]> Raphaƫl G. Git Repositories - youtubedl/blobdiff - youtube_dl/postprocessor/ffmpeg.py
Imported Upstream version 2015.07.21
[youtubedl] / youtube_dl / postprocessor / ffmpeg.py
index 5b0ff32b14747d91b1c5c7223fa4efaae7aac574..1f723908be8d4ff0247affc5aed9ffc44e777602 100644 (file)
@@ -1,8 +1,8 @@
 from __future__ import unicode_literals
 
+import io
 import os
 import subprocess
-import sys
 import time
 
 
@@ -20,6 +20,8 @@ from ..utils import (
     prepend_extension,
     shell_quote,
     subtitles_filename,
+    dfxp2srt,
+    ISO639Utils,
 )
 
 
@@ -28,56 +30,100 @@ class FFmpegPostProcessorError(PostProcessingError):
 
 
 class FFmpegPostProcessor(PostProcessor):
-    def __init__(self, downloader=None, deletetempfiles=False):
+    def __init__(self, downloader=None):
         PostProcessor.__init__(self, downloader)
-        self._versions = self.get_versions()
-        self._deletetempfiles = deletetempfiles
+        self._determine_executables()
 
     def check_version(self):
-        if not self._executable:
+        if not self.available:
             raise FFmpegPostProcessorError('ffmpeg or avconv not found. Please install one.')
 
-        required_version = '10-0' if self._uses_avconv() else '1.0'
+        required_version = '10-0' if self.basename == 'avconv' else '1.0'
         if is_outdated_version(
-                self._versions[self._executable], required_version):
+                self._versions[self.basename], required_version):
             warning = 'Your copy of %s is outdated, update %s to version %s or newer if you encounter any errors.' % (
-                self._executable, self._executable, required_version)
+                self.basename, self.basename, required_version)
             if self._downloader:
                 self._downloader.report_warning(warning)
 
     @staticmethod
-    def get_versions():
-        programs = ['avprobe', 'avconv', 'ffmpeg', 'ffprobe']
-        return dict((p, get_exe_version(p, args=['-version'])) for p in programs)
-
-    @property
-    def available(self):
-        return self._executable is not None
+    def get_versions(downloader=None):
+        return FFmpegPostProcessor(downloader)._versions
 
-    @property
-    def _executable(self):
-        if self._downloader.params.get('prefer_ffmpeg', False):
+    def _determine_executables(self):
+        programs = ['avprobe', 'avconv', 'ffmpeg', 'ffprobe']
+        prefer_ffmpeg = self._downloader.params.get('prefer_ffmpeg', False)
+
+        self.basename = None
+        self.probe_basename = None
+
+        self._paths = None
+        self._versions = None
+        if self._downloader:
+            location = self._downloader.params.get('ffmpeg_location')
+            if location is not None:
+                if not os.path.exists(location):
+                    self._downloader.report_warning(
+                        'ffmpeg-location %s does not exist! '
+                        'Continuing without avconv/ffmpeg.' % (location))
+                    self._versions = {}
+                    return
+                elif not os.path.isdir(location):
+                    basename = os.path.splitext(os.path.basename(location))[0]
+                    if basename not in programs:
+                        self._downloader.report_warning(
+                            'Cannot identify executable %s, its basename should be one of %s. '
+                            'Continuing without avconv/ffmpeg.' %
+                            (location, ', '.join(programs)))
+                        self._versions = {}
+                        return None
+                    location = os.path.dirname(os.path.abspath(location))
+                    if basename in ('ffmpeg', 'ffprobe'):
+                        prefer_ffmpeg = True
+
+                self._paths = dict(
+                    (p, os.path.join(location, p)) for p in programs)
+                self._versions = dict(
+                    (p, get_exe_version(self._paths[p], args=['-version']))
+                    for p in programs)
+        if self._versions is None:
+            self._versions = dict(
+                (p, get_exe_version(p, args=['-version'])) for p in programs)
+            self._paths = dict((p, p) for p in programs)
+
+        if prefer_ffmpeg:
             prefs = ('ffmpeg', 'avconv')
         else:
             prefs = ('avconv', 'ffmpeg')
         for p in prefs:
             if self._versions[p]:
-                return p
-        return None
+                self.basename = p
+                break
 
-    @property
-    def _probe_executable(self):
-        if self._downloader.params.get('prefer_ffmpeg', False):
+        if prefer_ffmpeg:
             prefs = ('ffprobe', 'avprobe')
         else:
             prefs = ('avprobe', 'ffprobe')
         for p in prefs:
             if self._versions[p]:
-                return p
-        return None
+                self.probe_basename = p
+                break
+
+    @property
+    def available(self):
+        return self.basename is not None
 
-    def _uses_avconv(self):
-        return self._executable == 'avconv'
+    @property
+    def executable(self):
+        return self._paths[self.basename]
+
+    @property
+    def probe_available(self):
+        return self.probe_basename is not None
+
+    @property
+    def probe_executable(self):
+        return self._paths[self.probe_basename]
 
     def run_ffmpeg_multiple_files(self, input_paths, out_path, opts):
         self.check_version()
@@ -85,26 +131,25 @@ class FFmpegPostProcessor(PostProcessor):
         oldest_mtime = min(
             os.stat(encodeFilename(path)).st_mtime for path in input_paths)
 
+        opts += self._configuration_args()
+
         files_cmd = []
         for path in input_paths:
             files_cmd.extend([encodeArgument('-i'), encodeFilename(path, True)])
-        cmd = ([encodeFilename(self._executable, True), encodeArgument('-y')] +
+        cmd = ([encodeFilename(self.executable, True), encodeArgument('-y')] +
                files_cmd +
                [encodeArgument(o) for o in opts] +
                [encodeFilename(self._ffmpeg_filename_argument(out_path), True)])
 
         if self._downloader.params.get('verbose', False):
             self._downloader.to_screen('[debug] ffmpeg command line: %s' % shell_quote(cmd))
-        p = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+        p = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, stdin=subprocess.PIPE)
         stdout, stderr = p.communicate()
         if p.returncode != 0:
             stderr = stderr.decode('utf-8', 'replace')
             msg = stderr.strip().split('\n')[-1]
             raise FFmpegPostProcessorError(msg)
-        os.utime(encodeFilename(out_path), (oldest_mtime, oldest_mtime))
-        if self._deletetempfiles:
-            for ipath in input_paths:
-                os.remove(ipath)
+        self.try_utime(out_path, oldest_mtime, oldest_mtime)
 
     def run_ffmpeg(self, path, out_path, opts):
         self.run_ffmpeg_multiple_files([path], out_path, opts)
@@ -127,14 +172,16 @@ class FFmpegExtractAudioPP(FFmpegPostProcessor):
 
     def get_audio_codec(self, path):
 
-        if not self._probe_executable:
+        if not self.probe_available:
             raise PostProcessingError('ffprobe or avprobe not found. Please install one.')
         try:
             cmd = [
-                encodeFilename(self._probe_executable, True),
+                encodeFilename(self.probe_executable, True),
                 encodeArgument('-show_streams'),
                 encodeFilename(self._ffmpeg_filename_argument(path), True)]
-            handle = subprocess.Popen(cmd, stderr=compat_subprocess_get_DEVNULL(), stdout=subprocess.PIPE)
+            if self._downloader.params.get('verbose', False):
+                self._downloader.to_screen('[debug] %s command line: %s' % (self.basename, shell_quote(cmd)))
+            handle = subprocess.Popen(cmd, stderr=compat_subprocess_get_DEVNULL(), stdout=subprocess.PIPE, stdin=subprocess.PIPE)
             output = handle.communicate()[0]
             if handle.wait() != 0:
                 return None
@@ -166,14 +213,13 @@ class FFmpegExtractAudioPP(FFmpegPostProcessor):
         if filecodec is None:
             raise PostProcessingError('WARNING: unable to obtain file audio codec with ffprobe')
 
-        uses_avconv = self._uses_avconv()
         more_opts = []
         if self._preferredcodec == 'best' or self._preferredcodec == filecodec or (self._preferredcodec == 'm4a' and filecodec == 'aac'):
             if filecodec == 'aac' and self._preferredcodec in ['m4a', 'best']:
                 # Lossless, but in another container
                 acodec = 'copy'
                 extension = 'm4a'
-                more_opts = ['-bsf:a' if uses_avconv else '-absf', 'aac_adtstoasc']
+                more_opts = ['-bsf:a', 'aac_adtstoasc']
             elif filecodec in ['aac', 'mp3', 'vorbis', 'opus']:
                 # Lossless if possible
                 acodec = 'copy'
@@ -189,9 +235,9 @@ class FFmpegExtractAudioPP(FFmpegPostProcessor):
                 more_opts = []
                 if self._preferredquality is not None:
                     if int(self._preferredquality) < 10:
-                        more_opts += ['-q:a' if uses_avconv else '-aq', self._preferredquality]
+                        more_opts += ['-q:a', self._preferredquality]
                     else:
-                        more_opts += ['-b:a' if uses_avconv else '-ab', self._preferredquality + 'k']
+                        more_opts += ['-b:a', self._preferredquality + 'k']
         else:
             # We convert the audio (lossy)
             acodec = {'mp3': 'libmp3lame', 'aac': 'aac', 'm4a': 'aac', 'opus': 'opus', 'vorbis': 'libvorbis', 'wav': None}[self._preferredcodec]
@@ -200,13 +246,13 @@ class FFmpegExtractAudioPP(FFmpegPostProcessor):
             if self._preferredquality is not None:
                 # The opus codec doesn't support the -aq option
                 if int(self._preferredquality) < 10 and extension != 'opus':
-                    more_opts += ['-q:a' if uses_avconv else '-aq', self._preferredquality]
+                    more_opts += ['-q:a', self._preferredquality]
                 else:
-                    more_opts += ['-b:a' if uses_avconv else '-ab', self._preferredquality + 'k']
+                    more_opts += ['-b:a', self._preferredquality + 'k']
             if self._preferredcodec == 'aac':
                 more_opts += ['-f', 'adts']
             if self._preferredcodec == 'm4a':
-                more_opts += ['-bsf:a' if uses_avconv else '-absf', 'aac_adtstoasc']
+                more_opts += ['-bsf:a', 'aac_adtstoasc']
             if self._preferredcodec == 'vorbis':
                 extension = 'ogg'
             if self._preferredcodec == 'wav':
@@ -217,32 +263,30 @@ class FFmpegExtractAudioPP(FFmpegPostProcessor):
         new_path = prefix + sep + extension
 
         # If we download foo.mp3 and convert it to... foo.mp3, then don't delete foo.mp3, silly.
-        if new_path == path:
-            self._nopostoverwrites = True
+        if (new_path == path or
+                (self._nopostoverwrites and os.path.exists(encodeFilename(new_path)))):
+            self._downloader.to_screen('[ffmpeg] Post-process file %s exists, skipping' % new_path)
+            return [], information
 
         try:
-            if self._nopostoverwrites and os.path.exists(encodeFilename(new_path)):
-                self._downloader.to_screen('[youtube] Post-process file %s exists, skipping' % new_path)
-            else:
-                self._downloader.to_screen('[' + self._executable + '] Destination: ' + new_path)
-                self.run_ffmpeg(path, new_path, acodec, more_opts)
-        except:
-            etype, e, tb = sys.exc_info()
-            if isinstance(e, AudioConversionError):
-                msg = 'audio conversion failed: ' + e.msg
-            else:
-                msg = 'error running ' + self._executable
-            raise PostProcessingError(msg)
+            self._downloader.to_screen('[' + self.basename + '] Destination: ' + new_path)
+            self.run_ffmpeg(path, new_path, acodec, more_opts)
+        except AudioConversionError as e:
+            raise PostProcessingError(
+                'audio conversion failed: ' + e.msg)
+        except Exception:
+            raise PostProcessingError('error running ' + self.basename)
 
         # Try to update the date time for extracted audio file.
         if information.get('filetime') is not None:
-            try:
-                os.utime(encodeFilename(new_path), (time.time(), information['filetime']))
-            except:
-                self._downloader.report_warning('Cannot update utime of audio file')
+            self.try_utime(
+                new_path, time.time(), information['filetime'],
+                errnote='Cannot update utime of audio file')
 
         information['filepath'] = new_path
-        return self._nopostoverwrites, information
+        information['ext'] = extension
+
+        return [path], information
 
 
 class FFmpegVideoConvertorPP(FFmpegPostProcessor):
@@ -252,228 +296,36 @@ class FFmpegVideoConvertorPP(FFmpegPostProcessor):
 
     def run(self, information):
         path = information['filepath']
-        prefix, sep, ext = path.rpartition('.')
-        outpath = prefix + sep + self._preferedformat
         if information['ext'] == self._preferedformat:
             self._downloader.to_screen('[ffmpeg] Not converting video file %s - already is in target format %s' % (path, self._preferedformat))
-            return True, information
+            return [], information
+        options = []
+        if self._preferedformat == 'avi':
+            options.extend(['-c:v', 'libxvid', '-vtag', 'XVID'])
+        prefix, sep, ext = path.rpartition('.')
+        outpath = prefix + sep + self._preferedformat
         self._downloader.to_screen('[' + 'ffmpeg' + '] Converting video from %s to %s, Destination: ' % (information['ext'], self._preferedformat) + outpath)
-        self.run_ffmpeg(path, outpath, [])
+        self.run_ffmpeg(path, outpath, options)
         information['filepath'] = outpath
         information['format'] = self._preferedformat
         information['ext'] = self._preferedformat
-        return False, information
+        return [path], information
 
 
 class FFmpegEmbedSubtitlePP(FFmpegPostProcessor):
-    # See http://www.loc.gov/standards/iso639-2/ISO-639-2_utf-8.txt
-    _lang_map = {
-        'aa': 'aar',
-        'ab': 'abk',
-        'ae': 'ave',
-        'af': 'afr',
-        'ak': 'aka',
-        'am': 'amh',
-        'an': 'arg',
-        'ar': 'ara',
-        'as': 'asm',
-        'av': 'ava',
-        'ay': 'aym',
-        'az': 'aze',
-        'ba': 'bak',
-        'be': 'bel',
-        'bg': 'bul',
-        'bh': 'bih',
-        'bi': 'bis',
-        'bm': 'bam',
-        'bn': 'ben',
-        'bo': 'bod',
-        'br': 'bre',
-        'bs': 'bos',
-        'ca': 'cat',
-        'ce': 'che',
-        'ch': 'cha',
-        'co': 'cos',
-        'cr': 'cre',
-        'cs': 'ces',
-        'cu': 'chu',
-        'cv': 'chv',
-        'cy': 'cym',
-        'da': 'dan',
-        'de': 'deu',
-        'dv': 'div',
-        'dz': 'dzo',
-        'ee': 'ewe',
-        'el': 'ell',
-        'en': 'eng',
-        'eo': 'epo',
-        'es': 'spa',
-        'et': 'est',
-        'eu': 'eus',
-        'fa': 'fas',
-        'ff': 'ful',
-        'fi': 'fin',
-        'fj': 'fij',
-        'fo': 'fao',
-        'fr': 'fra',
-        'fy': 'fry',
-        'ga': 'gle',
-        'gd': 'gla',
-        'gl': 'glg',
-        'gn': 'grn',
-        'gu': 'guj',
-        'gv': 'glv',
-        'ha': 'hau',
-        'he': 'heb',
-        'hi': 'hin',
-        'ho': 'hmo',
-        'hr': 'hrv',
-        'ht': 'hat',
-        'hu': 'hun',
-        'hy': 'hye',
-        'hz': 'her',
-        'ia': 'ina',
-        'id': 'ind',
-        'ie': 'ile',
-        'ig': 'ibo',
-        'ii': 'iii',
-        'ik': 'ipk',
-        'io': 'ido',
-        'is': 'isl',
-        'it': 'ita',
-        'iu': 'iku',
-        'ja': 'jpn',
-        'jv': 'jav',
-        'ka': 'kat',
-        'kg': 'kon',
-        'ki': 'kik',
-        'kj': 'kua',
-        'kk': 'kaz',
-        'kl': 'kal',
-        'km': 'khm',
-        'kn': 'kan',
-        'ko': 'kor',
-        'kr': 'kau',
-        'ks': 'kas',
-        'ku': 'kur',
-        'kv': 'kom',
-        'kw': 'cor',
-        'ky': 'kir',
-        'la': 'lat',
-        'lb': 'ltz',
-        'lg': 'lug',
-        'li': 'lim',
-        'ln': 'lin',
-        'lo': 'lao',
-        'lt': 'lit',
-        'lu': 'lub',
-        'lv': 'lav',
-        'mg': 'mlg',
-        'mh': 'mah',
-        'mi': 'mri',
-        'mk': 'mkd',
-        'ml': 'mal',
-        'mn': 'mon',
-        'mr': 'mar',
-        'ms': 'msa',
-        'mt': 'mlt',
-        'my': 'mya',
-        'na': 'nau',
-        'nb': 'nob',
-        'nd': 'nde',
-        'ne': 'nep',
-        'ng': 'ndo',
-        'nl': 'nld',
-        'nn': 'nno',
-        'no': 'nor',
-        'nr': 'nbl',
-        'nv': 'nav',
-        'ny': 'nya',
-        'oc': 'oci',
-        'oj': 'oji',
-        'om': 'orm',
-        'or': 'ori',
-        'os': 'oss',
-        'pa': 'pan',
-        'pi': 'pli',
-        'pl': 'pol',
-        'ps': 'pus',
-        'pt': 'por',
-        'qu': 'que',
-        'rm': 'roh',
-        'rn': 'run',
-        'ro': 'ron',
-        'ru': 'rus',
-        'rw': 'kin',
-        'sa': 'san',
-        'sc': 'srd',
-        'sd': 'snd',
-        'se': 'sme',
-        'sg': 'sag',
-        'si': 'sin',
-        'sk': 'slk',
-        'sl': 'slv',
-        'sm': 'smo',
-        'sn': 'sna',
-        'so': 'som',
-        'sq': 'sqi',
-        'sr': 'srp',
-        'ss': 'ssw',
-        'st': 'sot',
-        'su': 'sun',
-        'sv': 'swe',
-        'sw': 'swa',
-        'ta': 'tam',
-        'te': 'tel',
-        'tg': 'tgk',
-        'th': 'tha',
-        'ti': 'tir',
-        'tk': 'tuk',
-        'tl': 'tgl',
-        'tn': 'tsn',
-        'to': 'ton',
-        'tr': 'tur',
-        'ts': 'tso',
-        'tt': 'tat',
-        'tw': 'twi',
-        'ty': 'tah',
-        'ug': 'uig',
-        'uk': 'ukr',
-        'ur': 'urd',
-        'uz': 'uzb',
-        've': 'ven',
-        'vi': 'vie',
-        'vo': 'vol',
-        'wa': 'wln',
-        'wo': 'wol',
-        'xh': 'xho',
-        'yi': 'yid',
-        'yo': 'yor',
-        'za': 'zha',
-        'zh': 'zho',
-        'zu': 'zul',
-    }
-
-    def __init__(self, downloader=None, subtitlesformat='srt'):
-        super(FFmpegEmbedSubtitlePP, self).__init__(downloader)
-        self._subformat = subtitlesformat
-
-    @classmethod
-    def _conver_lang_code(cls, code):
-        """Convert language code from ISO 639-1 to ISO 639-2/T"""
-        return cls._lang_map.get(code[:2])
-
     def run(self, information):
-        if information['ext'] != 'mp4':
-            self._downloader.to_screen('[ffmpeg] Subtitles can only be embedded in mp4 files')
-            return True, information
-        if not information.get('subtitles'):
+        if information['ext'] not in ['mp4', 'mkv']:
+            self._downloader.to_screen('[ffmpeg] Subtitles can only be embedded in mp4 or mkv files')
+            return [], information
+        subtitles = information.get('requested_subtitles')
+        if not subtitles:
             self._downloader.to_screen('[ffmpeg] There aren\'t any subtitles to embed')
-            return True, information
+            return [], information
 
-        sub_langs = [key for key in information['subtitles']]
+        sub_langs = list(subtitles.keys())
         filename = information['filepath']
-        input_files = [filename] + [subtitles_filename(filename, lang, self._subformat) for lang in sub_langs]
+        sub_filenames = [subtitles_filename(filename, lang, sub_info['ext']) for lang, sub_info in subtitles.items()]
+        input_files = [filename] + sub_filenames
 
         opts = [
             '-map', '0',
@@ -481,11 +333,12 @@ class FFmpegEmbedSubtitlePP(FFmpegPostProcessor):
             # Don't copy the existing subtitles, we may be running the
             # postprocessor a second time
             '-map', '-0:s',
-            '-c:s', 'mov_text',
         ]
+        if information['ext'] == 'mp4':
+            opts += ['-c:s', 'mov_text']
         for (i, lang) in enumerate(sub_langs):
             opts.extend(['-map', '%d:0' % (i + 1)])
-            lang_code = self._conver_lang_code(lang)
+            lang_code = ISO639Utils.short2long(lang)
             if lang_code is not None:
                 opts.extend(['-metadata:s:s:%d' % i, 'language=%s' % lang_code])
 
@@ -495,7 +348,7 @@ class FFmpegEmbedSubtitlePP(FFmpegPostProcessor):
         os.remove(encodeFilename(filename))
         os.rename(encodeFilename(temp_filename), encodeFilename(filename))
 
-        return True, information
+        return sub_filenames, information
 
 
 class FFmpegMetadataPP(FFmpegPostProcessor):
@@ -505,14 +358,23 @@ class FFmpegMetadataPP(FFmpegPostProcessor):
             metadata['title'] = info['title']
         if info.get('upload_date') is not None:
             metadata['date'] = info['upload_date']
-        if info.get('uploader') is not None:
+        if info.get('artist') is not None:
+            metadata['artist'] = info['artist']
+        elif info.get('uploader') is not None:
             metadata['artist'] = info['uploader']
         elif info.get('uploader_id') is not None:
             metadata['artist'] = info['uploader_id']
+        if info.get('description') is not None:
+            metadata['description'] = info['description']
+            metadata['comment'] = info['description']
+        if info.get('webpage_url') is not None:
+            metadata['purl'] = info['webpage_url']
+        if info.get('album') is not None:
+            metadata['album'] = info['album']
 
         if not metadata:
             self._downloader.to_screen('[ffmpeg] There isn\'t any metadata to add')
-            return True, info
+            return [], info
 
         filename = info['filepath']
         temp_filename = prepend_extension(filename, 'temp')
@@ -529,47 +391,130 @@ class FFmpegMetadataPP(FFmpegPostProcessor):
         self.run_ffmpeg(filename, temp_filename, options)
         os.remove(encodeFilename(filename))
         os.rename(encodeFilename(temp_filename), encodeFilename(filename))
-        return True, info
+        return [], info
 
 
 class FFmpegMergerPP(FFmpegPostProcessor):
     def run(self, info):
         filename = info['filepath']
+        temp_filename = prepend_extension(filename, 'temp')
         args = ['-c', 'copy', '-map', '0:v:0', '-map', '1:a:0']
         self._downloader.to_screen('[ffmpeg] Merging formats into "%s"' % filename)
-        self.run_ffmpeg_multiple_files(info['__files_to_merge'], filename, args)
-        return True, info
+        self.run_ffmpeg_multiple_files(info['__files_to_merge'], temp_filename, args)
+        os.rename(encodeFilename(temp_filename), encodeFilename(filename))
+        return info['__files_to_merge'], info
+
+    def can_merge(self):
+        # TODO: figure out merge-capable ffmpeg version
+        if self.basename != 'avconv':
+            return True
+
+        required_version = '10-0'
+        if is_outdated_version(
+                self._versions[self.basename], required_version):
+            warning = ('Your copy of %s is outdated and unable to properly mux separate video and audio files, '
+                       'youtube-dl will download single file media. '
+                       'Update %s to version %s or newer to fix this.') % (
+                           self.basename, self.basename, required_version)
+            if self._downloader:
+                self._downloader.report_warning(warning)
+            return False
+        return True
 
 
-class FFmpegAudioFixPP(FFmpegPostProcessor):
+class FFmpegFixupStretchedPP(FFmpegPostProcessor):
     def run(self, info):
+        stretched_ratio = info.get('stretched_ratio')
+        if stretched_ratio is None or stretched_ratio == 1:
+            return [], info
+
         filename = info['filepath']
         temp_filename = prepend_extension(filename, 'temp')
 
-        options = ['-vn', '-acodec', 'copy']
-        self._downloader.to_screen('[ffmpeg] Fixing audio file "%s"' % filename)
+        options = ['-c', 'copy', '-aspect', '%f' % stretched_ratio]
+        self._downloader.to_screen('[ffmpeg] Fixing aspect ratio in "%s"' % filename)
         self.run_ffmpeg(filename, temp_filename, options)
 
         os.remove(encodeFilename(filename))
         os.rename(encodeFilename(temp_filename), encodeFilename(filename))
 
-        return True, info
+        return [], info
 
 
-class FFmpegFixupStretchedPP(FFmpegPostProcessor):
+class FFmpegFixupM4aPP(FFmpegPostProcessor):
     def run(self, info):
-        stretched_ratio = info.get('stretched_ratio')
-        if stretched_ratio is None or stretched_ratio == 1:
-            return
+        if info.get('container') != 'm4a_dash':
+            return [], info
 
         filename = info['filepath']
         temp_filename = prepend_extension(filename, 'temp')
 
-        options = ['-c', 'copy', '-aspect', '%f' % stretched_ratio]
-        self._downloader.to_screen('[ffmpeg] Fixing aspect ratio in "%s"' % filename)
+        options = ['-c', 'copy', '-f', 'mp4']
+        self._downloader.to_screen('[ffmpeg] Correcting container in "%s"' % filename)
         self.run_ffmpeg(filename, temp_filename, options)
 
         os.remove(encodeFilename(filename))
         os.rename(encodeFilename(temp_filename), encodeFilename(filename))
 
-        return True, info
+        return [], info
+
+
+class FFmpegSubtitlesConvertorPP(FFmpegPostProcessor):
+    def __init__(self, downloader=None, format=None):
+        super(FFmpegSubtitlesConvertorPP, self).__init__(downloader)
+        self.format = format
+
+    def run(self, info):
+        subs = info.get('requested_subtitles')
+        filename = info['filepath']
+        new_ext = self.format
+        new_format = new_ext
+        if new_format == 'vtt':
+            new_format = 'webvtt'
+        if subs is None:
+            self._downloader.to_screen('[ffmpeg] There aren\'t any subtitles to convert')
+            return [], info
+        self._downloader.to_screen('[ffmpeg] Converting subtitles')
+        for lang, sub in subs.items():
+            ext = sub['ext']
+            if ext == new_ext:
+                self._downloader.to_screen(
+                    '[ffmpeg] Subtitle file for %s is already in the requested'
+                    'format' % new_ext)
+                continue
+            new_file = subtitles_filename(filename, lang, new_ext)
+
+            if ext == 'dfxp' or ext == 'ttml':
+                self._downloader.report_warning(
+                    'You have requested to convert dfxp (TTML) subtitles into another format, '
+                    'which results in style information loss')
+
+                dfxp_file = subtitles_filename(filename, lang, ext)
+                srt_file = subtitles_filename(filename, lang, 'srt')
+
+                with io.open(dfxp_file, 'rt', encoding='utf-8') as f:
+                    srt_data = dfxp2srt(f.read())
+
+                with io.open(srt_file, 'wt', encoding='utf-8') as f:
+                    f.write(srt_data)
+
+                ext = 'srt'
+                subs[lang] = {
+                    'ext': 'srt',
+                    'data': srt_data
+                }
+
+                if new_ext == 'srt':
+                    continue
+
+            self.run_ffmpeg(
+                subtitles_filename(filename, lang, ext),
+                new_file, ['-f', new_format])
+
+            with io.open(new_file, 'rt', encoding='utf-8') as f:
+                subs[lang] = {
+                    'ext': ext,
+                    'data': f.read(),
+                }
+
+        return [], info