diff --git a/youtube_dl/postprocessor/ffmpeg.py b/youtube_dl/postprocessor/ffmpeg.py
index fa99b0c2a6..8d1214ee2c 100644
--- a/youtube_dl/postprocessor/ffmpeg.py
+++ b/youtube_dl/postprocessor/ffmpeg.py
@@ -139,6 +139,30 @@ class FFmpegPostProcessor(PostProcessor):
     def probe_executable(self):
         return self._paths[self.probe_basename]
 
+    def get_audio_codec(self, path):
+        if not self.probe_available:
+            raise PostProcessingError('ffprobe or avprobe not found. Please install one.')
+        try:
+            cmd = [
+                encodeFilename(self.probe_executable, True),
+                encodeArgument('-show_streams'),
+                encodeFilename(self._ffmpeg_filename_argument(path), True)]
+            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
+        except (IOError, OSError):
+            return None
+        audio_codec = None
+        for line in output.decode('ascii', 'ignore').split('\n'):
+            if line.startswith('codec_name='):
+                audio_codec = line.split('=')[1].strip()
+            elif line.strip() == 'codec_type=audio' and audio_codec is not None:
+                return audio_codec
+        return None
+
     def run_ffmpeg_multiple_files(self, input_paths, out_path, opts):
         self.check_version()
 
@@ -188,31 +212,6 @@ class FFmpegExtractAudioPP(FFmpegPostProcessor):
         self._preferredquality = preferredquality
         self._nopostoverwrites = nopostoverwrites
 
-    def get_audio_codec(self, path):
-
-        if not self.probe_available:
-            raise PostProcessingError('ffprobe or avprobe not found. Please install one.')
-        try:
-            cmd = [
-                encodeFilename(self.probe_executable, True),
-                encodeArgument('-show_streams'),
-                encodeFilename(self._ffmpeg_filename_argument(path), True)]
-            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
-        except (IOError, OSError):
-            return None
-        audio_codec = None
-        for line in output.decode('ascii', 'ignore').split('\n'):
-            if line.startswith('codec_name='):
-                audio_codec = line.split('=')[1].strip()
-            elif line.strip() == 'codec_type=audio' and audio_codec is not None:
-                return audio_codec
-        return None
-
     def run_ffmpeg(self, path, out_path, codec, more_opts):
         if codec is None:
             acodec_opts = []
@@ -504,15 +503,15 @@ class FFmpegFixupM4aPP(FFmpegPostProcessor):
 class FFmpegFixupM3u8PP(FFmpegPostProcessor):
     def run(self, info):
         filename = info['filepath']
-        temp_filename = prepend_extension(filename, 'temp')
+        if self.get_audio_codec(filename) == 'aac':
+            temp_filename = prepend_extension(filename, 'temp')
 
-        options = ['-c', 'copy', '-f', 'mp4', '-bsf:a', 'aac_adtstoasc']
-        self._downloader.to_screen('[ffmpeg] Fixing malformated aac bitstream in "%s"' % filename)
-        self.run_ffmpeg(filename, temp_filename, options)
-
-        os.remove(encodeFilename(filename))
-        os.rename(encodeFilename(temp_filename), encodeFilename(filename))
+            options = ['-c', 'copy', '-f', 'mp4', '-bsf:a', 'aac_adtstoasc']
+            self._downloader.to_screen('[ffmpeg] Fixing malformated aac bitstream in "%s"' % filename)
+            self.run_ffmpeg(filename, temp_filename, options)
 
+            os.remove(encodeFilename(filename))
+            os.rename(encodeFilename(temp_filename), encodeFilename(filename))
         return [], info