Add an opt-in HKSV video-transcoding mode

camera-ui-homekit/src/camera/accessory.ts

@@ -415,6 +415,19 @@ export class CameraAccessory extends Subscribed {
           this.recordingDelegate?.refreshPrebuffer();
         },
       },
+      {
+        type: 'boolean',
+        key: 'forceVideoTranscodingForRecording',
+        title: 'Force Video Transcoding for HKSV',
+        description: 'Re-encode video for HomeKit Secure Video so its negotiated resolution, frame rate, and bitrate limits are applied.',
+        group: 'Advanced',
+        defaultValue: false,
+        store: true,
+        onSet: async (state: boolean) => {
+          this.cameraLogger.log('Force video transcoding for HKSV:', state);
+          this.recordingDelegate?.refreshPrebuffer();
+        },
+      },
     ]);
   }
 

camera-ui-homekit/src/camera/recordingSession.ts

@@ -236,7 +236,11 @@ export class RecordingSession extends EventEmitter {
     ];
 
     await session.startStream({
-      supportedVideoCodecs: ['h264'],
+      // An empty supported-codec list deliberately makes node-av transcode the
+      // input to H.264. This is useful for cameras whose already-compatible
+      // H.264 stream exceeds the resolution, frame-rate, or bitrate negotiated
+      // by HomeKit: stream-copy mode cannot apply those encoder constraints.
+      supportedVideoCodecs: this.cameraAccessory.cameraStorage.values.forceVideoTranscodingForRecording ? [] : ['h264'],
       supportedAudioCodecs: ['aac'],
       boxMode: true,
       fragDuration: (this.configuration?.mediaContainerConfiguration?.fragmentLength ?? 4000) * 1000,

camera-ui-homekit/src/types.ts

@@ -13,6 +13,7 @@ export interface CameraStorageValues {
   republishId: string;
   useHardwareAcceleration: boolean;
   useHardwareAccelerationForRecording: boolean;
+  forceVideoTranscodingForRecording: boolean;
   adaptiveStreamSource: boolean;
   advertiser: string;
 }