Fixed the ffmpeg empty partial movie file red error

Author: MysaaJava

docs/source/manim_directive.py

@@ -104,8 +104,9 @@ def run(self):
         hide_source = "hide_source" in self.options
         save_as_gif = "save_as_gif" in self.options
         save_last_frame = "save_last_frame" in self.options
+        write_to_movie = not save_last_frame
         assert not (save_as_gif and save_last_frame)
-
+        
         frame_rate = 30
         pixel_height = 480
         pixel_width = 854
@@ -178,6 +179,7 @@ def run(self):
             f'file_writer_config["text_dir"] = "{text_dir}"',
             f'file_writer_config["video_dir"] = "{video_dir}"',
             f'file_writer_config["save_last_frame"] = {save_last_frame}',
+            f'file_writer_config["write_to_movie"] = {write_to_movie}',
             f'file_writer_config["save_as_gif"] = {save_as_gif}',
             f'file_writer_config["output_file"] = "{output_file}"',
         ]

manim/scene/scene_file_writer.py

@@ -77,46 +77,48 @@ def init_output_directories(self, scene_name):
             )
 
         if file_writer_config["write_to_movie"]:
-            if file_writer_config["video_dir"]:
-                if not file_writer_config["custom_folders"]:
-                    movie_dir = guarantee_existence(
-                        os.path.join(
-                            file_writer_config["video_dir"],
-                            module_directory,
-                            self.get_resolution_directory(),
-                        )
-                    )
-                else:
-                    movie_dir = guarantee_existence(
-                        os.path.join(file_writer_config["video_dir"])
-                    )
-            self.movie_file_path = os.path.join(
-                movie_dir,
-                add_extension_if_not_present(
-                    default_name, file_writer_config["movie_file_extension"]
-                ),
-            )
-            self.gif_file_path = os.path.join(
-                movie_dir,
-                add_extension_if_not_present(default_name, GIF_FILE_EXTENSION),
-            )
+            pass
+        if file_writer_config["video_dir"]:
             if not file_writer_config["custom_folders"]:
-                self.partial_movie_directory = guarantee_existence(
+                movie_dir = guarantee_existence(
                     os.path.join(
-                        movie_dir,
-                        "partial_movie_files",
-                        default_name,
+                        file_writer_config["video_dir"],
+                        module_directory,
+                        self.get_resolution_directory(),
                     )
                 )
             else:
-                self.partial_movie_directory = guarantee_existence(
-                    os.path.join(
-                        file_writer_config["media_dir"],
-                        "temp_files",
-                        "partial_movie_files",
-                        default_name,
-                    )
+                movie_dir = guarantee_existence(
+                    os.path.join(file_writer_config["video_dir"])
                 )
+        self.movie_file_path = os.path.join(
+            movie_dir,
+            add_extension_if_not_present(
+                default_name, file_writer_config["movie_file_extension"]
+            ),
+        )
+        self.gif_file_path = os.path.join(
+            movie_dir,
+            add_extension_if_not_present(default_name, GIF_FILE_EXTENSION),
+        )
+        # The partial movie directory has to be set even if we do not write to movie
+        if not file_writer_config["custom_folders"]:
+            self.partial_movie_directory = guarantee_existence(
+                os.path.join(
+                    movie_dir,
+                    "partial_movie_files",
+                    default_name,
+                )
+            )
+        else:
+            self.partial_movie_directory = guarantee_existence(
+                os.path.join(
+                    file_writer_config["media_dir"],
+                    "temp_files",
+                    "partial_movie_files",
+                    default_name,
+                )
+            )
 
     def add_partial_movie_file(self, hash_animation):
         """Adds a new partial movie file path to scene.partial_movie_files from an hash. This method will compute the path from the hash.
@@ -482,11 +484,14 @@ def is_already_cached(self, hash_invocation):
         :class:`bool`
             Whether the file exists.
         """
-        path = os.path.join(
-            self.partial_movie_directory,
-            "{}{}".format(hash_invocation, self.movie_file_extension),
-        )
-        return os.path.exists(path)
+        if hasattr(self,'partial_movie_directory'):
+            path = os.path.join(
+                self.partial_movie_directory,
+                "{}{}".format(hash_invocation, self.movie_file_extension),
+            )
+            return os.path.exists(path)
+        else:
+            return False # If there is no partial movie directory, then the file is not cached
 
     def combine_movie_files(self):
         """