feat: Improve frame conversion strategy and logging in InferenceManager

app/inference/worker_manager.py

@@ -144,6 +144,12 @@ class InferenceManager(QObject):
           - manager is not running
           - manager is paused
           - worker is still busy with previous frame (drop_if_busy)
+
+        Frame conversion strategy:
+          Use QVideoFrame.toImage() → QImage.Format_RGB32 → bits().
+          This handles all pixel formats (NV12, YUV420P, BGRA, MJPG, etc.)
+          because Qt decodes them internally.  The cost is a CPU colour-space
+          conversion, but it only happens when the worker is idle (drop_if_busy).
         """
         if not self.is_running or self._paused or self._busy:
             return
@@ -151,44 +157,35 @@ class InferenceManager(QObject):
         if not frame.isValid():
             return
 
-        # Map frame to read-only memory, copy raw bytes, unmap
-        if not frame.map(QVideoFrame.MapMode.ReadOnly):
-            logger.warning("InferenceManager: failed to map QVideoFrame")
+        # Convert frame to RGB via Qt's built-in decoder.
+        # toImage() handles NV12, YUV420P, MJPG, BGRA — any pixel format.
+        image = frame.toImage()
+        if image.isNull():
+            logger.warning("InferenceManager: toImage() returned null")
             return
 
+        width = image.width()
+        height = image.height()
+
+        # Ensure we have packed RGB32 (BGRX on little-endian, 4 bytes/pixel)
+        from PySide6.QtGui import QImage  # noqa: PLC0415
+        if image.format() != QImage.Format.Format_RGB32:
+            image = image.convertToFormat(QImage.Format.Format_RGB32)
+
+        # Extract RGB bytes (drop alpha/padding channel)
         try:
-            width = frame.width()
-            height = frame.height()
-            raw = bytes(frame.bits(0))   # plane 0 — copies data
-        finally:
-            frame.unmap()
-
-        if not raw:
+            import numpy as np  # noqa: PLC0415
+            # bits() returns BGRX (B G R 0xFF) for Format_RGB32
+            ptr = image.bits()
+            arr = np.frombuffer(ptr, dtype=np.uint8).reshape((height, width, 4))
+            # Swap B↔R and drop X → RGB
+            rgb = arr[:, :, [2, 1, 0]].copy()
+            raw = rgb.tobytes()
+        except Exception as exc:
+            logger.warning("InferenceManager: frame conversion failed: %s", exc)
             return
 
-        # Detect number of channels from byte count
-        expected_rgb = width * height * 3
-        expected_rgba = width * height * 4
-        if len(raw) >= expected_rgba:
-            # BGRA / RGBA — convert to RGB by stripping alpha and swapping B/R
-            try:
-                import numpy as np  # noqa: PLC0415
-                arr = np.frombuffer(raw, dtype=np.uint8).reshape((height, width, 4))
-                # Qt delivers BGRA → swap to RGB
-                rgb = arr[:, :, [2, 1, 0]].copy()
-                raw = rgb.tobytes()
-                channels = 3
-            except Exception as exc:
-                logger.warning("Frame colour conversion failed: %s", exc)
-                return
-        elif len(raw) >= expected_rgb:
-            channels = 3
-        else:
-            logger.warning(
-                "Unexpected frame size: %d bytes for %dx%d",
-                len(raw), width, height,
-            )
-            return
+        channels = 3
 
         self._frame_id += 1
         packet = FramePacket(

app/pipeline/frame_dispatcher.py

@@ -69,7 +69,7 @@ class FrameDispatcher(QObject):
         if len(self._subscribers) < before:
             logger.debug("Subscriber removed: %r", callback)
         else:
-            logger.warning("Subscriber not found for removal: %r", callback)
+            logger.debug("Subscriber not found for removal: %r", callback)
 
     def subscriber_count(self) -> int:
         return len(self._subscribers)