diff --git a/examples/demo/detection_file.json b/examples/demo/detection_file.json
new file mode 100644
index 00000000..83964c27
--- /dev/null
+++ b/examples/demo/detection_file.json
@@ -0,0 +1,12 @@
+[
+    {
+        "image_id": "~/data/img/1_2-A6zakvKX2opVnyx9gplQ.jpg",
+        "bbox": [
+            1440.0252,
+            718.1178300000001,
+            99.15962999999999,
+            51.790379999999914
+        ],
+        "score": 0
+    }
+]
\ No newline at end of file
diff --git a/scripts/demo_inference.py b/scripts/demo_inference.py
index a4958cad..83e6e2bc 100644
--- a/scripts/demo_inference.py
+++ b/scripts/demo_inference.py
@@ -176,6 +176,9 @@ def loop():
         det_loader = DetectionLoader(input_source, get_detector(args), cfg, args, batchSize=args.detbatch, mode=mode, queueSize=args.qsize)
         det_worker = det_loader.start()
 
+    (inps, orig_img, im_name, boxes, scores, ids, cropped_boxes) = det_loader.read()
+    boxes = boxes.float()
+    
     # Load pose model
     pose_model = builder.build_sppe(cfg.MODEL, preset_cfg=cfg.DATA_PRESET)
 
@@ -224,7 +227,6 @@ def loop():
         for i in im_names_desc:
             start_time = getTime()
             with torch.no_grad():
-                (inps, orig_img, im_name, boxes, scores, ids, cropped_boxes) = det_loader.read()
                 if orig_img is None:
                     break
                 if boxes is None or boxes.nelement() == 0: