Fix round robin (#15035)

* Move camera SHM frame creation to main process

* Don't reset frame index

* Don't fail if shm exists

* Set more types

frigate/app.py

@@ -68,7 +68,7 @@ from frigate.stats.util import stats_init
 from frigate.storage import StorageMaintainer
 from frigate.timeline import TimelineProcessor
 from frigate.util.builtin import empty_and_close_queue
-from frigate.util.image import UntrackedSharedMemory
+from frigate.util.image import SharedMemoryFrameManager, UntrackedSharedMemory
 from frigate.util.object import get_camera_regions_grid
 from frigate.version import VERSION
 from frigate.video import capture_camera, track_camera
@@ -426,12 +426,18 @@ class FrigateApp:
 
     def start_camera_capture_processes(self) -> None:
         shm_frame_count = self.shm_frame_count()
+        frame_manager = SharedMemoryFrameManager()
 
         for name, config in self.config.cameras.items():
             if not self.config.cameras[name].enabled:
                 logger.info(f"Capture process not started for disabled camera {name}")
                 continue
 
+            # pre-create shms
+            for i in range(shm_frame_count):
+                frame_size = config.frame_shape_yuv[0] * config.frame_shape_yuv[1]
+                frame_manager.create(f"{config.name}{i}", frame_size)
+
             capture_process = util.Process(
                 target=capture_camera,
                 name=f"camera_capture:{name}",

frigate/util/image.py

@@ -790,11 +790,15 @@ class SharedMemoryFrameManager(FrameManager):
         self.shm_store: dict[str, UntrackedSharedMemory] = {}
 
     def create(self, name: str, size) -> AnyStr:
-        shm = UntrackedSharedMemory(
-            name=name,
-            create=True,
-            size=size,
-        )
+        try:
+            shm = UntrackedSharedMemory(
+                name=name,
+                create=True,
+                size=size,
+            )
+        except FileExistsError:
+            shm = UntrackedSharedMemory(name=name)
+
         self.shm_store[name] = shm
         return shm.buf
 

frigate/video.py

@@ -94,7 +94,8 @@ def capture_frames(
     ffmpeg_process,
     config: CameraConfig,
     shm_frame_count: int,
-    frame_shape,
+    frame_index: int,
+    frame_shape: tuple[int, int],
     frame_manager: FrameManager,
     frame_queue,
     fps: mp.Value,
@@ -108,12 +109,6 @@ def capture_frames(
     skipped_eps = EventsPerSecond()
     skipped_eps.start()
 
-    # pre-create shms
-    for i in range(shm_frame_count):
-        frame_manager.create(f"{config.name}{i}", frame_size)
-
-    frame_index = 0
-
     while True:
         fps.value = frame_rate.eps()
         skipped_fps.value = skipped_eps.eps()
@@ -159,7 +154,7 @@ class CameraWatchdog(threading.Thread):
         camera_name,
         config: CameraConfig,
         shm_frame_count: int,
-        frame_queue,
+        frame_queue: mp.Queue,
         camera_fps,
         skipped_fps,
         ffmpeg_pid,
@@ -181,6 +176,7 @@ class CameraWatchdog(threading.Thread):
         self.frame_shape = self.config.frame_shape_yuv
         self.frame_size = self.frame_shape[0] * self.frame_shape[1]
         self.fps_overflow_count = 0
+        self.frame_index = 0
         self.stop_event = stop_event
         self.sleeptime = self.config.ffmpeg.retry_interval
 
@@ -302,6 +298,7 @@ class CameraWatchdog(threading.Thread):
         self.capture_thread = CameraCapture(
             self.config,
             self.shm_frame_count,
+            self.frame_index,
             self.ffmpeg_detect_process,
             self.frame_shape,
             self.frame_queue,
@@ -342,9 +339,10 @@ class CameraCapture(threading.Thread):
         self,
         config: CameraConfig,
         shm_frame_count: int,
+        frame_index: int,
         ffmpeg_process,
-        frame_shape,
-        frame_queue,
+        frame_shape: tuple[int, int],
+        frame_queue: mp.Queue,
         fps,
         skipped_fps,
         stop_event,
@@ -353,6 +351,7 @@ class CameraCapture(threading.Thread):
         self.name = f"capture:{config.name}"
         self.config = config
         self.shm_frame_count = shm_frame_count
+        self.frame_index = frame_index
         self.frame_shape = frame_shape
         self.frame_queue = frame_queue
         self.fps = fps
@@ -368,6 +367,7 @@ class CameraCapture(threading.Thread):
             self.ffmpeg_process,
             self.config,
             self.shm_frame_count,
+            self.frame_index,
             self.frame_shape,
             self.frame_manager,
             self.frame_queue,