Add motion detection before object detection

build/version.hpp

@@ -4,11 +4,11 @@
 
 namespace version {
 
-const std::string GIT_COMMIT   = "87277f75";
+const std::string GIT_COMMIT   = "bed242d2";
 const std::string GIT_BRANCH   = "main";
 const std::string GIT_TAG      = "";
 const std::string BUILD_DATE   = "2026-07-06";
-const std::string BUILD_TIME   = "18:03:38";
+const std::string BUILD_TIME   = "22:54:19";
 const int         BUILD_YEAR   = 2026;
 const bool        BUILD_RKNN   = 1;
 

config.env.example

@@ -110,6 +110,13 @@ EXPORT_CSV=true
 CROSS_CSV=/opt/batch-counter/batch_crossings.csv
 
 # --- Rate / performance ---
+# Enable motion detection pre-filter: skip inference on frames with no movement
+# (true/false, default: false). When enabled, frames below MOTION_THRESHOLD are
+# skipped, saving NPU/CPU load.
+MOTION_DETECTION_ENABLED=false
+# Mean absolute pixel difference threshold (0–255) to consider a frame as having
+# motion. Lower = more sensitive. Default 5.0.
+MOTION_THRESHOLD=5.0
 # Sliding window in seconds for computing the crossing rate (objects/minute)
 RATE_WINDOW_SEC=60
 # Number of frames to discard at startup to let the stream buffer stabilise

src/config.cpp

@@ -119,6 +119,11 @@ void AppConfig::load_from_env(const char* env_path) {
     if (!ecsv.empty()) export_csv = (ecsv == "true");
     cross_csv = get_env("CROSS_CSV", output_dir + "/batch_crossings.csv");
 
+    auto mde_s = get_env("MOTION_DETECTION_ENABLED");
+    motion_detection_enabled = (mde_s == "true");
+    auto mt_s = get_env("MOTION_THRESHOLD");
+    if (!mt_s.empty()) motion_threshold = std::stof(mt_s);
+
     auto wf_s = get_env("WARMUP_FRAMES");
     if (!wf_s.empty()) warmup_frames = std::stoi(wf_s);
     auto rd_s = get_env("RECONNECT_DELAY_SEC");

src/config.hpp

@@ -51,6 +51,8 @@ struct AppConfig {
     bool export_csv = true;
     std::string cross_csv;
 
+    bool motion_detection_enabled = false;
+    float motion_threshold = 5.0f;
     int warmup_frames = 30;
     int reconnect_delay_sec = 3;
     int max_reconnect_attempts = 0;

src/main.cpp

@@ -217,6 +217,7 @@ int main(int argc, char* argv[]) {
 
     std::unordered_map<int, TrackedInfo> ayam_tracked;
     std::unordered_map<int, TrackedInfo> talenan_tracked;
+    cv::Mat prev_gray;
 
     while (!shutdown_requested) {
         cv::Mat frame;
@@ -257,10 +258,27 @@ int main(int argc, char* argv[]) {
 
         bool ayam_crossed_frame = false, batch_closed_frame = false, batch_started_frame = false;
 
-        auto inf_start = std::chrono::steady_clock::now();
-        std::vector<Detection> detections = model(frame);
-        float inf_ms = std::chrono::duration<float, std::milli>(
-            std::chrono::steady_clock::now() - inf_start).count();
+        bool skip_inference = false;
+        if (g_config.motion_detection_enabled) {
+            cv::Mat gray;
+            cv::cvtColor(frame, gray, cv::COLOR_BGR2GRAY);
+            if (!prev_gray.empty()) {
+                cv::Mat diff;
+                cv::absdiff(gray, prev_gray, diff);
+                double mean_diff = cv::mean(diff)[0];
+                skip_inference = (mean_diff < g_config.motion_threshold);
+            }
+            prev_gray = gray;
+        }
+
+        std::vector<Detection> detections;
+        float inf_ms = 0.0f;
+        if (!skip_inference) {
+            auto inf_start = std::chrono::steady_clock::now();
+            detections = model(frame);
+            inf_ms = std::chrono::duration<float, std::milli>(
+                std::chrono::steady_clock::now() - inf_start).count();
+        }
         inf_ema = inf_ema * 0.9f + inf_ms * 0.1f;
 
         if (!detections.empty()) {