Use FFmpeg for embedding thumbnails into MP3

Embedding thumbnails inside ID3v2 tags is done by FFmpeg quite nicely, there's no need to depend on the external dependency. Also, FFmpeg already used for many post-processing and conversion work.

youtube_dl/postprocessor/embedthumbnail.py

@@ -6,14 +6,14 @@ import os
 
 try:
     import imghdr
-    from mutagen.id3 import PictureType, ID3, APIC, ID3NoHeaderError
     from mutagen.mp4 import MP4, MP4Cover, MP4MetadataError
 except ImportError:
-    raise Exception('[embedthumbnail] Mutagen isn\'t found as a dependency to embed thumbnails!')
+    raise Exception('[embedthumbnail] Mutagen isn\'t found, install from PyPI.')
 
 from .ffmpeg import FFmpegPostProcessor
 
 from ..utils import (
+    prepend_extension,
     encodeFilename,
     PostProcessingError
 )
@@ -30,6 +30,7 @@ class EmbedThumbnailPP(FFmpegPostProcessor):
 
     def run(self, info):
         filename = info['filepath']
+        temp_filename = prepend_extension(filename, 'temp')
 
         if not info.get('thumbnails'):
             self._downloader.to_screen('[embedthumbnail] There aren\'t any thumbnails to embed')
@@ -43,23 +44,18 @@ class EmbedThumbnailPP(FFmpegPostProcessor):
             return [], info
 
         if info['ext'] == 'mp3':
-            try:
-                meta = ID3(filename)
-            except ID3NoHeaderError:
-                raise EmbedThumbnailPPError("MP3 file doesn't have a existing ID3v2 tag.")
+            options = [
+                '-c', 'copy', '-map', '0', '-map', '1',
+                '-metadata:s:v', 'title="Album cover"', '-metadata:s:v', 'comment="Cover (Front)"']
 
-            # Appends a Cover-front thumbnail, it's the most common
-            # type of thumbnail distributed with.
-            meta.add(APIC(
-                data=open(thumbnail_filename, 'rb').read(),
-                mime='image/' + imghdr.what(thumbnail_filename),
-                type=PictureType.COVER_FRONT))
+            self._downloader.to_screen('[ffmpeg] Adding thumbnail to "%s"' % filename)
 
-            meta.save()  # Save the changes to file, does in-place replacement.
-            self._downloader.to_screen('[mutagen.id3] Merged Thumbnail into "%s"' % filename)
+            self.run_ffmpeg_multiple_files([filename, thumbnail_filename], temp_filename, options)
 
             if not self._already_have_thumbnail:
                 os.remove(encodeFilename(thumbnail_filename))
+            os.remove(encodeFilename(filename))
+            os.rename(encodeFilename(temp_filename), encodeFilename(filename))
 
         elif info['ext'] in ['m4a', 'mp4']:
             try: