]> Raphaƫl G. Git Repositories - youtubedl/blobdiff - youtube_dl/FileDownloader.py
debian/control: Update long description with list of supported sites.
[youtubedl] / youtube_dl / FileDownloader.py
index 14e872a98a922606b8a3f3ea15a9d3d61ef87274..8ecabab1a517467c118dad0857c47291bcb2f929 100644 (file)
-#!/usr/bin/env python
-# -*- coding: utf-8 -*-
-
-import httplib
 import math
 import os
 import re
-import socket
 import subprocess
 import sys
 import time
-import urllib2
+import traceback
 
 if os.name == 'nt':
-       import ctypes
-       
-from utils import *
+    import ctypes
+
+from .utils import *
 
 
 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.
-       forcethumbnail:   Force printing thumbnail URL.
-       forcedescription: Force printing description.
-       forcefilename:    Force printing final filename.
-       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 5xx
-       continuedl:       Try to continue downloads if possible.
-       noprogress:       Do not print the progress bar.
-       playliststart:    Playlist item to start at.
-       playlistend:      Playlist item to end at.
-       matchtitle:       Download only matching titles.
-       rejecttitle:      Reject downloads for matching titles.
-       logtostderr:      Log messages to stderr instead of stdout.
-       consoletitle:     Display progress in console window's titlebar.
-       nopart:           Do not use temporary .part files.
-       updatetime:       Use the Last-modified header to set output file timestamps.
-       writedescription: Write the video description to a .description file
-       writeinfojson:    Write the video description to a .info.json file
-       writesubtitles:   Write the video subtitles to a .srt file
-       subtitleslang:    Language of the subtitles to download
-       """
-
-       params = None
-       _ies = []
-       _pps = []
-       _download_retcode = None
-       _num_downloads = None
-       _screen_file = 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._screen_file = [sys.stdout, sys.stderr][params.get('logtostderr', False)]
-               self.params = params
-
-       @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))
-
-       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_screen(self, message, skip_eol=False):
-               """Print message to stdout if not in quiet mode."""
-               assert type(message) == type(u'')
-               if not self.params.get('quiet', False):
-                       terminator = [u'\n', u''][skip_eol]
-                       output = message + terminator
-
-                       if 'b' not in self._screen_file.mode or sys.version_info[0] < 3: # Python 2 lies about the mode of sys.stdout/sys.stderr
-                               output = output.encode(preferredencoding(), 'ignore')
-                       self._screen_file.write(output)
-                       self._screen_file.flush()
-
-       def to_stderr(self, message):
-               """Print message to stderr."""
-               print >>sys.stderr, message.encode(preferredencoding())
-
-       def to_cons_title(self, message):
-               """Set console/terminal window title to message."""
-               if not self.params.get('consoletitle', False):
-                       return
-               if os.name == 'nt' and ctypes.windll.kernel32.GetConsoleWindow():
-                       # c_wchar_p() might not be necessary if `message` is
-                       # already of type unicode()
-                       ctypes.windll.kernel32.SetConsoleTitleW(ctypes.c_wchar_p(message))
-               elif 'TERM' in os.environ:
-                       sys.stderr.write('\033]0;%s\007' % 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 temp_name(self, filename):
-               """Returns a temporary filename for the given filename."""
-               if self.params.get('nopart', False) or filename == u'-' or \
-                               (os.path.exists(encodeFilename(filename)) and not os.path.isfile(encodeFilename(filename))):
-                       return filename
-               return filename + u'.part'
-
-       def undo_temp_name(self, filename):
-               if filename.endswith(u'.part'):
-                       return filename[:-len(u'.part')]
-               return filename
-
-       def try_rename(self, old_filename, new_filename):
-               try:
-                       if old_filename == new_filename:
-                               return
-                       os.rename(encodeFilename(old_filename), encodeFilename(new_filename))
-               except (IOError, OSError), err:
-                       self.trouble(u'ERROR: unable to rename file')
-
-       def try_utime(self, filename, last_modified_hdr):
-               """Try to set the last-modified time of the given file."""
-               if last_modified_hdr is None:
-                       return
-               if not os.path.isfile(encodeFilename(filename)):
-                       return
-               timestr = last_modified_hdr
-               if timestr is None:
-                       return
-               filetime = timeconvert(timestr)
-               if filetime is None:
-                       return filetime
-               try:
-                       os.utime(filename, (time.time(), filetime))
-               except:
-                       pass
-               return filetime
-
-       def report_writedescription(self, descfn):
-               """ Report that the description file is being written """
-               self.to_screen(u'[info] Writing video description to: ' + descfn)
-
-       def report_writesubtitles(self, srtfn):
-               """ Report that the subtitles file is being written """
-               self.to_screen(u'[info] Writing video subtitles to: ' + srtfn)
-
-       def report_writeinfojson(self, infofn):
-               """ Report that the metadata file has been written """
-               self.to_screen(u'[info] Video description metadata as JSON to: ' + infofn)
-
-       def report_destination(self, filename):
-               """Report destination filename."""
-               self.to_screen(u'[download] Destination: ' + filename)
-
-       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_screen(u'\r[download] %s of %s at %s ETA %s' %
-                               (percent_str, data_len_str, speed_str, eta_str), skip_eol=True)
-               self.to_cons_title(u'youtube-dl - %s of %s at %s ETA %s' %
-                               (percent_str.strip(), data_len_str.strip(), speed_str.strip(), eta_str.strip()))
-
-       def report_resuming_byte(self, resume_len):
-               """Report attempt to resume at given byte."""
-               self.to_screen(u'[download] Resuming download at byte %s' % resume_len)
-
-       def report_retry(self, count, retries):
-               """Report retry in case of HTTP error 5xx"""
-               self.to_screen(u'[download] Got server HTTP error. 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_screen(u'[download] %s has already been downloaded' % file_name)
-               except (UnicodeEncodeError), err:
-                       self.to_screen(u'[download] The file has already been downloaded')
-
-       def report_unable_to_resume(self):
-               """Report it was impossible to resume download."""
-               self.to_screen(u'[download] Unable to resume')
-
-       def report_finish(self):
-               """Report download finished."""
-               if self.params.get('noprogress', False):
-                       self.to_screen(u'[download] Download completed')
-               else:
-                       self.to_screen(u'')
-
-       def increment_downloads(self):
-               """Increment the ordinal that assigns a number to each file."""
-               self._num_downloads += 1
-
-       def prepare_filename(self, info_dict):
-               """Generate the output filename."""
-               try:
-                       template_dict = dict(info_dict)
-                       template_dict['epoch'] = unicode(long(time.time()))
-                       template_dict['autonumber'] = unicode('%05d' % self._num_downloads)
-                       filename = self.params['outtmpl'] % template_dict
-                       return filename
-               except (ValueError, KeyError), err:
-                       self.trouble(u'ERROR: invalid system charset or erroneous output template')
-                       return None
-
-       def _match_entry(self, info_dict):
-               """ Returns None iff the file should be downloaded """
-
-               title = info_dict['title']
-               matchtitle = self.params.get('matchtitle', False)
-               if matchtitle and not re.search(matchtitle, title, re.IGNORECASE):
-                       return u'[download] "' + title + '" title did not match pattern "' + matchtitle + '"'
-               rejecttitle = self.params.get('rejecttitle', False)
-               if rejecttitle and re.search(rejecttitle, title, re.IGNORECASE):
-                       return u'"' + title + '" title matched reject pattern "' + rejecttitle + '"'
-               return None
-
-       def process_info(self, info_dict):
-               """Process a single dictionary returned by an InfoExtractor."""
-
-               info_dict['stitle'] = sanitize_filename(info_dict['title'])
-
-               reason = self._match_entry(info_dict)
-               if reason is not None:
-                       self.to_screen(u'[download] ' + reason)
-                       return
-
-               max_downloads = self.params.get('max_downloads')
-               if max_downloads is not None:
-                       if self._num_downloads > int(max_downloads):
-                               raise MaxDownloadsReached()
-
-               filename = self.prepare_filename(info_dict)
-               
-               # 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')
-               if self.params.get('forcefilename', False) and filename is not None:
-                       print filename.encode(preferredencoding(), 'xmlcharrefreplace')
-               if self.params.get('forceformat', False):
-                       print info_dict['format'].encode(preferredencoding(), 'xmlcharrefreplace')
-
-               # Do nothing else if in simulate mode
-               if self.params.get('simulate', False):
-                       return
-
-               if filename is None:
-                       return
-
-               try:
-                       dn = os.path.dirname(encodeFilename(filename))
-                       if dn != '' and not os.path.exists(dn): # dn is already encoded
-                               os.makedirs(dn)
-               except (OSError, IOError), err:
-                       self.trouble(u'ERROR: unable to create directory ' + unicode(err))
-                       return
-
-               if self.params.get('writedescription', False):
-                       try:
-                               descfn = filename + u'.description'
-                               self.report_writedescription(descfn)
-                               descfile = open(encodeFilename(descfn), 'wb')
-                               try:
-                                       descfile.write(info_dict['description'].encode('utf-8'))
-                               finally:
-                                       descfile.close()
-                       except (OSError, IOError):
-                               self.trouble(u'ERROR: Cannot write description file ' + descfn)
-                               return
-                               
-               if self.params.get('writesubtitles', False) and 'subtitles' in info_dict and info_dict['subtitles']:
-                       # subtitles download errors are already managed as troubles in relevant IE
-                       # that way it will silently go on when used with unsupporting IE 
-                       try:
-                               srtfn = filename.rsplit('.', 1)[0] + u'.srt'
-                               self.report_writesubtitles(srtfn)
-                               srtfile = open(encodeFilename(srtfn), 'wb')
-                               try:
-                                       srtfile.write(info_dict['subtitles'].encode('utf-8'))
-                               finally:
-                                       srtfile.close()
-                       except (OSError, IOError):
-                               self.trouble(u'ERROR: Cannot write subtitles file ' + descfn)
-                               return
-
-               if self.params.get('writeinfojson', False):
-                       infofn = filename + u'.info.json'
-                       self.report_writeinfojson(infofn)
-                       try:
-                               json.dump
-                       except (NameError,AttributeError):
-                               self.trouble(u'ERROR: No JSON encoder found. Update to Python 2.6+, setup a json module, or leave out --write-info-json.')
-                               return
-                       try:
-                               infof = open(encodeFilename(infofn), 'wb')
-                               try:
-                                       json_info_dict = dict((k,v) for k,v in info_dict.iteritems() if not k in ('urlhandle',))
-                                       json.dump(json_info_dict, infof)
-                               finally:
-                                       infof.close()
-                       except (OSError, IOError):
-                               self.trouble(u'ERROR: Cannot write metadata to JSON file ' + infofn)
-                               return
-
-               if not self.params.get('skip_download', False):
-                       if self.params.get('nooverwrites', False) and os.path.exists(encodeFilename(filename)):
-                               success = True
-                       else:
-                               try:
-                                       success = self._do_download(filename, info_dict)
-                               except (OSError, IOError), err:
-                                       raise UnavailableVideoError
-                               except (urllib2.URLError, httplib.HTTPException, socket.error), err:
-                                       self.trouble(u'ERROR: unable to download video data: %s' % str(err))
-                                       return
-                               except (ContentTooShortError, ), err:
-                                       self.trouble(u'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(u'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
-                               videos = ie.extract(url)
-                               for video in videos or []:
-                                       try:
-                                               self.increment_downloads()
-                                               self.process_info(video)
-                                       except UnavailableVideoError:
-                                               self.trouble(u'\nERROR: unable to download video')
-
-                               # Suitable InfoExtractor had been found; go to next URL
-                               break
-
-                       if not suitable_found:
-                               self.trouble(u'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)
-               tmpfilename = self.temp_name(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', tmpfilename]
-               args = basic_args + [[], ['-e', '-k', '1']][self.params.get('continuedl', False)]
-               if self.params.get('verbose', False):
-                       try:
-                               import pipes
-                               shell_quote = lambda args: ' '.join(map(pipes.quote, args))
-                       except ImportError:
-                               shell_quote = repr
-                       self.to_screen(u'[debug] rtmpdump command line: ' + shell_quote(args))
-               retval = subprocess.call(args)
-               while retval == 2 or retval == 1:
-                       prevsize = os.path.getsize(encodeFilename(tmpfilename))
-                       self.to_screen(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(encodeFilename(tmpfilename))
-                       if prevsize == cursize and retval == 1:
-                               break
-                        # Some rtmp streams seem abort after ~ 99.8%. Don't complain for those
-                       if prevsize == cursize and retval == 2 and cursize > 1024:
-                               self.to_screen(u'\r[rtmpdump] Could not download the whole video. This can happen for some advertisements.')
-                               retval = 0
-                               break
-               if retval == 0:
-                       self.to_screen(u'\r[rtmpdump] %s bytes' % os.path.getsize(encodeFilename(tmpfilename)))
-                       self.try_rename(tmpfilename, filename)
-                       return True
-               else:
-                       self.trouble(u'\nERROR: rtmpdump exited with code %d' % retval)
-                       return False
-
-       def _do_download(self, filename, info_dict):
-               url = info_dict['url']
-               player_url = info_dict.get('player_url', None)
-
-               # Check file already present
-               if self.params.get('continuedl', False) and os.path.isfile(encodeFilename(filename)) and not self.params.get('nopart', False):
-                       self.report_file_already_downloaded(filename)
-                       return True
-
-               # Attempt to download using rtmpdump
-               if url.startswith('rtmp'):
-                       return self._download_with_rtmpdump(filename, url, player_url)
-
-               tmpfilename = self.temp_name(filename)
-               stream = None
-
-               # Do not include the Accept-Encoding header
-               headers = {'Youtubedl-no-compression': 'True'}
-               basic_request = urllib2.Request(url, None, headers)
-               request = urllib2.Request(url, None, headers)
-
-               # Establish possible resume length
-               if os.path.isfile(encodeFilename(tmpfilename)):
-                       resume_len = os.path.getsize(encodeFilename(tmpfilename))
-               else:
-                       resume_len = 0
-
-               open_mode = 'wb'
-               if resume_len != 0:
-                       if self.params.get('continuedl', False):
-                               self.report_resuming_byte(resume_len)
-                               request.add_header('Range','bytes=%d-' % resume_len)
-                               open_mode = 'ab'
-                       else:
-                               resume_len = 0
-
-               count = 0
-               retries = self.params.get('retries', 0)
-               while count <= retries:
-                       # Establish connection
-                       try:
-                               if count == 0 and 'urlhandle' in info_dict:
-                                       data = info_dict['urlhandle']
-                               data = urllib2.urlopen(request)
-                               break
-                       except (urllib2.HTTPError, ), err:
-                               if (err.code < 500 or err.code >= 600) and err.code != 416:
-                                       # Unexpected HTTP error
-                                       raise
-                               elif err.code == 416:
-                                       # Unable to resume (requested range not satisfiable)
-                                       try:
-                                               # Open the connection again without the range header
-                                               data = urllib2.urlopen(basic_request)
-                                               content_length = data.info()['Content-Length']
-                                       except (urllib2.HTTPError, ), err:
-                                               if err.code < 500 or err.code >= 600:
-                                                       raise
-                                       else:
-                                               # Examine the reported length
-                                               if (content_length is not None and
-                                                               (resume_len - 100 < long(content_length) < resume_len + 100)):
-                                                       # The file had already been fully downloaded.
-                                                       # Explanation to the above condition: in issue #175 it was revealed that
-                                                       # YouTube sometimes adds or removes a few bytes from the end of the file,
-                                                       # changing the file size slightly and causing problems for some users. So
-                                                       # I decided to implement a suggested change and consider the file
-                                                       # completely downloaded if the file size differs less than 100 bytes from
-                                                       # the one in the hard drive.
-                                                       self.report_file_already_downloaded(filename)
-                                                       self.try_rename(tmpfilename, filename)
-                                                       return True
-                                               else:
-                                                       # The length does not match, we start the download over
-                                                       self.report_unable_to_resume()
-                                                       open_mode = 'wb'
-                                                       break
-                       # Retry
-                       count += 1
-                       if count <= retries:
-                               self.report_retry(count, retries)
-
-               if count > retries:
-                       self.trouble(u'ERROR: giving up after %s retries' % retries)
-                       return False
-
-               data_len = data.info().get('Content-length', None)
-               if data_len is not None:
-                       data_len = long(data_len) + resume_len
-               data_len_str = self.format_bytes(data_len)
-               byte_counter = 0 + resume_len
-               block_size = 1024
-               start = time.time()
-               while True:
-                       # Download and write
-                       before = time.time()
-                       data_block = data.read(block_size)
-                       after = time.time()
-                       if len(data_block) == 0:
-                               break
-                       byte_counter += len(data_block)
-
-                       # Open file just in time
-                       if stream is None:
-                               try:
-                                       (stream, tmpfilename) = sanitize_open(tmpfilename, open_mode)
-                                       assert stream is not None
-                                       filename = self.undo_temp_name(tmpfilename)
-                                       self.report_destination(filename)
-                               except (OSError, IOError), err:
-                                       self.trouble(u'ERROR: unable to open for writing: %s' % str(err))
-                                       return False
-                       try:
-                               stream.write(data_block)
-                       except (IOError, OSError), err:
-                               self.trouble(u'\nERROR: unable to write data: %s' % str(err))
-                               return False
-                       block_size = self.best_block_size(after - before, len(data_block))
-
-                       # Progress message
-                       speed_str = self.calc_speed(start, time.time(), byte_counter - resume_len)
-                       if data_len is None:
-                               self.report_progress('Unknown %', data_len_str, speed_str, 'Unknown ETA')
-                       else:
-                               percent_str = self.calc_percent(byte_counter, data_len)
-                               eta_str = self.calc_eta(start, time.time(), data_len - resume_len, byte_counter - resume_len)
-                               self.report_progress(percent_str, data_len_str, speed_str, eta_str)
-
-                       # Apply rate limit
-                       self.slow_down(start, byte_counter - resume_len)
-
-               if stream is None:
-                       self.trouble(u'\nERROR: Did not get any data blocks')
-                       return False
-               stream.close()
-               self.report_finish()
-               if data_len is not None and byte_counter != data_len:
-                       raise ContentTooShortError(byte_counter, long(data_len))
-               self.try_rename(tmpfilename, filename)
-
-               # Update file modification time
-               if self.params.get('updatetime', True):
-                       info_dict['filetime'] = self.try_utime(filename, data.info().get('last-modified', None))
-
-               return True
+    """File Downloader class.
+
+    File downloader objects are the ones responsible of downloading the
+    actual video file and writing it to disk.
+
+    File downloaders accept a lot of parameters. In order not to saturate
+    the object constructor with arguments, it receives a dictionary of
+    options instead.
+
+    Available options:
+
+    verbose:           Print additional info to stdout.
+    quiet:             Do not print messages to stdout.
+    ratelimit:         Download speed limit, in bytes/sec.
+    retries:           Number of times to retry for HTTP error 5xx
+    buffersize:        Size of download buffer in bytes.
+    noresizebuffer:    Do not automatically resize the download buffer.
+    continuedl:        Try to continue downloads if possible.
+    noprogress:        Do not print the progress bar.
+    logtostderr:       Log messages to stderr instead of stdout.
+    consoletitle:      Display progress in console window's titlebar.
+    nopart:            Do not use temporary .part files.
+    updatetime:        Use the Last-modified header to set output file timestamps.
+    test:              Download only first bytes to test the downloader.
+    min_filesize:      Skip files smaller than this size
+    max_filesize:      Skip files larger than this size
+    """
+
+    params = None
+
+    def __init__(self, ydl, params):
+        """Create a FileDownloader object with the given options."""
+        self.ydl = ydl
+        self._progress_hooks = []
+        self.params = params
+
+    @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 = int(math.log(bytes, 1024.0))
+        suffix = ['B','KiB','MiB','GiB','TiB','PiB','EiB','ZiB','YiB'][exponent]
+        converted = float(bytes) / float(1024 ** exponent)
+        return '%.2f%s' % (converted, suffix)
+
+    @staticmethod
+    def format_seconds(seconds):
+        (mins, secs) = divmod(seconds, 60)
+        (hours, mins) = divmod(mins, 60)
+        if hours > 99:
+            return '--:--:--'
+        if hours == 0:
+            return '%02d:%02d' % (mins, secs)
+        else:
+            return '%02d:%02d:%02d' % (hours, mins, secs)
+
+    @staticmethod
+    def calc_percent(byte_counter, data_len):
+        if data_len is None:
+            return None
+        return float(byte_counter) / float(data_len) * 100.0
+
+    @staticmethod
+    def format_percent(percent):
+        if percent is None:
+            return '---.-%'
+        return '%6s' % ('%3.1f%%' % percent)
+
+    @staticmethod
+    def calc_eta(start, now, total, current):
+        if total is None:
+            return None
+        dif = now - start
+        if current == 0 or dif < 0.001: # One millisecond
+            return None
+        rate = float(current) / dif
+        return int((float(total) - float(current)) / rate)
+
+    @staticmethod
+    def format_eta(eta):
+        if eta is None:
+            return '--:--'
+        return FileDownloader.format_seconds(eta)
+
+    @staticmethod
+    def calc_speed(start, now, bytes):
+        dif = now - start
+        if bytes == 0 or dif < 0.001: # One millisecond
+            return None
+        return float(bytes) / dif
+
+    @staticmethod
+    def format_speed(speed):
+        if speed is None:
+            return '%10s' % '---b/s'
+        return '%10s' % ('%s/s' % FileDownloader.format_bytes(speed))
+
+    @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 int(new_max)
+        rate = bytes / elapsed_time
+        if rate > new_max:
+            return int(new_max)
+        if rate < new_min:
+            return int(new_min)
+        return int(rate)
+
+    @staticmethod
+    def parse_bytes(bytestr):
+        """Parse a string indicating a byte quantity into an 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 int(round(number * multiplier))
+
+    def to_screen(self, *args, **kargs):
+        self.ydl.to_screen(*args, **kargs)
+
+    def to_stderr(self, message):
+        self.ydl.to_screen(message)
+
+    def to_cons_title(self, message):
+        """Set console/terminal window title to message."""
+        if not self.params.get('consoletitle', False):
+            return
+        if os.name == 'nt' and ctypes.windll.kernel32.GetConsoleWindow():
+            # c_wchar_p() might not be necessary if `message` is
+            # already of type unicode()
+            ctypes.windll.kernel32.SetConsoleTitleW(ctypes.c_wchar_p(message))
+        elif 'TERM' in os.environ:
+            self.to_screen('\033]0;%s\007' % message, skip_eol=True)
+
+    def trouble(self, *args, **kargs):
+        self.ydl.trouble(*args, **kargs)
+
+    def report_warning(self, *args, **kargs):
+        self.ydl.report_warning(*args, **kargs)
+
+    def report_error(self, *args, **kargs):
+        self.ydl.report_error(*args, **kargs)
+
+    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 temp_name(self, filename):
+        """Returns a temporary filename for the given filename."""
+        if self.params.get('nopart', False) or filename == u'-' or \
+                (os.path.exists(encodeFilename(filename)) and not os.path.isfile(encodeFilename(filename))):
+            return filename
+        return filename + u'.part'
+
+    def undo_temp_name(self, filename):
+        if filename.endswith(u'.part'):
+            return filename[:-len(u'.part')]
+        return filename
+
+    def try_rename(self, old_filename, new_filename):
+        try:
+            if old_filename == new_filename:
+                return
+            os.rename(encodeFilename(old_filename), encodeFilename(new_filename))
+        except (IOError, OSError) as err:
+            self.report_error(u'unable to rename file')
+
+    def try_utime(self, filename, last_modified_hdr):
+        """Try to set the last-modified time of the given file."""
+        if last_modified_hdr is None:
+            return
+        if not os.path.isfile(encodeFilename(filename)):
+            return
+        timestr = last_modified_hdr
+        if timestr is None:
+            return
+        filetime = timeconvert(timestr)
+        if filetime is None:
+            return filetime
+        # Ignore obviously invalid dates
+        if filetime == 0:
+            return
+        try:
+            os.utime(filename, (time.time(), filetime))
+        except:
+            pass
+        return filetime
+
+    def report_destination(self, filename):
+        """Report destination filename."""
+        self.to_screen(u'[download] Destination: ' + filename)
+
+    def report_progress(self, percent, data_len_str, speed, eta):
+        """Report download progress."""
+        if self.params.get('noprogress', False):
+            return
+        clear_line = (u'\x1b[K' if sys.stderr.isatty() and os.name != 'nt' else u'')
+        eta_str = self.format_eta(eta)
+        percent_str = self.format_percent(percent)
+        speed_str = self.format_speed(speed)
+        if self.params.get('progress_with_newline', False):
+            self.to_screen(u'[download] %s of %s at %s ETA %s' %
+                (percent_str, data_len_str, speed_str, eta_str))
+        else:
+            self.to_screen(u'\r%s[download] %s of %s at %s ETA %s' %
+                (clear_line, percent_str, data_len_str, speed_str, eta_str), skip_eol=True)
+        self.to_cons_title(u'youtube-dl - %s of %s at %s ETA %s' %
+                (percent_str.strip(), data_len_str.strip(), speed_str.strip(), eta_str.strip()))
+
+    def report_resuming_byte(self, resume_len):
+        """Report attempt to resume at given byte."""
+        self.to_screen(u'[download] Resuming download at byte %s' % resume_len)
+
+    def report_retry(self, count, retries):
+        """Report retry in case of HTTP error 5xx"""
+        self.to_screen(u'[download] Got server HTTP error. 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_screen(u'[download] %s has already been downloaded' % file_name)
+        except (UnicodeEncodeError) as err:
+            self.to_screen(u'[download] The file has already been downloaded')
+
+    def report_unable_to_resume(self):
+        """Report it was impossible to resume download."""
+        self.to_screen(u'[download] Unable to resume')
+
+    def report_finish(self, data_len_str, tot_time):
+        """Report download finished."""
+        if self.params.get('noprogress', False):
+            self.to_screen(u'[download] Download completed')
+        else:
+            clear_line = (u'\x1b[K' if sys.stderr.isatty() and os.name != 'nt' else u'')
+            self.to_screen(u'\r%s[download] 100%% of %s in %s' %
+                (clear_line, data_len_str, self.format_seconds(tot_time)))
+
+    def _download_with_rtmpdump(self, filename, url, player_url, page_url, play_path, tc_url):
+        self.report_destination(filename)
+        tmpfilename = self.temp_name(filename)
+        test = self.params.get('test', False)
+
+        # Check for rtmpdump first
+        try:
+            subprocess.call(['rtmpdump', '-h'], stdout=(open(os.path.devnull, 'w')), stderr=subprocess.STDOUT)
+        except (OSError, IOError):
+            self.report_error(u'RTMP download detected but "rtmpdump" could not be run')
+            return False
+        verbosity_option = '--verbose' if self.params.get('verbose', False) else '--quiet'
+
+        # 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', verbosity_option, '-r', url, '-o', tmpfilename]
+        if player_url is not None:
+            basic_args += ['--swfVfy', player_url]
+        if page_url is not None:
+            basic_args += ['--pageUrl', page_url]
+        if play_path is not None:
+            basic_args += ['--playpath', play_path]
+        if tc_url is not None:
+            basic_args += ['--tcUrl', url]
+        if test:
+            basic_args += ['--stop', '1']
+        args = basic_args + [[], ['--resume', '--skip', '1']][self.params.get('continuedl', False)]
+        if self.params.get('verbose', False):
+            try:
+                import pipes
+                shell_quote = lambda args: ' '.join(map(pipes.quote, args))
+            except ImportError:
+                shell_quote = repr
+            self.to_screen(u'[debug] rtmpdump command line: ' + shell_quote(args))
+        retval = subprocess.call(args)
+        while (retval == 2 or retval == 1) and not test:
+            prevsize = os.path.getsize(encodeFilename(tmpfilename))
+            self.to_screen(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(encodeFilename(tmpfilename))
+            if prevsize == cursize and retval == 1:
+                break
+             # Some rtmp streams seem abort after ~ 99.8%. Don't complain for those
+            if prevsize == cursize and retval == 2 and cursize > 1024:
+                self.to_screen(u'\r[rtmpdump] Could not download the whole video. This can happen for some advertisements.')
+                retval = 0
+                break
+        if retval == 0 or (test and retval == 2):
+            fsize = os.path.getsize(encodeFilename(tmpfilename))
+            self.to_screen(u'\r[rtmpdump] %s bytes' % fsize)
+            self.try_rename(tmpfilename, filename)
+            self._hook_progress({
+                'downloaded_bytes': fsize,
+                'total_bytes': fsize,
+                'filename': filename,
+                'status': 'finished',
+            })
+            return True
+        else:
+            self.to_stderr(u"\n")
+            self.report_error(u'rtmpdump exited with code %d' % retval)
+            return False
+
+    def _download_with_mplayer(self, filename, url):
+        self.report_destination(filename)
+        tmpfilename = self.temp_name(filename)
+
+        args = ['mplayer', '-really-quiet', '-vo', 'null', '-vc', 'dummy', '-dumpstream', '-dumpfile', tmpfilename, url]
+        # Check for mplayer first
+        try:
+            subprocess.call(['mplayer', '-h'], stdout=(open(os.path.devnull, 'w')), stderr=subprocess.STDOUT)
+        except (OSError, IOError):
+            self.report_error(u'MMS or RTSP download detected but "%s" could not be run' % args[0] )
+            return False
+
+        # Download using mplayer. 
+        retval = subprocess.call(args)
+        if retval == 0:
+            fsize = os.path.getsize(encodeFilename(tmpfilename))
+            self.to_screen(u'\r[%s] %s bytes' % (args[0], fsize))
+            self.try_rename(tmpfilename, filename)
+            self._hook_progress({
+                'downloaded_bytes': fsize,
+                'total_bytes': fsize,
+                'filename': filename,
+                'status': 'finished',
+            })
+            return True
+        else:
+            self.to_stderr(u"\n")
+            self.report_error(u'mplayer exited with code %d' % retval)
+            return False
+
+    def _download_m3u8_with_ffmpeg(self, filename, url):
+        self.report_destination(filename)
+        tmpfilename = self.temp_name(filename)
+
+        args = ['ffmpeg', '-y', '-i', url, '-f', 'mp4', tmpfilename]
+        # Check for ffmpeg first
+        try:
+            subprocess.call(['ffmpeg', '-h'], stdout=(open(os.path.devnull, 'w')), stderr=subprocess.STDOUT)
+        except (OSError, IOError):
+            self.report_error(u'm3u8 download detected but "%s" could not be run' % args[0] )
+            return False
+
+        retval = subprocess.call(args)
+        if retval == 0:
+            fsize = os.path.getsize(encodeFilename(tmpfilename))
+            self.to_screen(u'\r[%s] %s bytes' % (args[0], fsize))
+            self.try_rename(tmpfilename, filename)
+            self._hook_progress({
+                'downloaded_bytes': fsize,
+                'total_bytes': fsize,
+                'filename': filename,
+                'status': 'finished',
+            })
+            return True
+        else:
+            self.to_stderr(u"\n")
+            self.report_error(u'ffmpeg exited with code %d' % retval)
+            return False
+
+
+    def _do_download(self, filename, info_dict):
+        url = info_dict['url']
+
+        # Check file already present
+        if self.params.get('continuedl', False) and os.path.isfile(encodeFilename(filename)) and not self.params.get('nopart', False):
+            self.report_file_already_downloaded(filename)
+            self._hook_progress({
+                'filename': filename,
+                'status': 'finished',
+                'total_bytes': os.path.getsize(encodeFilename(filename)),
+            })
+            return True
+
+        # Attempt to download using rtmpdump
+        if url.startswith('rtmp'):
+            return self._download_with_rtmpdump(filename, url,
+                                                info_dict.get('player_url', None),
+                                                info_dict.get('page_url', None),
+                                                info_dict.get('play_path', None),
+                                                info_dict.get('tc_url', None))
+
+        # Attempt to download using mplayer
+        if url.startswith('mms') or url.startswith('rtsp'):
+            return self._download_with_mplayer(filename, url)
+
+        # m3u8 manifest are downloaded with ffmpeg
+        if determine_ext(url) == u'm3u8':
+            return self._download_m3u8_with_ffmpeg(filename, url)
+
+        tmpfilename = self.temp_name(filename)
+        stream = None
+
+        # Do not include the Accept-Encoding header
+        headers = {'Youtubedl-no-compression': 'True'}
+        if 'user_agent' in info_dict:
+            headers['Youtubedl-user-agent'] = info_dict['user_agent']
+        basic_request = compat_urllib_request.Request(url, None, headers)
+        request = compat_urllib_request.Request(url, None, headers)
+
+        if self.params.get('test', False):
+            request.add_header('Range','bytes=0-10240')
+
+        # Establish possible resume length
+        if os.path.isfile(encodeFilename(tmpfilename)):
+            resume_len = os.path.getsize(encodeFilename(tmpfilename))
+        else:
+            resume_len = 0
+
+        open_mode = 'wb'
+        if resume_len != 0:
+            if self.params.get('continuedl', False):
+                self.report_resuming_byte(resume_len)
+                request.add_header('Range','bytes=%d-' % resume_len)
+                open_mode = 'ab'
+            else:
+                resume_len = 0
+
+        count = 0
+        retries = self.params.get('retries', 0)
+        while count <= retries:
+            # Establish connection
+            try:
+                if count == 0 and 'urlhandle' in info_dict:
+                    data = info_dict['urlhandle']
+                data = compat_urllib_request.urlopen(request)
+                break
+            except (compat_urllib_error.HTTPError, ) as err:
+                if (err.code < 500 or err.code >= 600) and err.code != 416:
+                    # Unexpected HTTP error
+                    raise
+                elif err.code == 416:
+                    # Unable to resume (requested range not satisfiable)
+                    try:
+                        # Open the connection again without the range header
+                        data = compat_urllib_request.urlopen(basic_request)
+                        content_length = data.info()['Content-Length']
+                    except (compat_urllib_error.HTTPError, ) as err:
+                        if err.code < 500 or err.code >= 600:
+                            raise
+                    else:
+                        # Examine the reported length
+                        if (content_length is not None and
+                                (resume_len - 100 < int(content_length) < resume_len + 100)):
+                            # The file had already been fully downloaded.
+                            # Explanation to the above condition: in issue #175 it was revealed that
+                            # YouTube sometimes adds or removes a few bytes from the end of the file,
+                            # changing the file size slightly and causing problems for some users. So
+                            # I decided to implement a suggested change and consider the file
+                            # completely downloaded if the file size differs less than 100 bytes from
+                            # the one in the hard drive.
+                            self.report_file_already_downloaded(filename)
+                            self.try_rename(tmpfilename, filename)
+                            self._hook_progress({
+                                'filename': filename,
+                                'status': 'finished',
+                            })
+                            return True
+                        else:
+                            # The length does not match, we start the download over
+                            self.report_unable_to_resume()
+                            open_mode = 'wb'
+                            break
+            # Retry
+            count += 1
+            if count <= retries:
+                self.report_retry(count, retries)
+
+        if count > retries:
+            self.report_error(u'giving up after %s retries' % retries)
+            return False
+
+        data_len = data.info().get('Content-length', None)
+        if data_len is not None:
+            data_len = int(data_len) + resume_len
+            min_data_len = self.params.get("min_filesize", None)
+            max_data_len =  self.params.get("max_filesize", None)
+            if min_data_len is not None and data_len < min_data_len:
+                self.to_screen(u'\r[download] File is smaller than min-filesize (%s bytes < %s bytes). Aborting.' % (data_len, min_data_len))
+                return False
+            if max_data_len is not None and data_len > max_data_len:
+                self.to_screen(u'\r[download] File is larger than max-filesize (%s bytes > %s bytes). Aborting.' % (data_len, max_data_len))
+                return False
+
+        data_len_str = self.format_bytes(data_len)
+        byte_counter = 0 + resume_len
+        block_size = self.params.get('buffersize', 1024)
+        start = time.time()
+        while True:
+            # Download and write
+            before = time.time()
+            data_block = data.read(block_size)
+            after = time.time()
+            if len(data_block) == 0:
+                break
+            byte_counter += len(data_block)
+
+            # Open file just in time
+            if stream is None:
+                try:
+                    (stream, tmpfilename) = sanitize_open(tmpfilename, open_mode)
+                    assert stream is not None
+                    filename = self.undo_temp_name(tmpfilename)
+                    self.report_destination(filename)
+                except (OSError, IOError) as err:
+                    self.report_error(u'unable to open for writing: %s' % str(err))
+                    return False
+            try:
+                stream.write(data_block)
+            except (IOError, OSError) as err:
+                self.to_stderr(u"\n")
+                self.report_error(u'unable to write data: %s' % str(err))
+                return False
+            if not self.params.get('noresizebuffer', False):
+                block_size = self.best_block_size(after - before, len(data_block))
+
+            # Progress message
+            speed = self.calc_speed(start, time.time(), byte_counter - resume_len)
+            if data_len is None:
+                self.report_progress('Unknown %', data_len_str, speed_str, 'Unknown ETA')
+                eta = None
+            else:
+                percent = self.calc_percent(byte_counter, data_len)
+                eta = self.calc_eta(start, time.time(), data_len - resume_len, byte_counter - resume_len)
+                self.report_progress(percent, data_len_str, speed, eta)
+
+            self._hook_progress({
+                'downloaded_bytes': byte_counter,
+                'total_bytes': data_len,
+                'tmpfilename': tmpfilename,
+                'filename': filename,
+                'status': 'downloading',
+                'eta': eta,
+                'speed': speed,
+            })
+
+            # Apply rate limit
+            self.slow_down(start, byte_counter - resume_len)
+
+        if stream is None:
+            self.to_stderr(u"\n")
+            self.report_error(u'Did not get any data blocks')
+            return False
+        stream.close()
+        self.report_finish(data_len_str, (time.time() - start))
+        if data_len is not None and byte_counter != data_len:
+            raise ContentTooShortError(byte_counter, int(data_len))
+        self.try_rename(tmpfilename, filename)
+
+        # Update file modification time
+        if self.params.get('updatetime', True):
+            info_dict['filetime'] = self.try_utime(filename, data.info().get('last-modified', None))
+
+        self._hook_progress({
+            'downloaded_bytes': byte_counter,
+            'total_bytes': byte_counter,
+            'filename': filename,
+            'status': 'finished',
+        })
+
+        return True
+
+    def _hook_progress(self, status):
+        for ph in self._progress_hooks:
+            ph(status)
+
+    def add_progress_hook(self, ph):
+        """ ph gets called on download progress, with a dictionary with the entries
+        * filename: The final filename
+        * status: One of "downloading" and "finished"
+
+        It can also have some of the following entries:
+
+        * downloaded_bytes: Bytes on disks
+        * total_bytes: Total bytes, None if unknown
+        * tmpfilename: The filename we're currently writing to
+        * eta: The estimated time in seconds, None if unknown
+        * speed: The download speed in bytes/second, None if unknown
+
+        Hooks are guaranteed to be called at least once (with status "finished")
+        if the download is successful.
+        """
+        self._progress_hooks.append(ph)