update from upstream

14 files changed, 447 insertions, 228 deletions

diff --git a/hypervideo_dl/downloader/__init__.py b/hypervideo_dl/downloader/__init__.py
index 2449c74..96d484d 100644
--- a/hypervideo_dl/downloader/__init__.py
+++ b/hypervideo_dl/downloader/__init__.py
@@ -12,10 +12,15 @@ def get_suitable_downloader(info_dict, params={}, default=NO_DEFAULT, protocol=N
     info_copy = info_dict.copy()
     info_copy['to_stdout'] = to_stdout
 
-    downloaders = [_get_suitable_downloader(info_copy, proto, params, default)
-                   for proto in (protocol or info_copy['protocol']).split('+')]
+    protocols = (protocol or info_copy['protocol']).split('+')
+    downloaders = [_get_suitable_downloader(info_copy, proto, params, default) for proto in protocols]
+
     if set(downloaders) == {FFmpegFD} and FFmpegFD.can_merge_formats(info_copy, params):
         return FFmpegFD
+    elif (set(downloaders) == {DashSegmentsFD}
+          and not (to_stdout and len(protocols) > 1)
+          and set(protocols) == {'http_dash_segments_generator'}):
+        return DashSegmentsFD
     elif len(downloaders) == 1:
         return downloaders[0]
     return None
@@ -25,6 +30,7 @@ def get_suitable_downloader(info_dict, params={}, default=NO_DEFAULT, protocol=N
 from .common import FileDownloader
 from .dash import DashSegmentsFD
 from .f4m import F4mFD
+from .fc2 import FC2LiveFD
 from .hls import HlsFD
 from .http import HttpFD
 from .rtmp import RtmpFD
@@ -41,6 +47,7 @@ from .external import (
 
 PROTOCOL_MAP = {
     'rtmp': RtmpFD,
+    'rtmpe': RtmpFD,
     'rtmp_ffmpeg': FFmpegFD,
     'm3u8_native': HlsFD,
     'm3u8': FFmpegFD,
@@ -48,9 +55,11 @@ PROTOCOL_MAP = {
     'rtsp': RtspFD,
     'f4m': F4mFD,
     'http_dash_segments': DashSegmentsFD,
+    'http_dash_segments_generator': DashSegmentsFD,
     'ism': IsmFD,
     'mhtml': MhtmlFD,
     'niconico_dmc': NiconicoDmcFD,
+    'fc2_live': FC2LiveFD,
     'websocket_frag': WebSocketFragmentFD,
     'youtube_live_chat': YoutubeLiveChatFD,
     'youtube_live_chat_replay': YoutubeLiveChatFD,
@@ -62,6 +71,7 @@ def shorten_protocol_name(proto, simplify=False):
         'm3u8_native': 'm3u8_n',
         'rtmp_ffmpeg': 'rtmp_f',
         'http_dash_segments': 'dash',
+        'http_dash_segments_generator': 'dash_g',
         'niconico_dmc': 'dmc',
         'websocket_frag': 'WSfrag',
     }
@@ -70,6 +80,7 @@ def shorten_protocol_name(proto, simplify=False):
             'https': 'http',
             'ftps': 'ftp',
             'm3u8_native': 'm3u8',
+            'http_dash_segments_generator': 'dash',
             'rtmp_ffmpeg': 'rtmp',
             'm3u8_frag_urls': 'm3u8',
             'dash_frag_urls': 'dash',
@@ -108,7 +119,7 @@ def _get_suitable_downloader(info_dict, protocol, params, default):
             return FFmpegFD
         elif (external_downloader or '').lower() == 'native':
             return HlsFD
-        elif get_suitable_downloader(
+        elif protocol == 'm3u8_native' and get_suitable_downloader(
                 info_dict, params, None, protocol='m3u8_frag_urls', to_stdout=info_dict['to_stdout']):
             return HlsFD
         elif params.get('hls_prefer_native') is True:
diff --git a/hypervideo_dl/downloader/common.py b/hypervideo_dl/downloader/common.py
index 27ca2cd..7cef3e8 100644
--- a/hypervideo_dl/downloader/common.py
+++ b/hypervideo_dl/downloader/common.py
@@ -4,14 +4,17 @@ import os
 import re
 import time
 import random
+import errno
 
 from ..utils import (
     decodeArgument,
     encodeFilename,
     error_to_compat_str,
     format_bytes,
+    sanitize_open,
     shell_quote,
     timeconvert,
+    timetuple_from_msec,
 )
 from ..minicurses import (
     MultilineLogger,
@@ -38,6 +41,7 @@ class FileDownloader(object):
     ratelimit:          Download speed limit, in bytes/sec.
     throttledratelimit: Assume the download is being throttled below this speed (bytes/sec)
     retries:            Number of times to retry for HTTP error 5xx
+    file_access_retries:   Number of times to retry on file access error
     buffersize:         Size of download buffer in bytes.
     noresizebuffer:     Do not automatically resize the download buffer.
     continuedl:         Try to continue downloads if possible.
@@ -75,14 +79,12 @@ class FileDownloader(object):
 
     @staticmethod
     def format_seconds(seconds):
-        (mins, secs) = divmod(seconds, 60)
-        (hours, mins) = divmod(mins, 60)
-        if hours > 99:
+        time = timetuple_from_msec(seconds * 1000)
+        if time.hours > 99:
             return '--:--:--'
-        if hours == 0:
-            return '%02d:%02d' % (mins, secs)
-        else:
-            return '%02d:%02d:%02d' % (hours, mins, secs)
+        if not time.hours:
+            return '%02d:%02d' % time[1:-1]
+        return '%02d:%02d:%02d' % time[:-1]
 
     @staticmethod
     def calc_percent(byte_counter, data_len):
@@ -94,6 +96,8 @@ class FileDownloader(object):
     def format_percent(percent):
         if percent is None:
             return '---.-%'
+        elif percent == 100:
+            return '100%'
         return '%6s' % ('%3.1f%%' % percent)
 
     @staticmethod
@@ -155,7 +159,7 @@ class FileDownloader(object):
         return int(round(number * multiplier))
 
     def to_screen(self, *args, **kargs):
-        self.ydl.to_stdout(*args, quiet=self.params.get('quiet'), **kargs)
+        self.ydl.to_screen(*args, quiet=self.params.get('quiet'), **kargs)
 
     def to_stderr(self, message):
         self.ydl.to_stderr(message)
@@ -206,13 +210,41 @@ class FileDownloader(object):
     def ytdl_filename(self, filename):
         return filename + '.ytdl'
 
+    def wrap_file_access(action, *, fatal=False):
+        def outer(func):
+            def inner(self, *args, **kwargs):
+                file_access_retries = self.params.get('file_access_retries', 0)
+                retry = 0
+                while True:
+                    try:
+                        return func(self, *args, **kwargs)
+                    except (IOError, OSError) as err:
+                        retry = retry + 1
+                        if retry > file_access_retries or err.errno not in (errno.EACCES, errno.EINVAL):
+                            if not fatal:
+                                self.report_error(f'unable to {action} file: {err}')
+                                return
+                            raise
+                        self.to_screen(
+                            f'[download] Unable to {action} file due to file access error. '
+                            f'Retrying (attempt {retry} of {self.format_retries(file_access_retries)}) ...')
+                        time.sleep(0.01)
+            return inner
+        return outer
+
+    @wrap_file_access('open', fatal=True)
+    def sanitize_open(self, filename, open_mode):
+        return sanitize_open(filename, open_mode)
+
+    @wrap_file_access('remove')
+    def try_remove(self, filename):
+        os.remove(filename)
+
+    @wrap_file_access('rename')
     def try_rename(self, old_filename, new_filename):
         if old_filename == new_filename:
             return
-        try:
-            os.replace(old_filename, new_filename)
-        except (IOError, OSError) as err:
-            self.report_error(f'unable to rename file: {err}')
+        os.replace(old_filename, new_filename)
 
     def try_utime(self, filename, last_modified_hdr):
         """Try to set the last-modified time of the given file."""
@@ -245,14 +277,32 @@ class FileDownloader(object):
         elif self.ydl.params.get('logger'):
             self._multiline = MultilineLogger(self.ydl.params['logger'], lines)
         elif self.params.get('progress_with_newline'):
-            self._multiline = BreaklineStatusPrinter(self.ydl._screen_file, lines)
+            self._multiline = BreaklineStatusPrinter(self.ydl._out_files['screen'], lines)
         else:
-            self._multiline = MultilinePrinter(self.ydl._screen_file, lines, not self.params.get('quiet'))
+            self._multiline = MultilinePrinter(self.ydl._out_files['screen'], lines, not self.params.get('quiet'))
+        self._multiline.allow_colors = self._multiline._HAVE_FULLCAP and not self.params.get('no_color')
 
     def _finish_multiline_status(self):
         self._multiline.end()
 
-    def _report_progress_status(self, s):
+    _progress_styles = {
+        'downloaded_bytes': 'light blue',
+        'percent': 'light blue',
+        'eta': 'yellow',
+        'speed': 'green',
+        'elapsed': 'bold white',
+        'total_bytes': '',
+        'total_bytes_estimate': '',
+    }
+
+    def _report_progress_status(self, s, default_template):
+        for name, style in self._progress_styles.items():
+            name = f'_{name}_str'
+            if name not in s:
+                continue
+            s[name] = self._format_progress(s[name], style)
+        s['_default_template'] = default_template % s
+
         progress_dict = s.copy()
         progress_dict.pop('info_dict')
         progress_dict = {'info': s['info_dict'], 'progress': progress_dict}
@@ -265,6 +315,10 @@ class FileDownloader(object):
             progress_template.get('download-title') or 'hypervideo %(progress._default_template)s',
             progress_dict))
 
+    def _format_progress(self, *args, **kwargs):
+        return self.ydl._format_text(
+            self._multiline.stream, self._multiline.allow_colors, *args, **kwargs)
+
     def report_progress(self, s):
         if s['status'] == 'finished':
             if self.params.get('noprogress'):
@@ -277,8 +331,7 @@ class FileDownloader(object):
                 s['_elapsed_str'] = self.format_seconds(s['elapsed'])
                 msg_template += ' in %(_elapsed_str)s'
             s['_percent_str'] = self.format_percent(100)
-            s['_default_template'] = msg_template % s
-            self._report_progress_status(s)
+            self._report_progress_status(s, msg_template)
             return
 
         if s['status'] != 'downloading':
@@ -287,7 +340,7 @@ class FileDownloader(object):
         if s.get('eta') is not None:
             s['_eta_str'] = self.format_eta(s['eta'])
         else:
-            s['_eta_str'] = 'Unknown ETA'
+            s['_eta_str'] = 'Unknown'
 
         if s.get('total_bytes') and s.get('downloaded_bytes') is not None:
             s['_percent_str'] = self.format_percent(100 * s['downloaded_bytes'] / s['total_bytes'])
@@ -319,9 +372,12 @@ class FileDownloader(object):
                 else:
                     msg_template = '%(_downloaded_bytes_str)s at %(_speed_str)s'
             else:
-                msg_template = '%(_percent_str)s % at %(_speed_str)s ETA %(_eta_str)s'
-        s['_default_template'] = msg_template % s
-        self._report_progress_status(s)
+                msg_template = '%(_percent_str)s at %(_speed_str)s ETA %(_eta_str)s'
+        if s.get('fragment_index') and s.get('fragment_count'):
+            msg_template += ' (frag %(fragment_index)s/%(fragment_count)s)'
+        elif s.get('fragment_index'):
+            msg_template += ' (frag %(fragment_index)s)'
+        self._report_progress_status(s, msg_template)
 
     def report_resuming_byte(self, resume_len):
         """Report attempt to resume at given byte."""
@@ -372,6 +428,7 @@ class FileDownloader(object):
                     'status': 'finished',
                     'total_bytes': os.path.getsize(encodeFilename(filename)),
                 }, info_dict)
+                self._finish_multiline_status()
                 return True, False
 
         if subtitle is False:
diff --git a/hypervideo_dl/downloader/dash.py b/hypervideo_dl/downloader/dash.py
index 6444ad6..a845ee7 100644
--- a/hypervideo_dl/downloader/dash.py
+++ b/hypervideo_dl/downloader/dash.py
@@ -1,4 +1,5 @@
 from __future__ import unicode_literals
+import time
 
 from ..downloader import get_suitable_downloader
 from .fragment import FragmentFD
@@ -15,27 +16,53 @@ class DashSegmentsFD(FragmentFD):
     FD_NAME = 'dashsegments'
 
     def real_download(self, filename, info_dict):
-        if info_dict.get('is_live'):
+        if info_dict.get('is_live') and set(info_dict['protocol'].split('+')) != {'http_dash_segments_generator'}:
             self.report_error('Live DASH videos are not supported')
 
-        fragment_base_url = info_dict.get('fragment_base_url')
-        fragments = info_dict['fragments'][:1] if self.params.get(
-            'test', False) else info_dict['fragments']
-
+        real_start = time.time()
         real_downloader = get_suitable_downloader(
             info_dict, self.params, None, protocol='dash_frag_urls', to_stdout=(filename == '-'))
 
-        ctx = {
-            'filename': filename,
-            'total_frags': len(fragments),
-        }
+        requested_formats = [{**info_dict, **fmt} for fmt in info_dict.get('requested_formats', [])]
+        args = []
+        for fmt in requested_formats or [info_dict]:
+            try:
+                fragment_count = 1 if self.params.get('test') else len(fmt['fragments'])
+            except TypeError:
+                fragment_count = None
+            ctx = {
+                'filename': fmt.get('filepath') or filename,
+                'live': 'is_from_start' if fmt.get('is_from_start') else fmt.get('is_live'),
+                'total_frags': fragment_count,
+            }
+
+            if real_downloader:
+                self._prepare_external_frag_download(ctx)
+            else:
+                self._prepare_and_start_frag_download(ctx, fmt)
+            ctx['start'] = real_start
+
+            fragments_to_download = self._get_fragments(fmt, ctx)
+
+            if real_downloader:
+                self.to_screen(
+                    '[%s] Fragment downloads will be delegated to %s' % (self.FD_NAME, real_downloader.get_basename()))
+                info_dict['fragments'] = list(fragments_to_download)
+                fd = real_downloader(self.ydl, self.params)
+                return fd.real_download(filename, info_dict)
+
+            args.append([ctx, fragments_to_download, fmt])
 
-        if real_downloader:
-            self._prepare_external_frag_download(ctx)
-        else:
-            self._prepare_and_start_frag_download(ctx, info_dict)
+        return self.download_and_append_fragments_multiple(*args)
+
+    def _resolve_fragments(self, fragments, ctx):
+        fragments = fragments(ctx) if callable(fragments) else fragments
+        return [next(iter(fragments))] if self.params.get('test') else fragments
+
+    def _get_fragments(self, fmt, ctx):
+        fragment_base_url = fmt.get('fragment_base_url')
+        fragments = self._resolve_fragments(fmt['fragments'], ctx)
 
-        fragments_to_download = []
         frag_index = 0
         for i, fragment in enumerate(fragments):
             frag_index += 1
@@ -46,17 +73,8 @@ class DashSegmentsFD(FragmentFD):
                 assert fragment_base_url
                 fragment_url = urljoin(fragment_base_url, fragment['path'])
 
-            fragments_to_download.append({
+            yield {
                 'frag_index': frag_index,
                 'index': i,
                 'url': fragment_url,
-            })
-
-        if real_downloader:
-            self.to_screen(
-                '[%s] Fragment downloads will be delegated to %s' % (self.FD_NAME, real_downloader.get_basename()))
-            info_dict['fragments'] = fragments_to_download
-            fd = real_downloader(self.ydl, self.params)
-            return fd.real_download(filename, info_dict)
-
-        return self.download_and_append_fragments(ctx, fragments_to_download, info_dict)
+            }
diff --git a/hypervideo_dl/downloader/external.py b/hypervideo_dl/downloader/external.py
index 74adb05..b99dc37 100644
--- a/hypervideo_dl/downloader/external.py
+++ b/hypervideo_dl/downloader/external.py
@@ -13,17 +13,18 @@ from ..compat import (
 )
 from ..postprocessor.ffmpeg import FFmpegPostProcessor, EXT_TO_OUT_FORMATS
 from ..utils import (
+    classproperty,
     cli_option,
     cli_valueless_option,
     cli_bool_option,
     _configuration_args,
+    determine_ext,
     encodeFilename,
     encodeArgument,
     handle_youtubedl_headers,
     check_executable,
-    is_outdated_version,
-    process_communicate_or_kill,
-    sanitize_open,
+    Popen,
+    remove_end,
 )
 
 
@@ -73,17 +74,23 @@ class ExternalFD(FragmentFD):
     def get_basename(cls):
         return cls.__name__[:-2].lower()
 
+    @classproperty
+    def EXE_NAME(cls):
+        return cls.get_basename()
+
     @property
     def exe(self):
-        return self.get_basename()
+        return self.EXE_NAME
 
     @classmethod
     def available(cls, path=None):
-        path = check_executable(path or cls.get_basename(), [cls.AVAILABLE_OPT])
-        if path:
-            cls.exe = path
-            return path
-        return False
+        path = check_executable(
+            cls.EXE_NAME if path in (None, cls.get_basename()) else path,
+            [cls.AVAILABLE_OPT])
+        if not path:
+            return False
+        cls.exe = path
+        return path
 
     @classmethod
     def supports(cls, info_dict):
@@ -106,7 +113,7 @@ class ExternalFD(FragmentFD):
 
     def _configuration_args(self, keys=None, *args, **kwargs):
         return _configuration_args(
-            self.get_basename(), self.params.get('external_downloader_args'), self.get_basename(),
+            self.get_basename(), self.params.get('external_downloader_args'), self.EXE_NAME,
             keys, *args, **kwargs)
 
     def _call_downloader(self, tmpfilename, info_dict):
@@ -116,9 +123,8 @@ class ExternalFD(FragmentFD):
         self._debug_cmd(cmd)
 
         if 'fragments' not in info_dict:
-            p = subprocess.Popen(
-                cmd, stderr=subprocess.PIPE)
-            _, stderr = process_communicate_or_kill(p)
+            p = Popen(cmd, stderr=subprocess.PIPE)
+            _, stderr = p.communicate_or_kill()
             if p.returncode != 0:
                 self.to_stderr(stderr.decode('utf-8', 'replace'))
             return p.returncode
@@ -128,9 +134,8 @@ class ExternalFD(FragmentFD):
 
         count = 0
         while count <= fragment_retries:
-            p = subprocess.Popen(
-                cmd, stderr=subprocess.PIPE)
-            _, stderr = process_communicate_or_kill(p)
+            p = Popen(cmd, stderr=subprocess.PIPE)
+            _, stderr = p.communicate_or_kill()
             if p.returncode == 0:
                 break
             # TODO: Decide whether to retry based on error code
@@ -147,23 +152,23 @@ class ExternalFD(FragmentFD):
                 return -1
 
         decrypt_fragment = self.decrypter(info_dict)
-        dest, _ = sanitize_open(tmpfilename, 'wb')
+        dest, _ = self.sanitize_open(tmpfilename, 'wb')
         for frag_index, fragment in enumerate(info_dict['fragments']):
             fragment_filename = '%s-Frag%d' % (tmpfilename, frag_index)
             try:
-                src, _ = sanitize_open(fragment_filename, 'rb')
-            except IOError:
+                src, _ = self.sanitize_open(fragment_filename, 'rb')
+            except IOError as err:
                 if skip_unavailable_fragments and frag_index > 1:
-                    self.to_screen('[%s] Skipping fragment %d ...' % (self.get_basename(), frag_index))
+                    self.report_skip_fragment(frag_index, err)
                     continue
-                self.report_error('Unable to open fragment %d' % frag_index)
+                self.report_error(f'Unable to open fragment {frag_index}; {err}')
                 return -1
             dest.write(decrypt_fragment(fragment, src.read()))
             src.close()
             if not self.params.get('keep_fragments', False):
-                os.remove(encodeFilename(fragment_filename))
+                self.try_remove(encodeFilename(fragment_filename))
         dest.close()
-        os.remove(encodeFilename('%s.frag.urls' % tmpfilename))
+        self.try_remove(encodeFilename('%s.frag.urls' % tmpfilename))
         return 0
 
 
@@ -171,7 +176,7 @@ class CurlFD(ExternalFD):
     AVAILABLE_OPT = '-V'
 
     def _make_cmd(self, tmpfilename, info_dict):
-        cmd = [self.exe, '--location', '-o', tmpfilename]
+        cmd = [self.exe, '--location', '-o', tmpfilename, '--compressed']
         if info_dict.get('http_headers') is not None:
             for key, val in info_dict['http_headers'].items():
                 cmd += ['--header', '%s: %s' % (key, val)]
@@ -199,8 +204,8 @@ class CurlFD(ExternalFD):
         self._debug_cmd(cmd)
 
         # curl writes the progress to stderr so don't capture it.
-        p = subprocess.Popen(cmd)
-        process_communicate_or_kill(p)
+        p = Popen(cmd)
+        p.communicate_or_kill()
         return p.returncode
 
 
@@ -221,7 +226,7 @@ class WgetFD(ExternalFD):
     AVAILABLE_OPT = '--version'
 
     def _make_cmd(self, tmpfilename, info_dict):
-        cmd = [self.exe, '-O', tmpfilename, '-nv', '--no-cookies']
+        cmd = [self.exe, '-O', tmpfilename, '-nv', '--no-cookies', '--compression=auto']
         if info_dict.get('http_headers') is not None:
             for key, val in info_dict['http_headers'].items():
                 cmd += ['--header', '%s: %s' % (key, val)]
@@ -232,7 +237,10 @@ class WgetFD(ExternalFD):
                 retry[1] = '0'
             cmd += retry
         cmd += self._option('--bind-address', 'source_address')
-        cmd += self._option('--proxy', 'proxy')
+        proxy = self.params.get('proxy')
+        if proxy:
+            for var in ('http_proxy', 'https_proxy'):
+                cmd += ['--execute', '%s=%s' % (var, proxy)]
         cmd += self._valueless_option('--no-check-certificate', 'nocheckcertificate')
         cmd += self._configuration_args()
         cmd += ['--', info_dict['url']]
@@ -255,7 +263,7 @@ class Aria2cFD(ExternalFD):
     def _make_cmd(self, tmpfilename, info_dict):
         cmd = [self.exe, '-c',
                '--console-log-level=warn', '--summary-interval=0', '--download-result=hide',
-               '--file-allocation=none', '-x16', '-j16', '-s16']
+               '--http-accept-gzip=true', '--file-allocation=none', '-x16', '-j16', '-s16']
         if 'fragments' in info_dict:
             cmd += ['--allow-overwrite=true', '--allow-piece-length-change=true']
         else:
@@ -269,6 +277,7 @@ class Aria2cFD(ExternalFD):
         cmd += self._option('--all-proxy', 'proxy')
         cmd += self._bool_option('--check-certificate', 'nocheckcertificate', 'false', 'true', '=')
         cmd += self._bool_option('--remote-time', 'updatetime', 'true', 'false', '=')
+        cmd += self._bool_option('--show-console-readout', 'noprogress', 'false', 'true', '=')
         cmd += self._configuration_args()
 
         # aria2c strips out spaces from the beginning/end of filenames and paths.
@@ -293,7 +302,7 @@ class Aria2cFD(ExternalFD):
             for frag_index, fragment in enumerate(info_dict['fragments']):
                 fragment_filename = '%s-Frag%d' % (os.path.basename(tmpfilename), frag_index)
                 url_list.append('%s\n\tout=%s' % (fragment['url'], fragment_filename))
-            stream, _ = sanitize_open(url_list_file, 'wb')
+            stream, _ = self.sanitize_open(url_list_file, 'wb')
             stream.write('\n'.join(url_list).encode('utf-8'))
             stream.close()
             cmd += ['-i', url_list_file]
@@ -304,10 +313,7 @@ class Aria2cFD(ExternalFD):
 
 class HttpieFD(ExternalFD):
     AVAILABLE_OPT = '--version'
-
-    @classmethod
-    def available(cls, path=None):
-        return ExternalFD.available(cls, path or 'http')
+    EXE_NAME = 'http'
 
     def _make_cmd(self, tmpfilename, info_dict):
         cmd = ['http', '--download', '--output', tmpfilename, info_dict['url']]
@@ -446,8 +452,7 @@ class FFmpegFD(ExternalFD):
         if info_dict.get('requested_formats') or protocol == 'http_dash_segments':
             for (i, fmt) in enumerate(info_dict.get('requested_formats') or [info_dict]):
                 stream_number = fmt.get('manifest_stream_number', 0)
-                a_or_v = 'a' if fmt.get('acodec') != 'none' else 'v'
-                args.extend(['-map', f'{i}:{a_or_v}:{stream_number}'])
+                args.extend(['-map', f'{i}:{stream_number}'])
 
         if self.params.get('test', False):
             args += ['-fs', compat_str(self._TEST_FILE_SIZE)]
@@ -461,12 +466,21 @@ class FFmpegFD(ExternalFD):
                 args += ['-f', 'mpegts']
             else:
                 args += ['-f', 'mp4']
-                if (ffpp.basename == 'ffmpeg' and is_outdated_version(ffpp._versions['ffmpeg'], '3.2', False)) and (not info_dict.get('acodec') or info_dict['acodec'].split('.')[0] in ('aac', 'mp4a')):
+                if (ffpp.basename == 'ffmpeg' and ffpp._features.get('needs_adtstoasc')) and (not info_dict.get('acodec') or info_dict['acodec'].split('.')[0] in ('aac', 'mp4a')):
                     args += ['-bsf:a', 'aac_adtstoasc']
         elif protocol == 'rtmp':
             args += ['-f', 'flv']
         elif ext == 'mp4' and tmpfilename == '-':
             args += ['-f', 'mpegts']
+        elif ext == 'unknown_video':
+            ext = determine_ext(remove_end(tmpfilename, '.part'))
+            if ext == 'unknown_video':
+                self.report_warning(
+                    'The video format is unknown and cannot be downloaded by ffmpeg. '
+                    'Explicitly set the extension in the filename to attempt download in that format')
+            else:
+                self.report_warning(f'The video format is unknown. Trying to download as {ext} according to the filename')
+                args += ['-f', EXT_TO_OUT_FORMATS.get(ext, ext)]
         else:
             args += ['-f', EXT_TO_OUT_FORMATS.get(ext, ext)]
 
@@ -476,7 +490,7 @@ class FFmpegFD(ExternalFD):
         args.append(encodeFilename(ffpp._ffmpeg_filename_argument(tmpfilename), True))
         self._debug_cmd(args)
 
-        proc = subprocess.Popen(args, stdin=subprocess.PIPE, env=env)
+        proc = Popen(args, stdin=subprocess.PIPE, env=env)
         if url in ('-', 'pipe:'):
             self.on_process_started(proc, proc.stdin)
         try:
@@ -488,7 +502,7 @@ class FFmpegFD(ExternalFD):
             # streams). Note that Windows is not affected and produces playable
             # files (see https://github.com/ytdl-org/youtube-dl/issues/8300).
             if isinstance(e, KeyboardInterrupt) and sys.platform != 'win32' and url not in ('-', 'pipe:'):
-                process_communicate_or_kill(proc, b'q')
+                proc.communicate_or_kill(b'q')
             else:
                 proc.kill()
                 proc.wait()
@@ -500,11 +514,13 @@ class AVconvFD(FFmpegFD):
     pass
 
 
-_BY_NAME = dict(
-    (klass.get_basename(), klass)
+_BY_NAME = {
+    klass.get_basename(): klass
     for name, klass in globals().items()
     if name.endswith('FD') and name not in ('ExternalFD', 'FragmentFD')
-)
+}
+
+_BY_EXE = {klass.EXE_NAME: klass for klass in _BY_NAME.values()}
 
 
 def list_external_downloaders():
@@ -516,4 +532,4 @@ def get_external_downloader(external_downloader):
         downloader . """
     # Drop .exe extension on Windows
     bn = os.path.splitext(os.path.basename(external_downloader))[0]
-    return _BY_NAME.get(bn)
+    return _BY_NAME.get(bn, _BY_EXE.get(bn))
diff --git a/hypervideo_dl/downloader/f4m.py b/hypervideo_dl/downloader/f4m.py
index 9da2776..0008b7c 100644
--- a/hypervideo_dl/downloader/f4m.py
+++ b/hypervideo_dl/downloader/f4m.py
@@ -366,7 +366,7 @@ class F4mFD(FragmentFD):
         ctx = {
             'filename': filename,
             'total_frags': total_frags,
-            'live': live,
+            'live': bool(live),
         }
 
         self._prepare_frag_download(ctx)
diff --git a/hypervideo_dl/downloader/fc2.py b/hypervideo_dl/downloader/fc2.py
new file mode 100644
index 0000000..157bcf2
--- /dev/null
+++ b/hypervideo_dl/downloader/fc2.py
@@ -0,0 +1,41 @@
+from __future__ import division, unicode_literals
+
+import threading
+
+from .common import FileDownloader
+from .external import FFmpegFD
+
+
+class FC2LiveFD(FileDownloader):
+    """
+    Downloads FC2 live without being stopped. <br>
+    Note, this is not a part of public API, and will be removed without notice.
+    DO NOT USE
+    """
+
+    def real_download(self, filename, info_dict):
+        ws = info_dict['ws']
+
+        heartbeat_lock = threading.Lock()
+        heartbeat_state = [None, 1]
+
+        def heartbeat():
+            try:
+                heartbeat_state[1] += 1
+                ws.send('{"name":"heartbeat","arguments":{},"id":%d}' % heartbeat_state[1])
+            except Exception:
+                self.to_screen('[fc2:live] Heartbeat failed')
+
+            with heartbeat_lock:
+                heartbeat_state[0] = threading.Timer(30, heartbeat)
+                heartbeat_state[0]._daemonic = True
+                heartbeat_state[0].start()
+
+        heartbeat()
+
+        new_info_dict = info_dict.copy()
+        new_info_dict.update({
+            'ws': None,
+            'protocol': 'live_ffmpeg',
+        })
+        return FFmpegFD(self.ydl, self.params or {}).download(filename, new_info_dict)
diff --git a/hypervideo_dl/downloader/fragment.py b/hypervideo_dl/downloader/fragment.py
index 57068db..a991c6d 100644
--- a/hypervideo_dl/downloader/fragment.py
+++ b/hypervideo_dl/downloader/fragment.py
@@ -1,9 +1,10 @@
 from __future__ import division, unicode_literals
 
+import http.client
+import json
+import math
 import os
 import time
-import json
-from math import ceil
 
 try:
     import concurrent.futures
@@ -13,8 +14,9 @@ except ImportError:
 
 from .common import FileDownloader
 from .http import HttpFD
-from ..aes import aes_cbc_decrypt_bytes
+from ..aes import aes_cbc_decrypt_bytes, unpad_pkcs7
 from ..compat import (
+    compat_os_name,
     compat_urllib_error,
     compat_struct_pack,
 )
@@ -22,8 +24,8 @@ from ..utils import (
     DownloadError,
     error_to_compat_str,
     encodeFilename,
-    sanitize_open,
     sanitized_Request,
+    traverse_obj,
 )
 
 
@@ -31,6 +33,10 @@ class HttpQuietDownloader(HttpFD):
     def to_screen(self, *args, **kargs):
         pass
 
+    def report_retry(self, err, count, retries):
+        super().to_screen(
+            f'[download] Got server HTTP error: {err}. Retrying (attempt {count} of {self.format_retries(retries)}) ...')
+
 
 class FragmentFD(FileDownloader):
     """
@@ -44,6 +50,7 @@ class FragmentFD(FileDownloader):
                         Skip unavailable fragments (DASH and hlsnative only)
     keep_fragments:     Keep downloaded fragments on disk after downloading is
                         finished
+    concurrent_fragment_downloads:  The number of threads to use for native hls and dash downloads
     _no_ytdl_file:      Don't use .ytdl file
 
     For each incomplete fragment download hypervideo keeps on disk a special
@@ -72,8 +79,9 @@ class FragmentFD(FileDownloader):
             '\r[download] Got server HTTP error: %s. Retrying fragment %d (attempt %d of %s) ...'
             % (error_to_compat_str(err), frag_index, count, self.format_retries(retries)))
 
-    def report_skip_fragment(self, frag_index):
-        self.to_screen('[download] Skipping fragment %d ...' % frag_index)
+    def report_skip_fragment(self, frag_index, err=None):
+        err = f' {err};' if err else ''
+        self.to_screen(f'[download]{err} Skipping fragment {frag_index:d} ...')
 
     def _prepare_url(self, info_dict, url):
         headers = info_dict.get('http_headers')
@@ -84,11 +92,11 @@ class FragmentFD(FileDownloader):
         self._start_frag_download(ctx, info_dict)
 
     def __do_ytdl_file(self, ctx):
-        return not ctx['live'] and not ctx['tmpfilename'] == '-' and not self.params.get('_no_ytdl_file')
+        return ctx['live'] is not True and ctx['tmpfilename'] != '-' and not self.params.get('_no_ytdl_file')
 
     def _read_ytdl_file(self, ctx):
         assert 'ytdl_corrupt' not in ctx
-        stream, _ = sanitize_open(self.ytdl_filename(ctx['filename']), 'r')
+        stream, _ = self.sanitize_open(self.ytdl_filename(ctx['filename']), 'r')
         try:
             ytdl_data = json.loads(stream.read())
             ctx['fragment_index'] = ytdl_data['downloader']['current_fragment']['index']
@@ -100,7 +108,7 @@ class FragmentFD(FileDownloader):
             stream.close()
 
     def _write_ytdl_file(self, ctx):
-        frag_index_stream, _ = sanitize_open(self.ytdl_filename(ctx['filename']), 'w')
+        frag_index_stream, _ = self.sanitize_open(self.ytdl_filename(ctx['filename']), 'w')
         try:
             downloader = {
                 'current_fragment': {
@@ -125,14 +133,19 @@ class FragmentFD(FileDownloader):
         }
         success = ctx['dl'].download(fragment_filename, fragment_info_dict)
         if not success:
-            return False, None
+            return False
         if fragment_info_dict.get('filetime'):
             ctx['fragment_filetime'] = fragment_info_dict.get('filetime')
         ctx['fragment_filename_sanitized'] = fragment_filename
-        return True, self._read_fragment(ctx)
+        return True
 
     def _read_fragment(self, ctx):
-        down, frag_sanitized = sanitize_open(ctx['fragment_filename_sanitized'], 'rb')
+        try:
+            down, frag_sanitized = self.sanitize_open(ctx['fragment_filename_sanitized'], 'rb')
+        except FileNotFoundError:
+            if ctx.get('live'):
+                return None
+            raise
         ctx['fragment_filename_sanitized'] = frag_sanitized
         frag_content = down.read()
         down.close()
@@ -146,7 +159,7 @@ class FragmentFD(FileDownloader):
             if self.__do_ytdl_file(ctx):
                 self._write_ytdl_file(ctx)
             if not self.params.get('keep_fragments', False):
-                os.remove(encodeFilename(ctx['fragment_filename_sanitized']))
+                self.try_remove(encodeFilename(ctx['fragment_filename_sanitized']))
             del ctx['fragment_filename_sanitized']
 
     def _prepare_frag_download(self, ctx):
@@ -165,8 +178,8 @@ class FragmentFD(FileDownloader):
         dl = HttpQuietDownloader(
             self.ydl,
             {
-                'continuedl': True,
-                'quiet': True,
+                'continuedl': self.params.get('continuedl', True),
+                'quiet': self.params.get('quiet'),
                 'noprogress': True,
                 'ratelimit': self.params.get('ratelimit'),
                 'retries': self.params.get('retries', 0),
@@ -208,7 +221,7 @@ class FragmentFD(FileDownloader):
                 self._write_ytdl_file(ctx)
                 assert ctx['fragment_index'] == 0
 
-        dest_stream, tmpfilename = sanitize_open(tmpfilename, open_mode)
+        dest_stream, tmpfilename = self.sanitize_open(tmpfilename, open_mode)
 
         ctx.update({
             'dl': dl,
@@ -236,6 +249,7 @@ class FragmentFD(FileDownloader):
         start = time.time()
         ctx.update({
             'started': start,
+            'fragment_started': start,
             # Amount of fragment's bytes downloaded by the time of the previous
             # frag progress hook invocation
             'prev_frag_downloaded_bytes': 0,
@@ -266,6 +280,9 @@ class FragmentFD(FileDownloader):
                 ctx['fragment_index'] = state['fragment_index']
                 state['downloaded_bytes'] += frag_total_bytes - ctx['prev_frag_downloaded_bytes']
                 ctx['complete_frags_downloaded_bytes'] = state['downloaded_bytes']
+                ctx['speed'] = state['speed'] = self.calc_speed(
+                    ctx['fragment_started'], time_now, frag_total_bytes)
+                ctx['fragment_started'] = time.time()
                 ctx['prev_frag_downloaded_bytes'] = 0
             else:
                 frag_downloaded_bytes = s['downloaded_bytes']
@@ -274,8 +291,8 @@ class FragmentFD(FileDownloader):
                     state['eta'] = self.calc_eta(
                         start, time_now, estimated_size - resume_len,
                         state['downloaded_bytes'] - resume_len)
-                state['speed'] = s.get('speed') or ctx.get('speed')
-                ctx['speed'] = state['speed']
+                ctx['speed'] = state['speed'] = self.calc_speed(
+                    ctx['fragment_started'], time_now, frag_downloaded_bytes)
                 ctx['prev_frag_downloaded_bytes'] = frag_downloaded_bytes
             self._hook_progress(state, info_dict)
 
@@ -288,7 +305,7 @@ class FragmentFD(FileDownloader):
         if self.__do_ytdl_file(ctx):
             ytdl_filename = encodeFilename(self.ytdl_filename(ctx['filename']))
             if os.path.isfile(ytdl_filename):
-                os.remove(ytdl_filename)
+                self.try_remove(ytdl_filename)
         elapsed = time.time() - ctx['started']
 
         if ctx['tmpfilename'] == '-':
@@ -355,9 +372,7 @@ class FragmentFD(FileDownloader):
             # not what it decrypts to.
             if self.params.get('test', False):
                 return frag_content
-            padding_len = 16 - (len(frag_content) % 16)
-            decrypted_data = aes_cbc_decrypt_bytes(frag_content + bytes([padding_len] * padding_len), decrypt_info['KEY'], iv)
-            return decrypted_data[:-decrypted_data[-1]]
+            return unpad_pkcs7(aes_cbc_decrypt_bytes(frag_content, decrypt_info['KEY'], iv))
 
         return decrypt_fragment
 
@@ -366,64 +381,105 @@ class FragmentFD(FileDownloader):
         @params (ctx1, fragments1, info_dict1), (ctx2, fragments2, info_dict2), ...
                 all args must be either tuple or list
         '''
+        interrupt_trigger = [True]
         max_progress = len(args)
         if max_progress == 1:
             return self.download_and_append_fragments(*args[0], pack_func=pack_func, finish_func=finish_func)
-        max_workers = self.params.get('concurrent_fragment_downloads', max_progress)
-        self._prepare_multiline_status(max_progress)
+        max_workers = self.params.get('concurrent_fragment_downloads', 1)
+        if max_progress > 1:
+            self._prepare_multiline_status(max_progress)
+        is_live = any(traverse_obj(args, (..., 2, 'is_live'), default=[]))
 
         def thread_func(idx, ctx, fragments, info_dict, tpe):
             ctx['max_progress'] = max_progress
             ctx['progress_idx'] = idx
-            return self.download_and_append_fragments(ctx, fragments, info_dict, pack_func=pack_func, finish_func=finish_func, tpe=tpe)
+            return self.download_and_append_fragments(
+                ctx, fragments, info_dict, pack_func=pack_func, finish_func=finish_func,
+                tpe=tpe, interrupt_trigger=interrupt_trigger)
 
         class FTPE(concurrent.futures.ThreadPoolExecutor):
             # has to stop this or it's going to wait on the worker thread itself
             def __exit__(self, exc_type, exc_val, exc_tb):
                 pass
 
+        if compat_os_name == 'nt':
+            def future_result(future):
+                while True:
+                    try:
+                        return future.result(0.1)
+                    except KeyboardInterrupt:
+                        raise
+                    except concurrent.futures.TimeoutError:
+                        continue
+        else:
+            def future_result(future):
+                return future.result()
+
+        def interrupt_trigger_iter(fg):
+            for f in fg:
+                if not interrupt_trigger[0]:
+                    break
+                yield f
+
         spins = []
         for idx, (ctx, fragments, info_dict) in enumerate(args):
-            tpe = FTPE(ceil(max_workers / max_progress))
-            job = tpe.submit(thread_func, idx, ctx, fragments, info_dict, tpe)
+            tpe = FTPE(math.ceil(max_workers / max_progress))
+            job = tpe.submit(thread_func, idx, ctx, interrupt_trigger_iter(fragments), info_dict, tpe)
             spins.append((tpe, job))
 
         result = True
         for tpe, job in spins:
             try:
-                result = result and job.result()
+                result = result and future_result(job)
+            except KeyboardInterrupt:
+                interrupt_trigger[0] = False
             finally:
                 tpe.shutdown(wait=True)
+        if not interrupt_trigger[0] and not is_live:
+            raise KeyboardInterrupt()
+        # we expect the user wants to stop and DO WANT the preceding postprocessors to run;
+        # so returning a intermediate result here instead of KeyboardInterrupt on live
         return result
 
-    def download_and_append_fragments(self, ctx, fragments, info_dict, *, pack_func=None, finish_func=None, tpe=None):
+    def download_and_append_fragments(
+            self, ctx, fragments, info_dict, *, pack_func=None, finish_func=None,
+            tpe=None, interrupt_trigger=None):
+        if not interrupt_trigger:
+            interrupt_trigger = (True, )
+
         fragment_retries = self.params.get('fragment_retries', 0)
-        is_fatal = (lambda idx: idx == 0) if self.params.get('skip_unavailable_fragments', True) else (lambda _: True)
+        is_fatal = (
+            ((lambda _: False) if info_dict.get('is_live') else (lambda idx: idx == 0))
+            if self.params.get('skip_unavailable_fragments', True) else (lambda _: True))
+
         if not pack_func:
             pack_func = lambda frag_content, _: frag_content
 
         def download_fragment(fragment, ctx):
+            if not interrupt_trigger[0]:
+                return
+
             frag_index = ctx['fragment_index'] = fragment['frag_index']
+            ctx['last_error'] = None
             headers = info_dict.get('http_headers', {}).copy()
             byte_range = fragment.get('byte_range')
             if byte_range:
                 headers['Range'] = 'bytes=%d-%d' % (byte_range['start'], byte_range['end'] - 1)
 
             # Never skip the first fragment
-            fatal = is_fatal(fragment.get('index') or (frag_index - 1))
-            count, frag_content = 0, None
+            fatal, count = is_fatal(fragment.get('index') or (frag_index - 1)), 0
             while count <= fragment_retries:
                 try:
-                    success, frag_content = self._download_fragment(ctx, fragment['url'], info_dict, headers)
-                    if not success:
-                        return False, frag_index
-                    break
-                except compat_urllib_error.HTTPError as err:
+                    if self._download_fragment(ctx, fragment['url'], info_dict, headers):
+                        break
+                    return
+                except (compat_urllib_error.HTTPError, http.client.IncompleteRead) as err:
                     # Unavailable (possibly temporary) fragments may be served.
                     # First we try to retry then either skip or abort.
                     # See https://github.com/ytdl-org/youtube-dl/issues/10165,
                     # https://github.com/ytdl-org/youtube-dl/issues/10448).
                     count += 1
+                    ctx['last_error'] = err
                     if count <= fragment_retries:
                         self.report_retry_fragment(err, frag_index, count, fragment_retries)
                 except DownloadError:
@@ -433,49 +489,46 @@ class FragmentFD(FileDownloader):
                         break
                     raise
 
-            if count > fragment_retries:
-                if not fatal:
-                    return False, frag_index
+            if count > fragment_retries and fatal:
                 ctx['dest_stream'].close()
                 self.report_error('Giving up after %s fragment retries' % fragment_retries)
-                return False, frag_index
-            return frag_content, frag_index
 
         def append_fragment(frag_content, frag_index, ctx):
-            if not frag_content:
-                if not is_fatal(frag_index - 1):
-                    self.report_skip_fragment(frag_index)
-                    return True
-                else:
-                    ctx['dest_stream'].close()
-                    self.report_error(
-                        'fragment %s not found, unable to continue' % frag_index)
-                    return False
-            self._append_fragment(ctx, pack_func(frag_content, frag_index))
+            if frag_content:
+                self._append_fragment(ctx, pack_func(frag_content, frag_index))
+            elif not is_fatal(frag_index - 1):
+                self.report_skip_fragment(frag_index, 'fragment not found')
+            else:
+                ctx['dest_stream'].close()
+                self.report_error(f'fragment {frag_index} not found, unable to continue')
+                return False
             return True
 
         decrypt_fragment = self.decrypter(info_dict)
 
-        max_workers = self.params.get('concurrent_fragment_downloads', 1)
+        max_workers = math.ceil(
+            self.params.get('concurrent_fragment_downloads', 1) / ctx.get('max_progress', 1))
         if can_threaded_download and max_workers > 1:
 
             def _download_fragment(fragment):
                 ctx_copy = ctx.copy()
-                frag_content, frag_index = download_fragment(fragment, ctx_copy)
-                return fragment, frag_content, frag_index, ctx_copy.get('fragment_filename_sanitized')
+                download_fragment(fragment, ctx_copy)
+                return fragment, fragment['frag_index'], ctx_copy.get('fragment_filename_sanitized')
 
             self.report_warning('The download speed shown is only of one thread. This is a known issue and patches are welcome')
             with tpe or concurrent.futures.ThreadPoolExecutor(max_workers) as pool:
-                for fragment, frag_content, frag_index, frag_filename in pool.map(_download_fragment, fragments):
+                for fragment, frag_index, frag_filename in pool.map(_download_fragment, fragments):
                     ctx['fragment_filename_sanitized'] = frag_filename
                     ctx['fragment_index'] = frag_index
-                    result = append_fragment(decrypt_fragment(fragment, frag_content), frag_index, ctx)
+                    result = append_fragment(decrypt_fragment(fragment, self._read_fragment(ctx)), frag_index, ctx)
                     if not result:
                         return False
         else:
             for fragment in fragments:
-                frag_content, frag_index = download_fragment(fragment, ctx)
-                result = append_fragment(decrypt_fragment(fragment, frag_content), frag_index, ctx)
+                if not interrupt_trigger[0]:
+                    break
+                download_fragment(fragment, ctx)
+                result = append_fragment(decrypt_fragment(fragment, self._read_fragment(ctx)), fragment['frag_index'], ctx)
                 if not result:
                     return False
 
diff --git a/hypervideo_dl/downloader/hls.py b/hypervideo_dl/downloader/hls.py
index ef8a81b..f3f32b5 100644
--- a/hypervideo_dl/downloader/hls.py
+++ b/hypervideo_dl/downloader/hls.py
@@ -77,6 +77,15 @@ class HlsFD(FragmentFD):
                 message = ('The stream has AES-128 encryption and neither ffmpeg nor pycryptodome are available; '
                            'Decryption will be performed natively, but will be extremely slow')
         if not can_download:
+            has_drm = re.search('|'.join([
+                r'#EXT-X-FAXS-CM:',  # Adobe Flash Access
+                r'#EXT-X-(?:SESSION-)?KEY:.*?URI="skd://',  # Apple FairPlay
+            ]), s)
+            if has_drm and not self.params.get('allow_unplayable_formats'):
+                self.report_error(
+                    'This video is DRM protected; Try selecting another format with --format or '
+                    'add --check-formats to automatically fallback to the next best format')
+                return False
             message = message or 'Unsupported features have been detected'
             fd = FFmpegFD(self.ydl, self.params)
             self.report_warning(f'{message}; extraction will be delegated to {fd.get_basename()}')
diff --git a/hypervideo_dl/downloader/http.py b/hypervideo_dl/downloader/http.py
index 2e95bb9..591a9b0 100644
--- a/hypervideo_dl/downloader/http.py
+++ b/hypervideo_dl/downloader/http.py
@@ -1,29 +1,30 @@
 from __future__ import unicode_literals
 
-import errno
 import os
-import socket
+import ssl
 import time
 import random
-import re
 
 from .common import FileDownloader
 from ..compat import (
-    compat_str,
     compat_urllib_error,
+    compat_http_client
 )
 from ..utils import (
     ContentTooShortError,
     encodeFilename,
     int_or_none,
-    sanitize_open,
+    parse_http_range,
     sanitized_Request,
     ThrottledDownload,
+    try_call,
     write_xattr,
     XAttrMetadataError,
     XAttrUnavailableError,
 )
 
+RESPONSE_READ_EXCEPTIONS = (TimeoutError, ConnectionError, ssl.SSLError, compat_http_client.HTTPException)
+
 
 class HttpFD(FileDownloader):
     def real_download(self, filename, info_dict):
@@ -54,11 +55,11 @@ class HttpFD(FileDownloader):
 
         ctx.open_mode = 'wb'
         ctx.resume_len = 0
-        ctx.data_len = None
         ctx.block_size = self.params.get('buffersize', 1024)
         ctx.start_time = time.time()
-        ctx.chunk_size = None
-        throttle_start = None
+
+        # parse given Range
+        req_start, req_end, _ = parse_http_range(headers.get('Range'))
 
         if self.params.get('continuedl', True):
             # Establish possible resume length
@@ -81,43 +82,50 @@ class HttpFD(FileDownloader):
         class NextFragment(Exception):
             pass
 
-        def set_range(req, start, end):
-            range_header = 'bytes=%d-' % start
-            if end:
-                range_header += compat_str(end)
-            req.add_header('Range', range_header)
-
         def establish_connection():
             ctx.chunk_size = (random.randint(int(chunk_size * 0.95), chunk_size)
                               if not is_test and chunk_size else chunk_size)
             if ctx.resume_len > 0:
                 range_start = ctx.resume_len
+                if req_start is not None:
+                    # offset the beginning of Range to be within request
+                    range_start += req_start
                 if ctx.is_resume:
                     self.report_resuming_byte(ctx.resume_len)
                 ctx.open_mode = 'ab'
+            elif req_start is not None:
+                range_start = req_start
             elif ctx.chunk_size > 0:
                 range_start = 0
             else:
                 range_start = None
             ctx.is_resume = False
-            range_end = range_start + ctx.chunk_size - 1 if ctx.chunk_size else None
-            if range_end and ctx.data_len is not None and range_end >= ctx.data_len:
-                range_end = ctx.data_len - 1
-            has_range = range_start is not None
-            ctx.has_range = has_range
+
+            if ctx.chunk_size:
+                chunk_aware_end = range_start + ctx.chunk_size - 1
+                # we're not allowed to download outside Range
+                range_end = chunk_aware_end if req_end is None else min(chunk_aware_end, req_end)
+            elif req_end is not None:
+                # there's no need for chunked downloads, so download until the end of Range
+                range_end = req_end
+            else:
+                range_end = None
+
+            if try_call(lambda: range_start > range_end):
+                ctx.resume_len = 0
+                ctx.open_mode = 'wb'
+                raise RetryDownload(Exception(f'Conflicting range. (start={range_start} > end={range_end})'))
+
+            if try_call(lambda: range_end >= ctx.content_len):
+                range_end = ctx.content_len - 1
+
             request = sanitized_Request(url, request_data, headers)
+            has_range = range_start is not None
             if has_range:
-                set_range(request, range_start, range_end)
+                request.add_header('Range', f'bytes={int(range_start)}-{int_or_none(range_end) or ""}')
             # Establish connection
             try:
-                try:
-                    ctx.data = self.ydl.urlopen(request)
-                except (compat_urllib_error.URLError, ) as err:
-                    # reason may not be available, e.g. for urllib2.HTTPError on python 2.6
-                    reason = getattr(err, 'reason', None)
-                    if isinstance(reason, socket.timeout):
-                        raise RetryDownload(err)
-                    raise err
+                ctx.data = self.ydl.urlopen(request)
                 # When trying to resume, Content-Range HTTP header of response has to be checked
                 # to match the value of requested Range HTTP header. This is due to a webservers
                 # that don't support resuming and serve a whole file with no Content-Range
@@ -125,31 +133,27 @@ class HttpFD(FileDownloader):
                 # https://github.com/ytdl-org/youtube-dl/issues/6057#issuecomment-126129799)
                 if has_range:
                     content_range = ctx.data.headers.get('Content-Range')
-                    if content_range:
-                        content_range_m = re.search(r'bytes (\d+)-(\d+)?(?:/(\d+))?', content_range)
+                    content_range_start, content_range_end, content_len = parse_http_range(content_range)
+                    if content_range_start is not None and range_start == content_range_start:
                         # Content-Range is present and matches requested Range, resume is possible
-                        if content_range_m:
-                            if range_start == int(content_range_m.group(1)):
-                                content_range_end = int_or_none(content_range_m.group(2))
-                                content_len = int_or_none(content_range_m.group(3))
-                                accept_content_len = (
-                                    # Non-chunked download
-                                    not ctx.chunk_size
-                                    # Chunked download and requested piece or
-                                    # its part is promised to be served
-                                    or content_range_end == range_end
-                                    or content_len < range_end)
-                                if accept_content_len:
-                                    ctx.data_len = content_len
-                                    return
+                        accept_content_len = (
+                            # Non-chunked download
+                            not ctx.chunk_size
+                            # Chunked download and requested piece or
+                            # its part is promised to be served
+                            or content_range_end == range_end
+                            or content_len < range_end)
+                        if accept_content_len:
+                            ctx.content_len = content_len
+                            ctx.data_len = min(content_len, req_end or content_len) - (req_start or 0)
+                            return
                     # Content-Range is either not present or invalid. Assuming remote webserver is
                     # trying to send the whole file, resume is not possible, so wiping the local file
                     # and performing entire redownload
                     self.report_unable_to_resume()
                     ctx.resume_len = 0
                     ctx.open_mode = 'wb'
-                ctx.data_len = int_or_none(ctx.data.info().get('Content-length', None))
-                return
+                ctx.data_len = ctx.content_len = int_or_none(ctx.data.info().get('Content-length', None))
             except (compat_urllib_error.HTTPError, ) as err:
                 if err.code == 416:
                     # Unable to resume (requested range not satisfiable)
@@ -191,14 +195,16 @@ class HttpFD(FileDownloader):
                     # Unexpected HTTP error
                     raise
                 raise RetryDownload(err)
-            except socket.error as err:
-                if err.errno != errno.ECONNRESET:
-                    # Connection reset is no problem, just retry
+            except compat_urllib_error.URLError as err:
+                if isinstance(err.reason, ssl.CertificateError):
                     raise
                 raise RetryDownload(err)
+            # In urllib.request.AbstractHTTPHandler, the response is partially read on request.
+            # Any errors that occur during this will not be wrapped by URLError
+            except RESPONSE_READ_EXCEPTIONS as err:
+                raise RetryDownload(err)
 
         def download():
-            nonlocal throttle_start
             data_len = ctx.data.info().get('Content-length', None)
 
             # Range HTTP header may be ignored/unsupported by a webserver
@@ -241,16 +247,8 @@ class HttpFD(FileDownloader):
                 try:
                     # Download and write
                     data_block = ctx.data.read(block_size if not is_test else min(block_size, data_len - byte_counter))
-                # socket.timeout is a subclass of socket.error but may not have
-                # errno set
-                except socket.timeout as e:
-                    retry(e)
-                except socket.error as e:
-                    # SSLError on python 2 (inherits socket.error) may have
-                    # no errno set but this error message
-                    if e.errno in (errno.ECONNRESET, errno.ETIMEDOUT) or getattr(e, 'message', None) == 'The read operation timed out':
-                        retry(e)
-                    raise
+                except RESPONSE_READ_EXCEPTIONS as err:
+                    retry(err)
 
                 byte_counter += len(data_block)
 
@@ -261,7 +259,7 @@ class HttpFD(FileDownloader):
                 # Open destination file just in time
                 if ctx.stream is None:
                     try:
-                        ctx.stream, ctx.tmpfilename = sanitize_open(
+                        ctx.stream, ctx.tmpfilename = self.sanitize_open(
                             ctx.tmpfilename, ctx.open_mode)
                         assert ctx.stream is not None
                         ctx.filename = self.undo_temp_name(ctx.tmpfilename)
@@ -321,16 +319,16 @@ class HttpFD(FileDownloader):
                 if speed and speed < (self.params.get('throttledratelimit') or 0):
                     # The speed must stay below the limit for 3 seconds
                     # This prevents raising error when the speed temporarily goes down
-                    if throttle_start is None:
-                        throttle_start = now
-                    elif now - throttle_start > 3:
+                    if ctx.throttle_start is None:
+                        ctx.throttle_start = now
+                    elif now - ctx.throttle_start > 3:
                         if ctx.stream is not None and ctx.tmpfilename != '-':
                             ctx.stream.close()
                         raise ThrottledDownload()
                 elif speed:
-                    throttle_start = None
+                    ctx.throttle_start = None
 
-            if not is_test and ctx.chunk_size and ctx.data_len is not None and byte_counter < ctx.data_len:
+            if not is_test and ctx.chunk_size and ctx.content_len is not None and byte_counter < ctx.content_len:
                 ctx.resume_len = byte_counter
                 # ctx.block_size = block_size
                 raise NextFragment()
diff --git a/hypervideo_dl/downloader/ism.py b/hypervideo_dl/downloader/ism.py
index 09516ab..4d5618c 100644
--- a/hypervideo_dl/downloader/ism.py
+++ b/hypervideo_dl/downloader/ism.py
@@ -263,9 +263,11 @@ class IsmFD(FragmentFD):
             count = 0
             while count <= fragment_retries:
                 try:
-                    success, frag_content = self._download_fragment(ctx, segment['url'], info_dict)
+                    success = self._download_fragment(ctx, segment['url'], info_dict)
                     if not success:
                         return False
+                    frag_content = self._read_fragment(ctx)
+
                     if not extra_state['ism_track_written']:
                         tfhd_data = extract_box_data(frag_content, [b'moof', b'traf', b'tfhd'])
                         info_dict['_download_params']['track_id'] = u32.unpack(tfhd_data[4:8])[0]
diff --git a/hypervideo_dl/downloader/mhtml.py b/hypervideo_dl/downloader/mhtml.py
index f0f4dc6..c8332c0 100644
--- a/hypervideo_dl/downloader/mhtml.py
+++ b/hypervideo_dl/downloader/mhtml.py
@@ -114,8 +114,8 @@ body > figure > img {
         fragment_base_url = info_dict.get('fragment_base_url')
         fragments = info_dict['fragments'][:1] if self.params.get(
             'test', False) else info_dict['fragments']
-        title = info_dict['title']
-        origin = info_dict['webpage_url']
+        title = info_dict.get('title', info_dict['format_id'])
+        origin = info_dict.get('webpage_url', info_dict['url'])
 
         ctx = {
             'filename': filename,
@@ -166,10 +166,15 @@ body > figure > img {
             if (i + 1) <= ctx['fragment_index']:
                 continue
 
-            fragment_url = urljoin(fragment_base_url, fragment['path'])
-            success, frag_content = self._download_fragment(ctx, fragment_url, info_dict)
+            fragment_url = fragment.get('url')
+            if not fragment_url:
+                assert fragment_base_url
+                fragment_url = urljoin(fragment_base_url, fragment['path'])
+
+            success = self._download_fragment(ctx, fragment_url, info_dict)
             if not success:
                 continue
+            frag_content = self._read_fragment(ctx)
 
             mime_type = b'image/jpeg'
             if frag_content.startswith(b'\x89PNG\r\n\x1a\n'):
diff --git a/hypervideo_dl/downloader/rtmp.py b/hypervideo_dl/downloader/rtmp.py
index 6dca647..90f1acf 100644
--- a/hypervideo_dl/downloader/rtmp.py
+++ b/hypervideo_dl/downloader/rtmp.py
@@ -12,6 +12,7 @@ from ..utils import (
     encodeFilename,
     encodeArgument,
     get_exe_version,
+    Popen,
 )
 
 
@@ -26,7 +27,7 @@ class RtmpFD(FileDownloader):
             start = time.time()
             resume_percent = None
             resume_downloaded_data_len = None
-            proc = subprocess.Popen(args, stderr=subprocess.PIPE)
+            proc = Popen(args, stderr=subprocess.PIPE)
             cursor_in_new_line = True
             proc_stderr_closed = False
             try:
diff --git a/hypervideo_dl/downloader/websocket.py b/hypervideo_dl/downloader/websocket.py
index 0882220..58e2bce 100644
--- a/hypervideo_dl/downloader/websocket.py
+++ b/hypervideo_dl/downloader/websocket.py
@@ -5,9 +5,12 @@ import threading
 
 try:
     import websockets
-    has_websockets = True
-except ImportError:
+except (ImportError, SyntaxError):
+    # websockets 3.10 on python 3.6 causes SyntaxError
+    # See https://github.com/hypervideo/hypervideo/issues/2633
     has_websockets = False
+else:
+    has_websockets = True
 
 from .common import FileDownloader
 from .external import FFmpegFD
diff --git a/hypervideo_dl/downloader/youtube_live_chat.py b/hypervideo_dl/downloader/youtube_live_chat.py
index ef4205e..dd21ac8 100644
--- a/hypervideo_dl/downloader/youtube_live_chat.py
+++ b/hypervideo_dl/downloader/youtube_live_chat.py
@@ -22,6 +22,9 @@ class YoutubeLiveChatFD(FragmentFD):
     def real_download(self, filename, info_dict):
         video_id = info_dict['video_id']
         self.to_screen('[%s] Downloading live chat' % self.FD_NAME)
+        if not self.params.get('skip_download') and info_dict['protocol'] == 'youtube_live_chat':
+            self.report_warning('Live chat download runs until the livestream ends. '
+                                'If you wish to download the video simultaneously, run a separate hypervideo instance')
 
         fragment_retries = self.params.get('fragment_retries', 0)
         test = self.params.get('test', False)
@@ -112,9 +115,10 @@ class YoutubeLiveChatFD(FragmentFD):
             count = 0
             while count <= fragment_retries:
                 try:
-                    success, raw_fragment = dl_fragment(url, request_data, headers)
+                    success = dl_fragment(url, request_data, headers)
                     if not success:
                         return False, None, None, None
+                    raw_fragment = self._read_fragment(ctx)
                     try:
                         data = ie.extract_yt_initial_data(video_id, raw_fragment.decode('utf-8', 'replace'))
                     except RegexNotFoundError:
@@ -142,9 +146,10 @@ class YoutubeLiveChatFD(FragmentFD):
 
         self._prepare_and_start_frag_download(ctx, info_dict)
 
-        success, raw_fragment = dl_fragment(info_dict['url'])
+        success = dl_fragment(info_dict['url'])
         if not success:
             return False
+        raw_fragment = self._read_fragment(ctx)
         try:
             data = ie.extract_yt_initial_data(video_id, raw_fragment.decode('utf-8', 'replace'))
         except RegexNotFoundError: