Video Processing Project

import cv2
import numpy as np
import time
import os

class VideoAnalyser:
    """
    A complete video analysis system:
    - Reads input video
    - Applies background subtraction for motion detection
    - Annotates frames with motion status and statistics
    - Saves processed video
    """

    def __init__(self, source, output_path="analysed_output.mp4"):
        self.source = source
        self.output_path = output_path
        self.cap = None
        self.writer = None
        self.subtractor = cv2.createBackgroundSubtractorMOG2(
            history=300, varThreshold=50, detectShadows=False
        )

    def open(self):
        self.cap = cv2.VideoCapture(self.source)
        if not self.cap.isOpened():
            raise ValueError(f"Cannot open: {self.source}")

        self.fps    = self.cap.get(cv2.CAP_PROP_FPS) or 30
        self.width  = int(self.cap.get(cv2.CAP_PROP_FRAME_WIDTH))
        self.height = int(self.cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
        self.total  = int(self.cap.get(cv2.CAP_PROP_FRAME_COUNT))

        fourcc = cv2.VideoWriter_fourcc(*"mp4v")
        self.writer = cv2.VideoWriter(
            self.output_path, fourcc, self.fps, (self.width, self.height)
        )
        print(f"Opened: {self.width}x{self.height} @ {self.fps:.1f} FPS")

    def process(self, max_frames=None):
        self.open()
        frame_count = 0
        motion_frames = 0
        kernel = cv2.getStructuringElement(cv2.MORPH_ELLIPSE, (5, 5))

        while True:
            ret, frame = self.cap.read()
            if not ret or (max_frames and frame_count >= max_frames):
                break

            # Motion detection
            fg_mask = self.subtractor.apply(frame)
            fg_mask = cv2.morphologyEx(fg_mask, cv2.MORPH_OPEN, kernel)
            moving = cv2.countNonZero(fg_mask)
            motion = moving > 2000

            if motion:
                motion_frames += 1

            # Annotate frame
            status = "MOTION" if motion else "STATIC"
            colour = (0, 0, 255) if motion else (0, 255, 0)
            cv2.putText(frame, status, (10, 35),
                       cv2.FONT_HERSHEY_SIMPLEX, 1.0, colour, 2)
            cv2.putText(frame, f"Frame: {frame_count}", (10, 65),
                       cv2.FONT_HERSHEY_SIMPLEX, 0.6, (255,255,255), 1)

            self.writer.write(frame)
            frame_count += 1

        self.cap.release()
        self.writer.release()

        print(f"Processed {frame_count} frames")
        print(f"Motion frames: {motion_frames} ({motion_frames/frame_count*100:.1f}%)")
        print(f"Saved: {self.output_path}")

analyser = VideoAnalyser("input_video.mp4", "processed.mp4")
analyser.process(max_frames=600)