going in the right direction.

.gitignore

@@ -1 +1,4 @@
 env
+*.mp4
+.idea
+.DS_Store

helper.py

@@ -0,0 +1,34 @@
+import contextlib
+import time
+import cv2
+
+
+def create_video_writer(video_cap, output_filename):
+
+    # 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(output_filename, fourcc, fps,
+                             (frame_width, frame_height))
+
+    return writer
+
+
+def iter_frames(video_cap):
+    while 1:
+        ret, frame = video_cap.read()
+        if not ret:
+            return
+        yield frame
+
+
+@contextlib.contextmanager
+def time_tracker():
+    start = time.monotonic()
+    yield
+    end = time.monotonic()
+    print(f"Time to process 1 frame: {(end-start) * 1000:.0f} milliseconds")

main.py

@@ -1,5 +1,19 @@
 import cv2 as cv
-img = cv.imread("/Users/didier/ahuntsic/cours-420-301-ah/cours/images/json/001.jpg")
 
-cv.imshow("Display window", img)
+minute = 60
-k = cv.waitKey(0) # Wait for a keystroke in the window
+video_start = 9 * minute + 30
+video_end = 12 * minute + 56
+
+cap = cv.VideoCapture('out.mp4')
+while cap.isOpened():
+    ret, frame = cap.read()
+    # if frame is read correctly ret is True
+    if not ret:
+        print("Can't receive frame (stream end?). Exiting ...")
+        break
+    gray = cv.cvtColor(frame, cv.COLOR_BGR2GRAY)
+    cv.imshow('frame', gray)
+    if cv.waitKey(1) == ord('q'):
+        break
+cap.release()
+cv.destroyAllWindows()

object_tracking.py

@@ -0,0 +1,81 @@
+from ultralytics import YOLO
+import cv2
+from helper import create_video_writer, iter_frames, time_tracker
+import matplotlib
+from numpy import arange
+
+Color = tuple[int, int, int]
+
+
+class DetectedObjectBox:
+    def __init__(self, min_threshold: float, color: Color):
+        self.min_threshold = min_threshold
+        self.color = color
+
+    def __lt__(self, other):
+        return self.min_threshold < other.min_threshold
+
+    @classmethod
+    def from_viridis(cls, min_threshold):
+        cm = matplotlib.colormaps['viridis']
+        color: Color = tuple((int(255 * cm(min_threshold)[i]) for i in range(3)))
+        return cls(min_threshold, color)
+
+
+def write_frame(writer, frame):
+    cv2.imshow("Frame", frame)
+    writer.write(frame)
+
+
+def extract_box(data):
+    return int(data[0]), int(data[1]), int(data[2]), int(data[3])
+
+
+def plot_boxe_to_frame(data, frame, detected_box_objects):
+    confidence = float(data[4])
+    for detected_box_object in detected_box_objects:
+
+        if detected_box_object.min_threshold < confidence:
+            xmin, ymin, xmax, ymax = extract_box(data)
+            cv2.rectangle(frame, (xmin, ymin), (xmax, ymax), detected_box_object.color, 2)
+            return
+
+
+def run_model_on_frame(model, frame):
+    return model(frame)[0]
+
+
+def main(input_filename, output_filename, detected_box_objects):
+    # define some constants
+    detected_box_objects = sorted(detected_box_objects, reverse=True)
+
+    video_cap = cv2.VideoCapture(input_filename)
+    writer = create_video_writer(video_cap, output_filename)
+
+    # load the pre-trained YOLOv8n model
+    model = YOLO("yolov8n.pt")
+
+    for frame in iter_frames(video_cap):
+        with time_tracker():
+            # run the YOLO model on the frame
+            detections = run_model_on_frame(model, frame)
+            for data in detections.boxes.data.tolist():
+                plot_boxe_to_frame(data, frame, detected_box_objects)
+
+            # show the frame to our screen
+            write_frame(writer, frame)
+
+            if cv2.waitKey(1) == ord("q"):
+                break
+
+    video_cap.release()
+    writer.release()
+    cv2.destroyAllWindows()
+
+
+if __name__ == "__main__":
+    detected_box_objects = [
+        DetectedObjectBox.from_viridis(threshold) for threshold in arange(0.5, 1, 0.05)
+    ]
+
+    main("micro.mp4", "output.mp4", detected_box_objects)