Add an audio extracting PostProcessor using ffmpeg (closes #2)

diff --git a/youtube-dl b/youtube-dl
index 2e04c05b05934bc98da638d862f21340e40c3988..b0981da0d824952456e0114b00384242507756dd 100755 (executable)
--- a/youtube-dl
+++ b/youtube-dl
@@ -2609,6 +2609,85 @@ class PostProcessor(object):
                """
                return information # by default, do nothing
 
+class FFmpegExtractAudioPP(PostProcessor):
+
+       def __init__(self, downloader=None, preferredcodec=None):
+               PostProcessor.__init__(self, downloader)
+               if preferredcodec is None:
+                       preferredcodec = 'best'
+               self._preferredcodec = preferredcodec
+
+       @staticmethod
+       def get_audio_codec(path):
+               handle = subprocess.Popen(['ffprobe', '-show_streams', path],
+                               stderr=file(os.path.devnull, 'w'), stdout=subprocess.PIPE)
+               output = handle.communicate()[0]
+               if handle.wait() != 0:
+                       return None
+               audio_codec = None
+               for line in output.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
+
+       @staticmethod
+       def run_ffmpeg(path, out_path, codec, more_opts):
+               try:
+                       ret = subprocess.call(['ffmpeg', '-y', '-i', path, '-vn', '-acodec', codec] + more_opts + [out_path],
+                                       stdout=file(os.path.devnull, 'w'), stderr=subprocess.STDOUT)
+                       return (ret == 0)
+               except (IOError, OSError):
+                       return False
+
+       def run(self, information):
+               path = information['filepath']
+
+               filecodec = self.get_audio_codec(path)
+               if filecodec is None:
+                       self._downloader.to_stderr(u'WARNING: no audio codec found in file')
+                       return None
+
+               more_opts = []
+               if self._preferredcodec == 'best' or self._preferredcodec == filecodec:
+                       if filecodec == 'aac' or filecodec == 'mp3':
+                               # Lossless if possible
+                               acodec = 'copy'
+                               extension = filecodec
+                               if filecodec == 'aac':
+                                       more_opts = ['-f', 'adts']
+                       else:
+                               # MP3 otherwise.
+                               acodec = 'libmp3lame'
+                               extension = 'mp3'
+                               more_opts = ['-ab', '128k']
+               else:
+                       # We convert the audio (lossy)
+                       acodec = {'mp3': 'libmp3lame', 'aac': 'aac'}[self._preferredcodec]
+                       extension = self._preferredcodec
+                       more_opts = ['-ab', '128k']
+                       if self._preferredcodec == 'aac':
+                               more_opts += ['-f', 'adts']
+
+               (prefix, ext) = os.path.splitext(path)
+               new_path = prefix + '.' + extension
+               self._downloader.to_screen(u'[ffmpeg] Destination: %s' % new_path)
+               status = self.run_ffmpeg(path, new_path, acodec, more_opts)
+
+               if not status:
+                       self._downloader.to_stderr(u'WARNING: error running ffmpeg' % ret)
+                       return None
+
+               try:
+                       os.remove(path)
+               except (IOError, OSError):
+                       self._downloader.to_stderr(u'WARNING: Unable to remove downloaded video file')
+                       return None
+
+               information['filepath'] = new_path
+               return information
+
 ### MAIN PROGRAM ###
 if __name__ == '__main__':
        try:
@@ -2733,6 +2812,13 @@ if __name__ == '__main__':
                                help='do not use the Last-modified header to set the file modification time', default=True)
                parser.add_option_group(filesystem)
 
+               postproc = optparse.OptionGroup(parser, 'Post-processing Options')
+               postproc.add_option('--extract-audio', action='store_true', dest='extractaudio', default=False,
+                               help='convert video files to audio-only files (requires ffmpeg and ffprobe)')
+               postproc.add_option('--audio-format', metavar='FORMAT', dest='audioformat', default='best',
+                               help='"best", "aac" or "mp3"; best by default')
+               parser.add_option_group(postproc)
+
                (opts, args) = parser.parse_args()
 
                # Open appropriate CookieJar
@@ -2804,6 +2890,9 @@ if __name__ == '__main__':
                                raise ValueError
                except (TypeError, ValueError), err:
                        parser.error(u'invalid playlist end number specified')
+               if opts.extractaudio:
+                       if opts.audioformat not in ['best', 'aac', 'mp3']:
+                               parser.error(u'invalid audio format specified')
 
                # Information extractors
                youtube_ie = YoutubeIE()
@@ -2876,6 +2965,10 @@ if __name__ == '__main__':
                # fallback if none of the others work
                fd.add_info_extractor(generic_ie)
 
+               # PostProcessors
+               if opts.extractaudio:
+                       fd.add_post_processor(FFmpegExtractAudioPP(preferredcodec=opts.audioformat))
+
                # Update version
                if opts.update_self:
                        update_self(fd, sys.argv[0])