Add option for AAC -> MP3 conversion post-processor

youtube_dl/__init__.py

@@ -287,6 +287,10 @@ def _real_main(argv=None):
         postprocessors.append({
             'key': 'FFmpegEmbedSubtitle',
         })
+    if opts.aacToMp3:
+        postprocessors.append({
+            'key': 'ConvertAACToMP3PP',
+        })
     if opts.embedthumbnail:
         already_have_thumbnail = opts.writethumbnail or opts.write_all_thumbnails
         postprocessors.append({

youtube_dl/options.py

@@ -818,6 +818,11 @@ def parseOpts(overrideArguments=None):
         '--no-post-overwrites',
         action='store_true', dest='nopostoverwrites', default=False,
         help='Do not overwrite post-processed files; the post-processed files are overwritten by default')
+    postproc.add_option(
+        '--aac-to-mp3',
+        action='store_true', dest='aacToMp3', default=False,
+        help='Convert AAC files to MP3',
+    )
     postproc.add_option(
         '--embed-subs',
         action='store_true', dest='embedsubtitles', default=False,

youtube_dl/postprocessor/__init__.py

@@ -2,6 +2,7 @@ from __future__ import unicode_literals
 
 from .embedthumbnail import EmbedThumbnailPP
 from .ffmpeg import (
+    ConvertAACToMP3PP,
     FFmpegPostProcessor,
     FFmpegEmbedSubtitlePP,
     FFmpegExtractAudioPP,
@@ -23,6 +24,7 @@ def get_postprocessor(key):
 
 
 __all__ = [
+    'ConvertAACToMP3PP',
     'EmbedThumbnailPP',
     'ExecAfterDownloadPP',
     'FFmpegEmbedSubtitlePP',