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Running on Zero
File size: 1,524 Bytes
0d65642 b220d7c 0d65642 b220d7c 0d65642 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 | import cv2
import os
def extract_pre_alert_clip(video_path, alert_time, output_path="./extracted_clip.mp4"):
"""Extract a context clip around the alert time at 4fps."""
cap = cv2.VideoCapture(video_path)
fps = cap.get(cv2.CAP_PROP_FPS)
total_frames = int(cap.get(cv2.CAP_PROP_FRAME_COUNT))
duration_sec = float(total_frames / fps) if fps else 0.0
start_time = max(0, alert_time - 8)
end_time = min(duration_sec, alert_time + 3)
start_frame = int(start_time * fps)
end_frame = int(end_time * fps)
frame_interval = max(1, int(round(fps / 4)))
frames = []
for frame_idx in range(start_frame, end_frame, frame_interval):
cap.set(cv2.CAP_PROP_POS_FRAMES, frame_idx)
ret, frame = cap.read()
if not ret:
break
frames.append(frame)
cap.release()
if frames:
height, width, _ = frames[0].shape
fourcc = cv2.VideoWriter_fourcc(*'mp4v')
out = cv2.VideoWriter(output_path, fourcc, 4.0, (width, height))
for frame in frames:
out.write(frame)
out.release()
print(f"Extracted clip saved to {output_path} ({start_time:.2f}s to {end_time:.2f}s)")
return output_path
else:
print("No frames extracted")
return None
if __name__ == "__main__":
video_path = "./nexar_data/sample_videos/sample_dashcam_2.mp4"
alert_time = 5.0 # assumed or from BADAS
extract_pre_alert_clip(video_path, alert_time)
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