yt-dlp/yt_dlp/downloader/external.py

import enum
import functools
import json
import os
import re
import subprocess
import tempfile
import time
import uuid

from .fragment import FragmentFD
from ..networking import Request
from ..postprocessor.ffmpeg import (
    EXT_TO_OUT_FORMATS,
    FFmpegPostProcessor,
    FFmpegProgressTracker,
)
from ..utils import (
    Popen,
    RetryManager,
    _configuration_args,
    check_executable,
    classproperty,
    cli_bool_option,
    cli_option,
    cli_valueless_option,
    determine_ext,
    encodeArgument,
    encodeFilename,
    find_available_port,
    remove_end,
    traverse_obj,
)


class Features(enum.Enum):
    TO_STDOUT = enum.auto()
    MULTIPLE_FORMATS = enum.auto()


class ExternalFD(FragmentFD):
    SUPPORTED_PROTOCOLS = ('http', 'https', 'ftp', 'ftps')
    SUPPORTED_FEATURES = ()
    _CAPTURE_STDERR = True

    def real_download(self, filename, info_dict):
        self.report_destination(filename)
        tmpfilename = self.temp_name(filename)
        self._cookies_tempfile = None

        try:
            started = time.time()
            retval = self._call_downloader(tmpfilename, info_dict)
        except KeyboardInterrupt:
            if not info_dict.get('is_live'):
                raise
            # Live stream downloading cancellation should be considered as
            # correct and expected termination thus all postprocessing
            # should take place
            retval = 0
            self.to_screen(f'[{self.get_basename()}] Interrupted by user')
        finally:
            if self._cookies_tempfile:
                self.try_remove(self._cookies_tempfile)

        if retval == 0:
            status = {
                'filename': filename,
                'status': 'finished',
                'elapsed': time.time() - started,
            }
            if filename != '-':
                fsize = os.path.getsize(encodeFilename(tmpfilename))
                self.try_rename(tmpfilename, filename)
                status.update({
                    'downloaded_bytes': fsize,
                    'total_bytes': fsize,
                })
            self._hook_progress(status, info_dict)
            return True
        else:
            self.to_stderr('\n')
            self.report_error('%s exited with code %d' % (
                self.get_basename(), retval))
            return False

    @classmethod
    def get_basename(cls):
        return cls.__name__[:-2].lower()

    @classproperty
    def EXE_NAME(cls):
        return cls.get_basename()

    @functools.cached_property
    def exe(self):
        return self.EXE_NAME

    @classmethod
    def available(cls, path=None):
        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):
        return all((
            not info_dict.get('to_stdout') or Features.TO_STDOUT in cls.SUPPORTED_FEATURES,
            '+' not in info_dict['protocol'] or Features.MULTIPLE_FORMATS in cls.SUPPORTED_FEATURES,
            not traverse_obj(info_dict, ('hls_aes', ...), 'extra_param_to_segment_url', 'extra_param_to_key_url'),
            all(proto in cls.SUPPORTED_PROTOCOLS for proto in info_dict['protocol'].split('+')),
        ))

    @classmethod
    def can_download(cls, info_dict, path=None):
        return cls.available(path) and cls.supports(info_dict)

    def _option(self, command_option, param):
        return cli_option(self.params, command_option, param)

    def _bool_option(self, command_option, param, true_value='true', false_value='false', separator=None):
        return cli_bool_option(self.params, command_option, param, true_value, false_value, separator)

    def _valueless_option(self, command_option, param, expected_value=True):
        return cli_valueless_option(self.params, command_option, param, expected_value)

    def _configuration_args(self, keys=None, *args, **kwargs):
        return _configuration_args(
            self.get_basename(), self.params.get('external_downloader_args'), self.EXE_NAME,
            keys, *args, **kwargs)

    def _write_cookies(self):
        if not self.ydl.cookiejar.filename:
            tmp_cookies = tempfile.NamedTemporaryFile(suffix='.cookies', delete=False)
            tmp_cookies.close()
            self._cookies_tempfile = tmp_cookies.name
            self.to_screen(f'[download] Writing temporary cookies file to "{self._cookies_tempfile}"')
        # real_download resets _cookies_tempfile; if it's None then save() will write to cookiejar.filename
        self.ydl.cookiejar.save(self._cookies_tempfile)
        return self.ydl.cookiejar.filename or self._cookies_tempfile

    def _call_downloader(self, tmpfilename, info_dict):
        """ Either overwrite this or implement _make_cmd """
        cmd = [encodeArgument(a) for a in self._make_cmd(tmpfilename, info_dict)]

        self._debug_cmd(cmd)

        if 'fragments' not in info_dict:
            _, stderr, returncode = self._call_process(cmd, info_dict)
            if returncode and stderr:
                self.to_stderr(stderr)
            return returncode

        skip_unavailable_fragments = self.params.get('skip_unavailable_fragments', True)

        retry_manager = RetryManager(self.params.get('fragment_retries'), self.report_retry,
                                     frag_index=None, fatal=not skip_unavailable_fragments)
        for retry in retry_manager:
            _, stderr, returncode = self._call_process(cmd, info_dict)
            if not returncode:
                break
            # TODO: Decide whether to retry based on error code
            # https://aria2.github.io/manual/en/html/aria2c.html#exit-status
            if stderr:
                self.to_stderr(stderr)
            retry.error = Exception()
            continue
        if not skip_unavailable_fragments and retry_manager.error:
            return -1

        decrypt_fragment = self.decrypter(info_dict)
        dest, _ = self.sanitize_open(tmpfilename, 'wb')
        for frag_index, fragment in enumerate(info_dict['fragments']):
            fragment_filename = f'{tmpfilename}-Frag{frag_index}'
            try:
                src, _ = self.sanitize_open(fragment_filename, 'rb')
            except OSError as err:
                if skip_unavailable_fragments and frag_index > 1:
                    self.report_skip_fragment(frag_index, err)
                    continue
                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):
                self.try_remove(encodeFilename(fragment_filename))
        dest.close()
        self.try_remove(encodeFilename(f'{tmpfilename}.frag.urls'))
        return 0

    def _call_process(self, cmd, info_dict):
        return Popen.run(cmd, text=True, stderr=subprocess.PIPE if self._CAPTURE_STDERR else None)


class CurlFD(ExternalFD):
    AVAILABLE_OPT = '-V'
    _CAPTURE_STDERR = False  # curl writes the progress to stderr

    def _make_cmd(self, tmpfilename, info_dict):
        cmd = [self.exe, '--location', '-o', tmpfilename, '--compressed']
        cookie_header = self.ydl.cookiejar.get_cookie_header(info_dict['url'])
        if cookie_header:
            cmd += ['--cookie', cookie_header]
        if info_dict.get('http_headers') is not None:
            for key, val in info_dict['http_headers'].items():
                cmd += ['--header', f'{key}: {val}']

        cmd += self._bool_option('--continue-at', 'continuedl', '-', '0')
        cmd += self._valueless_option('--silent', 'noprogress')
        cmd += self._valueless_option('--verbose', 'verbose')
        cmd += self._option('--limit-rate', 'ratelimit')
        retry = self._option('--retry', 'retries')
        if len(retry) == 2:
            if retry[1] in ('inf', 'infinite'):
                retry[1] = '2147483647'
            cmd += retry
        cmd += self._option('--max-filesize', 'max_filesize')
        cmd += self._option('--interface', 'source_address')
        cmd += self._option('--proxy', 'proxy')
        cmd += self._valueless_option('--insecure', 'nocheckcertificate')
        cmd += self._configuration_args()
        cmd += ['--', info_dict['url']]
        return cmd


class AxelFD(ExternalFD):
    AVAILABLE_OPT = '-V'

    def _make_cmd(self, tmpfilename, info_dict):
        cmd = [self.exe, '-o', tmpfilename]
        if info_dict.get('http_headers') is not None:
            for key, val in info_dict['http_headers'].items():
                cmd += ['-H', f'{key}: {val}']
        cookie_header = self.ydl.cookiejar.get_cookie_header(info_dict['url'])
        if cookie_header:
            cmd += ['-H', f'Cookie: {cookie_header}', '--max-redirect=0']
        cmd += self._configuration_args()
        cmd += ['--', info_dict['url']]
        return cmd


class WgetFD(ExternalFD):
    AVAILABLE_OPT = '--version'

    def _make_cmd(self, tmpfilename, info_dict):
        cmd = [self.exe, '-O', tmpfilename, '-nv', '--compression=auto']
        if self.ydl.cookiejar.get_cookie_header(info_dict['url']):
            cmd += ['--load-cookies', self._write_cookies()]
        if info_dict.get('http_headers') is not None:
            for key, val in info_dict['http_headers'].items():
                cmd += ['--header', f'{key}: {val}']
        cmd += self._option('--limit-rate', 'ratelimit')
        retry = self._option('--tries', 'retries')
        if len(retry) == 2:
            if retry[1] in ('inf', 'infinite'):
                retry[1] = '0'
            cmd += retry
        cmd += self._option('--bind-address', 'source_address')
        proxy = self.params.get('proxy')
        if proxy:
            for var in ('http_proxy', 'https_proxy'):
                cmd += ['--execute', f'{var}={proxy}']
        cmd += self._valueless_option('--no-check-certificate', 'nocheckcertificate')
        cmd += self._configuration_args()
        cmd += ['--', info_dict['url']]
        return cmd


class Aria2cFD(ExternalFD):
    AVAILABLE_OPT = '-v'
    SUPPORTED_PROTOCOLS = ('http', 'https', 'ftp', 'ftps', 'dash_frag_urls', 'm3u8_frag_urls')

    @staticmethod
    def supports_manifest(manifest):
        UNSUPPORTED_FEATURES = [
            r'#EXT-X-BYTERANGE',  # playlists composed of byte ranges of media files [1]
            # 1. https://tools.ietf.org/html/draft-pantos-http-live-streaming-17#section-4.3.2.2
        ]
        check_results = (not re.search(feature, manifest) for feature in UNSUPPORTED_FEATURES)
        return all(check_results)

    @staticmethod
    def _aria2c_filename(fn):
        return fn if os.path.isabs(fn) else f'.{os.path.sep}{fn}'

    def _call_downloader(self, tmpfilename, info_dict):
        # FIXME: Disabled due to https://github.com/yt-dlp/yt-dlp/issues/5931
        if False and 'no-external-downloader-progress' not in self.params.get('compat_opts', []):
            info_dict['__rpc'] = {
                'port': find_available_port() or 19190,
                'secret': str(uuid.uuid4()),
            }
        return super()._call_downloader(tmpfilename, info_dict)

    def _make_cmd(self, tmpfilename, info_dict):
        cmd = [self.exe, '-c', '--no-conf',
               '--console-log-level=warn', '--summary-interval=0', '--download-result=hide',
               '--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:
            cmd += ['--min-split-size', '1M']

        if self.ydl.cookiejar.get_cookie_header(info_dict['url']):
            cmd += [f'--load-cookies={self._write_cookies()}']
        if info_dict.get('http_headers') is not None:
            for key, val in info_dict['http_headers'].items():
                cmd += ['--header', f'{key}: {val}']
        cmd += self._option('--max-overall-download-limit', 'ratelimit')
        cmd += self._option('--interface', 'source_address')
        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()

        if '__rpc' in info_dict:
            cmd += [
                '--enable-rpc',
                f'--rpc-listen-port={info_dict["__rpc"]["port"]}',
                f'--rpc-secret={info_dict["__rpc"]["secret"]}']

        # aria2c strips out spaces from the beginning/end of filenames and paths.
        # We work around this issue by adding a "./" to the beginning of the
        # filename and relative path, and adding a "/" at the end of the path.
        # See: https://github.com/yt-dlp/yt-dlp/issues/276
        # https://github.com/ytdl-org/youtube-dl/issues/20312
        # https://github.com/aria2/aria2/issues/1373
        dn = os.path.dirname(tmpfilename)
        if dn:
            cmd += ['--dir', self._aria2c_filename(dn) + os.path.sep]
        if 'fragments' not in info_dict:
            cmd += ['--out', self._aria2c_filename(os.path.basename(tmpfilename))]
        cmd += ['--auto-file-renaming=false']

        if 'fragments' in info_dict:
            cmd += ['--uri-selector=inorder']
            url_list_file = f'{tmpfilename}.frag.urls'
            url_list = []
            for frag_index, fragment in enumerate(info_dict['fragments']):
                fragment_filename = f'{os.path.basename(tmpfilename)}-Frag{frag_index}'
                url_list.append('{}\n\tout={}'.format(fragment['url'], self._aria2c_filename(fragment_filename)))
            stream, _ = self.sanitize_open(url_list_file, 'wb')
            stream.write('\n'.join(url_list).encode())
            stream.close()
            cmd += ['-i', self._aria2c_filename(url_list_file)]
        else:
            cmd += ['--', info_dict['url']]
        return cmd

    def aria2c_rpc(self, rpc_port, rpc_secret, method, params=()):
        # Does not actually need to be UUID, just unique
        sanitycheck = str(uuid.uuid4())
        d = json.dumps({
            'jsonrpc': '2.0',
            'id': sanitycheck,
            'method': method,
            'params': [f'token:{rpc_secret}', *params],
        }).encode()
        request = Request(
            f'http://localhost:{rpc_port}/jsonrpc',
            data=d, headers={
                'Content-Type': 'application/json',
                'Content-Length': f'{len(d)}',
            }, proxies={'all': None})
        with self.ydl.urlopen(request) as r:
            resp = json.load(r)
        assert resp.get('id') == sanitycheck, 'Something went wrong with RPC server'
        return resp['result']

    def _call_process(self, cmd, info_dict):
        if '__rpc' not in info_dict:
            return super()._call_process(cmd, info_dict)

        send_rpc = functools.partial(self.aria2c_rpc, info_dict['__rpc']['port'], info_dict['__rpc']['secret'])
        started = time.time()

        fragmented = 'fragments' in info_dict
        frag_count = len(info_dict['fragments']) if fragmented else 1
        status = {
            'filename': info_dict.get('_filename'),
            'status': 'downloading',
            'elapsed': 0,
            'downloaded_bytes': 0,
            'fragment_count': frag_count if fragmented else None,
            'fragment_index': 0 if fragmented else None,
        }
        self._hook_progress(status, info_dict)

        def get_stat(key, *obj, average=False):
            val = tuple(filter(None, map(float, traverse_obj(obj, (..., ..., key))))) or [0]
            return sum(val) / (len(val) if average else 1)

        with Popen(cmd, text=True, stdout=subprocess.DEVNULL, stderr=subprocess.PIPE) as p:
            # Add a small sleep so that RPC client can receive response,
            # or the connection stalls infinitely
            time.sleep(0.2)
            retval = p.poll()
            while retval is None:
                # We don't use tellStatus as we won't know the GID without reading stdout
                # Ref: https://aria2.github.io/manual/en/html/aria2c.html#aria2.tellActive
                active = send_rpc('aria2.tellActive')
                completed = send_rpc('aria2.tellStopped', [0, frag_count])

                downloaded = get_stat('totalLength', completed) + get_stat('completedLength', active)
                speed = get_stat('downloadSpeed', active)
                total = frag_count * get_stat('totalLength', active, completed, average=True)
                if total < downloaded:
                    total = None

                status.update({
                    'downloaded_bytes': int(downloaded),
                    'speed': speed,
                    'total_bytes': None if fragmented else total,
                    'total_bytes_estimate': total,
                    'eta': (total - downloaded) / (speed or 1),
                    'fragment_index': min(frag_count, len(completed) + 1) if fragmented else None,
                    'elapsed': time.time() - started,
                })
                self._hook_progress(status, info_dict)

                if not active and len(completed) >= frag_count:
                    send_rpc('aria2.shutdown')
                    retval = p.wait()
                    break

                time.sleep(0.1)
                retval = p.poll()

            return '', p.stderr.read(), retval


class HttpieFD(ExternalFD):
    AVAILABLE_OPT = '--version'
    EXE_NAME = 'http'

    def _make_cmd(self, tmpfilename, info_dict):
        cmd = ['http', '--download', '--output', tmpfilename, info_dict['url']]

        if info_dict.get('http_headers') is not None:
            for key, val in info_dict['http_headers'].items():
                cmd += [f'{key}:{val}']

        # httpie 3.1.0+ removes the Cookie header on redirect, so this should be safe for now. [1]
        # If we ever need cookie handling for redirects, we can export the cookiejar into a session. [2]
        # 1: https://github.com/httpie/httpie/security/advisories/GHSA-9w4w-cpc8-h2fq
        # 2: https://httpie.io/docs/cli/sessions
        cookie_header = self.ydl.cookiejar.get_cookie_header(info_dict['url'])
        if cookie_header:
            cmd += [f'Cookie:{cookie_header}']
        return cmd


class FFmpegFD(ExternalFD):
    SUPPORTED_PROTOCOLS = ('http', 'https', 'ftp', 'ftps', 'm3u8', 'm3u8_native', 'rtsp', 'rtmp', 'rtmp_ffmpeg', 'mms', 'http_dash_segments')
    SUPPORTED_FEATURES = (Features.TO_STDOUT, Features.MULTIPLE_FORMATS)

    @classmethod
    def available(cls, path=None):
        # TODO: Fix path for ffmpeg
        # Fixme: This may be wrong when --ffmpeg-location is used
        return FFmpegPostProcessor().available

    def on_process_started(self, proc, stdin):
        """ Override this in subclasses  """
        pass

    @classmethod
    def can_merge_formats(cls, info_dict, params):
        return (
            info_dict.get('requested_formats')
            and info_dict.get('protocol')
            and not params.get('allow_unplayable_formats')
            and 'no-direct-merge' not in params.get('compat_opts', [])
            and cls.can_download(info_dict))

    def _call_downloader(self, tmpfilename, info_dict):
        ffpp = FFmpegPostProcessor(downloader=self)
        if not ffpp.available:
            self.report_error('m3u8 download detected but ffmpeg could not be found. Please install')
            return False
        ffpp.check_version()

        args = [ffpp.executable, '-y']

        for log_level in ('quiet', 'verbose'):
            if self.params.get(log_level, False):
                args += ['-loglevel', log_level]
                break
        if not self.params.get('verbose'):
            args += ['-hide_banner']

        args += traverse_obj(info_dict, ('downloader_options', 'ffmpeg_args', ...))

        # These exists only for compatibility. Extractors should use
        # info_dict['downloader_options']['ffmpeg_args'] instead
        args += info_dict.get('_ffmpeg_args') or []
        seekable = info_dict.get('_seekable')
        if seekable is not None:
            # setting -seekable prevents ffmpeg from guessing if the server
            # supports seeking(by adding the header `Range: bytes=0-`), which
            # can cause problems in some cases
            # https://github.com/ytdl-org/youtube-dl/issues/11800#issuecomment-275037127
            # http://trac.ffmpeg.org/ticket/6125#comment:10
            args += ['-seekable', '1' if seekable else '0']

        env = None
        proxy = self.params.get('proxy')
        if proxy:
            if not re.match(r'[\da-zA-Z]+://', proxy):
                proxy = f'http://{proxy}'

            if proxy.startswith('socks'):
                self.report_warning(
                    f'{self.get_basename()} does not support SOCKS proxies. Downloading is likely to fail. '
                    'Consider adding --hls-prefer-native to your command.')

            # Since December 2015 ffmpeg supports -http_proxy option (see
            # http://git.videolan.org/?p=ffmpeg.git;a=commit;h=b4eb1f29ebddd60c41a2eb39f5af701e38e0d3fd)
            # We could switch to the following code if we are able to detect version properly
            # args += ['-http_proxy', proxy]
            env = os.environ.copy()
            env['HTTP_PROXY'] = proxy
            env['http_proxy'] = proxy

        protocol = info_dict.get('protocol')

        if protocol == 'rtmp':
            player_url = info_dict.get('player_url')
            page_url = info_dict.get('page_url')
            app = info_dict.get('app')
            play_path = info_dict.get('play_path')
            tc_url = info_dict.get('tc_url')
            flash_version = info_dict.get('flash_version')
            live = info_dict.get('rtmp_live', False)
            conn = info_dict.get('rtmp_conn')
            if player_url is not None:
                args += ['-rtmp_swfverify', player_url]
            if page_url is not None:
                args += ['-rtmp_pageurl', page_url]
            if app is not None:
                args += ['-rtmp_app', app]
            if play_path is not None:
                args += ['-rtmp_playpath', play_path]
            if tc_url is not None:
                args += ['-rtmp_tcurl', tc_url]
            if flash_version is not None:
                args += ['-rtmp_flashver', flash_version]
            if live:
                args += ['-rtmp_live', 'live']
            if isinstance(conn, list):
                for entry in conn:
                    args += ['-rtmp_conn', entry]
            elif isinstance(conn, str):
                args += ['-rtmp_conn', conn]

        start_time, end_time = info_dict.get('section_start') or 0, info_dict.get('section_end')

        selected_formats = info_dict.get('requested_formats') or [info_dict]
        for i, fmt in enumerate(selected_formats):
            is_http = re.match(r'https?://', fmt['url'])
            cookies = self.ydl.cookiejar.get_cookies_for_url(fmt['url']) if is_http else []
            if cookies:
                args.extend(['-cookies', ''.join(
                    f'{cookie.name}={cookie.value}; path={cookie.path}; domain={cookie.domain};\r\n'
                    for cookie in cookies)])
            if fmt.get('http_headers') and is_http:
                # Trailing \r\n after each HTTP header is important to prevent warning from ffmpeg/avconv:
                # [http @ 00000000003d2fa0] No trailing CRLF found in HTTP header.
                args.extend(['-headers', ''.join(f'{key}: {val}\r\n' for key, val in fmt['http_headers'].items())])

            if start_time:
                args += ['-ss', str(start_time)]
            if end_time:
                args += ['-t', str(end_time - start_time)]

            args += [*self._configuration_args((f'_i{i + 1}', '_i')), '-i', fmt['url']]

        if not (start_time or end_time) or not self.params.get('force_keyframes_at_cuts'):
            args += ['-c', 'copy']

        if info_dict.get('requested_formats') or protocol == 'http_dash_segments':
            for i, fmt in enumerate(selected_formats):
                stream_number = fmt.get('manifest_stream_number', 0)
                args.extend(['-map', f'{i}:{stream_number}'])

        if self.params.get('test', False):
            args += ['-fs', str(self._TEST_FILE_SIZE)]

        ext = info_dict['ext']
        if protocol in ('m3u8', 'm3u8_native'):
            use_mpegts = (tmpfilename == '-') or self.params.get('hls_use_mpegts')
            if use_mpegts is None:
                use_mpegts = info_dict.get('is_live')
            if use_mpegts:
                args += ['-f', 'mpegts']
            else:
                args += ['-f', 'mp4']
                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)]

        args += traverse_obj(info_dict, ('downloader_options', 'ffmpeg_args_out', ...))

        args += self._configuration_args(('_o1', '_o', ''))

        args = [encodeArgument(opt) for opt in args]
        args.append(encodeFilename(ffpp._ffmpeg_filename_argument(tmpfilename), True))
        args += ['-progress', 'pipe:1']
        self._debug_cmd(args)

        piped = any(fmt['url'] in ('-', 'pipe:') for fmt in selected_formats)
        self._debug_cmd(args)
        ffmpeg_progress_tracker = FFmpegProgressTracker(info_dict, args, self._ffmpeg_hook)
        proc = ffmpeg_progress_tracker.ffmpeg_proc
        if piped:
            self.on_process_started(proc, proc.stdin)
        _, _, return_code = ffmpeg_progress_tracker.run_ffmpeg_subprocess()
        return return_code

    def _ffmpeg_hook(self, status, info_dict):
        status['downloaded_bytes'] = status.get('outputted', 0)
        if status.get('status') == 'ffmpeg_running':
            status['status'] = 'downloading'
        self._hook_progress(status, info_dict)


class AVconvFD(FFmpegFD):
    pass


_BY_NAME = {
    klass.get_basename(): klass
    for name, klass in globals().items()
    if name.endswith('FD') and name not in ('ExternalFD', 'FragmentFD')
}


def list_external_downloaders():
    return sorted(_BY_NAME.keys())


def get_external_downloader(external_downloader):
    """ Given the name of the executable, see whether we support the given downloader """
    bn = os.path.splitext(os.path.basename(external_downloader))[0]
    return _BY_NAME.get(bn) or next((
        klass for klass in _BY_NAME.values() if klass.EXE_NAME in bn
    ), None)