youtube_dl/postprocessor/ffmpeg.py

   1 from __future__ import unicode_literals
   2
   3 import io
   4 import os
   5 import subprocess
   6 import time
   7 import re
   8
   9
  10 from .common import AudioConversionError, PostProcessor
  11
  12 from ..utils import (
  13     encodeArgument,
  14     encodeFilename,
  15     get_exe_version,
  16     is_outdated_version,
  17     PostProcessingError,
  18     prepend_extension,
  19     shell_quote,
  20     subtitles_filename,
  21     dfxp2srt,
  22     ISO639Utils,
  23     replace_extension,
  24 )
  25
  26
  27 EXT_TO_OUT_FORMATS = {
  28     'aac': 'adts',
  29     'flac': 'flac',
  30     'm4a': 'ipod',
  31     'mka': 'matroska',
  32     'mkv': 'matroska',
  33     'mpg': 'mpeg',
  34     'ogv': 'ogg',
  35     'ts': 'mpegts',
  36     'wma': 'asf',
  37     'wmv': 'asf',
  38 }
  39 ACODECS = {
  40     'mp3': 'libmp3lame',
  41     'aac': 'aac',
  42     'flac': 'flac',
  43     'm4a': 'aac',
  44     'opus': 'libopus',
  45     'vorbis': 'libvorbis',
  46     'wav': None,
  47 }
  48
  49
  50 class FFmpegPostProcessorError(PostProcessingError):
  51     pass
  52
  53
  54 class FFmpegPostProcessor(PostProcessor):
  55     def __init__(self, downloader=None):
  56         PostProcessor.__init__(self, downloader)
  57         self._determine_executables()
  58
  59     def check_version(self):
  60         if not self.available:
  61             raise FFmpegPostProcessorError('ffmpeg or avconv not found. Please install one.')
  62
  63         required_version = '10-0' if self.basename == 'avconv' else '1.0'
  64         if is_outdated_version(
  65                 self._versions[self.basename], required_version):
  66             warning = 'Your copy of %s is outdated, update %s to version %s or newer if you encounter any errors.' % (
  67                 self.basename, self.basename, required_version)
  68             if self._downloader:
  69                 self._downloader.report_warning(warning)
  70
  71     @staticmethod
  72     def get_versions(downloader=None):
  73         return FFmpegPostProcessor(downloader)._versions
  74
  75     def _determine_executables(self):
  76         programs = ['avprobe', 'avconv', 'ffmpeg', 'ffprobe']
  77         prefer_ffmpeg = True
  78
  79         def get_ffmpeg_version(path):
  80             ver = get_exe_version(path, args=['-version'])
  81             if ver:
  82                 regexs = [
  83                     r'(?:\d+:)?([0-9.]+)-[0-9]+ubuntu[0-9.]+$',  # Ubuntu, see [1]
  84                     r'n([0-9.]+)$',  # Arch Linux
  85                     # 1. http://www.ducea.com/2006/06/17/ubuntu-package-version-naming-explanation/
  86                 ]
  87                 for regex in regexs:
  88                     mobj = re.match(regex, ver)
  89                     if mobj:
  90                         ver = mobj.group(1)
  91             return ver
  92
  93         self.basename = None
  94         self.probe_basename = None
  95
  96         self._paths = None
  97         self._versions = None
  98         if self._downloader:
  99             prefer_ffmpeg = self._downloader.params.get('prefer_ffmpeg', True)
 100             location = self._downloader.params.get('ffmpeg_location')
 101             if location is not None:
 102                 if not os.path.exists(location):
 103                     self._downloader.report_warning(
 104                         'ffmpeg-location %s does not exist! '
 105                         'Continuing without avconv/ffmpeg.' % (location))
 106                     self._versions = {}
 107                     return
 108                 elif not os.path.isdir(location):
 109                     basename = os.path.splitext(os.path.basename(location))[0]
 110                     if basename not in programs:
 111                         self._downloader.report_warning(
 112                             'Cannot identify executable %s, its basename should be one of %s. '
 113                             'Continuing without avconv/ffmpeg.' %
 114                             (location, ', '.join(programs)))
 115                         self._versions = {}
 116                         return None
 117                     location = os.path.dirname(os.path.abspath(location))
 118                     if basename in ('ffmpeg', 'ffprobe'):
 119                         prefer_ffmpeg = True
 120
 121                 self._paths = dict(
 122                     (p, os.path.join(location, p)) for p in programs)
 123                 self._versions = dict(
 124                     (p, get_ffmpeg_version(self._paths[p])) for p in programs)
 125         if self._versions is None:
 126             self._versions = dict(
 127                 (p, get_ffmpeg_version(p)) for p in programs)
 128             self._paths = dict((p, p) for p in programs)
 129
 130         if prefer_ffmpeg is False:
 131             prefs = ('avconv', 'ffmpeg')
 132         else:
 133             prefs = ('ffmpeg', 'avconv')
 134         for p in prefs:
 135             if self._versions[p]:
 136                 self.basename = p
 137                 break
 138
 139         if prefer_ffmpeg is False:
 140             prefs = ('avprobe', 'ffprobe')
 141         else:
 142             prefs = ('ffprobe', 'avprobe')
 143         for p in prefs:
 144             if self._versions[p]:
 145                 self.probe_basename = p
 146                 break
 147
 148     @property
 149     def available(self):
 150         return self.basename is not None
 151
 152     @property
 153     def executable(self):
 154         return self._paths[self.basename]
 155
 156     @property
 157     def probe_available(self):
 158         return self.probe_basename is not None
 159
 160     @property
 161     def probe_executable(self):
 162         return self._paths[self.probe_basename]
 163
 164     def get_audio_codec(self, path):
 165         if not self.probe_available and not self.available:
 166             raise PostProcessingError('ffprobe/avprobe and ffmpeg/avconv not found. Please install one.')
 167         try:
 168             if self.probe_available:
 169                 cmd = [
 170                     encodeFilename(self.probe_executable, True),
 171                     encodeArgument('-show_streams')]
 172             else:
 173                 cmd = [
 174                     encodeFilename(self.executable, True),
 175                     encodeArgument('-i')]
 176             cmd.append(encodeFilename(self._ffmpeg_filename_argument(path), True))
 177             if self._downloader.params.get('verbose', False):
 178                 self._downloader.to_screen(
 179                     '[debug] %s command line: %s' % (self.basename, shell_quote(cmd)))
 180             handle = subprocess.Popen(
 181                 cmd, stderr=subprocess.PIPE,
 182                 stdout=subprocess.PIPE, stdin=subprocess.PIPE)
 183             stdout_data, stderr_data = handle.communicate()
 184             expected_ret = 0 if self.probe_available else 1
 185             if handle.wait() != expected_ret:
 186                 return None
 187         except (IOError, OSError):
 188             return None
 189         output = (stdout_data if self.probe_available else stderr_data).decode('ascii', 'ignore')
 190         if self.probe_available:
 191             audio_codec = None
 192             for line in output.split('\n'):
 193                 if line.startswith('codec_name='):
 194                     audio_codec = line.split('=')[1].strip()
 195                 elif line.strip() == 'codec_type=audio' and audio_codec is not None:
 196                     return audio_codec
 197         else:
 198             # Stream #FILE_INDEX:STREAM_INDEX[STREAM_ID](LANGUAGE): CODEC_TYPE: CODEC_NAME
 199             mobj = re.search(
 200                 r'Stream\s*#\d+:\d+(?:\[0x[0-9a-f]+\])?(?:\([a-z]{3}\))?:\s*Audio:\s*([0-9a-z]+)',
 201                 output)
 202             if mobj:
 203                 return mobj.group(1)
 204         return None
 205
 206     def run_ffmpeg_multiple_files(self, input_paths, out_path, opts):
 207         self.check_version()
 208
 209         oldest_mtime = min(
 210             os.stat(encodeFilename(path)).st_mtime for path in input_paths)
 211
 212         opts += self._configuration_args()
 213
 214         files_cmd = []
 215         for path in input_paths:
 216             files_cmd.extend([
 217                 encodeArgument('-i'),
 218                 encodeFilename(self._ffmpeg_filename_argument(path), True)
 219             ])
 220         cmd = ([encodeFilename(self.executable, True), encodeArgument('-y')] +
 221                files_cmd +
 222                [encodeArgument(o) for o in opts] +
 223                [encodeFilename(self._ffmpeg_filename_argument(out_path), True)])
 224
 225         if self._downloader.params.get('verbose', False):
 226             self._downloader.to_screen('[debug] ffmpeg command line: %s' % shell_quote(cmd))
 227         p = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, stdin=subprocess.PIPE)
 228         stdout, stderr = p.communicate()
 229         if p.returncode != 0:
 230             stderr = stderr.decode('utf-8', 'replace')
 231             msg = stderr.strip().split('\n')[-1]
 232             raise FFmpegPostProcessorError(msg)
 233         self.try_utime(out_path, oldest_mtime, oldest_mtime)
 234
 235     def run_ffmpeg(self, path, out_path, opts):
 236         self.run_ffmpeg_multiple_files([path], out_path, opts)
 237
 238     def _ffmpeg_filename_argument(self, fn):
 239         # Always use 'file:' because the filename may contain ':' (ffmpeg
 240         # interprets that as a protocol) or can start with '-' (-- is broken in
 241         # ffmpeg, see https://ffmpeg.org/trac/ffmpeg/ticket/2127 for details)
 242         # Also leave '-' intact in order not to break streaming to stdout.
 243         return 'file:' + fn if fn != '-' else fn
 244
 245
 246 class FFmpegExtractAudioPP(FFmpegPostProcessor):
 247     def __init__(self, downloader=None, preferredcodec=None, preferredquality=None, nopostoverwrites=False):
 248         FFmpegPostProcessor.__init__(self, downloader)
 249         if preferredcodec is None:
 250             preferredcodec = 'best'
 251         self._preferredcodec = preferredcodec
 252         self._preferredquality = preferredquality
 253         self._nopostoverwrites = nopostoverwrites
 254
 255     def run_ffmpeg(self, path, out_path, codec, more_opts):
 256         if codec is None:
 257             acodec_opts = []
 258         else:
 259             acodec_opts = ['-acodec', codec]
 260         opts = ['-vn'] + acodec_opts + more_opts
 261         try:
 262             FFmpegPostProcessor.run_ffmpeg(self, path, out_path, opts)
 263         except FFmpegPostProcessorError as err:
 264             raise AudioConversionError(err.msg)
 265
 266     def run(self, information):
 267         path = information['filepath']
 268
 269         filecodec = self.get_audio_codec(path)
 270         if filecodec is None:
 271             raise PostProcessingError('WARNING: unable to obtain file audio codec with ffprobe')
 272
 273         more_opts = []
 274         if self._preferredcodec == 'best' or self._preferredcodec == filecodec or (self._preferredcodec == 'm4a' and filecodec == 'aac'):
 275             if filecodec == 'aac' and self._preferredcodec in ['m4a', 'best']:
 276                 # Lossless, but in another container
 277                 acodec = 'copy'
 278                 extension = 'm4a'
 279                 more_opts = ['-bsf:a', 'aac_adtstoasc']
 280             elif filecodec in ['aac', 'flac', 'mp3', 'vorbis', 'opus']:
 281                 # Lossless if possible
 282                 acodec = 'copy'
 283                 extension = filecodec
 284                 if filecodec == 'aac':
 285                     more_opts = ['-f', 'adts']
 286                 if filecodec == 'vorbis':
 287                     extension = 'ogg'
 288             else:
 289                 # MP3 otherwise.
 290                 acodec = 'libmp3lame'
 291                 extension = 'mp3'
 292                 more_opts = []
 293                 if self._preferredquality is not None:
 294                     if int(self._preferredquality) < 10:
 295                         more_opts += ['-q:a', self._preferredquality]
 296                     else:
 297                         more_opts += ['-b:a', self._preferredquality + 'k']
 298         else:
 299             # We convert the audio (lossy if codec is lossy)
 300             acodec = ACODECS[self._preferredcodec]
 301             extension = self._preferredcodec
 302             more_opts = []
 303             if self._preferredquality is not None:
 304                 # The opus codec doesn't support the -aq option
 305                 if int(self._preferredquality) < 10 and extension != 'opus':
 306                     more_opts += ['-q:a', self._preferredquality]
 307                 else:
 308                     more_opts += ['-b:a', self._preferredquality + 'k']
 309             if self._preferredcodec == 'aac':
 310                 more_opts += ['-f', 'adts']
 311             if self._preferredcodec == 'm4a':
 312                 more_opts += ['-bsf:a', 'aac_adtstoasc']
 313             if self._preferredcodec == 'vorbis':
 314                 extension = 'ogg'
 315             if self._preferredcodec == 'wav':
 316                 extension = 'wav'
 317                 more_opts += ['-f', 'wav']
 318
 319         prefix, sep, ext = path.rpartition('.')  # not os.path.splitext, since the latter does not work on unicode in all setups
 320         new_path = prefix + sep + extension
 321
 322         information['filepath'] = new_path
 323         information['ext'] = extension
 324
 325         # If we download foo.mp3 and convert it to... foo.mp3, then don't delete foo.mp3, silly.
 326         if (new_path == path or
 327                 (self._nopostoverwrites and os.path.exists(encodeFilename(new_path)))):
 328             self._downloader.to_screen('[ffmpeg] Post-process file %s exists, skipping' % new_path)
 329             return [], information
 330
 331         try:
 332             self._downloader.to_screen('[ffmpeg] Destination: ' + new_path)
 333             self.run_ffmpeg(path, new_path, acodec, more_opts)
 334         except AudioConversionError as e:
 335             raise PostProcessingError(
 336                 'audio conversion failed: ' + e.msg)
 337         except Exception:
 338             raise PostProcessingError('error running ' + self.basename)
 339
 340         # Try to update the date time for extracted audio file.
 341         if information.get('filetime') is not None:
 342             self.try_utime(
 343                 new_path, time.time(), information['filetime'],
 344                 errnote='Cannot update utime of audio file')
 345
 346         return [path], information
 347
 348
 349 class FFmpegVideoConvertorPP(FFmpegPostProcessor):
 350     def __init__(self, downloader=None, preferedformat=None):
 351         super(FFmpegVideoConvertorPP, self).__init__(downloader)
 352         self._preferedformat = preferedformat
 353
 354     def run(self, information):
 355         path = information['filepath']
 356         if information['ext'] == self._preferedformat:
 357             self._downloader.to_screen('[ffmpeg] Not converting video file %s - already is in target format %s' % (path, self._preferedformat))
 358             return [], information
 359         options = []
 360         if self._preferedformat == 'avi':
 361             options.extend(['-c:v', 'libxvid', '-vtag', 'XVID'])
 362         prefix, sep, ext = path.rpartition('.')
 363         outpath = prefix + sep + self._preferedformat
 364         self._downloader.to_screen('[' + 'ffmpeg' + '] Converting video from %s to %s, Destination: ' % (information['ext'], self._preferedformat) + outpath)
 365         self.run_ffmpeg(path, outpath, options)
 366         information['filepath'] = outpath
 367         information['format'] = self._preferedformat
 368         information['ext'] = self._preferedformat
 369         return [path], information
 370
 371
 372 class FFmpegEmbedSubtitlePP(FFmpegPostProcessor):
 373     def run(self, information):
 374         if information['ext'] not in ('mp4', 'webm', 'mkv'):
 375             self._downloader.to_screen('[ffmpeg] Subtitles can only be embedded in mp4, webm or mkv files')
 376             return [], information
 377         subtitles = information.get('requested_subtitles')
 378         if not subtitles:
 379             self._downloader.to_screen('[ffmpeg] There aren\'t any subtitles to embed')
 380             return [], information
 381
 382         filename = information['filepath']
 383
 384         ext = information['ext']
 385         sub_langs = []
 386         sub_filenames = []
 387         webm_vtt_warn = False
 388
 389         for lang, sub_info in subtitles.items():
 390             sub_ext = sub_info['ext']
 391             if ext != 'webm' or ext == 'webm' and sub_ext == 'vtt':
 392                 sub_langs.append(lang)
 393                 sub_filenames.append(subtitles_filename(filename, lang, sub_ext))
 394             else:
 395                 if not webm_vtt_warn and ext == 'webm' and sub_ext != 'vtt':
 396                     webm_vtt_warn = True
 397                     self._downloader.to_screen('[ffmpeg] Only WebVTT subtitles can be embedded in webm files')
 398
 399         if not sub_langs:
 400             return [], information
 401
 402         input_files = [filename] + sub_filenames
 403
 404         opts = [
 405             '-map', '0',
 406             '-c', 'copy',
 407             # Don't copy the existing subtitles, we may be running the
 408             # postprocessor a second time
 409             '-map', '-0:s',
 410             # Don't copy Apple TV chapters track, bin_data (see #19042, #19024,
 411             # https://trac.ffmpeg.org/ticket/6016)
 412             '-map', '-0:d',
 413         ]
 414         if information['ext'] == 'mp4':
 415             opts += ['-c:s', 'mov_text']
 416         for (i, lang) in enumerate(sub_langs):
 417             opts.extend(['-map', '%d:0' % (i + 1)])
 418             lang_code = ISO639Utils.short2long(lang) or lang
 419             opts.extend(['-metadata:s:s:%d' % i, 'language=%s' % lang_code])
 420
 421         temp_filename = prepend_extension(filename, 'temp')
 422         self._downloader.to_screen('[ffmpeg] Embedding subtitles in \'%s\'' % filename)
 423         self.run_ffmpeg_multiple_files(input_files, temp_filename, opts)
 424         os.remove(encodeFilename(filename))
 425         os.rename(encodeFilename(temp_filename), encodeFilename(filename))
 426
 427         return sub_filenames, information
 428
 429
 430 class FFmpegMetadataPP(FFmpegPostProcessor):
 431     def run(self, info):
 432         metadata = {}
 433
 434         def add(meta_list, info_list=None):
 435             if not info_list:
 436                 info_list = meta_list
 437             if not isinstance(meta_list, (list, tuple)):
 438                 meta_list = (meta_list,)
 439             if not isinstance(info_list, (list, tuple)):
 440                 info_list = (info_list,)
 441             for info_f in info_list:
 442                 if info.get(info_f) is not None:
 443                     for meta_f in meta_list:
 444                         metadata[meta_f] = info[info_f]
 445                     break
 446
 447         add('title', ('track', 'title'))
 448         add('date', 'upload_date')
 449         add(('description', 'comment'), 'description')
 450         add('purl', 'webpage_url')
 451         add('track', 'track_number')
 452         add('artist', ('artist', 'creator', 'uploader', 'uploader_id'))
 453         add('genre')
 454         add('album')
 455         add('album_artist')
 456         add('disc', 'disc_number')
 457
 458         if not metadata:
 459             self._downloader.to_screen('[ffmpeg] There isn\'t any metadata to add')
 460             return [], info
 461
 462         filename = info['filepath']
 463         temp_filename = prepend_extension(filename, 'temp')
 464         in_filenames = [filename]
 465         options = []
 466
 467         if info['ext'] == 'm4a':
 468             options.extend(['-vn', '-acodec', 'copy'])
 469         else:
 470             options.extend(['-c', 'copy'])
 471
 472         for (name, value) in metadata.items():
 473             options.extend(['-metadata', '%s=%s' % (name, value)])
 474
 475         chapters = info.get('chapters', [])
 476         if chapters:
 477             metadata_filename = replace_extension(filename, 'meta')
 478             with io.open(metadata_filename, 'wt', encoding='utf-8') as f:
 479                 def ffmpeg_escape(text):
 480                     return re.sub(r'(=|;|#|\\|\n)', r'\\\1', text)
 481
 482                 metadata_file_content = ';FFMETADATA1\n'
 483                 for chapter in chapters:
 484                     metadata_file_content += '[CHAPTER]\nTIMEBASE=1/1000\n'
 485                     metadata_file_content += 'START=%d\n' % (chapter['start_time'] * 1000)
 486                     metadata_file_content += 'END=%d\n' % (chapter['end_time'] * 1000)
 487                     chapter_title = chapter.get('title')
 488                     if chapter_title:
 489                         metadata_file_content += 'title=%s\n' % ffmpeg_escape(chapter_title)
 490                 f.write(metadata_file_content)
 491                 in_filenames.append(metadata_filename)
 492                 options.extend(['-map_metadata', '1'])
 493
 494         self._downloader.to_screen('[ffmpeg] Adding metadata to \'%s\'' % filename)
 495         self.run_ffmpeg_multiple_files(in_filenames, temp_filename, options)
 496         if chapters:
 497             os.remove(metadata_filename)
 498         os.remove(encodeFilename(filename))
 499         os.rename(encodeFilename(temp_filename), encodeFilename(filename))
 500         return [], info
 501
 502
 503 class FFmpegMergerPP(FFmpegPostProcessor):
 504     def run(self, info):
 505         filename = info['filepath']
 506         temp_filename = prepend_extension(filename, 'temp')
 507         args = ['-c', 'copy', '-map', '0:v:0', '-map', '1:a:0']
 508         self._downloader.to_screen('[ffmpeg] Merging formats into "%s"' % filename)
 509         self.run_ffmpeg_multiple_files(info['__files_to_merge'], temp_filename, args)
 510         os.rename(encodeFilename(temp_filename), encodeFilename(filename))
 511         return info['__files_to_merge'], info
 512
 513     def can_merge(self):
 514         # TODO: figure out merge-capable ffmpeg version
 515         if self.basename != 'avconv':
 516             return True
 517
 518         required_version = '10-0'
 519         if is_outdated_version(
 520                 self._versions[self.basename], required_version):
 521             warning = ('Your copy of %s is outdated and unable to properly mux separate video and audio files, '
 522                        'youtube-dl will download single file media. '
 523                        'Update %s to version %s or newer to fix this.') % (
 524                            self.basename, self.basename, required_version)
 525             if self._downloader:
 526                 self._downloader.report_warning(warning)
 527             return False
 528         return True
 529
 530
 531 class FFmpegFixupStretchedPP(FFmpegPostProcessor):
 532     def run(self, info):
 533         stretched_ratio = info.get('stretched_ratio')
 534         if stretched_ratio is None or stretched_ratio == 1:
 535             return [], info
 536
 537         filename = info['filepath']
 538         temp_filename = prepend_extension(filename, 'temp')
 539
 540         options = ['-c', 'copy', '-aspect', '%f' % stretched_ratio]
 541         self._downloader.to_screen('[ffmpeg] Fixing aspect ratio in "%s"' % filename)
 542         self.run_ffmpeg(filename, temp_filename, options)
 543
 544         os.remove(encodeFilename(filename))
 545         os.rename(encodeFilename(temp_filename), encodeFilename(filename))
 546
 547         return [], info
 548
 549
 550 class FFmpegFixupM4aPP(FFmpegPostProcessor):
 551     def run(self, info):
 552         if info.get('container') != 'm4a_dash':
 553             return [], info
 554
 555         filename = info['filepath']
 556         temp_filename = prepend_extension(filename, 'temp')
 557
 558         options = ['-c', 'copy', '-f', 'mp4']
 559         self._downloader.to_screen('[ffmpeg] Correcting container in "%s"' % filename)
 560         self.run_ffmpeg(filename, temp_filename, options)
 561
 562         os.remove(encodeFilename(filename))
 563         os.rename(encodeFilename(temp_filename), encodeFilename(filename))
 564
 565         return [], info
 566
 567
 568 class FFmpegFixupM3u8PP(FFmpegPostProcessor):
 569     def run(self, info):
 570         filename = info['filepath']
 571         if self.get_audio_codec(filename) == 'aac':
 572             temp_filename = prepend_extension(filename, 'temp')
 573
 574             options = ['-c', 'copy', '-f', 'mp4', '-bsf:a', 'aac_adtstoasc']
 575             self._downloader.to_screen('[ffmpeg] Fixing malformed AAC bitstream in "%s"' % filename)
 576             self.run_ffmpeg(filename, temp_filename, options)
 577
 578             os.remove(encodeFilename(filename))
 579             os.rename(encodeFilename(temp_filename), encodeFilename(filename))
 580         return [], info
 581
 582
 583 class FFmpegSubtitlesConvertorPP(FFmpegPostProcessor):
 584     def __init__(self, downloader=None, format=None):
 585         super(FFmpegSubtitlesConvertorPP, self).__init__(downloader)
 586         self.format = format
 587
 588     def run(self, info):
 589         subs = info.get('requested_subtitles')
 590         filename = info['filepath']
 591         new_ext = self.format
 592         new_format = new_ext
 593         if new_format == 'vtt':
 594             new_format = 'webvtt'
 595         if subs is None:
 596             self._downloader.to_screen('[ffmpeg] There aren\'t any subtitles to convert')
 597             return [], info
 598         self._downloader.to_screen('[ffmpeg] Converting subtitles')
 599         sub_filenames = []
 600         for lang, sub in subs.items():
 601             ext = sub['ext']
 602             if ext == new_ext:
 603                 self._downloader.to_screen(
 604                     '[ffmpeg] Subtitle file for %s is already in the requested format' % new_ext)
 605                 continue
 606             old_file = subtitles_filename(filename, lang, ext)
 607             sub_filenames.append(old_file)
 608             new_file = subtitles_filename(filename, lang, new_ext)
 609
 610             if ext in ('dfxp', 'ttml', 'tt'):
 611                 self._downloader.report_warning(
 612                     'You have requested to convert dfxp (TTML) subtitles into another format, '
 613                     'which results in style information loss')
 614
 615                 dfxp_file = old_file
 616                 srt_file = subtitles_filename(filename, lang, 'srt')
 617
 618                 with open(dfxp_file, 'rb') as f:
 619                     srt_data = dfxp2srt(f.read())
 620
 621                 with io.open(srt_file, 'wt', encoding='utf-8') as f:
 622                     f.write(srt_data)
 623                 old_file = srt_file
 624
 625                 subs[lang] = {
 626                     'ext': 'srt',
 627                     'data': srt_data
 628                 }
 629
 630                 if new_ext == 'srt':
 631                     continue
 632                 else:
 633                     sub_filenames.append(srt_file)
 634
 635             self.run_ffmpeg(old_file, new_file, ['-f', new_format])
 636
 637             with io.open(new_file, 'rt', encoding='utf-8') as f:
 638                 subs[lang] = {
 639                     'ext': new_ext,
 640                     'data': f.read(),
 641                 }
 642
 643         return sub_filenames, info