diff --git a/yt_dlp/mp4_parser.py b/yt_dlp/mp4_parser.py
index 08b516f94..436080ba5 100644
--- a/yt_dlp/mp4_parser.py
+++ b/yt_dlp/mp4_parser.py
@@ -91,6 +91,7 @@ def unpack_ver_flags(value: bytes) -> Tuple[int, int]:
 MP4_CONTAINER_BOXES = ('moov', 'trak', 'edts', 'mdia', 'minf', 'dinf', 'stbl', 'mvex', 'moof', 'traf', 'vttc', 'tref', 'iref', 'mfra', 'meco', 'hnti', 'hinf', 'strk', 'strd', 'sinf', 'rinf', 'schi', 'trgr', 'udta', 'iprp', 'ipco')
 """ List of boxes that nests the other boxes """
 
+
 def parse_mp4_boxes(r: RawIOBase):
     """
     Parses an ISO BMFF (which MP4 follows) and yields its boxes as a sequence.
diff --git a/yt_dlp/postprocessor/mp4direct.py b/yt_dlp/postprocessor/mp4direct.py
index cde516d28..506138ee3 100644
--- a/yt_dlp/postprocessor/mp4direct.py
+++ b/yt_dlp/postprocessor/mp4direct.py
@@ -102,7 +102,6 @@ def transform(r, bmdt_offset, sdur_cutoff):
                 continue
             yield (btype, content)
 
-
     def modify_mp4(self, src, dst, bmdt_offset, sdur_cutoff):
         with open(src, 'rb') as r, open(dst, 'wb') as w:
             write_mp4_boxes(w, self.transform(parse_mp4_boxes(r)))