Save canvas size and don't recalculate

frigate/output.py

@@ -29,6 +29,38 @@ from frigate.util import SharedMemoryFrameManager, copy_yuv_to_position, get_yuv
 logger = logging.getLogger(__name__)
 
 
+def get_standard_aspect_ratio(camera_width, camera_height) -> tuple[int, int]:
+    """Ensure that only standard aspect ratios are used."""
+    known_aspects = [
+        (16, 9),
+        (9, 16),
+        (32, 9),
+        (12, 9),
+        (9, 12),
+    ]  # aspects are scaled to have common relative size
+    known_aspects_ratios = list(
+        map(lambda aspect: aspect[0] / aspect[1], known_aspects)
+    )
+    closest = min(
+        known_aspects_ratios,
+        key=lambda x: abs(x - (camera_width / camera_height)),
+    )
+    return known_aspects[known_aspects_ratios.index(closest)]
+
+
+class Canvas:
+    def __init__(self, canvas_width: int, canvas_height: int) -> None:
+        canvas_gcd = math.gcd(canvas_width, canvas_height)
+        self.aspect = get_standard_aspect_ratio(
+            (canvas_width / canvas_gcd), (canvas_height / canvas_gcd)
+        )
+        self.width = canvas_width
+        self.height = (self.width * self.aspect[1]) / self.aspect[0]
+
+    def get_aspect(self, coefficient: int) -> tuple[int, int]:
+        return (self.aspect[0] * coefficient, self.aspect[1] * coefficient)
+
+
 class FFMpegConverter:
     def __init__(
         self,
@@ -170,6 +202,7 @@ class BirdsEyeFrameManager:
         self.frame_shape = (height, width)
         self.yuv_shape = (height * 3 // 2, width)
         self.frame = np.ndarray(self.yuv_shape, dtype=np.uint8)
+        self.canvas = Canvas(width, height)
         self.stop_event = stop_event
 
         # initialize the frame as black and with the Frigate logo
@@ -318,16 +351,15 @@ class BirdsEyeFrameManager:
                 ),
             )
 
-            canvas_width = self.config.birdseye.width
-            canvas_height = self.config.birdseye.height
-
             if len(active_cameras) == 1:
                 # show single camera as fullscreen
                 camera = active_cameras_to_add[0]
                 camera_dims = self.cameras[camera]["dimensions"].copy()
-                scaled_width = int(canvas_height * camera_dims[0] / camera_dims[1])
+                scaled_width = int(self.canvas.height * camera_dims[0] / camera_dims[1])
                 coefficient = (
-                    1 if scaled_width <= canvas_width else canvas_width / scaled_width
+                    1
+                    if scaled_width <= self.canvas.width
+                    else self.canvas.width / scaled_width
                 )
                 self.camera_layout = [
                     [
@@ -337,7 +369,7 @@ class BirdsEyeFrameManager:
                                 0,
                                 0,
                                 int(scaled_width * coefficient),
-                                int(canvas_height * coefficient),
+                                int(self.canvas.height * coefficient),
                             ),
                         )
                     ]
@@ -353,7 +385,6 @@ class BirdsEyeFrameManager:
                         return
 
                     layout_candidate = self.calculate_layout(
-                        (canvas_width, canvas_height),
                         active_cameras_to_add,
                         coefficient,
                     )
@@ -378,29 +409,9 @@ class BirdsEyeFrameManager:
 
         return True
 
-    def calculate_layout(
+    def calculate_layout(self, cameras_to_add: list[str], coefficient) -> tuple[any]:
-        self, canvas, cameras_to_add: list[str], coefficient
-    ) -> tuple[any]:
         """Calculate the optimal layout for 2+ cameras."""
 
-        def get_standard_aspect_ratio(camera_width, camera_height) -> tuple[int, int]:
-            """Ensure that only standard aspect ratios are used."""
-            known_aspects = [
-                (16, 9),
-                (9, 16),
-                (32, 9),
-                (12, 9),
-                (9, 12),
-            ]  # aspects are scaled to have common relative size
-            known_aspects_ratios = list(
-                map(lambda aspect: aspect[0] / aspect[1], known_aspects)
-            )
-            closest = min(
-                known_aspects_ratios,
-                key=lambda x: abs(x - (camera_width / camera_height)),
-            )
-            return known_aspects[known_aspects_ratios.index(closest)]
-
         def map_layout(row_height: int):
             """Map the calculated layout."""
             candidate_layout = []
@@ -427,8 +438,8 @@ class BirdsEyeFrameManager:
 
                     # layout is too large
                     if (
-                        x + scaled_width > canvas_width
+                        x + scaled_width > self.canvas.width
-                        or y + scaled_height > canvas_height
+                        or y + scaled_height > self.canvas.height
                     ):
                         return 0, 0, None
 
@@ -440,16 +451,9 @@ class BirdsEyeFrameManager:
 
             return max_width, y, candidate_layout
 
-        canvas_width = canvas[0]
+        canvas_aspect_x, canvas_aspect_y = self.canvas.get_aspect(coefficient)
         camera_layout: list[list[any]] = []
         camera_layout.append([])
-        canvas_gcd = math.gcd(canvas_width, canvas[1])
-        canvas_aspect = get_standard_aspect_ratio(
-            (canvas_width / canvas_gcd), (canvas[1] / canvas_gcd)
-        )
-        canvas_aspect_x = canvas_aspect[0] * coefficient
-        canvas_aspect_y = canvas_aspect[1] * coefficient
-        canvas_height = (canvas_width * canvas_aspect_y) / canvas_aspect_x
         starting_x = 0
         x = starting_x
         y = 0
@@ -506,15 +510,16 @@ class BirdsEyeFrameManager:
         if y + max_y > canvas_aspect_y:
             return None
 
-        row_height = int(canvas_height / coefficient)
+        row_height = int(self.canvas.height / coefficient)
         total_width, total_height, standard_candidate_layout = map_layout(row_height)
 
         # layout can't be optimized more
-        if total_width / canvas_width >= 0.99:
+        if total_width / self.canvas.width >= 0.99:
             return standard_candidate_layout
 
         scale_up_percent = min(
-            1 - (total_width / canvas_width), 1 - (total_height / canvas_height)
+            1 - (total_width / self.canvas.width),
+            1 - (total_height / self.canvas.height),
         )
         row_height = int(row_height * (1 + round(scale_up_percent, 1)))
         _, _, scaled_layout = map_layout(row_height)