Fix NV12 crash issue when recreate camera object

modules/ANSLPR/ANSLPR_OD.h

@@ -24,7 +24,7 @@ namespace ANSCENTER
         ANSCENTER::ModelConfig _lpdmodelConfig;
         ANSCENTER::ModelConfig _ocrModelConfig;
 		ANSCENTER::ModelConfig _lpColourModelConfig;
-        cv::Ptr<cv::CLAHE>     _clahe;  // Reusable CLAHE instance
+        // _clahe moved to thread-local in enhanceForOCR() for thread safety
         ANSCENTER::NV12PreprocessHelper _nv12Helper;  // NV12 crop for high-res plate OCR
 
         std::string             _lpdLabels;
@@ -147,6 +147,7 @@ namespace ANSCENTER
             int framesSinceLastSeen = 0;
         };
         // cameraId → list of tracked plate identities
+        std::mutex _plateIdentitiesMutex;  // Fine-grained lock for plate identity tracking
         std::unordered_map<std::string, std::vector<SpatialPlateIdentity>> _plateIdentities;
         static constexpr float PLATE_SPATIAL_MATCH_THRESHOLD = 0.3f; // IoU threshold for same plate
         void ensureUniquePlateText(std::vector<Object>& results, const std::string& cameraId);
@@ -176,6 +177,7 @@ namespace ANSCENTER
             std::string colour;
             int         hitCount = 0;
         };
+        std::mutex _colourCacheMutex;  // Fine-grained lock for colour cache only
         std::unordered_map<std::string, ColourCacheEntry> _colourCache;
         static constexpr size_t COLOUR_CACHE_MAX_SIZE = 200;