fix: GPS缺失下的数据缺失问题

backend/config/settings.py

@@ -91,6 +91,12 @@ USE_TZ = True
 
 STATIC_URL = 'static/'
 CORS_ALLOW_ALL_ORIGINS = True
+CORS_EXPOSE_HEADERS = [
+    'X-Blitz-Frame-Seq',
+    'X-Blitz-Backend-Received-Unix-Ns',
+    'X-Blitz-Frame-Hash',
+    'X-Blitz-BSide-Capture-To-Send-Ms',
+]
 
 DEFAULT_AUTO_FIELD = 'django.db.models.BigAutoField'
 

backend/monitoring/telemetry.py

@@ -105,13 +105,30 @@ class GpsDataService:
         }
 
     def _build_payload_from_metadata(self, metadata: FrameTrailerMetadata) -> dict[str, Any]:
-        timestamp_seconds = metadata.timestamp_ns / 1_000_000_000
         updated_at = _utc_from_epoch(metadata.received_at) or ""
+        if not metadata.has_gps_fix:
+            return {
+                "has_fix": False,
+                "utc_time": "--:--:--",
+                "latitude": None,
+                "longitude": None,
+                "raw_latitude_hex": f"0x{metadata.raw_latitude_hex}",
+                "raw_longitude_hex": f"0x{metadata.raw_longitude_hex}",
+                "satellites": None,
+                "altitude_m": None,
+                "coordinate_system": "WGS84",
+                "source_sentence": "VIDEO_TRAILER",
+                "raw_coordinate_format": VIDEO_TRAILER_COORDINATE_FORMAT,
+                "source_mode": "video-frame-trailer-no-fix",
+                "updated_at": updated_at,
+            }
+
+        timestamp_seconds = metadata.timestamp_ns / 1_000_000_000
         return {
             "has_fix": True,
             "utc_time": datetime.fromtimestamp(timestamp_seconds, timezone.utc).strftime("%H:%M:%S"),
-            "latitude": round(metadata.latitude, 6),
+            "latitude": round(metadata.latitude, 6) if metadata.latitude is not None else None,
-            "longitude": round(metadata.longitude, 6),
+            "longitude": round(metadata.longitude, 6) if metadata.longitude is not None else None,
             "raw_latitude_hex": f"0x{metadata.raw_latitude_hex}",
             "raw_longitude_hex": f"0x{metadata.raw_longitude_hex}",
             "satellites": None,

backend/monitoring/video.py

@@ -103,13 +103,17 @@ class VideoDisplayProbeStore:
 @dataclass(frozen=True)
 class FrameTrailerMetadata:
     timestamp_ns: int
-    latitude: float
+    latitude: float | None
-    longitude: float
+    longitude: float | None
     capture_to_send_ms: int
     raw_latitude_hex: str
     raw_longitude_hex: str
     received_at: float
 
+    @property
+    def has_gps_fix(self) -> bool:
+        return self.latitude is not None and self.longitude is not None
+
 
 @dataclass(frozen=True)
 class VideoDisplayProbeStatus:
@@ -271,21 +275,23 @@ class OmniSocketVideoReceiver:
 
         if timestamp_ms <= 0:
             return None
-        if not math.isfinite(latitude) or not math.isfinite(longitude):
-            return None
-        if not (-90.0 <= latitude <= 90.0) or not (-180.0 <= longitude <= 180.0):
-            return None
-        if abs(latitude) < 1e-9 and abs(longitude) < 1e-9:
-            return None
 
         timestamp_ns = timestamp_ms * VIDEO_TRAILER_TIMESTAMP_MULTIPLIER_NS
         if abs(time.time_ns() - timestamp_ns) > VIDEO_TRAILER_TIMESTAMP_MAX_SKEW_NS:
             return None
 
+        gps_fix_available = (
+            math.isfinite(latitude)
+            and math.isfinite(longitude)
+            and (-90.0 <= latitude <= 90.0)
+            and (-180.0 <= longitude <= 180.0)
+            and not (abs(latitude) < 1e-9 and abs(longitude) < 1e-9)
+        )
+
         return FrameTrailerMetadata(
             timestamp_ns=timestamp_ns,
-            latitude=latitude,
+            latitude=latitude if gps_fix_available else None,
-            longitude=longitude,
+            longitude=longitude if gps_fix_available else None,
             capture_to_send_ms=int(capture_to_send_ms),
             raw_latitude_hex=trailer[8:16].hex(),
             raw_longitude_hex=trailer[16:24].hex(),