definitively going somewhere.

dodgeballtracker/video_writer.py

@@ -0,0 +1,67 @@
+import abc
+from pathlib import Path
+
+import cv2
+
+def create_video_writer(video_cap: cv2.VideoCapture, output_filename: Path) -> cv2.VideoWriter:
+
+    # grab the width, height, and fps of the frames in the video stream.
+    frame_width = int(video_cap.get(cv2.CAP_PROP_FRAME_WIDTH))
+    frame_height = int(video_cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
+    fps = int(video_cap.get(cv2.CAP_PROP_FPS))
+
+    # initialize the FourCC and a video writer object
+    fourcc = cv2.VideoWriter_fourcc(*'mp4v')
+    writer = cv2.VideoWriter(str(output_filename.absolute()),
+                             fourcc,
+                             fps,
+                             (frame_width, frame_height))
+
+    return writer
+
+
+class VideoWriter(abc.ABC):
+
+    @abc.abstractmethod
+    def write_frame(self, frame) -> None:
+        pass
+
+    @abc.abstractmethod
+    def close(self) -> None:
+        pass
+
+
+class NoopVideoWriter(VideoWriter):
+
+    def write_frame(self, frame) -> None:
+        pass
+
+    def close(self) -> None:
+        pass
+
+
+class MP4VVideoWriter(VideoWriter):
+
+    def __init__(self, video_writer: cv2.VideoWriter) -> None:
+        self._video_writer = video_writer
+
+    def write_frame(self, frame) -> None:
+        self._video_writer.write(frame)
+
+    def close(self) -> None:
+        self._video_writer.release()
+        cv2.destroyAllWindows()
+
+    @classmethod
+    def from_frame(cls, input_: Path, output: Path) -> VideoWriter:
+        video_cap = cv2.VideoCapture(str(input_))
+        try:
+            return cls(create_video_writer(video_cap, output))
+        finally:
+            video_cap.release()
+
+
+class MP4VVideoWriterWithFrame(MP4VVideoWriter):
+    def write_frame(self, frame) -> None:
+        super().write_frame(frame)
+        cv2.imshow("Frame", frame)