diff --git a/tools/chatgui-android/app/src/main/java/com/utun/chat/data/CallVideoEngine.kt b/tools/chatgui-android/app/src/main/java/com/utun/chat/data/CallVideoEngine.kt
index 6b9e0f87..3b31163a 100644
--- a/tools/chatgui-android/app/src/main/java/com/utun/chat/data/CallVideoEngine.kt
+++ b/tools/chatgui-android/app/src/main/java/com/utun/chat/data/CallVideoEngine.kt
@@ -60,6 +60,7 @@ class CallVideoEngine(private val context: Context, private val id: Long) {
     private var realtime = false
     private var sensorOffset: Long? = null
     private var openedAt = 0L
+    private var lastCaptureAt = 0L
     private var reportAt = 0L
     private var encodedBytes = 0L
     private var encodedFrames = 0
@@ -119,6 +120,7 @@ class CallVideoEngine(private val context: Context, private val id: Long) {
         if (stopped) return
         try {
             val s = CallVideoNative.status(id) ?: return
+            check(s[5] == 0L) { "Core rejected video format" }
             if (s[6] >= 300000 && s[7] >= s[6]) mutable.value = mutable.value.copy(range = CallVideoBitrateRange((s[6] / 1000).toInt(), (s[7] / 1000).toInt()))
             if (keySerial != s[0]) { keySerial = s[0]; needKey = true }
             val current = format
@@ -145,7 +147,8 @@ class CallVideoEngine(private val context: Context, private val id: Long) {
                 if (peer != null) change(peer)
             }
             drain()
-            if (active != null && System.nanoTime() - openedAt > 8_000_000_000 && lastPts < 0) fail("Camera produced no frames")
+            if (active != null && !opening && !closing && lastCaptureAt != 0L
+                && System.nanoTime() - lastCaptureAt > 8_000_000_000) fail("Camera stopped producing frames")
         } catch (e: Exception) { fail("Video worker: ${e.message}") }
         if (!stopped) handler.postDelayed(::tick, 10)
     }
@@ -202,6 +205,7 @@ class CallVideoEngine(private val context: Context, private val id: Long) {
             try {
                 if (stopped || token != cameraToken || !wanted.enabled) return@setOnImageAvailableListener
                 val now = System.nanoTime()
+                lastCaptureAt = now
                 val offset = if (realtime) now - SystemClock.elapsedRealtimeNanos() else sensorOffset ?: (now - image.timestamp).also {
                     sensorOffset = it; LogManager.addLog("WARN", "call", "camera timestamp calibrated from arrival id=$id offset=$it")
                 }
@@ -229,7 +233,7 @@ class CallVideoEngine(private val context: Context, private val id: Long) {
             } catch (e: Exception) { fail("Camera encode: ${e.message}") }
             finally { image.close() }
         }, handler)
-        opening = true; openedAt = System.nanoTime()
+        opening = true; openedAt = System.nanoTime(); lastCaptureAt = openedAt
         manager.openCamera(settings.camera, object : CameraDevice.StateCallback() {
             override fun onOpened(device: CameraDevice) {
                 opening = false; camera = device
diff --git a/tools/chatgui/src/call_video_engine.cpp b/tools/chatgui/src/call_video_engine.cpp
index 85fd5f36..1c6c3eb9 100644
--- a/tools/chatgui/src/call_video_engine.cpp
+++ b/tools/chatgui/src/call_video_engine.cpp
@@ -153,6 +153,7 @@ void CallVideoEngine::transmit() {
     while (m->running) {
         struct call_video_port_status state{};
         if (call_video_port_status(m->id, &state) < 0) break;
+        if (state.error) { m->report(tr("Core rejected video format")); break; }
         uint64_t revision; bool enabled; int width, height, codec; int64_t pts;
 #ifdef HAVE_STREAM_CAPTURE
         QVideoFrame raw;