[iOS] Fix incorrectly oriented frames when rapidly switching between cameras.

webrtc/sdk/objc/Framework/Classes/Video/RTCAVFoundationVideoCapturerInternal.mm

Index: webrtc/sdk/objc/Framework/Classes/Video/RTCAVFoundationVideoCapturerInternal.mm
diff --git a/webrtc/sdk/objc/Framework/Classes/Video/RTCAVFoundationVideoCapturerInternal.mm b/webrtc/sdk/objc/Framework/Classes/Video/RTCAVFoundationVideoCapturerInternal.mm
index 166a609824941775e629936bb6e4c03905d20242..c67a87d3b369abc267b8b0ff2e0826178186c30a 100644
--- a/webrtc/sdk/objc/Framework/Classes/Video/RTCAVFoundationVideoCapturerInternal.mm
+++ b/webrtc/sdk/objc/Framework/Classes/Video/RTCAVFoundationVideoCapturerInternal.mm
@@ -28,11 +28,13 @@
   AVCaptureVideoDataOutput *_videoDataOutput;
   // The cricket::VideoCapturer that owns this class. Should never be NULL.
   webrtc::AVFoundationVideoCapturer *_capturer;
-  webrtc::VideoRotation _rotation;
   BOOL _hasRetriedOnFatalError;
   BOOL _isRunning;
   BOOL _hasStarted;
   rtc::CriticalSection _crit;
+#if TARGET_OS_IPHONE
+  UIDeviceOrientation _orientation;
+#endif
 }
 
 @synthesize captureSession = _captureSession;
@@ -57,6 +59,7 @@
     }
     NSNotificationCenter *center = [NSNotificationCenter defaultCenter];
 #if TARGET_OS_IPHONE
+    _orientation = UIDeviceOrientationPortrait;
     [center addObserver:self
                selector:@selector(deviceOrientationDidChange:)
                    name:UIDeviceOrientationDidChangeNotification
@@ -157,24 +160,17 @@
   if (self.hasStarted) {
     return;
   }
-  self.hasStarted = YES;
+  self.hasStarted = NO;
   [RTCDispatcher
       dispatchAsyncOnType:RTCDispatcherTypeCaptureSession
                     block:^{
-#if TARGET_OS_IPHONE
-                        // Default to portrait orientation on iPhone. This will be reset in
-                        // updateOrientation unless orientation is unknown/faceup/facedown.
-                        _rotation = webrtc::kVideoRotation_90;
-#else
-                        // No rotation on Mac.
-                        _rotation = webrtc::kVideoRotation_0;
-#endif
                         [self updateOrientation];
 #if TARGET_OS_IPHONE
                         [[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];
 #endif
                         AVCaptureSession *captureSession = self.captureSession;
                         [captureSession startRunning];
+                        self.hasStarted = YES;
                     }];
 }
 
@@ -215,10 +211,47 @@
     didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
            fromConnection:(AVCaptureConnection *)connection {
   NSParameterAssert(captureOutput == _videoDataOutput);
-  if (!self.hasStarted) {
+  if (!self.hasStarted || !self.isRunning || !connection.enabled ||
+      !connection.active) {
     return;
   }
-  _capturer->CaptureSampleBuffer(sampleBuffer, _rotation);
+
+#if TARGET_OS_IPHONE
+  // Default to portrait orientation on iPhone.
+  webrtc::VideoRotation rotation = webrtc::kVideoRotation_90;
+  AVCaptureDeviceInput *deviceInput =
+      (AVCaptureDeviceInput *)((AVCaptureInputPort *)
+                                   connection.inputPorts.firstObject)
+          .input;
+  BOOL usingFrontCamera =
+      deviceInput.device.position == AVCaptureDevicePositionFront;
+  switch (_orientation) {
+  case UIDeviceOrientationPortrait:
+    rotation = webrtc::kVideoRotation_90;
+    break;
+  case UIDeviceOrientationPortraitUpsideDown:
+    rotation = webrtc::kVideoRotation_270;
+    break;
+  case UIDeviceOrientationLandscapeLeft:
+    rotation = usingFrontCamera ? webrtc::kVideoRotation_180
+                                : webrtc::kVideoRotation_0;
+    break;
+  case UIDeviceOrientationLandscapeRight:
+    rotation = usingFrontCamera ? webrtc::kVideoRotation_0
+                                : webrtc::kVideoRotation_180;
+    break;
+  case UIDeviceOrientationFaceUp:
+  case UIDeviceOrientationFaceDown:
+  case UIDeviceOrientationUnknown:
+    // Ignore.
+    break;
+  }
+#else
+  // No rotation on Mac.
+  webrtc::VideoRotation rotation = webrtc::kVideoRotation_0;
+#endif
+
+  _capturer->CaptureSampleBuffer(sampleBuffer, rotation);
 }
 
 - (void)captureOutput:(AVCaptureOutput *)captureOutput
@@ -448,32 +481,13 @@
 // Called from capture session queue.
 - (void)updateOrientation {
 #if TARGET_OS_IPHONE
-  switch ([UIDevice currentDevice].orientation) {
-    case UIDeviceOrientationPortrait:
-      _rotation = webrtc::kVideoRotation_90;
-      break;
-    case UIDeviceOrientationPortraitUpsideDown:
-      _rotation = webrtc::kVideoRotation_270;
-      break;
-    case UIDeviceOrientationLandscapeLeft:
-      _rotation =
-          _capturer->GetUseBackCamera() ? webrtc::kVideoRotation_0 : webrtc::kVideoRotation_180;
-      break;
-    case UIDeviceOrientationLandscapeRight:
-      _rotation =
-          _capturer->GetUseBackCamera() ? webrtc::kVideoRotation_180 : webrtc::kVideoRotation_0;
-      break;
-    case UIDeviceOrientationFaceUp:
-    case UIDeviceOrientationFaceDown:
-    case UIDeviceOrientationUnknown:
-      // Ignore.
-      break;
-  }
+  _orientation = [UIDevice currentDevice].orientation;
 #endif
 }
 
 // Update the current session input to match what's stored in _useBackCamera.
 - (void)updateSessionInputForUseBackCamera:(BOOL)useBackCamera {
+  self.isRunning = NO;
   [RTCDispatcher dispatchAsyncOnType:RTCDispatcherTypeCaptureSession
                                block:^{
                                    [_captureSession beginConfiguration];
@@ -497,6 +511,7 @@
                                    webrtc::SetFormatForCaptureDevice(
                                        newDevice, _captureSession, *format);
                                    [_captureSession commitConfiguration];
+                                   self.isRunning = YES;
                                }];
 }