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

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

 /*
  *  Copyright 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 10 matching lines @@
 
 #include "avfoundationformatmapper.h"
 
 @implementation RTCAVFoundationVideoCapturerInternal {
   // Keep pointers to inputs for convenience.
   AVCaptureDeviceInput *_frontCameraInput;
   AVCaptureDeviceInput *_backCameraInput;
   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;
 @synthesize frameQueue = _frameQueue;
 @synthesize useBackCamera = _useBackCamera;
 
 @synthesize isRunning = _isRunning;
 @synthesize hasStarted = _hasStarted;
 
 // This is called from the thread that creates the video source, which is likely
 // the main thread.
 - (instancetype)initWithCapturer:(webrtc::AVFoundationVideoCapturer *)capturer {
   RTC_DCHECK(capturer);
   if (self = [super init]) {
     _capturer = capturer;
     // Create the capture session and all relevant inputs and outputs. We need
     // to do this in init because the application may want the capture session
     // before we start the capturer for e.g. AVCapturePreviewLayer. All objects
     // created here are retained until dealloc and never recreated.
     if (![self setupCaptureSession]) {
       return nil;
     }
     NSNotificationCenter *center = [NSNotificationCenter defaultCenter];
 #if TARGET_OS_IPHONE
+    _orientation = UIDeviceOrientationPortrait;
     [center addObserver:self
                selector:@selector(deviceOrientationDidChange:)
                    name:UIDeviceOrientationDidChangeNotification
                  object:nil];
     [center addObserver:self
                selector:@selector(handleCaptureSessionInterruption:)
                    name:AVCaptureSessionWasInterruptedNotification
                  object:_captureSession];
     [center addObserver:self
                selector:@selector(handleCaptureSessionInterruptionEnded:)
@@ skipping 80 matching lines @@
     _useBackCamera = useBackCamera;
     [self updateSessionInputForUseBackCamera:useBackCamera];
   }
 }
 
 // Called from WebRTC thread.
 - (void)start {
   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;
                     }];
 }
 
 // Called from same thread as start.
 - (void)stop {
   if (!self.hasStarted) {
     return;
   }
   self.hasStarted = NO;
   // Due to this async block, it's possible that the ObjC object outlives the
@@ skipping 20 matching lines @@
                                }];
 }
 #endif
 
 #pragma mark AVCaptureVideoDataOutputSampleBufferDelegate
 
 - (void)captureOutput:(AVCaptureOutput *)captureOutput
     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
     didDropSampleBuffer:(CMSampleBufferRef)sampleBuffer
          fromConnection:(AVCaptureConnection *)connection {
   RTCLogError(@"Dropped sample buffer.");
 }
 
 #pragma mark - AVCaptureSession notifications
 
@@ skipping 209 matching lines @@
       return nil;
     }
     _backCameraInput = backCameraInput;
   }
   return _backCameraInput;
 }
 
 // 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];
                                    AVCaptureDeviceInput *oldInput = _backCameraInput;
                                    AVCaptureDeviceInput *newInput = _frontCameraInput;
                                    if (useBackCamera) {
                                      oldInput = _frontCameraInput;
                                      newInput = _backCameraInput;
                                    }
                                    if (oldInput) {
                                      // Ok to remove this even if it's not attached. Will be no-op.
                                      [_captureSession removeInput:oldInput];
                                    }
                                    if (newInput) {
                                      [_captureSession addInput:newInput];
                                    }
                                    [self updateOrientation];
                                    AVCaptureDevice *newDevice = newInput.device;
                                    const cricket::VideoFormat *format =
                                      _capturer->GetCaptureFormat();
                                    webrtc::SetFormatForCaptureDevice(
                                        newDevice, _captureSession, *format);
                                    [_captureSession commitConfiguration];
+                                   self.isRunning = YES;
                                }];
 }
 
 @end