diff --git a/include/mynteye/utils.h b/include/mynteye/utils.h
index 0b8f474..7ca41bd 100644
--- a/include/mynteye/utils.h
+++ b/include/mynteye/utils.h
@@ -25,14 +25,22 @@ class Device;
 
 namespace device {
 
-/** Detecting MYNT EYE devices and prompt user to select one */
+/**
+ * Detecting MYNT EYE devices and prompt user to select one.
+ * @return the selected device, or `nullptr` if none.
+ */
 MYNTEYE_API std::shared_ptr<Device> select();
 
 }  // namespace device
 
 namespace utils {
 
-/** Get real exposure time in ms from virtual value, according to its frame rate
+/**
+ * Get real exposure time in ms from virtual value, according to its frame rate.
+ * @param frame_rate the frame rate of the device.
+ * @param exposure_time the virtual exposure time.
+ * @return the real exposure time in ms, or the virtual value if frame rate is
+ * invalid.
  */
 MYNTEYE_API float get_real_exposure_time(
     std::int32_t frame_rate, std::uint16_t exposure_time);
diff --git a/samples/api/camera.cc b/samples/api/camera.cc
index d5aff62..5cddd85 100644
--- a/samples/api/camera.cc
+++ b/samples/api/camera.cc
@@ -22,6 +22,8 @@ MYNTEYE_USE_NAMESPACE
 
 int main(int argc, char *argv[]) {
   auto &&api = API::Create(argc, argv);
+  if (!api)
+    return 1;
 
   // api->SetOptionValue(Option::FRAME_RATE, 25);
   // api->SetOptionValue(Option::IMU_FREQUENCY, 500);
diff --git a/samples/device/camera.cc b/samples/device/camera.cc
index d9b210f..bcd9695 100644
--- a/samples/device/camera.cc
+++ b/samples/device/camera.cc
@@ -27,6 +27,8 @@ int main(int argc, char *argv[]) {
   glog_init _(argc, argv);
 
   auto &&device = device::select();
+  if (!device)
+    return 1;
   /*
   {  // auto-exposure
     device->SetOptionValue(Option::EXPOSURE_MODE, 0);
diff --git a/samples/tutorials/control/auto_exposure.cc b/samples/tutorials/control/auto_exposure.cc
index c517256..f1f5c13 100644
--- a/samples/tutorials/control/auto_exposure.cc
+++ b/samples/tutorials/control/auto_exposure.cc
@@ -23,6 +23,8 @@ MYNTEYE_USE_NAMESPACE
 
 int main(int argc, char *argv[]) {
   auto &&api = API::Create(argc, argv);
+  if (!api)
+    return 1;
 
   // auto-exposure: 0
   api->SetOptionValue(Option::EXPOSURE_MODE, 0);
diff --git a/samples/tutorials/control/framerate.cc b/samples/tutorials/control/framerate.cc
index 882fa1f..55cfd30 100644
--- a/samples/tutorials/control/framerate.cc
+++ b/samples/tutorials/control/framerate.cc
@@ -24,6 +24,8 @@ MYNTEYE_USE_NAMESPACE
 
 int main(int argc, char *argv[]) {
   auto &&api = API::Create(argc, argv);
+  if (!api)
+    return 1;
 
   // Attention: must set FRAME_RATE and IMU_FREQUENCY together, otherwise won't
   // succeed.
diff --git a/samples/tutorials/control/infrared.cc b/samples/tutorials/control/infrared.cc
index da0e12b..7ed6286 100644
--- a/samples/tutorials/control/infrared.cc
+++ b/samples/tutorials/control/infrared.cc
@@ -21,6 +21,8 @@ MYNTEYE_USE_NAMESPACE
 
 int main(int argc, char *argv[]) {
   auto &&api = API::Create(argc, argv);
+  if (!api)
+    return 1;
 
   // Detect infrared add-ons
   LOG(INFO) << "Support infrared: " << std::boolalpha
diff --git a/samples/tutorials/control/manual_exposure.cc b/samples/tutorials/control/manual_exposure.cc
index 74c4b68..12aef0e 100644
--- a/samples/tutorials/control/manual_exposure.cc
+++ b/samples/tutorials/control/manual_exposure.cc
@@ -23,6 +23,8 @@ MYNTEYE_USE_NAMESPACE
 
 int main(int argc, char *argv[]) {
   auto &&api = API::Create(argc, argv);
+  if (!api)
+    return 1;
 
   // manual-exposure: 1
   api->SetOptionValue(Option::EXPOSURE_MODE, 1);
diff --git a/samples/tutorials/data/get_depth.cc b/samples/tutorials/data/get_depth.cc
index 2b5e2a9..274c8ee 100644
--- a/samples/tutorials/data/get_depth.cc
+++ b/samples/tutorials/data/get_depth.cc
@@ -21,6 +21,8 @@ MYNTEYE_USE_NAMESPACE
 
 int main(int argc, char *argv[]) {
   auto &&api = API::Create(argc, argv);
+  if (!api)
+    return 1;
 
   api->EnableStreamData(Stream::DEPTH);
 
diff --git a/samples/tutorials/data/get_device_info.cc b/samples/tutorials/data/get_device_info.cc
index 1701373..ee41348 100644
--- a/samples/tutorials/data/get_device_info.cc
+++ b/samples/tutorials/data/get_device_info.cc
@@ -19,6 +19,8 @@ MYNTEYE_USE_NAMESPACE
 
 int main(int argc, char *argv[]) {
   auto &&api = API::Create(argc, argv);
+  if (!api)
+    return 1;
 
   LOG(INFO) << "Device name: " << api->GetInfo(Info::DEVICE_NAME);
   LOG(INFO) << "Serial number: " << api->GetInfo(Info::SERIAL_NUMBER);
diff --git a/samples/tutorials/data/get_disparity.cc b/samples/tutorials/data/get_disparity.cc
index a96196d..5a9f798 100644
--- a/samples/tutorials/data/get_disparity.cc
+++ b/samples/tutorials/data/get_disparity.cc
@@ -21,6 +21,8 @@ MYNTEYE_USE_NAMESPACE
 
 int main(int argc, char *argv[]) {
   auto &&api = API::Create(argc, argv);
+  if (!api)
+    return 1;
 
   // api->EnableStreamData(Stream::DISPARITY);
   api->EnableStreamData(Stream::DISPARITY_NORMALIZED);
diff --git a/samples/tutorials/data/get_from_callbacks.cc b/samples/tutorials/data/get_from_callbacks.cc
index f73b358..cb51875 100644
--- a/samples/tutorials/data/get_from_callbacks.cc
+++ b/samples/tutorials/data/get_from_callbacks.cc
@@ -28,6 +28,8 @@ MYNTEYE_USE_NAMESPACE
 
 int main(int argc, char *argv[]) {
   auto &&api = API::Create(argc, argv);
+  if (!api)
+    return 1;
 
   // Attention: must not block the callbacks.
 
diff --git a/samples/tutorials/data/get_img_params.cc b/samples/tutorials/data/get_img_params.cc
index e43be7d..4298c38 100644
--- a/samples/tutorials/data/get_img_params.cc
+++ b/samples/tutorials/data/get_img_params.cc
@@ -19,6 +19,8 @@ MYNTEYE_USE_NAMESPACE
 
 int main(int argc, char *argv[]) {
   auto &&api = API::Create(argc, argv);
+  if (!api)
+    return 1;
 
   LOG(INFO) << "Intrinsics left: {" << api->GetIntrinsics(Stream::LEFT) << "}";
   LOG(INFO) << "Intrinsics right: {" << api->GetIntrinsics(Stream::RIGHT)
diff --git a/samples/tutorials/data/get_imu.cc b/samples/tutorials/data/get_imu.cc
index b52cb5f..6ed0552 100644
--- a/samples/tutorials/data/get_imu.cc
+++ b/samples/tutorials/data/get_imu.cc
@@ -23,6 +23,8 @@ MYNTEYE_USE_NAMESPACE
 
 int main(int argc, char *argv[]) {
   auto &&api = API::Create(argc, argv);
+  if (!api)
+    return 1;
 
   // Enable this will cache the motion datas until you get them.
   api->EnableMotionDatas();
diff --git a/samples/tutorials/data/get_imu_params.cc b/samples/tutorials/data/get_imu_params.cc
index 8ab5ac2..ddcfd49 100644
--- a/samples/tutorials/data/get_imu_params.cc
+++ b/samples/tutorials/data/get_imu_params.cc
@@ -19,6 +19,8 @@ MYNTEYE_USE_NAMESPACE
 
 int main(int argc, char *argv[]) {
   auto &&api = API::Create(argc, argv);
+  if (!api)
+    return 1;
 
   LOG(INFO) << "Motion intrinsics: {" << api->GetMotionIntrinsics() << "}";
   LOG(INFO) << "Motion extrinsics left to imu: {"
diff --git a/samples/tutorials/data/get_points.cc b/samples/tutorials/data/get_points.cc
index 246c10b..828418d 100644
--- a/samples/tutorials/data/get_points.cc
+++ b/samples/tutorials/data/get_points.cc
@@ -23,6 +23,8 @@ MYNTEYE_USE_NAMESPACE
 
 int main(int argc, char *argv[]) {
   auto &&api = API::Create(argc, argv);
+  if (!api)
+    return 1;
 
   api->EnableStreamData(Stream::POINTS);
 
diff --git a/samples/tutorials/data/get_stereo.cc b/samples/tutorials/data/get_stereo.cc
index 284a778..a82a9e9 100644
--- a/samples/tutorials/data/get_stereo.cc
+++ b/samples/tutorials/data/get_stereo.cc
@@ -21,6 +21,8 @@ MYNTEYE_USE_NAMESPACE
 
 int main(int argc, char *argv[]) {
   auto &&api = API::Create(argc, argv);
+  if (!api)
+    return 1;
 
   api->Start(Source::VIDEO_STREAMING);
 
diff --git a/samples/tutorials/data/get_stereo_rectified.cc b/samples/tutorials/data/get_stereo_rectified.cc
index f36899e..04c4eae 100644
--- a/samples/tutorials/data/get_stereo_rectified.cc
+++ b/samples/tutorials/data/get_stereo_rectified.cc
@@ -21,6 +21,8 @@ MYNTEYE_USE_NAMESPACE
 
 int main(int argc, char *argv[]) {
   auto &&api = API::Create(argc, argv);
+  if (!api)
+    return 1;
 
   api->EnableStreamData(Stream::LEFT_RECTIFIED);
   api->EnableStreamData(Stream::RIGHT_RECTIFIED);
diff --git a/samples/tutorials/data/get_with_plugin.cc b/samples/tutorials/data/get_with_plugin.cc
index 1fd0e57..a2201ba 100644
--- a/samples/tutorials/data/get_with_plugin.cc
+++ b/samples/tutorials/data/get_with_plugin.cc
@@ -21,6 +21,8 @@ MYNTEYE_USE_NAMESPACE
 
 int main(int argc, char *argv[]) {
   auto &&api = API::Create(argc, argv);
+  if (!api)
+    return 1;
 
   api->EnablePlugin("plugins/linux-x86_64/libplugin_g_cuda9.1_opencv3.4.0.so");
 
diff --git a/src/api/api.cc b/src/api/api.cc
index e10184c..a8ae126 100644
--- a/src/api/api.cc
+++ b/src/api/api.cc
@@ -41,17 +41,24 @@ std::shared_ptr<API> API::Create() {
 }
 
 std::shared_ptr<API> API::Create(std::shared_ptr<Device> device) {
+  if (!device)
+    return nullptr;
   return std::make_shared<API>(device);
 }
 
 std::shared_ptr<API> API::Create(int argc, char *argv[]) {
   static glog_init _(argc, argv);
-  return std::make_shared<API>(device::select());
+  auto &&device = device::select();
+  if (!device)
+    return nullptr;
+  return std::make_shared<API>(device);
 }
 
 std::shared_ptr<API> API::Create(
     int argc, char *argv[], std::shared_ptr<Device> device) {
   static glog_init _(argc, argv);
+  if (!device)
+    return nullptr;
   return std::make_shared<API>(device);
 }
 
diff --git a/src/api/api.h b/src/api/api.h
index 285e604..a172b05 100644
--- a/src/api/api.h
+++ b/src/api/api.h
@@ -51,9 +51,35 @@ class MYNTEYE_API API {
   explicit API(std::shared_ptr<Device> device);
   /*virtual*/ ~API();
 
+  /**
+   * Create the API instance.
+   * @return the API instance.
+   * @note This will call device::select() to select a device.
+   */
   static std::shared_ptr<API> Create();
+  /**
+   * Create the API instance.
+   * @param device the selected device.
+   * @return the API instance.
+   */
   static std::shared_ptr<API> Create(std::shared_ptr<Device> device);
+  /**
+   * Create the API instance.
+   * @param argc the arg count.
+   * @param argv the arg values.
+   * @return the API instance.
+   * @note This will init glog with args and call device::select() to select a
+   * device.
+   */
   static std::shared_ptr<API> Create(int argc, char *argv[]);
+  /**
+   * Create the API instance.
+   * @param argc the arg count.
+   * @param argv the arg values.
+   * @param device the selected device.
+   * @return the API instance.
+   * @note This will init glog with args.
+   */
   static std::shared_ptr<API> Create(
       int argc, char *argv[], std::shared_ptr<Device> device);
 
diff --git a/src/public/utils.cc b/src/public/utils.cc
index af33e53..f4ad5b3 100644
--- a/src/public/utils.cc
+++ b/src/public/utils.cc
@@ -28,7 +28,10 @@ std::shared_ptr<Device> select() {
   auto &&devices = context.devices();
 
   size_t n = devices.size();
-  LOG_IF(FATAL, n <= 0) << "No MYNT EYE devices :(";
+  if (n <= 0) {
+    LOG(ERROR) << "No MYNT EYE devices :(";
+    return nullptr;
+  }
 
   LOG(INFO) << "MYNT EYE devices:";
   for (size_t i = 0; i < n; i++) {
diff --git a/tools/dataset/record.cc b/tools/dataset/record.cc
index 8e19057..e3de362 100644
--- a/tools/dataset/record.cc
+++ b/tools/dataset/record.cc
@@ -29,6 +29,8 @@ int main(int argc, char *argv[]) {
   glog_init _(argc, argv);
 
   auto &&device = device::select();
+  if (!device)
+    return 1;
   /*
   {  // auto-exposure
     device->SetOptionValue(Option::EXPOSURE_MODE, 0);
diff --git a/tools/writer/device_info_writer.cc b/tools/writer/device_info_writer.cc
index 3eaf394..1625b7a 100644
--- a/tools/writer/device_info_writer.cc
+++ b/tools/writer/device_info_writer.cc
@@ -32,6 +32,8 @@ int main(int argc, char *argv[]) {
   }
 
   auto &&device = device::select();
+  if (!device)
+    return 1;
 
   tools::DeviceWriter writer(device);
   writer.WriteDeviceInfo(filepath);
diff --git a/tools/writer/img_params_writer.cc b/tools/writer/img_params_writer.cc
index 0afcf54..77647a5 100644
--- a/tools/writer/img_params_writer.cc
+++ b/tools/writer/img_params_writer.cc
@@ -32,6 +32,8 @@ int main(int argc, char *argv[]) {
   }
 
   auto &&device = device::select();
+  if (!device)
+    return 1;
 
   tools::DeviceWriter writer(device);
   writer.WriteImgParams(filepath);
diff --git a/tools/writer/imu_params_writer.cc b/tools/writer/imu_params_writer.cc
index 29d33b1..9f2034b 100644
--- a/tools/writer/imu_params_writer.cc
+++ b/tools/writer/imu_params_writer.cc
@@ -32,6 +32,8 @@ int main(int argc, char *argv[]) {
   }
 
   auto &&device = device::select();
+  if (!device)
+    return 1;
 
   tools::DeviceWriter writer(device);
   writer.WriteImuParams(filepath);
diff --git a/tools/writer/save_all_infos.cc b/tools/writer/save_all_infos.cc
index dcfa97f..a4ff051 100644
--- a/tools/writer/save_all_infos.cc
+++ b/tools/writer/save_all_infos.cc
@@ -29,6 +29,8 @@ int main(int argc, char *argv[]) {
   }
 
   auto &&device = device::select();
+  if (!device)
+    return 1;
 
   dir.append(OS_SEP "SN").append(device->GetInfo()->serial_number);