diff --git a/scanner/pages/camera/camera.js b/scanner/pages/camera/camera.js
index db665ad..8a3ff97 100644
--- a/scanner/pages/camera/camera.js
+++ b/scanner/pages/camera/camera.js
@@ -48,6 +48,9 @@ Page({
     frame_upload_seq_num: 0,
     qrarc_class: "sm",
     qrmarkers_class: "hidden",
+    frame_upload_in_flight: 0,
+    frame_upload_time_cost: 0,
+    frame_upload_interval_ms: 2000,
   },
 
   make_hint_text(r) {
@@ -365,15 +368,18 @@ Page({
     }
   },
   handle_image_data_url(data_url) {
-    return;
     const now = Date.now();
-    const interval_ms = 2000;
-    if (now - this.data.last_frame_upload_time < interval_ms) {
+    if (
+      now - this.data.last_frame_upload_time < this.data.frame_upload_interval_ms ||
+      this.data.frame_upload_in_flight > 0
+    ) {
       return;
     }
+    var begin = Date.now();
     this.setData({
       last_frame_upload_time: now,
       frame_upload_seq_num: this.data.frame_upload_seq_num + 1,
+      frame_upload_in_flight: this.data.frame_upload_in_flight + 1,
     });
     var seq_num = this.data.frame_upload_seq_num.toString().padStart(3, '0');
     var fd = {
@@ -383,16 +389,27 @@ Page({
       image_data_url: data_url,
     }
     wx.request({
-      url: getApp().globalData.server_url + '/api/v1/camera-frame/',
+      url: "https://research.themblem.com/event/camera-frame",
       method: "POST",
-      data: fd,
+      data: JSON.stringify(fd),
+      header: {
+        "Content-Type": "application/json",
+      },
       success: (res) => {
         this.setData({
           frame_uploaded: this.data.frame_uploaded + 1,
+          frame_upload_in_flight: this.data.frame_upload_in_flight - 1,
+          frame_upload_time_cost: Date.now() - begin,
+          frame_upload_interval_ms: this.data.frame_upload_interval_ms * 2,
         });
       },
       fail: (e) => {
         this.log("frame upload failed", e);
+        this.setData({
+          frame_upload_in_flight: this.data.frame_upload_in_flight - 1,
+          frame_upload_time_cost: Date.now() - begin,
+          frame_upload_interval_ms: this.data.frame_upload_interval_ms * 2,
+        });
       },
     });
   },
diff --git a/scanner/pages/camera/camera.wxml b/scanner/pages/camera/camera.wxml
index 54ea186..6d835d5 100644
--- a/scanner/pages/camera/camera.wxml
+++ b/scanner/pages/camera/camera.wxml
@@ -33,7 +33,7 @@
         <view>model: {{ phone_model }}</view>
         <view>zoom: {{ zoom }}</view>
         <view>sensitivity: {{ camera_sensitivity }}</view>
-        <view>frame uploaded: {{ frame_uploaded }}</view>
+        <view>frame uploaded: {{ frame_uploaded }} (upload cost {{ frame_upload_time_cost }}ms)</view>
         <view>max zoom: {{ max_zoom }}</view>
         <view>result: {{ result }}</view>
     </view>