fix(lib): revert reverse-... utils because of warnings

Author: jeertmans

manim_slides/utils.py

@@ -95,7 +95,7 @@ def reverse_video_file(src: Path, dest: Path) -> None:
     ) as output_container:
         input_stream = input_container.streams.video[0]
         output_stream = output_container.add_stream(
-            codec_name=input_stream.codec_context.name, rate=input_stream.base_rate
+            codec_name="libx264", rate=input_stream.base_rate
         )
         output_stream.width = input_stream.width
         output_stream.height = input_stream.height
@@ -118,9 +118,8 @@ def reverse_video_file(src: Path, dest: Path) -> None:
 
         for _ in range(frames_count):
             frame = graph.pull()
-
-            for packet in output_stream.encode(frame):
-                output_container.mux(packet)
+            frame.pict_type = 5  # Otherwise we get a warning saying it is changed
+            output_container.mux(output_stream.encode(frame))
 
         for packet in output_stream.encode():
             output_container.mux(packet)