diff --git a/demo/cdc_acm_template.c b/demo/cdc_acm_template.c
index d12b0a47..d733c8b3 100644
--- a/demo/cdc_acm_template.c
+++ b/demo/cdc_acm_template.c
@@ -142,8 +142,7 @@ void cdc_acm_init(void)
     usbd_interface_add_endpoint(&cdc_data_intf, &cdc_out_ep);
     usbd_interface_add_endpoint(&cdc_data_intf, &cdc_in_ep);
 
-    extern int usb_dc_init(void);
-    usb_dc_init();
+    usbd_initialize();
 }
 
 volatile uint8_t dtr_enable = 0;
diff --git a/demo/hid_custom_keyboard_template.c b/demo/hid_custom_keyboard_template.c
index b4041018..fca6f15b 100644
--- a/demo/hid_custom_keyboard_template.c
+++ b/demo/hid_custom_keyboard_template.c
@@ -381,8 +381,7 @@ void hid_custom_keyboard_init(void)
     /*!< register report descriptor interface 1 */
     usbd_hid_report_descriptor_register(1, hid_custom_report_desc, HID_CUSTOM_REPORT_DESC_SIZE);
 
-    extern int usb_dc_init(void);
-    usb_dc_init();
+    usbd_initialize();
 }
 
 /**
diff --git a/demo/hid_keyboard_template.c b/demo/hid_keyboard_template.c
index 15531379..310f4a4c 100644
--- a/demo/hid_keyboard_template.c
+++ b/demo/hid_keyboard_template.c
@@ -192,6 +192,5 @@ void hid_keyboard_init(void)
     usbd_interface_add_endpoint(&hid_intf, &hid_in_ep);
     usbd_hid_report_descriptor_register(0, hid_keyboard_report_desc, HID_KEYBOARD_REPORT_DESC_SIZE);
 
-    extern int usb_dc_init(void);
-    usb_dc_init();
+    usbd_initialize();
 }
\ No newline at end of file
diff --git a/demo/hid_mouse_template.c b/demo/hid_mouse_template.c
index c2e00f2f..eeee23a8 100644
--- a/demo/hid_mouse_template.c
+++ b/demo/hid_mouse_template.c
@@ -234,8 +234,8 @@ void hid_mouse_init(void)
     /*!< register report descriptor */
     usbd_hid_report_descriptor_register(0, hid_mouse_report_desc, HID_MOUSE_REPORT_DESC_SIZE);
 
-    extern int usb_dc_init(void);
-    usb_dc_init();
+    usbd_initialize();
+
     /*!< init mouse report data */
     mouse_cfg.buttons = 0;
     mouse_cfg.wheel = 0;
diff --git a/demo/midi_template.c b/demo/midi_template.c
index 6ecb9b3d..6bf8c0f8 100644
--- a/demo/midi_template.c
+++ b/demo/midi_template.c
@@ -156,12 +156,11 @@ usbd_endpoint_t midi_in_ep = {
 void midi_init(void)
 {
     usbd_desc_register(midi_descriptor);
-    
+
     usbd_class_add_interface(&midi_class, &midi_cmd_intf);
     usbd_class_add_interface(&midi_class, &midi_data_intf);
     usbd_interface_add_endpoint(&midi_data_intf, &midi_out_ep);
     usbd_interface_add_endpoint(&midi_data_intf, &midi_in_ep);
 
-    extern int usb_dc_init(void);
-    usb_dc_init();
+    usbd_initialize();
 }
\ No newline at end of file
diff --git a/demo/msc_ram_template.c b/demo/msc_ram_template.c
index 722c2e99..1240c15e 100644
--- a/demo/msc_ram_template.c
+++ b/demo/msc_ram_template.c
@@ -130,6 +130,5 @@ void msc_ram_init(void)
     usbd_desc_register(msc_ram_descriptor);
     usbd_msc_class_init(MSC_OUT_EP, MSC_IN_EP);
 
-    extern int usb_dc_init(void);
-    usb_dc_init();
+    usbd_initialize();
 }
diff --git a/demo/stm32/usb_device/stm32f429igt6/Core/Src/main.c b/demo/stm32/usb_device/stm32f429igt6/Core/Src/main.c
index d55c7cef..ed8aaca3 100644
--- a/demo/stm32/usb_device/stm32f429igt6/Core/Src/main.c
+++ b/demo/stm32/usb_device/stm32f429igt6/Core/Src/main.c
@@ -208,9 +208,6 @@ void usb_dc_low_level_init(void)
     HAL_NVIC_EnableIRQ(OTG_HS_IRQn);
 }
 
-
-extern void usb_dc_init(void);
-
 volatile uint8_t dtr_enable = 0;
 
 void usbd_cdc_acm_set_dtr(bool dtr)
@@ -262,7 +259,7 @@ int main(void)
   usbd_interface_add_endpoint(&cdc_data_intf, &cdc_out_ep);
   usbd_interface_add_endpoint(&cdc_data_intf, &cdc_in_ep);
 
-  usb_dc_init();
+  usbd_initialize();
 
   /* USER CODE END 2 */
 
diff --git a/demo/stm32/usb_device/stm32h743vbt6/Core/Src/main.c b/demo/stm32/usb_device/stm32h743vbt6/Core/Src/main.c
index 1cc5e23f..ad8865eb 100644
--- a/demo/stm32/usb_device/stm32h743vbt6/Core/Src/main.c
+++ b/demo/stm32/usb_device/stm32h743vbt6/Core/Src/main.c
@@ -223,7 +223,6 @@ void usb_dc_low_level_init(void)
 
     /* USER CODE END USB_OTG_FS_MspInit 1 */
 }
-extern void usb_dc_init(void);
 
 volatile uint8_t dtr_enable = 0;
 
@@ -277,7 +276,7 @@ int main(void)
     usbd_interface_add_endpoint(&cdc_data_intf, &cdc_out_ep);
     usbd_interface_add_endpoint(&cdc_data_intf, &cdc_in_ep);
 
-    usb_dc_init();
+    usbd_initialize();
 
     while (!usb_device_is_configured()) {
     }
diff --git a/demo/video_hs_mjpeg_template.c b/demo/video_hs_mjpeg_template.c
index 6f17d8cd..9c9034a0 100644
--- a/demo/video_hs_mjpeg_template.c
+++ b/demo/video_hs_mjpeg_template.c
@@ -277,10 +277,9 @@ static usbd_class_t video_class;
 static usbd_interface_t video_control_intf;
 static usbd_interface_t video_stream_intf;
 
-volatile uint8_t ios_complete = 0;
 void usbd_video_iso_callback(uint8_t ep)
 {
-    ios_complete = 1;
+
 }
 
 static usbd_endpoint_t video_in_ep = {
@@ -296,6 +295,8 @@ void video_init()
     usbd_interface_add_endpoint(&video_stream_intf, &video_in_ep);
 
     usbd_video_probe_and_commit_controls_init(CAM_FPS, MAX_FRAME_SIZE, MAX_PAYLOAD_SIZE);
+
+    usbd_initialize();
 }
 
 uint8_t packet_buffer[10 * 1024];
@@ -303,12 +304,11 @@ uint8_t packet_buffer[10 * 1024];
 void video_test()
 {
     uint32_t out_len;
-    uint32_t packets = usbd_video_mjpeg_payload_fill((uint8_t *)jpeg_data, sizeof(jpeg_data), packet_buffer, &out_len);
 
     while (1) {
         if (tx_flag) {
+            usbd_video_mjpeg_payload_fill((uint8_t *)jpeg_data, sizeof(jpeg_data), packet_buffer, &out_len);
             usbd_ep_write(0x81, packet_buffer, out_len, NULL);
-            usbd_video_mjpeg_payload_header_toggle(packet_buffer, packets);
         }
     }
 }
\ No newline at end of file