Made a working cross correlation via opencv

opencv_cross_correlation.py

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+import cv2
+import numpy as np
+from scipy import signal
+import matplotlib.pyplot as plt
+
+def get_video_signal(path):
+    cap = cv2.VideoCapture(path)
+    motion_signal = []
+    prev_gray = None
+    
+    while True:
+        ret, frame = cap.read()
+        if not ret:
+            break
+            
+        # 1. Shrink the frame (makes it faster and removes noise)
+        small_frame = cv2.resize(frame, (160, 90))
+        gray = cv2.cvtColor(small_frame, cv2.COLOR_BGR2GRAY)
+        
+        if prev_gray is not None:
+            # 2. Calculate the difference between this frame and the last
+            # This detects the "movement" or "cuts"
+            diff = cv2.absdiff(gray, prev_gray)
+            motion_signal.append(np.sum(diff))
+        else:
+            motion_signal.append(0)
+            
+        prev_gray = gray
+        
+    cap.release()
+    return np.array(motion_signal)
+
+def find_offset(video_a, video_b):
+    # print("Extracting signals (this may take a moment)...")
+    sig_a = get_video_signal(video_a)
+    # print("sig_a finished")
+    sig_b = get_video_signal(video_b)
+    # print("sig_b finished")
+
+    # Normalize signals (subtract mean, divide by std dev) to improve correlation
+    sig_a = (sig_a - np.mean(sig_a)) / (np.std(sig_a) + 1e-5)
+    sig_b = (sig_b - np.mean(sig_b)) / (np.std(sig_b) + 1e-5)
+
+    # Perform Cross-Correlation
+    correlation = signal.correlate(sig_a, sig_b, mode='full')
+    lags = signal.correlation_lags(len(sig_a), len(sig_b), mode='full')
+    # plt.plot(lags)
+    
+    # The peak of the correlation is our offset in frames
+    best_lag = lags[np.argmax(correlation)]
+    
+    return best_lag
+
+# Usage
+# for i in range(1, 12):
+#     # print(f"{i:02}")
+#     video_a = f"/home/honney/projects/mkv/AnoHana The Flower We Saw That Day (2011-2011) [imdbid-tt1913273]/Season 01/AnoHana The Flower We Saw That Day S01E0{i:02}.mkv"
+#     video_b = f"/home/honney/projects/mkv/Anohana - The Flower We Saw That Day - S01 (BD 1080p HEVC Opus) [derpie]/[derpie] Anohana - The Flower We Saw That Day - S01E{i:02} (BD 1080p HEVC Opus) [Dual Audio].mkv"
+
+#     offset_frames = find_offset(video_a, video_b)
+#     print(f"{i}: Video B is offset by {offset_frames} frames relative to Video A.")
+
+# print(f"{i:02}")
+video_a = f"/home/honney/projects/mkv/output.mkv"
+video_b = f"/home/honney/projects/mkv/Anohana - The Flower We Saw That Day - S01 (BD 1080p HEVC Opus) [derpie]/[derpie] Anohana - The Flower We Saw That Day - S01E01 (BD 1080p HEVC Opus) [Dual Audio].mkv"
+
+offset_frames = find_offset(video_a, video_b)
+print(f"Video B is offset by {offset_frames} frames relative to Video A.")