X-Git-Url: https://git.rapsys.eu/youtubedl/blobdiff_plain/45ea099fd5d7f239294d8fff875ac509c45bea40..54fb3c3f9f318073aa3dd0578929316ad45af1a4:/youtube-dl

diff --git a/youtube-dl b/youtube-dl
index 84b3f8e..5afff4e 100755
--- a/youtube-dl
+++ b/youtube-dl
@@ -1,250 +1,1228 @@
 #!/usr/bin/env python
-#
-# Copyright (c) 2006 Ricardo Garcia Gonzalez
-#
-# Permission is hereby granted, free of charge, to any person obtaining a
-# copy of this software and associated documentation files (the "Software"),
-# to deal in the Software without restriction, including without limitation
-# the rights to use, copy, modify, merge, publish, distribute, sublicense,
-# and/or sell copies of the Software, and to permit persons to whom the
-# Software is furnished to do so, subject to the following conditions:
-# 
-# The above copyright notice and this permission notice shall be included
-# in all copies or substantial portions of the Software.
-# 
-# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
-# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
-# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
-# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
-# OTHER DEALINGS IN THE SOFTWARE.
-# 
-# Except as contained in this notice, the name(s) of the above copyright
-# holders shall not be used in advertising or otherwise to promote the
-# sale, use or other dealings in this Software without prior written
-# authorization.
-#
-import sys
-import optparse
+# -*- coding: utf-8 -*-
+# Author: Ricardo Garcia Gonzalez
+# Author: Danny Colligan
+# License: Public domain code
+import htmlentitydefs
 import httplib
-import urllib2
+import locale
+import math
+import netrc
+import os
+import os.path
 import re
+import socket
+import string
+import sys
+import time
+import urllib
+import urllib2
 
-# First off, check Python and refuse to run
-if sys.hexversion < 0x020400f0:
-	sys.exit('Error: Python 2.4 or later needed to run the program')
-
-# Exit status constants
-exit_failure = 1
-exit_success = 0
-
-# Global constants
-const_video_url_str = 'http://www.youtube.com/watch?v=%s'
-const_video_url_re = re.compile(r'http://(?:www\.)?youtube\.com/(?:v/|(?:watch(?:\.php)?)?\?v=)([^&]+).*')
-const_login_url_str = 'http://www.youtube.com/signup?next=/'
-const_login_post_str = 'current_form=loginForm&next=%%2F&username=%s&password=%s&action_login=Log+In'
-const_age_url_str = 'http://www.youtube.com/verify_age?next_url=/watch%%3Fv%%3D%s'
-const_age_post_str = 'next_url=%%2Fwatch%%3Fv%%3D%s&action_confirm=Confirm'
-const_video_url_params_re = re.compile(r'player2\.swf\?([^"]+)"', re.M)
-const_video_url_real_str = 'http://www.youtube.com/get_video?%s'
-const_1k = 1024
-const_block_size = 10 * const_1k
-
-# Print error message, followed by standard advice information, and then exit
-def error_advice_exit(error_text):
-	global exit_failure
-	sys.stderr.write('Error: %s.\n' % error_text)
-	sys.stderr.write('Try again several times. It may be a temporal problem.\n')
-	sys.stderr.write('Other typical problems:\n\n')
-	sys.stderr.write('\tVideo no longer exists.\n')
-	sys.stderr.write('\tVideo requires age confirmation but you did not provide an account.\n')
-	sys.stderr.write('\tYou provided the account data, but it is not valid.\n')
-	sys.stderr.write('\tThe connection was cut suddenly for some reason.\n')
-	sys.stderr.write('\tYouTube changed their system, and the program no longer works.\n')
-	sys.stderr.write('\nTry to confirm you are able to view the video using a web browser.\n')
-	sys.stderr.write('Use the same video URL and account information, if needed, with this program.\n')
-	sys.stderr.write('When using a proxy, make sure http_proxy has http://host:port format.\n')
-	sys.stderr.write('Try again several times and contact me if the problem persists.\n')
-	sys.exit(exit_failure)
-
-# Wrapper to create custom requests with typical headers
-def request_create(url, data=None):
-	retval = urllib2.Request(url)
-	if not data is None:
-		retval.add_data(data)
-	# Try to mimic Firefox, at least a little bit
-	retval.add_header('User-Agent', 'Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.6) Gecko/20060728 Firefox/1.5.0.6')
-	retval.add_header('Accept-Charset', 'ISO-8859-1,utf-8;q=0.7,*;q=0.7')
-	retval.add_header('Accept', 'text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5')
-	retval.add_header('Accept-Language', 'en-us,en;q=0.5')
-	return retval
-
-# Perform a request, process headers and return response
-def perform_request(url, data=None):
-	request = request_create(url, data)
-	response = urllib2.urlopen(request)
-	return response
-
-# Convert bytes to KiB
-def to_k(bytes):
-	global const_1k
-	return bytes / const_1k
-
-# Conditional print
-def cond_print(str):
-	global cmdl_opts
-	if not cmdl_opts.quiet:
-		sys.stdout.write(str)
-		sys.stdout.flush()
-
-# Create the command line options parser and parse command line
-cmdl_usage = 'usage: %prog [options] video_url'
-cmdl_version = '2006.09.25'
-cmdl_parser = optparse.OptionParser(usage=cmdl_usage, version=cmdl_version, conflict_handler='resolve')
-cmdl_parser.add_option('-h', '--help', action='help', help='print this help text and exit')
-cmdl_parser.add_option('-v', '--version', action='version', help='print program version and exit')
-cmdl_parser.add_option('-u', '--username', dest='username', metavar='USERNAME', help='account username')
-cmdl_parser.add_option('-p', '--password', dest='password', metavar='PASSWORD', help='account password')
-cmdl_parser.add_option('-o', '--output', dest='outfile', metavar='FILE', help='output video file name')
-cmdl_parser.add_option('-q', '--quiet', action='store_true', dest='quiet', help='activates quiet mode')
-cmdl_parser.add_option('-s', '--simulate', action='store_true', dest='simulate', help='do not download video')
-(cmdl_opts, cmdl_args) = cmdl_parser.parse_args()
-
-# Get video URL
-if len(cmdl_args) != 1:
-	cmdl_parser.print_help()
-	sys.exit(exit_failure)
-video_url_cmdl = cmdl_args[0]
-
-# Verify video URL format and convert to "standard" format
-video_url_mo = const_video_url_re.match(video_url_cmdl)
-if video_url_mo is None:
-	sys.exit('Error: URL does not seem to be a youtube video URL. If it is, report a bug.')
-video_url_id = video_url_mo.group(1)
-video_url = const_video_url_str % video_url_id
-
-# Check conflicting options
-if not cmdl_opts.outfile is None and cmdl_opts.simulate:
-	sys.stderr.write('Warning: video file name given but will not be used.\n')
-
-# Get output file name 
-if cmdl_opts.outfile is None:
-	video_filename = '%s.flv' % video_url_id
-else:
-	video_filename = cmdl_opts.outfile
-
-# Check name
-if not video_filename.lower().endswith('.flv'):
-	sys.stderr.write('Warning: video file name does not end in .flv\n')
-
-# Verify both or none present
-if ((cmdl_opts.username is None and not cmdl_opts.password is None) or
-    (not cmdl_opts.username is None and cmdl_opts.password is None)):
-	sys.exit('Error: both username and password must be given, or none.')
-
-# Test writable file
-if not cmdl_opts.simulate:
-	try:
-		disk_test = open(video_filename, 'wb')
-		disk_test.close()
+std_headers = {
+	'User-Agent': 'Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.1.2) Gecko/20090729 Firefox/3.5.2',
+	'Accept-Charset': 'ISO-8859-1,utf-8;q=0.7,*;q=0.7',
+	'Accept': 'text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5',
+	'Accept-Language': 'en-us,en;q=0.5',
+}
 
-	except (OSError, IOError):
-		sys.exit('Error: unable to open %s for writing.' % video_filename)
+simple_title_chars = string.ascii_letters.decode('ascii') + string.digits.decode('ascii')
 
-# Install cookie and proxy handlers
-urllib2.install_opener(urllib2.build_opener(urllib2.HTTPCookieProcessor()))
-urllib2.install_opener(urllib2.build_opener(urllib2.ProxyHandler()))
+def preferredencoding():
+	"""Get preferred encoding.
 
-# Login and confirm age if needed
-if not cmdl_opts.username is None:
+	Returns the best encoding scheme for the system, based on
+	locale.getpreferredencoding() and some further tweaks.
+	"""
 	try:
+		pref = locale.getpreferredencoding()
+		# Mac OSX systems have this problem sometimes
+		if pref == '':
+			return 'UTF-8'
+		return pref
+	except:
+		sys.stderr.write('WARNING: problem obtaining preferred encoding. Falling back to UTF-8.\n')
+		return 'UTF-8'
+
+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.
+	outtmpl:	Template for output names.
+	ignoreerrors:	Do not stop on download errors.
+	ratelimit:	Download speed limit, in bytes/sec.
+	nooverwrites:	Prevent overwriting files.
+	continuedl:	Try to continue downloads if possible.
+	"""
+
+	params = None
+	_ies = []
+	_pps = []
+	_download_retcode = None
+
+	def __init__(self, params):
+		"""Create a FileDownloader object with the given options."""
+		self._ies = []
+		self._pps = []
+		self._download_retcode = 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):
+		"""Print message to stdout if not in quiet mode."""
+		if not self.params.get('quiet', False):
+			print (u'%s%s' % (message, [u'\n', u''][skip_eol])).encode(preferredencoding()),
+			sys.stdout.flush()
+	
+	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)
+	
+	def report_progress(self, percent_str, data_len_str, speed_str, eta_str):
+		"""Report download progress."""
+		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_file_already_downloaded(self, file_name):
+		"""Report file has already been fully downloaded."""
+		self.to_stdout(u'[download] %s has already been downloaded' % file_name)
+	
+	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."""
+		self.to_stdout(u'')
+
+	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):
+			try:
+				info_dict['url'] = self.verify_url(info_dict['url'])
+			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())
+			if self.params.get('forceurl', False):
+				print info_dict['url'].encode(preferredencoding())
+
+			return
+			
+		try:
+			template_dict = dict(info_dict)
+			template_dict['epoch'] = unicode(long(time.time()))
+			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['nooverwrites'] 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'])
+		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 _do_download(self, filename, url):
+		stream = None
+		open_mode = 'ab'
+
+		basic_request = urllib2.Request(url, None, std_headers)
+		request = urllib2.Request(url, None, std_headers)
+
+		# Attempt to resume download with "continuedl" option
+		if os.path.isfile(filename):
+			resume_len = os.path.getsize(filename)
+		else:
+			resume_len = 0
+		if self.params['continuedl'] and resume_len != 0:
+			self.report_resuming_byte(resume_len)
+			request.add_header('Range','bytes=%d-' % resume_len)
+
+		# Establish connection
+		try:
+			data = urllib2.urlopen(request)
+		except (urllib2.HTTPError, ), err:
+			if err.code != 416: #  416 is 'Requested range not satisfiable'
+				raise
+			data = urllib2.urlopen(basic_request)
+			content_length = data.info()['Content-Length']
+			if content_length is not None and long(content_length) == resume_len:
+				self.report_file_already_downloaded(filename)
+				return True
+			else:
+				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 = 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
+			stream.write(data_block)
+			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.
+
+	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://)?(?:\w+\.)?youtube\.com/(?:(?:v/)|(?:(?:watch(?:\.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'
+	_available_formats = ['22', '35', '18', '5', '17', '13', None] # listed in order of priority for -b flag
+	_video_extensions = {
+		'13': '3gp',
+		'17': 'mp4',
+		'18': 'mp4',
+		'22': 'mp4',
+	}
+
+	@staticmethod
+	def suitable(url):
+		return (re.match(YoutubeIE._VALID_URL, url) is not None)
+
+	@staticmethod
+	def htmlentity_transform(matchobj):
+		"""Transforms an HTML entity to a Unicode character."""
+		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 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_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 _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
-		cond_print('Logging in... ')
-		perform_request(const_login_url_str, const_login_post_str % (cmdl_opts.username, cmdl_opts.password)).read()
-		cond_print('done.\n')
+		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
 
-	except (urllib2.URLError, ValueError, httplib.HTTPException, TypeError):
-		cond_print('failed.\n')
-		error_advice_exit('unable to login')
+	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
+		video_id = mobj.group(2)
 
-	except KeyboardInterrupt:
-		sys.exit('\n')
+		# Downloader parameters
+		best_quality = 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_param = self._available_formats[quality_index]
+				best_quality = True
 
-	try:
-		# Get age confirmation cookie
-		cond_print('Confirming age... ')
-		perform_request(const_age_url_str % video_url_id, const_age_post_str % video_url_id).read()
-		cond_print('done.\n')
+		while True:
+			# Extension
+			video_extension = self._video_extensions.get(format_param, 'flv')
 
-	except (urllib2.URLError, ValueError, httplib.HTTPException, TypeError):
-		cond_print('failed.\n')
-		error_advice_exit('unable to confirm age')
+			# Get video info
+			video_info_url = 'http://www.youtube.com/get_video_info?&video_id=%s&el=detailpage&ps=default&eurl=&gl=US&hl=en' % video_id
+			request = urllib2.Request(video_info_url, None, std_headers)
+			try:
+				self.report_video_info_webpage_download(video_id)
+				video_info_webpage = urllib2.urlopen(request).read()
+			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)
 
-	except KeyboardInterrupt:
-		sys.exit('\n')
+			# "t" param
+			mobj = re.search(r'(?m)&token=([^&]+)(?:&|$)', video_info_webpage)
+			if mobj is None:
+				# Attempt to see if YouTube has issued an error message
+				mobj = re.search(r'(?m)&reason=([^&]+)(?:&|$)', video_info_webpage)
+				if mobj is None:
+					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(mobj.group(1))
+					self._downloader.trouble(u'ERROR: YouTube said: %s' % reason.decode('utf-8'))
+				return
+			token = urllib.unquote(mobj.group(1))
+			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)
+
+			# uploader
+			mobj = re.search(r'(?m)&author=([^&]+)(?:&|$)', video_info_webpage)
+			if mobj is None:
+				self._downloader.trouble(u'ERROR: unable to extract uploader nickname')
+				return
+			video_uploader = urllib.unquote(mobj.group(1))
+
+			# title
+			mobj = re.search(r'(?m)&title=([^&]+)(?:&|$)', video_info_webpage)
+			if mobj is None:
+				self._downloader.trouble(u'ERROR: unable to extract video title')
+				return
+			video_title = urllib.unquote(mobj.group(1))
+			video_title = video_title.decode('utf-8')
+			video_title = re.sub(ur'(?u)&(.+?);', self.htmlentity_transform, video_title)
+			video_title = video_title.replace(os.sep, u'%')
+
+			# simplified title
+			simple_title = re.sub(ur'(?u)([^%s]+)' % simple_title_chars, ur'_', video_title)
+			simple_title = simple_title.strip(ur'_')
+
+			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'),
+				})
+
+				return
 
-# Retrieve video webpage
-try:
-	cond_print('Retrieving video webpage... ')
-	video_webpage = perform_request(video_url).read()
-	cond_print('done.\n')
+			except UnavailableFormatError, err:
+				if best_quality:
+					if quality_index == len(self._available_formats) - 1:
+						# I don't ever expect this to happen
+						self._downloader.trouble(u'ERROR: no known formats available for video')
+						return
+					else:
+						self.report_unavailable_format(video_id, format_param)
+						quality_index += 1
+						format_param = self._available_formats[quality_index]
+						continue
+				else: 
+					self._downloader.trouble('ERROR: format not available for video')
+					return
 
-except (urllib2.URLError, ValueError, httplib.HTTPException, TypeError):
-	cond_print('failed.\n')
-	error_advice_exit('unable to download video webpage')
 
-except KeyboardInterrupt:
-	sys.exit('\n')
+class MetacafeIE(InfoExtractor):
+	"""Information Extractor for metacafe.com."""
 
-# Extract needed video URL parameters
-try:
-	cond_print('Extracting video URL parameters... ')
-	video_url_params_mo = const_video_url_params_re.search(video_webpage)
+	_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)
 	
-	if video_url_params_mo is None:
-		cond_print('failed.\n')
-		error_advice_exit('unable to extract URL parameters')
+	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
+
+		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')
+
+		mobj = re.search(r'(?ms)<li id="ChnlUsr">.*?Submitter:.*?<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'),
+			})
+		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
 	
-	video_url_params = video_url_params_mo.group(1)
-	video_url_real = const_video_url_real_str % video_url_params
-	cond_print('done.\n')
+	@staticmethod
+	def suitable(url):
+		return (re.match(YoutubeSearchIE._VALID_QUERY, url) is not None)
 
-except KeyboardInterrupt:
-	sys.exit('\n')
+	def report_download_page(self, query, pagenum):
+		"""Report attempt to download playlist page with given number."""
+		self._downloader.to_stdout(u'[youtube] query "%s": Downloading page %s' % (query, pagenum))
 
-# Retrieve video data
-try:
-	video_data = perform_request(video_url_real)
-	cond_print('Video data found at %s\n' % video_data.geturl())
+	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
 
-	# Abort here if in simulate mode
-	if cmdl_opts.simulate:
-		sys.exit()
+		prefix, query = query.split(':')
+		prefix = prefix[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
 
-	cond_print('Retrieving video data... ')
-	video_file = open(video_filename, 'wb')
+	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 YoutubePlaylistIE(InfoExtractor):
+	"""Information Extractor for YouTube playlists."""
+
+	_VALID_URL = r'(?:http://)?(?:\w+\.)?youtube.com/(?:view_play_list|my_playlists)\?.*?p=([^&]+).*'
+	_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'/view_play_list?p=%s&page=%s'
+	_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 (self._MORE_PAGES_INDICATOR % (playlist_id.upper(), pagenum + 1)) not in page:
+				break
+			pagenum = pagenum + 1
+
+		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:
-		video_len_str = '%sk' % to_k(int(video_data.info()['Content-length']))
-	except KeyError:
-		video_len_str = '(unknown)'
-
-	byte_counter = 0
-	video_block = video_data.read(const_block_size)
-	while len(video_block) != 0:
-		byte_counter += len(video_block)
-		video_file.write(video_block)
-		cond_print('\rRetrieving video data... %sk of %s ' % (to_k(byte_counter), video_len_str))
-		video_block = video_data.read(const_block_size)
-
-	video_file.close()
-	cond_print('done.\n')
-	cond_print('Video data saved to %s\n' % video_filename)
-	sys.exit()
-
-except (urllib2.URLError, ValueError, httplib.HTTPException, TypeError):
-	cond_print('failed.\n')
-	error_advice_exit('unable to download video data')
-
-except KeyboardInterrupt:
-	sys.exit('\n')
+		# Modules needed only when running the main program
+		import getpass
+		import optparse
+
+		# 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='2009.09.13',
+			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('-i', '--ignore-errors',
+				action='store_true', dest='ignoreerrors', help='continue on download errors', default=False)
+		parser.add_option('-r', '--rate-limit',
+				dest='ratelimit', metavar='L', help='download rate limit (e.g. 50k or 44.6m)')
+
+		authentication = optparse.OptionGroup(parser, 'Authentication Options')
+		authentication.add_option('-u', '--username',
+				dest='username', metavar='UN', help='account username')
+		authentication.add_option('-p', '--password',
+				dest='password', metavar='PW', 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='FMT', 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')
+		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)
+		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='TPL', help='output filename template')
+		filesystem.add_option('-a', '--batch-file',
+				dest='batchfile', metavar='F', help='file containing URLs to download')
+		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:
+				batchurls = open(opts.batchfile, 'r').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 len(all_urls) < 1:
+			parser.error(u'you must provide at least one URL')
+		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
+
+		# Information extractors
+		youtube_ie = YoutubeIE()
+		metacafe_ie = MetacafeIE(youtube_ie)
+		youtube_pl_ie = YoutubePlaylistIE(youtube_ie)
+		youtube_search_ie = YoutubeSearchIE(youtube_ie)
+
+		# File downloader
+		fd = FileDownloader({
+			'usenetrc': opts.usenetrc,
+			'username': opts.username,
+			'password': opts.password,
+			'quiet': (opts.quiet or opts.geturl or opts.gettitle),
+			'forceurl': opts.geturl,
+			'forcetitle': opts.gettitle,
+			'simulate': (opts.simulate or opts.geturl or opts.gettitle),
+			'format': opts.format,
+			'outtmpl': ((opts.outtmpl is not None and opts.outtmpl.decode(preferredencoding()))
+				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,
+			'continuedl': opts.continue_dl,
+			})
+		fd.add_info_extractor(youtube_search_ie)
+		fd.add_info_extractor(youtube_pl_ie)
+		fd.add_info_extractor(metacafe_ie)
+		fd.add_info_extractor(youtube_ie)
+		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')