]> Raphaƫl G. Git Repositories - youtubedl/blobdiff - youtube_dl/FileDownloader.py
New test release.
[youtubedl] / youtube_dl / FileDownloader.py
index b43acd19b42a1b7ad8b4c8329657864b35b365b3..155895fe26bb13c11d0e5ae5cec5379a911460df 100644 (file)
@@ -1,12 +1,6 @@
-#!/usr/bin/env python
-# -*- coding: utf-8 -*-
-
-from __future__ import absolute_import
-
 import math
 import os
 import re
-import socket
 import subprocess
 import sys
 import time
@@ -22,85 +16,39 @@ 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.
+    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. 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".
+    options instead.
 
     Available options:
 
-    username:          Username for authentication purposes.
-    password:          Password for authentication purposes.
-    usenetrc:          Use netrc for authentication instead.
+    verbose:           Print additional info to stdout.
     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.
-    restrictfilenames: Do not allow "&" and spaces in file 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
     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.
-    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
     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
-    _ies = []
-    _pps = []
-    _download_retcode = None
-    _num_downloads = None
-    _screen_file = None
 
-    def __init__(self, params):
+    def __init__(self, ydl, 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.ydl = ydl
+        self._progress_hooks = []
         self.params = params
 
-        if '%(stitle)s' in self.params['outtmpl']:
-            self.to_stderr(u'WARNING: %(stitle)s is deprecated. Use the %(title)s and the --restrict-filenames flag(which also secures %(uploader)s et al) instead.')
-
     @staticmethod
     def format_bytes(bytes):
         if bytes is None:
@@ -111,7 +59,7 @@ class FileDownloader(object):
             exponent = 0
         else:
             exponent = int(math.log(bytes, 1024.0))
-        suffix = 'bkMGTPEZY'[exponent]
+        suffix = ['B','KiB','MiB','GiB','TiB','PiB','EiB','ZiB','YiB'][exponent]
         converted = float(bytes) / float(1024 ** exponent)
         return '%.2f%s' % (converted, suffix)
 
@@ -165,34 +113,11 @@ class FileDownloader(object):
         multiplier = 1024.0 ** 'bkmgtpezy'.index(matchobj.group(2).lower())
         return int(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' in getattr(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_screen(self, *args, **kargs):
+        self.ydl.to_screen(*args, **kargs)
 
     def to_stderr(self, message):
-        """Print message to stderr."""
-        assert type(message) == type(u'')
-        output = message + u'\n'
-        if 'b' in getattr(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())
-        sys.stderr.write(output)
+        self.ydl.to_screen(message)
 
     def to_cons_title(self, message):
         """Set console/terminal window title to message."""
@@ -203,26 +128,16 @@ class FileDownloader(object):
             # 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()))
+            self.to_screen('\033]0;%s\007' % message, skip_eol=True)
 
-    def fixed_template(self):
-        """Checks if the output template is fixed."""
-        return (re.search(u'(?u)%\\(.+?\\)s', self.params['outtmpl']) is None)
+    def trouble(self, *args, **kargs):
+        self.ydl.trouble(*args, **kargs)
 
-    def trouble(self, message=None):
-        """Determine action to take when a download problem appears.
+    def report_warning(self, *args, **kargs):
+        self.ydl.report_warning(*args, **kargs)
 
-        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 self.params.get('verbose'):
-            self.to_stderr(u''.join(traceback.format_list(traceback.extract_stack())))
-        if not self.params.get('ignoreerrors', False):
-            raise DownloadError(message)
-        self._download_retcode = 1
+    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."""
@@ -255,7 +170,7 @@ class FileDownloader(object):
                 return
             os.rename(encodeFilename(old_filename), encodeFilename(new_filename))
         except (IOError, OSError) as err:
-            self.trouble(u'ERROR: unable to rename file')
+            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."""
@@ -269,24 +184,15 @@ class FileDownloader(object):
         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_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)
@@ -295,8 +201,13 @@ class FileDownloader(object):
         """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)
+        clear_line = (u'\x1b[K' if sys.stderr.isatty() and os.name != 'nt' else u'')
+        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()))
 
@@ -326,228 +237,31 @@ class FileDownloader(object):
         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'] = int(time.time())
-            template_dict['autonumber'] = u'%05d' % self._num_downloads
-
-            sanitize = lambda k,v: sanitize_filename(
-                u'NA' if v is None else compat_str(v),
-                restricted=self.params.get('restrictfilenames'),
-                is_id=(k==u'id'))
-            template_dict = dict((k, sanitize(k, v)) for k,v in template_dict.items())
-
-            filename = self.params['outtmpl'] % template_dict
-            return filename
-        except (ValueError, KeyError) as 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:
-            matchtitle = matchtitle.decode('utf8')
-            if 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:
-            rejecttitle = rejecttitle.decode('utf8')
-            if 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."""
-
-        # Keep for backwards compatibility
-        info_dict['stitle'] = info_dict['title']
-
-        if not 'format' in info_dict:
-            info_dict['format'] = info_dict['ext']
-
-        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):
-            compat_print(info_dict['title'])
-        if self.params.get('forceurl', False):
-            compat_print(info_dict['url'])
-        if self.params.get('forcethumbnail', False) and 'thumbnail' in info_dict:
-            compat_print(info_dict['thumbnail'])
-        if self.params.get('forcedescription', False) and 'description' in info_dict:
-            compat_print(info_dict['description'])
-        if self.params.get('forcefilename', False) and filename is not None:
-            compat_print(filename)
-        if self.params.get('forceformat', False):
-            compat_print(info_dict['format'])
-
-        # 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) as err:
-            self.trouble(u'ERROR: unable to create directory ' + compat_str(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) as err:
-                    raise UnavailableVideoError()
-                except (compat_urllib_error.URLError, compat_http_client.HTTPException, socket.error) as err:
-                    self.trouble(u'ERROR: unable to download video data: %s' % str(err))
-                    return
-                except (ContentTooShortError, ) as 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) as 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
-
-                # Warn if the _WORKING attribute is False
-                if not ie.working():
-                    self.trouble(u'WARNING: the program functionality for this site has been marked as broken, '
-                                 u'and will probably not work. If you want to go on, use the -i option.')
-
-                # Suitable InfoExtractor found
-                suitable_found = True
-
-                # Extract information from URL and process it
-                videos = ie.extract(url)
-                for video in videos or []:
-                    video['extractor'] = ie.IE_NAME
-                    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):
+    def _download_with_rtmpdump(self, filename, url, player_url, page_url, play_path, tc_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)
+            subprocess.call(['rtmpdump', '-h'], stdout=(open(os.path.devnull, 'w')), stderr=subprocess.STDOUT)
         except (OSError, IOError):
-            self.trouble(u'ERROR: RTMP download detected but "rtmpdump" could not be run')
+            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', '-q'] + [[], ['-W', player_url]][player_url is not None] + ['-r', url, '-o', tmpfilename]
-        args = basic_args + [[], ['-e', '-k', '1']][self.params.get('continuedl', False)]
+        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]
+        args = basic_args + [[], ['--resume', '--skip', '1']][self.params.get('continuedl', False)]
         if self.params.get('verbose', False):
             try:
                 import pipes
@@ -570,31 +284,83 @@ class FileDownloader(object):
                 retval = 0
                 break
         if retval == 0:
-            self.to_screen(u'\r[rtmpdump] %s bytes' % os.path.getsize(encodeFilename(tmpfilename)))
+            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.trouble(u'\nERROR: rtmpdump exited with code %d' % retval)
+            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 _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)
+            self._hook_progress({
+                'filename': filename,
+                'status': 'finished',
+            })
             return True
 
         # Attempt to download using rtmpdump
         if url.startswith('rtmp'):
-            return self._download_with_rtmpdump(filename, url, player_url)
+            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)
 
         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)
 
@@ -651,6 +417,10 @@ class FileDownloader(object):
                             # 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
@@ -663,12 +433,21 @@ class FileDownloader(object):
                 self.report_retry(count, retries)
 
         if count > retries:
-            self.trouble(u'ERROR: giving up after %s retries' % 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)
@@ -690,12 +469,13 @@ class FileDownloader(object):
                     filename = self.undo_temp_name(tmpfilename)
                     self.report_destination(filename)
                 except (OSError, IOError) as err:
-                    self.trouble(u'ERROR: unable to open for writing: %s' % str(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.trouble(u'\nERROR: unable to write data: %s' % str(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))
@@ -709,11 +489,20 @@ class FileDownloader(object):
                 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)
 
+            self._hook_progress({
+                'downloaded_bytes': byte_counter,
+                'total_bytes': data_len,
+                'tmpfilename': tmpfilename,
+                'filename': filename,
+                'status': 'downloading',
+            })
+
             # 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')
+            self.to_stderr(u"\n")
+            self.report_error(u'Did not get any data blocks')
             return False
         stream.close()
         self.report_finish()
@@ -725,4 +514,31 @@ class FileDownloader(object):
         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
+
+        Hooks are guaranteed to be called at least once (with status "finished")
+        if the download is successful.
+        """
+        self._progress_hooks.append(ph)