diff --git a/samples/tutorials/data/get_imu_correspondence.cc b/samples/tutorials/data/get_imu_correspondence.cc
index 77d3398..7faef67 100644
--- a/samples/tutorials/data/get_imu_correspondence.cc
+++ b/samples/tutorials/data/get_imu_correspondence.cc
@@ -55,76 +55,77 @@ int main(int argc, char *argv[]) {
 
     auto &&left_data = api->GetStreamData(Stream::LEFT);
     auto &&right_data = api->GetStreamData(Stream::RIGHT);
-    if (left_data.frame.empty() || right_data.frame.empty()) {
-      continue;
-    }
+    if (!left_data.frame.empty() || !right_data.frame.empty()) {
+      auto img_stamp = left_data.img->timestamp;
+      LOG(INFO) << "Img timestamp: " << img_stamp
+          << ", diff_prev=" << (img_stamp - prev_img_stamp);
+      prev_img_stamp = img_stamp;
 
-    auto img_stamp = left_data.img->timestamp;
-    LOG(INFO) << "Img timestamp: " << img_stamp
-        << ", diff_prev=" << (img_stamp - prev_img_stamp);
-    prev_img_stamp = img_stamp;
+      cv::Mat img;
+      cv::hconcat(left_data.frame, right_data.frame, img);
 
-    cv::Mat img;
-    cv::hconcat(left_data.frame, right_data.frame, img);
-
-    auto &&motion_datas = api->GetMotionDatas();
-    LOG(INFO) << "Imu count: " << motion_datas.size();
-    for (size_t i = 0, n = motion_datas.size() - 1; i <= n; ++i) {
-      auto data = motion_datas[i];
-      auto imu_flag = data.imu->flag;
-      auto imu_stamp = data.imu->timestamp;
-
-      std::stringstream ss;
-      if (imu_flag == 0) {  // accel + gyro
-        ss << "Imu";
-      } else if (imu_flag == 1) {  // accel
-        ss << "Accel";
-      } else if (imu_flag == 2) {  // gyro
-        ss << "Gyro";
+      auto &&motion_datas = api->GetMotionDatas();
+      LOG(INFO) << "Imu count: " << motion_datas.size();
+      if (motion_datas.size() == 0) {
+        continue;
       }
-      ss << " timestamp: " << imu_stamp
-          << ", diff_prev=" << (imu_stamp - prev_imu_stamp)
-          << ", diff_img=" << (1.0f + imu_stamp - img_stamp);
-#ifdef CHECK_ACCEL_THEN_GYRO
-      if (imu_flag > 0) {
-        bool ok = false;
-        if (i == 0) {  // first
-          ok = (imu_flag == SEQ_FIRST);
-        } else if (i == n) {  // last
-          ok = (imu_flag == SEQ_SECOND);
-        } else {
-          if (imu_flag == SEQ_FIRST) {
-            ok = (prev_imu_flag == SEQ_SECOND);
-          } else if (imu_flag == SEQ_SECOND) {
-            ok = (prev_imu_flag == SEQ_FIRST);
+      for (size_t i = 0, n = motion_datas.size() - 1; i <= n; ++i) {
+        auto data = motion_datas[i];
+        auto imu_flag = data.imu->flag;
+        auto imu_stamp = data.imu->timestamp;
+
+        std::stringstream ss;
+        if (imu_flag == 0) {  // accel + gyro
+          ss << "Imu";
+        } else if (imu_flag == 1) {  // accel
+          ss << "Accel";
+        } else if (imu_flag == 2) {  // gyro
+          ss << "Gyro";
+        }
+        ss << " timestamp: " << imu_stamp
+            << ", diff_prev=" << (imu_stamp - prev_imu_stamp)
+            << ", diff_img=" << (1.0f + imu_stamp - img_stamp);
+  #ifdef CHECK_ACCEL_THEN_GYRO
+        if (imu_flag > 0) {
+          bool ok = false;
+          if (i == 0) {  // first
+            ok = (imu_flag == SEQ_FIRST);
+          } else if (i == n) {  // last
+            ok = (imu_flag == SEQ_SECOND);
+          } else {
+            if (imu_flag == SEQ_FIRST) {
+              ok = (prev_imu_flag == SEQ_SECOND);
+            } else if (imu_flag == SEQ_SECOND) {
+              ok = (prev_imu_flag == SEQ_FIRST);
+            }
+          }
+          ss << (ok ? " ✓" : " x");
+          if (!ok) ++imu_disorder_count;
+          prev_imu_flag = imu_flag;
+          if (!exit) {
+            if (!ok) exit = true;
           }
         }
-        ss << (ok ? " ✓" : " x");
-        if (!ok) ++imu_disorder_count;
-        prev_imu_flag = imu_flag;
-        if (!exit) {
-          if (!ok) exit = true;
-        }
+  #endif
+        LOG(INFO) << ss.str();
+
+        prev_imu_stamp = imu_stamp;
       }
-#endif
-      LOG(INFO) << ss.str();
+      LOG(INFO);
+  #ifdef CHECK_ACCEL_THEN_GYRO
+      imu_count += motion_datas.size();
+      if (exit) break;
+  #endif
 
-      prev_imu_stamp = imu_stamp;
+      /*
+      painter.DrawImgData(img, *left_data.img);
+      if (!motion_datas.empty()) {
+        painter.DrawImuData(img, *motion_datas[0].imu);
+      }
+      */
+
+      cv::imshow("frame", img);
     }
-    LOG(INFO);
-#ifdef CHECK_ACCEL_THEN_GYRO
-    imu_count += motion_datas.size();
-    if (exit) break;
-#endif
-
-    /*
-    painter.DrawImgData(img, *left_data.img);
-    if (!motion_datas.empty()) {
-      painter.DrawImuData(img, *motion_datas[0].imu);
-    }
-    */
-
-    cv::imshow("frame", img);
 
     char key = static_cast<char>(cv::waitKey(1));
     if (key == 27 || key == 'q' || key == 'Q') {  // ESC/Q