diff --git a/video2x/decoder.py b/video2x/decoder.py
index 4b4a0f0..e2a074d 100755
--- a/video2x/decoder.py
+++ b/video2x/decoder.py
@@ -19,7 +19,7 @@ along with this program. If not, see <https://www.gnu.org/licenses/>.
 Name: Video Decoder
 Author: K4YT3X
 Date Created: June 17, 2021
-Last Modified: February 12, 2022
+Last Modified: February 16, 2022
 """
 
 # built-in imports
@@ -59,7 +59,7 @@ class VideoDecoder(threading.Thread):
         processing_queue: queue.Queue,
         processing_settings: tuple,
         ignore_max_image_pixels=True,
-    ):
+    ) -> None:
         threading.Thread.__init__(self)
         self.running = False
         self.input_path = input_path
@@ -91,7 +91,7 @@ class VideoDecoder(threading.Thread):
             # stderr=subprocess.DEVNULL,
         )
 
-    def run(self):
+    def run(self) -> None:
         self.running = True
 
         # the index of the frame
@@ -164,5 +164,5 @@ class VideoDecoder(threading.Thread):
         self.running = False
         return super().run()
 
-    def stop(self):
+    def stop(self) -> None:
         self.running = False
diff --git a/video2x/encoder.py b/video2x/encoder.py
index ce7efa7..b006c90 100755
--- a/video2x/encoder.py
+++ b/video2x/encoder.py
@@ -19,7 +19,7 @@ along with this program. If not, see <https://www.gnu.org/licenses/>.
 Name: Video Encoder
 Author: K4YT3X
 Date Created: June 17, 2021
-Last Modified: June 30, 2021
+Last Modified: February 16, 2022
 """
 
 # built-in imports
@@ -61,7 +61,11 @@ class VideoEncoder(threading.Thread):
         total_frames: int,
         processed_frames: multiprocessing.managers.ListProxy,
         processed: multiprocessing.sharedctypes.Synchronized,
-    ):
+        copy_audio: bool = True,
+        copy_subtitle: bool = True,
+        copy_data: bool = False,
+        copy_attachments: bool = False,
+    ) -> None:
         threading.Thread.__init__(self)
         self.running = False
         self.input_path = input_path
@@ -82,31 +86,31 @@ class VideoEncoder(threading.Thread):
             r=frame_rate,
         )
 
-        # map additional streams from original file
-        """
+        # copy additional streams from original file
+        # https://ffmpeg.org/ffmpeg.html#Stream-specifiers-1
         additional_streams = [
-            # self.original["v?"],
-            self.original["a?"],
-            self.original["s?"],
-            self.original["d?"],
-            self.original["t?"],
+            # self.original["1:v?"],
+            self.original["a?"] if copy_audio is True else None,
+            self.original["s?"] if copy_subtitle is True else None,
+            self.original["d?"] if copy_data is True else None,
+            self.original["t?"] if copy_attachments is True else None,
         ]
-        """
 
         # run FFmpeg and produce final output
         self.encoder = subprocess.Popen(
             ffmpeg.compile(
                 ffmpeg.output(
                     frames,
+                    *[s for s in additional_streams if s is not None],
                     str(self.output_path),
                     pix_fmt="yuv420p",
                     vcodec="libx264",
-                    acodec="copy",
+                    # acodec="copy",
                     r=frame_rate,
                     crf=17,
                     vsync="1",
-                    # map_metadata=1,
-                    # metadata="comment=Upscaled with Video2X",
+                    map_metadata=1,
+                    metadata="comment=Processed with Video2X",
                 )
                 .global_args("-hide_banner")
                 .global_args("-nostats")
@@ -123,7 +127,7 @@ class VideoEncoder(threading.Thread):
             # stderr=subprocess.DEVNULL,
         )
 
-    def run(self):
+    def run(self) -> None:
         self.running = True
         frame_index = 0
         while self.running and frame_index < self.total_frames:
@@ -165,5 +169,5 @@ class VideoEncoder(threading.Thread):
         self.running = False
         return super().run()
 
-    def stop(self):
+    def stop(self) -> None:
         self.running = False
diff --git a/video2x/interpolator.py b/video2x/interpolator.py
index 193b83f..f88beaa 100755
--- a/video2x/interpolator.py
+++ b/video2x/interpolator.py
@@ -19,7 +19,7 @@ along with this program. If not, see <https://www.gnu.org/licenses/>.
 Name: Interpolator
 Author: K4YT3X
 Date Created: May 27, 2021
-Last Modified: February 2, 2022
+Last Modified: February 16, 2022
 """
 
 # local imports
@@ -46,7 +46,7 @@ class Interpolator(multiprocessing.Process):
         self,
         processing_queue: multiprocessing.Queue,
         processed_frames: multiprocessing.managers.ListProxy,
-    ):
+    ) -> None:
         multiprocessing.Process.__init__(self)
         self.running = False
         self.processing_queue = processing_queue
@@ -54,7 +54,7 @@ class Interpolator(multiprocessing.Process):
 
         signal.signal(signal.SIGTERM, self._stop)
 
-    def run(self):
+    def run(self) -> None:
         self.running = True
         logger.info(f"Interpolator process {self.name} initiating")
         processor_objects = {}
@@ -116,5 +116,5 @@ class Interpolator(multiprocessing.Process):
         self.running = False
         return super().run()
 
-    def _stop(self, _signal_number, _frame):
+    def _stop(self, _signal_number, _frame) -> None:
         self.running = False
diff --git a/video2x/upscaler.py b/video2x/upscaler.py
index fad6670..201a53d 100755
--- a/video2x/upscaler.py
+++ b/video2x/upscaler.py
@@ -19,7 +19,7 @@ along with this program. If not, see <https://www.gnu.org/licenses/>.
 Name: Upscaler
 Author: K4YT3X
 Date Created: May 27, 2021
-Last Modified: August 17, 2021
+Last Modified: February 16, 2022
 """
 
 # local imports
@@ -56,7 +56,7 @@ class Upscaler(multiprocessing.Process):
         self,
         processing_queue: multiprocessing.Queue,
         processed_frames: multiprocessing.managers.ListProxy,
-    ):
+    ) -> None:
         multiprocessing.Process.__init__(self)
         self.running = False
         self.processing_queue = processing_queue
@@ -64,7 +64,7 @@ class Upscaler(multiprocessing.Process):
 
         signal.signal(signal.SIGTERM, self._stop)
 
-    def run(self):
+    def run(self) -> None:
         self.running = True
         logger.opt(colors=True).info(
             f"Upscaler process <blue>{self.name}</blue> initiating"
@@ -193,5 +193,5 @@ class Upscaler(multiprocessing.Process):
         self.running = False
         return super().run()
 
-    def _stop(self, _signal_number, _frame):
+    def _stop(self, _signal_number, _frame) -> None:
         self.running = False
diff --git a/video2x/video2x.py b/video2x/video2x.py
index 89013e4..7cea11c 100755
--- a/video2x/video2x.py
+++ b/video2x/video2x.py
@@ -26,8 +26,8 @@ __      __  _       _                  ___   __   __
 
 Name: Video2X
 Creator: K4YT3X
-Date Created: Feb 24, 2018
-Last Modified: February 15, 2022
+Date Created: February 24, 2018
+Last Modified: February 16, 2022
 
 Editor: BrianPetkovsek
 Last Modified: June 17, 2019
@@ -122,10 +122,10 @@ class Video2X:
         - interpolate: perform motion interpolation on a file
     """
 
-    def __init__(self):
+    def __init__(self) -> None:
         self.version = __version__
 
-    def _get_video_info(self, path: pathlib.Path):
+    def _get_video_info(self, path: pathlib.Path) -> tuple:
         """
         get video file information with FFmpeg
 
@@ -167,7 +167,7 @@ class Video2X:
         mode: str,
         processes: int,
         processing_settings: tuple,
-    ):
+    ) -> None:
 
         # record original STDOUT and STDERR for restoration
         original_stdout = sys.stdout
@@ -453,7 +453,10 @@ def parse_arguments() -> argparse.Namespace:
         "-t",
         "--threshold",
         type=float,
-        help="skip if the percent difference between two adjacent frames is below this value; set to 0 to process all frames",
+        help=(
+            "skip if the percent difference between two adjacent frames is below this"
+            " value; set to 0 to process all frames"
+        ),
         default=0,
     )
 
@@ -478,14 +481,17 @@ def parse_arguments() -> argparse.Namespace:
         "-t",
         "--threshold",
         type=float,
-        help="skip if the percent difference between two adjacent frames exceeds this value; set to 100 to interpolate all frames",
+        help=(
+            "skip if the percent difference between two adjacent frames exceeds this"
+            " value; set to 100 to interpolate all frames"
+        ),
         default=10,
     )
 
     return parser.parse_args()
 
 
-def main():
+def main() -> None:
     """
     command line direct invocation
     program entry point