Replace green screen with error message and force camera_fps to 0 (#4544)

* Move to images specific folder

* Send error image when camera stream is not available

* Immediately set camera_fps to 0 if camera crashes

* Cache error image so it is not read from file system on each run

* Move camera fps set

frigate/http.py

@@ -1,6 +1,7 @@
 import base64
 from datetime import datetime, timedelta
 import copy
+import glob
 import logging
 import json
 import os
@@ -62,6 +63,7 @@ def create_app(
     app.stats_tracking = stats_tracking
     app.detected_frames_processor = detected_frames_processor
     app.plus_api = plus_api
+    app.camera_error_image = None
 
     app.register_blueprint(bp)
 
@@ -657,8 +659,20 @@ def latest_frame(camera_name):
         frame = current_app.detected_frames_processor.get_current_frame(
             camera_name, draw_options
         )
-        if frame is None:
-            frame = np.zeros((720, 1280, 3), np.uint8)
+
+        if frame is None or datetime.now().timestamp() > (
+            current_app.detected_frames_processor.get_current_frame_time(camera_name)
+            + 10
+        ):
+            if current_app.camera_error_image is None:
+                error_image = glob.glob("/opt/frigate/frigate/images/camera-error.jpg")
+
+                if len(error_image) > 0:
+                    current_app.camera_error_image = cv2.imread(
+                        error_image[0], cv2.IMREAD_UNCHANGED
+                    )
+
+            frame = current_app.camera_error_image
 
         height = int(request.args.get("h", str(frame.shape[0])))
         width = int(height * frame.shape[1] / frame.shape[0])