <= 0:
                                        self._downloader.trouble(u'ERROR: invalid download number %s for query "%s"' % (n, query))
                                        return
                                elif n > self._max_youtube_results:
                                        self._downloader.to_stderr(u'WARNING: ytsearch returns max %i results (you requested %i)'  % (self._max_youtube_results, n))
                                        n = self._max_youtube_results
                                self._download_n_results(query, n)
                                return
                        except ValueError: # parsing prefix as integer fails
                                self._download_n_results(query, 1)
                                return

        def _download_n_results(self, query, n):
                """Downloads a specified number of results for a query"""

                video_ids = []
                already_seen = set()
                pagenum = 1

                while True:
                        self.report_download_page(query, pagenum)
                        result_url = self._TEMPLATE_URL % (urllib.quote_plus(query), pagenum)
                        request = urllib2.Request(result_url, None, std_headers)
                        try:
                                page = urllib2.urlopen(request).read()
                        except (urllib2.URLError, httplib.HTTPException, socket.error), err:
                                self._downloader.trouble(u'ERROR: unable to download webpage: %s' % str(err))
                                return

                        # Extract video identifiers
                        for mobj in re.finditer(self._VIDEO_INDICATOR, page):
                                video_id = page[mobj.span()[0]:mobj.span()[1]].split('=')[2][:-1]
                                if video_id not in already_seen:
                                        video_ids.append(video_id)
                                        already_seen.add(video_id)
                                        if len(video_ids) == n:
                                                # Specified n videos reached
                                                for id in video_ids:
                                                        self._youtube_ie.extract('http://www.youtube.com/watch?v=%s' % id)
                                                return

                        if re.search(self._MORE_PAGES_INDICATOR, page) is None:
                                for id in video_ids:
                                        self._youtube_ie.extract('http://www.youtube.com/watch?v=%s' % id)
                                return

                        pagenum = pagenum + 1

class GoogleSearchIE(InfoExtractor):
        """Information Extractor for Google Video search queries."""
        _VALID_QUERY = r'gvsearch(\d+|all)?:[\s\S]+'
        _TEMPLATE_URL = 'http://video.google.com/videosearch?q=%s+site:video.google.com&start=%s&hl=en'
        _VIDEO_INDICATOR = r'videoplay\?docid=([^\&>]+)\&'
        _MORE_PAGES_INDICATOR = r'<span>Next</span>'
        _google_ie = None
        _max_google_results = 1000

        def __init__(self, google_ie, downloader=None):
                InfoExtractor.__init__(self, downloader)
                self._google_ie = google_ie
        
        @staticmethod
        def suitable(url):
                return (re.match(GoogleSearchIE._VALID_QUERY, url) is not None)

        def report_download_page(self, query, pagenum):
                """Report attempt to download playlist page with given number."""
                query = query.decode(preferredencoding())
                self._downloader.to_stdout(u'[video.google] query "%s": Downloading page %s' % (query, pagenum))

        def _real_initialize(self):
                self._google_ie.initialize()
        
        def _real_extract(self, query):
                mobj = re.match(self._VALID_QUERY, query)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: invalid search query "%s"' % query)
                        return

                prefix, query = query.split(':')
                prefix = prefix[8:]
                query  = query.encode('utf-8')
                if prefix == '':
                        self._download_n_results(query, 1)
                        return
                elif prefix == 'all':
                        self._download_n_results(query, self._max_google_results)
                        return
                else:
                        try:
                                n = long(prefix)
                                if n <= 0:
                                        self._downloader.trouble(u'ERROR: invalid download number %s for query "%s"' % (n, query))
                                        return
                                elif n > self._max_google_results:
                                        self._downloader.to_stderr(u'WARNING: gvsearch returns max %i results (you requested %i)'  % (self._max_google_results, n))
                                        n = self._max_google_results
                                self._download_n_results(query, n)
                                return
                        except ValueError: # parsing prefix as integer fails
                                self._download_n_results(query, 1)
                                return

        def _download_n_results(self, query, n):
                """Downloads a specified number of results for a query"""

                video_ids = []
                already_seen = set()
                pagenum = 1

                while True:
                        self.report_download_page(query, pagenum)
                        result_url = self._TEMPLATE_URL % (urllib.quote_plus(query), pagenum)
                        request = urllib2.Request(result_url, None, std_headers)
                        try:
                                page = urllib2.urlopen(request).read()
                        except (urllib2.URLError, httplib.HTTPException, socket.error), err:
                                self._downloader.trouble(u'ERROR: unable to download webpage: %s' % str(err))
                                return

                        # Extract video identifiers
                        for mobj in re.finditer(self._VIDEO_INDICATOR, page):
                                video_id = mobj.group(1)
                                if video_id not in already_seen:
                                        video_ids.append(video_id)
                                        already_seen.add(video_id)
                                        if len(video_ids) == n:
                                                # Specified n videos reached
                                                for id in video_ids:
                                                        self._google_ie.extract('http://video.google.com/videoplay?docid=%s' % id)
                                                return

                        if re.search(self._MORE_PAGES_INDICATOR, page) is None:
                                for id in video_ids:
                                        self._google_ie.extract('http://video.google.com/videoplay?docid=%s' % id)
                                return

                        pagenum = pagenum + 1

class YahooSearchIE(InfoExtractor):
        """Information Extractor for Yahoo! Video search queries."""
        _VALID_QUERY = r'yvsearch(\d+|all)?:[\s\S]+'
        _TEMPLATE_URL = 'http://video.yahoo.com/search/?p=%s&o=%s'
        _VIDEO_INDICATOR = r'href="http://video\.yahoo\.com/watch/([0-9]+/[0-9]+)"'
        _MORE_PAGES_INDICATOR = r'\s*Next'
        _yahoo_ie = None
        _max_yahoo_results = 1000

        def __init__(self, yahoo_ie, downloader=None):
                InfoExtractor.__init__(self, downloader)
                self._yahoo_ie = yahoo_ie
        
        @staticmethod
        def suitable(url):
                return (re.match(YahooSearchIE._VALID_QUERY, url) is not None)

        def report_download_page(self, query, pagenum):
                """Report attempt to download playlist page with given number."""
                query = query.decode(preferredencoding())
                self._downloader.to_stdout(u'[video.yahoo] query "%s": Downloading page %s' % (query, pagenum))

        def _real_initialize(self):
                self._yahoo_ie.initialize()
        
        def _real_extract(self, query):
                mobj = re.match(self._VALID_QUERY, query)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: invalid search query "%s"' % query)
                        return

                prefix, query = query.split(':')
                prefix = prefix[8:]
                query  = query.encode('utf-8')
                if prefix == '':
                        self._download_n_results(query, 1)
                        return
                elif prefix == 'all':
                        self._download_n_results(query, self._max_yahoo_results)
                        return
                else:
                        try:
                                n = long(prefix)
                                if n <= 0:
                                        self._downloader.trouble(u'ERROR: invalid download number %s for query "%s"' % (n, query))
                                        return
                                elif n > self._max_yahoo_results:
                                        self._downloader.to_stderr(u'WARNING: yvsearch returns max %i results (you requested %i)'  % (self._max_yahoo_results, n))
                                        n = self._max_yahoo_results
                                self._download_n_results(query, n)
                                return
                        except ValueError: # parsing prefix as integer fails
                                self._download_n_results(query, 1)
                                return

        def _download_n_results(self, query, n):
                """Downloads a specified number of results for a query"""

                video_ids = []
                already_seen = set()
                pagenum = 1

                while True:
                        self.report_download_page(query, pagenum)
                        result_url = self._TEMPLATE_URL % (urllib.quote_plus(query), pagenum)
                        request = urllib2.Request(result_url, None, std_headers)
                        try:
                                page = urllib2.urlopen(request).read()
                        except (urllib2.URLError, httplib.HTTPException, socket.error), err:
                                self._downloader.trouble(u'ERROR: unable to download webpage: %s' % str(err))
                                return

                        # Extract video identifiers
                        for mobj in re.finditer(self._VIDEO_INDICATOR, page):
                                video_id = mobj.group(1)
                                if video_id not in already_seen:
                                        video_ids.append(video_id)
                                        already_seen.add(video_id)
                                        if len(video_ids) == n:
                                                # Specified n videos reached
                                                for id in video_ids:
                                                        self._yahoo_ie.extract('http://video.yahoo.com/watch/%s' % id)
                                                return

                        if re.search(self._MORE_PAGES_INDICATOR, page) is None:
                                for id in video_ids:
                                        self._yahoo_ie.extract('http://video.yahoo.com/watch/%s' % id)
                                return

                        pagenum = pagenum + 1

class YoutubePlaylistIE(InfoExtractor):
        """Information Extractor for YouTube playlists."""

        _VALID_URL = r'(?:http://)?(?:\w+\.)?youtube.com/(?:(?:view_play_list|my_playlists)\?.*?p=|user/.*?/user/)([^&]+).*'
        _TEMPLATE_URL = 'http://www.youtube.com/view_play_list?p=%s&page=%s&gl=US&hl=en'
        _VIDEO_INDICATOR = r'/watch\?v=(.+?)&'
        _MORE_PAGES_INDICATOR = r'(?m)>\s*Next\s*</a>'
        _youtube_ie = None

        def __init__(self, youtube_ie, downloader=None):
                InfoExtractor.__init__(self, downloader)
                self._youtube_ie = youtube_ie
        
        @staticmethod
        def suitable(url):
                return (re.match(YoutubePlaylistIE._VALID_URL, url) is not None)

        def report_download_page(self, playlist_id, pagenum):
                """Report attempt to download playlist page with given number."""
                self._downloader.to_stdout(u'[youtube] PL %s: Downloading page #%s' % (playlist_id, pagenum))

        def _real_initialize(self):
                self._youtube_ie.initialize()
        
        def _real_extract(self, url):
                # Extract playlist id
                mobj = re.match(self._VALID_URL, url)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: invalid url: %s' % url)
                        return

                # Download playlist pages
                playlist_id = mobj.group(1)
                video_ids = []
                pagenum = 1

                while True:
                        self.report_download_page(playlist_id, pagenum)
                        request = urllib2.Request(self._TEMPLATE_URL % (playlist_id, pagenum), None, std_headers)
                        try:
                                page = urllib2.urlopen(request).read()
                        except (urllib2.URLError, httplib.HTTPException, socket.error), err:
                                self._downloader.trouble(u'ERROR: unable to download webpage: %s' % str(err))
                                return

                        # Extract video identifiers
                        ids_in_page = []
                        for mobj in re.finditer(self._VIDEO_INDICATOR, page):
                                if mobj.group(1) not in ids_in_page:
                                        ids_in_page.append(mobj.group(1))
                        video_ids.extend(ids_in_page)

                        if re.search(self._MORE_PAGES_INDICATOR, page) is None:
                                break
                        pagenum = pagenum + 1

                for id in video_ids:
                        self._youtube_ie.extract('http://www.youtube.com/watch?v=%s' % id)
                return

class YoutubeUserIE(InfoExtractor):
        """Information Extractor for YouTube users."""

        _VALID_URL = r'(?:http://)?(?:\w+\.)?youtube.com/user/(.*)'
        _TEMPLATE_URL = 'http://gdata.youtube.com/feeds/api/users/%s'
        _VIDEO_INDICATOR = r'http://gdata.youtube.com/feeds/api/videos/(.*)' # XXX Fix this.
        _youtube_ie = None

        def __init__(self, youtube_ie, downloader=None):
                InfoExtractor.__init__(self, downloader)
                self._youtube_ie = youtube_ie
        
        @staticmethod
        def suitable(url):
                return (re.match(YoutubeUserIE._VALID_URL, url) is not None)

        def report_download_page(self, username):
                """Report attempt to download user page."""
                self._downloader.to_stdout(u'[youtube] user %s: Downloading page ' % (username))

        def _real_initialize(self):
                self._youtube_ie.initialize()
        
        def _real_extract(self, url):
                # Extract username
                mobj = re.match(self._VALID_URL, url)
                if mobj is None:
                        self._downloader.trouble(u'ERROR: invalid url: %s' % url)
                        return

                # Download user page
                username = mobj.group(1)
                video_ids = []
                pagenum = 1

                self.report_download_page(username)
                request = urllib2.Request(self._TEMPLATE_URL % (username), None, std_headers)
                try:
                        page = urllib2.urlopen(request).read()
                except (urllib2.URLError, httplib.HTTPException, socket.error), err:
                        self._downloader.trouble(u'ERROR: unable to download webpage: %s' % str(err))
                        return

                # Extract video identifiers
                ids_in_page = []

                for mobj in re.finditer(self._VIDEO_INDICATOR, page):
                        if mobj.group(1) not in ids_in_page:
                                ids_in_page.append(mobj.group(1))
                video_ids.extend(ids_in_page)

                for id in video_ids:
                        self._youtube_ie.extract('http://www.youtube.com/watch?v=%s' % id)
                return

class PostProcessor(object):
        """Post Processor class.

        PostProcessor objects can be added to downloaders with their
        add_post_processor() method. When the downloader has finished a
        successful download, it will take its internal chain of PostProcessors
        and start calling the run() method on each one of them, first with
        an initial argument and then with the returned value of the previous
        PostProcessor.

        The chain will be stopped if one of them ever returns None or the end
        of the chain is reached.

        PostProcessor objects follow a "mutual registration" process similar
        to InfoExtractor objects.
        """

        _downloader = None

        def __init__(self, downloader=None):
                self._downloader = downloader

        def set_downloader(self, downloader):
                """Sets the downloader for this PP."""
                self._downloader = downloader
        
        def run(self, information):
                """Run the PostProcessor.

                The "information" argument is a dictionary like the ones
                composed by InfoExtractors. The only difference is that this
                one has an extra field called "filepath" that points to the
                downloaded file.

                When this method returns None, the postprocessing chain is
                stopped. However, this method may return an information
                dictionary that will be passed to the next postprocessing
                object in the chain. It can be the one it received after
                changing some fields.

                In addition, this method may raise a PostProcessingError
                exception that will be taken into account by the downloader
                it was called from.
                """
                return information # by default, do nothing
        
### MAIN PROGRAM ###
if __name__ == '__main__':
        try:
                # Modules needed only when running the main program
                import getpass
                import optparse

                # Function to update the program file with the latest version from bitbucket.org
                def update_self(downloader, filename):
                        # Note: downloader only used for options
                        if not os.access (filename, os.W_OK):
                                sys.exit('ERROR: no write permissions on %s' % filename)

                        downloader.to_stdout('Updating to latest stable version...')
                        latest_url = 'http://bitbucket.org/rg3/youtube-dl/raw/tip/LATEST_VERSION'
                        latest_version = urllib.urlopen(latest_url).read().strip()
                        prog_url = 'http://bitbucket.org/rg3/youtube-dl/raw/%s/youtube-dl' % latest_version
                        newcontent = urllib.urlopen(prog_url).read()
                        stream = open(filename, 'w')
                        stream.write(newcontent)
                        stream.close()
                        downloader.to_stdout('Updated to version %s' % latest_version)

                # General configuration
                urllib2.install_opener(urllib2.build_opener(urllib2.ProxyHandler()))
                urllib2.install_opener(urllib2.build_opener(urllib2.HTTPCookieProcessor()))
                socket.setdefaulttimeout(300) # 5 minutes should be enough (famous last words)

                # Parse command line
                parser = optparse.OptionParser(
                        usage='Usage: %prog [options] url...',
                        version='2010.06.06',
                        conflict_handler='resolve',
                )

                parser.add_option('-h', '--help',
                                action='help', help='print this help text and exit')
                parser.add_option('-v', '--version',
                                action='version', help='print program version and exit')
                parser.add_option('-U', '--update',
                                action='store_true', dest='update_self', help='update this program to latest stable version')
                parser.add_option('-i', '--ignore-errors',
                                action='store_true', dest='ignoreerrors', help='continue on download errors', default=False)
                parser.add_option('-r', '--rate-limit',
                                dest='ratelimit', metavar='LIMIT', help='download rate limit (e.g. 50k or 44.6m)')
                parser.add_option('-R', '--retries',
                                dest='retries', metavar='RETRIES', help='number of retries (default is 10)', default=10)

                authentication = optparse.OptionGroup(parser, 'Authentication Options')
                authentication.add_option('-u', '--username',
                                dest='username', metavar='USERNAME', help='account username')
                authentication.add_option('-p', '--password',
                                dest='password', metavar='PASSWORD', help='account password')
                authentication.add_option('-n', '--netrc',
                                action='store_true', dest='usenetrc', help='use .netrc authentication data', default=False)
                parser.add_option_group(authentication)

                video_format = optparse.OptionGroup(parser, 'Video Format Options')
                video_format.add_option('-f', '--format',
                                action='store', dest='format', metavar='FORMAT', help='video format code')
                video_format.add_option('-b', '--best-quality',
                                action='store_const', dest='format', help='download the best quality video possible', const='0')
                video_format.add_option('-m', '--mobile-version',
                                action='store_const', dest='format', help='alias for -f 17', const='17')
                video_format.add_option('-d', '--high-def',
                                action='store_const', dest='format', help='alias for -f 22', const='22')
                video_format.add_option('--all-formats',
                                action='store_const', dest='format', help='download all available video formats', const='-1')
                video_format.add_option('--max-quality',
                                action='store', dest='format_limit', metavar='FORMAT', help='highest quality format limit for -b')
                parser.add_option_group(video_format)

                verbosity = optparse.OptionGroup(parser, 'Verbosity / Simulation Options')
                verbosity.add_option('-q', '--quiet',
                                action='store_true', dest='quiet', help='activates quiet mode', default=False)
                verbosity.add_option('-s', '--simulate',
                                action='store_true', dest='simulate', help='do not download video', default=False)
                verbosity.add_option('-g', '--get-url',
                                action='store_true', dest='geturl', help='simulate, quiet but print URL', default=False)
                verbosity.add_option('-e', '--get-title',
                                action='store_true', dest='gettitle', help='simulate, quiet but print title', default=False)
                verbosity.add_option('--get-thumbnail',
                                action='store_true', dest='getthumbnail', help='simulate, quiet but print thumbnail URL', default=False)
                verbosity.add_option('--get-description',
                                action='store_true', dest='getdescription', help='simulate, quiet but print video description', default=False)
                verbosity.add_option('--no-progress',
                                action='store_true', dest='noprogress', help='do not print progress bar', default=False)
                parser.add_option_group(verbosity)

                filesystem = optparse.OptionGroup(parser, 'Filesystem Options')
                filesystem.add_option('-t', '--title',
                                action='store_true', dest='usetitle', help='use title in file name', default=False)
                filesystem.add_option('-l', '--literal',
                                action='store_true', dest='useliteral', help='use literal title in file name', default=False)
                filesystem.add_option('-o', '--output',
                                dest='outtmpl', metavar='TEMPLATE', help='output filename template')
                filesystem.add_option('-a', '--batch-file',
                                dest='batchfile', metavar='FILE', help='file containing URLs to download (\'-\' for stdin)')
                filesystem.add_option('-w', '--no-overwrites',
                                action='store_true', dest='nooverwrites', help='do not overwrite files', default=False)
                filesystem.add_option('-c', '--continue',
                                action='store_true', dest='continue_dl', help='resume partially downloaded files', default=False)
                parser.add_option_group(filesystem)

                (opts, args) = parser.parse_args()

                # Batch file verification
                batchurls = []
                if opts.batchfile is not None:
                        try:
                                if opts.batchfile == '-':
                                        batchfd = sys.stdin
                                else:
                                        batchfd = open(opts.batchfile, 'r')
                                batchurls = batchfd.readlines()
                                batchurls = [x.strip() for x in batchurls]
                                batchurls = [x for x in batchurls if len(x) > 0]
                        except IOError:
                                sys.exit(u'ERROR: batch file could not be read')
                all_urls = batchurls + args

                # Conflicting, missing and erroneous options
                if opts.usenetrc and (opts.username is not None or opts.password is not None):
                        parser.error(u'using .netrc conflicts with giving username/password')
                if opts.password is not None and opts.username is None:
                        parser.error(u'account username missing')
                if opts.outtmpl is not None and (opts.useliteral or opts.usetitle):
                        parser.error(u'using output template conflicts with using title or literal title')
                if opts.usetitle and opts.useliteral:
                        parser.error(u'using title conflicts with using literal title')
                if opts.username is not None and opts.password is None:
                        opts.password = getpass.getpass(u'Type account password and press return:')
                if opts.ratelimit is not None:
                        numeric_limit = FileDownloader.parse_bytes(opts.ratelimit)
                        if numeric_limit is None:
                                parser.error(u'invalid rate limit specified')
                        opts.ratelimit = numeric_limit
                if opts.retries is not None:
                        try:
                                opts.retries = long(opts.retries)
                        except (TypeError, ValueError), err:
                                parser.error(u'invalid retry count specified')

                # Information extractors
                youtube_ie = YoutubeIE()
                metacafe_ie = MetacafeIE(youtube_ie)
                dailymotion_ie = DailymotionIE()
                youtube_pl_ie = YoutubePlaylistIE(youtube_ie)
                youtube_user_ie = YoutubeUserIE(youtube_ie)
                youtube_search_ie = YoutubeSearchIE(youtube_ie)
                google_ie = GoogleIE()
                google_search_ie = GoogleSearchIE(google_ie)
                photobucket_ie = PhotobucketIE()
                yahoo_ie = YahooIE()
                yahoo_search_ie = YahooSearchIE(yahoo_ie)
                generic_ie = GenericIE()

                # File downloader
                fd = FileDownloader({
                        'usenetrc': opts.usenetrc,
                        'username': opts.username,
                        'password': opts.password,
                        'quiet': (opts.quiet or opts.geturl or opts.gettitle or opts.getthumbnail or opts.getdescription),
                        'forceurl': opts.geturl,
                        'forcetitle': opts.gettitle,
                        'forcethumbnail': opts.getthumbnail,
                        'forcedescription': opts.getdescription,
                        'simulate': (opts.simulate or opts.geturl or opts.gettitle or opts.getthumbnail or opts.getdescription),
                        'format': opts.format,
                        'format_limit': opts.format_limit,
                        'outtmpl': ((opts.outtmpl is not None and opts.outtmpl.decode(preferredencoding()))
                                or (opts.format == '-1' and opts.usetitle and u'%(stitle)s-%(id)s-%(format)s.%(ext)s')
                                or (opts.format == '-1' and opts.useliteral and u'%(title)s-%(id)s-%(format)s.%(ext)s')
                                or (opts.format == '-1' and u'%(id)s-%(format)s.%(ext)s')
                                or (opts.usetitle and u'%(stitle)s-%(id)s.%(ext)s')
                                or (opts.useliteral and u'%(title)s-%(id)s.%(ext)s')
                                or u'%(id)s.%(ext)s'),
                        'ignoreerrors': opts.ignoreerrors,
                        'ratelimit': opts.ratelimit,
                        'nooverwrites': opts.nooverwrites,
                        'retries': opts.retries,
                        'continuedl': opts.continue_dl,
                        'noprogress': opts.noprogress,
                        })
                fd.add_info_extractor(youtube_search_ie)
                fd.add_info_extractor(youtube_pl_ie)
                fd.add_info_extractor(youtube_user_ie)
                fd.add_info_extractor(metacafe_ie)
                fd.add_info_extractor(dailymotion_ie)
                fd.add_info_extractor(youtube_ie)
                fd.add_info_extractor(google_ie)
                fd.add_info_extractor(google_search_ie)
                fd.add_info_extractor(photobucket_ie)
                fd.add_info_extractor(yahoo_ie)
                fd.add_info_extractor(yahoo_search_ie)

                # This must come last since it's the
                # fallback if none of the others work
                fd.add_info_extractor(generic_ie)

                # Update version
                if opts.update_self:
                        update_self(fd, sys.argv[0])

                # Maybe do nothing
                if len(all_urls) < 1:
                        if not opts.update_self:
                                parser.error(u'you must provide at least one URL')
                        else:
                                sys.exit()
                retcode = fd.download(all_urls)
                sys.exit(retcode)

        except DownloadError:
                sys.exit(1)
        except SameFileError:
                sys.exit(u'ERROR: fixed output name but more than one file to download')
        except KeyboardInterrupt:
                sys.exit(u'\nERROR: Interrupted by user')