changed --audio-quality behaviour to support both CBR and VBR

README.md

@@ -90,8 +90,9 @@ which means you can modify it, redistribute it or use it however you like.
                              ffmpeg or avconv and ffprobe or avprobe)
     --audio-format FORMAT    "best", "aac", "vorbis", "mp3", "m4a", or "wav";
                              best by default
-    --audio-quality QUALITY  ffmpeg/avconv audio bitrate specification, 128k by
-                             default
+    --audio-quality QUALITY  ffmpeg/avconv audio quality specification, insert a
+                             value between 0 (highest) and 9 (lowest) or a
+                             specific bitrate like 128 (default 5)
     -k, --keep-video         keeps the video file on disk after the post-
                              processing; the video is erased by default
 

youtube_dl/PostProcessor.py

@@ -142,14 +142,20 @@ class FFmpegExtractAudioPP(PostProcessor):
 				extension = 'mp3'
 				more_opts = []
 				if self._preferredquality is not None:
-					more_opts += [self._exes['avconv'] and '-b:a' or '-ab', self._preferredquality]
+					if int(self._preferredquality) < 10:
+						more_opts += [self._exes['avconv'] and '-q:a' or '-aq', self._preferredquality]
+					else:
+						more_opts += [self._exes['avconv'] and '-b:a' or '-ab', self._preferredquality]
 		else:
 			# We convert the audio (lossy)
 			acodec = {'mp3': 'libmp3lame', 'aac': 'aac', 'm4a': 'aac', 'vorbis': 'libvorbis', 'wav': None}[self._preferredcodec]
 			extension = self._preferredcodec
 			more_opts = []
 			if self._preferredquality is not None:
-				more_opts += [self._exes['avconv'] and '-b:a' or '-ab', self._preferredquality]
+				if int(self._preferredquality) < 10:
+					more_opts += [self._exes['avconv'] and '-q:a' or '-aq', self._preferredquality]
+				else:
+					more_opts += [self._exes['avconv'] and '-b:a' or '-ab', self._preferredquality]
 			if self._preferredcodec == 'aac':
 				more_opts += ['-f', 'adts']
 			if self._preferredcodec == 'm4a':

youtube_dl/__init__.py

@@ -296,8 +296,8 @@ def parseOpts():
 			help='convert video files to audio-only files (requires ffmpeg or avconv and ffprobe or avprobe)')
 	postproc.add_option('--audio-format', metavar='FORMAT', dest='audioformat', default='best',
 			help='"best", "aac", "vorbis", "mp3", "m4a", or "wav"; best by default')
-	postproc.add_option('--audio-quality', metavar='QUALITY', dest='audioquality', default='128K',
-			help='ffmpeg/avconv audio bitrate specification, 128k by default')
+	postproc.add_option('--audio-quality', metavar='QUALITY', dest='audioquality', default='5',
+			help='ffmpeg/avconv audio quality specification, insert a value between 0 (highest) and 9 (lowest) or a specific bitrate like 128 (default 5)')
 	postproc.add_option('-k', '--keep-video', action='store_true', dest='keepvideo', default=False,
 			help='keeps the video file on disk after the post-processing; the video is erased by default')