fix imencode call

app.py

@@ -138,7 +138,8 @@ def caption_frame(frame, size, model_file, clip_file, interval_ms, sys_prompt, u
     time.sleep(interval_ms / 1000)
 
     t_enc = time.time()
-    success, jpeg = cv2.imencode('.jpg', img, quality=50, )
+    params = [int(cv2.IMWRITE_JPEG_QUALITY), 50]
+    success, jpeg = cv2.imencode('.jpg', img, params)
     elapsed = (time.time() - t_enc) * 1000
     timestamp = time.strftime('%H:%M:%S')
     debug_msgs.append(f"[{timestamp}] JPEG encode: success={success}, bytes={len(jpeg)} in {elapsed:.1f} ms")