Upload video_utils.py

utils/video_utils.py

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+"""Frame extraction and video writing utilities."""
+
+import cv2
+import numpy as np
+from typing import List
+
+__all__ = [
+    "extract_frames_from_video",
+    "save_frames_to_video",
+]
+
+
+def extract_frames_from_video(video_path: str, target_fps: int = 30) -> List[np.ndarray]:
+    cap = cv2.VideoCapture(video_path)
+    if not cap.isOpened():
+        raise IOError(f"Cannot open video: {video_path}")
+
+    original_fps = cap.get(cv2.CAP_PROP_FPS) or target_fps
+    frame_interval = max(1, round(original_fps / target_fps))
+
+    frames, count = [], 0
+    while True:
+        ret, frame = cap.read()
+        if not ret:
+            break
+        if count % frame_interval == 0:
+            frames.append(frame)
+        count += 1
+    cap.release()
+    return frames
+
+
+def save_frames_to_video(frames: List[np.ndarray], output_path: str, fps: int = 30):
+    if not frames:
+        raise ValueError("No frames to save")
+
+    height, width = frames[0].shape[:2]
+    fourcc = cv2.VideoWriter_fourcc(*"mp4v")
+    writer = cv2.VideoWriter(output_path, fourcc, fps, (width, height))
+    for frm in frames:
+        writer.write(frm)
+    writer.release()