Keep call display format internal to the Android application

tools/chatgui-android/app/src/main/java/com/utun/chat/data/CallVideoEngine.kt

@@ -37,7 +37,7 @@ class CallVideoEngine(private val context: Context, private val id: Long) {
     private val handler = Handler(thread.looper)
     private val manager = context.getSystemService(CameraManager::class.java)
     private val player = CallVideoPlayer(id) { message -> handler.post { report(message) } }
-    val display: StateFlow<CallVideoFormat?> = player.display
+    internal val display: StateFlow<CallVideoFormat?> = player.display
     private val previewFrames = MutableStateFlow<Bitmap?>(null)
     val preview: StateFlow<Bitmap?> = previewFrames
     private var previewAt = 0L