WebRTC音视频通话-WebRTC视频自定义RTCVideoCapturer相机

在之前已经实现了WebRTC调用ossrs服务，实现直播视频通话功能。但是在使用过程中，RTCCameraVideoCapturer类提供的方法不能修改及调节相机的灯光等设置，那就需要自定义RTCVideoCapturer自行采集画面了。

iOS端WebRTC调用ossrs相关，实现直播视频通话功能请查看：
https://blog.csdn.net/gloryFlow/article/details/132262724

这里自定义RTCVideoCapturer

一、自定义相机需要的几个类

需要了解的几个类

• AVCaptureSession
  AVCaptureSession是iOS提供的一个管理和协调输入设备到输出设备之间数据流的对象。

• AVCaptureDevice
  AVCaptureDevice是指硬件设备。

• AVCaptureDeviceInput
  AVCaptureDeviceInput是用来从AVCaptureDevice对象捕获Input数据。

• AVCaptureMetadataOutput
  AVCaptureMetadataOutput是用来处理AVCaptureSession产生的定时元数据的捕获输出的。

• AVCaptureVideoDataOutput
  AVCaptureVideoDataOutput是用来处理视频数据输出的。

• AVCaptureVideoPreviewLayer
  AVCaptureVideoPreviewLayer是相机捕获的视频预览层，是用来展示视频的。

二、自定义RTCVideoCapturer相机采集

自定义相机，我们需要为AVCaptureSession添加AVCaptureVideoDataOutput的output

 self.dataOutput = [[AVCaptureVideoDataOutput alloc] init];
        [self.dataOutput setAlwaysDiscardsLateVideoFrames:YES];
        self.dataOutput.videoSettings = @{(id)kCVPixelBufferPixelFormatTypeKey : @(needYuvOutput ? kCVPixelFormatType_420YpCbCr8BiPlanarFullRange : kCVPixelFormatType_32BGRA)};
        self.dataOutput.alwaysDiscardsLateVideoFrames = YES;
        [self.dataOutput setSampleBufferDelegate:self queue:self.bufferQueue];

if ([self.session canAddOutput:self.dataOutput]) {
            
            [self.session addOutput:self.dataOutput];
        }else{
            
            NSLog( @"Could not add video data output to the session" );
            return nil;
        }

需要实现AVCaptureVideoDataOutputSampleBufferDelegate代理方法

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection;

将CMSampleBufferRef转换成CVPixelBufferRef，将处理后的CVPixelBufferRef生成RTCVideoFrame，通过调用WebRTC的localVideoSource中实现的didCaptureVideoFrame方法。

完整代码如下

SDCustomRTCCameraCapturer.h

#import <AVFoundation/AVFoundation.h>
#import <Foundation/Foundation.h>
#import <WebRTC/WebRTC.h>

@protocol SDCustomRTCCameraCapturerDelegate <NSObject>

- (void)rtcCameraVideoCapturer:(RTCVideoCapturer *)capturer didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer;

@end

@interface SDCustomRTCCameraCapturer : RTCVideoCapturer

@property(nonatomic, weak) id<SDCustomRTCCameraCapturerDelegate>delegate;

// Capture session that is used for capturing. Valid from initialization to dealloc.
@property(nonatomic, strong) AVCaptureSession *captureSession;

// Returns list of available capture devices that support video capture.
+ (NSArray<AVCaptureDevice *> *)captureDevices;
// Returns list of formats that are supported by this class for this device.
+ (NSArray<AVCaptureDeviceFormat *> *)supportedFormatsForDevice:(AVCaptureDevice *)device;

// Returns the most efficient supported output pixel format for this capturer.
- (FourCharCode)preferredOutputPixelFormat;

// Starts the capture session asynchronously and notifies callback on completion.
// The device will capture video in the format given in the `format` parameter. If the pixel format
// in `format` is supported by the WebRTC pipeline, the same pixel format will be used for the
// output. Otherwise, the format returned by `preferredOutputPixelFormat` will be used.
- (void)startCaptureWithDevice:(AVCaptureDevice *)device
                        format:(AVCaptureDeviceFormat *)format
                           fps:(NSInteger)fps
             completionHandler:(nullable void (^)(NSError *))completionHandler;
// Stops the capture session asynchronously and notifies callback on completion.
- (void)stopCaptureWithCompletionHandler:(nullable void (^)(void))completionHandler;

// Starts the capture session asynchronously.
- (void)startCaptureWithDevice:(AVCaptureDevice *)device
                        format:(AVCaptureDeviceFormat *)format
                           fps:(NSInteger)fps;
// Stops the capture session asynchronously.
- (void)stopCapture;

#pragma mark - 自定义相机
@property (nonatomic, readonly) dispatch_queue_t bufferQueue;

@property (nonatomic, assign) AVCaptureDevicePosition devicePosition; // default AVCaptureDevicePositionFront

@property (nonatomic, assign) AVCaptureVideoOrientation videoOrientation;

@property (nonatomic, assign) BOOL needVideoMirrored;

@property (nonatomic, strong , readonly) AVCaptureConnection *videoConnection;

@property (nonatomic, copy) NSString *sessionPreset;  // default 640x480

@property (nonatomic, strong) AVCaptureVideoPreviewLayer *previewLayer;

@property (nonatomic, assign) BOOL bSessionPause;

@property (nonatomic, assign) int iExpectedFPS;

@property (nonatomic, readwrite, strong) NSDictionary *videoCompressingSettings;


- (instancetype)initWithDevicePosition:(AVCaptureDevicePosition)iDevicePosition
                        sessionPresset:(AVCaptureSessionPreset)sessionPreset
                                   fps:(int)iFPS
                         needYuvOutput:(BOOL)needYuvOutput;

- (void)setExposurePoint:(CGPoint)point inPreviewFrame:(CGRect)frame;

- (void)setISOValue:(float)value;

- (void)startRunning;

- (void)stopRunning;

- (void)rotateCamera;

- (void)rotateCamera:(BOOL)isUseFrontCamera;

- (void)setWhiteBalance;

- (CGRect)getZoomedRectWithRect:(CGRect)rect scaleToFit:(BOOL)bScaleToFit;

@end

SDCustomRTCCameraCapturer.m

#import "SDCustomRTCCameraCapturer.h"
#import <UIKit/UIKit.h>
#import "EFMachineVersion.h"

//#import "base/RTCLogging.h"
//#import "base/RTCVideoFrameBuffer.h"
//#import "components/video_frame_buffer/RTCCVPixelBuffer.h"
//
//#if TARGET_OS_IPHONE
//#import "helpers/UIDevice+RTCDevice.h"
//#endif
//
//#import "helpers/AVCaptureSession+DevicePosition.h"
//#import "helpers/RTCDispatcher+Private.h"

typedef NS_ENUM(NSUInteger, STExposureModel) {
    STExposureModelPositive5,
    STExposureModelPositive4,
    STExposureModelPositive3,
    STExposureModelPositive2,
    STExposureModelPositive1,
    STExposureModel0,
    STExposureModelNegative1,
    STExposureModelNegative2,
    STExposureModelNegative3,
    STExposureModelNegative4,
    STExposureModelNegative5,
    STExposureModelNegative6,
    STExposureModelNegative7,
    STExposureModelNegative8,
};

static char * kEffectsCamera = "EffectsCamera";

static STExposureModel currentExposureMode;

@interface SDCustomRTCCameraCapturer ()<AVCaptureVideoDataOutputSampleBufferDelegate, AVCaptureAudioDataOutputSampleBufferDelegate, AVCaptureMetadataOutputObjectsDelegate>
@property(nonatomic, readonly) dispatch_queue_t frameQueue;
@property(nonatomic, strong) AVCaptureDevice *currentDevice;
@property(nonatomic, assign) BOOL hasRetriedOnFatalError;
@property(nonatomic, assign) BOOL isRunning;
// Will the session be running once all asynchronous operations have been completed?
@property(nonatomic, assign) BOOL willBeRunning;

@property (nonatomic, strong) AVCaptureDeviceInput *deviceInput;
@property (nonatomic, strong) AVCaptureVideoDataOutput *dataOutput;
@property (nonatomic, strong) AVCaptureMetadataOutput *metaOutput;
@property (nonatomic, strong) AVCaptureStillImageOutput *stillImageOutput;

@property (nonatomic, readwrite) dispatch_queue_t bufferQueue;

@property (nonatomic, strong, readwrite) AVCaptureConnection *videoConnection;

@property (nonatomic, strong) AVCaptureDevice *videoDevice;
@property (nonatomic, strong) AVCaptureSession *session;

@end

@implementation SDCustomRTCCameraCapturer {
  AVCaptureVideoDataOutput *_videoDataOutput;
  AVCaptureSession *_captureSession;
  FourCharCode _preferredOutputPixelFormat;
  FourCharCode _outputPixelFormat;
  RTCVideoRotation _rotation;
    float _autoISOValue;
#if TARGET_OS_IPHONE
  UIDeviceOrientation _orientation;
  BOOL _generatingOrientationNotifications;
#endif
}

@synthesize frameQueue = _frameQueue;
@synthesize captureSession = _captureSession;
@synthesize currentDevice = _currentDevice;
@synthesize hasRetriedOnFatalError = _hasRetriedOnFatalError;
@synthesize isRunning = _isRunning;
@synthesize willBeRunning = _willBeRunning;

- (instancetype)init {
  return [self initWithDelegate:nil captureSession:[[AVCaptureSession alloc] init]];
}

- (instancetype)initWithDelegate:(__weak id<RTCVideoCapturerDelegate>)delegate {
  return [self initWithDelegate:delegate captureSession:[[AVCaptureSession alloc] init]];
}

// This initializer is used for testing.
- (instancetype)initWithDelegate:(__weak id<RTCVideoCapturerDelegate>)delegate
                  captureSession:(AVCaptureSession *)captureSession {
  if (self = [super initWithDelegate:delegate]) {
    // 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:captureSession]) {
      return nil;
    }
    NSNotificationCenter *center = [NSNotificationCenter defaultCenter];
#if TARGET_OS_IPHONE
    _orientation = UIDeviceOrientationPortrait;
    _rotation = RTCVideoRotation_90;
    [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:)
                   name:AVCaptureSessionInterruptionEndedNotification
                 object:_captureSession];
    [center addObserver:self
               selector:@selector(handleApplicationDidBecomeActive:)
                   name:UIApplicationDidBecomeActiveNotification
                 object:[UIApplication sharedApplication]];
#endif
    [center addObserver:self
               selector:@selector(handleCaptureSessionRuntimeError:)
                   name:AVCaptureSessionRuntimeErrorNotification
                 object:_captureSession];
    [center addObserver:self
               selector:@selector(handleCaptureSessionDidStartRunning:)
                   name:AVCaptureSessionDidStartRunningNotification
                 object:_captureSession];
    [center addObserver:self
               selector:@selector(handleCaptureSessionDidStopRunning:)
                   name:AVCaptureSessionDidStopRunningNotification
                 object:_captureSession];
  }
  return self;
}

//- (void)dealloc {
//  NSAssert(
//      !_willBeRunning,
//      @"Session was still running in RTCCameraVideoCapturer dealloc. Forgot to call stopCapture?");
//  [[NSNotificationCenter defaultCenter] removeObserver:self];
//}

+ (NSArray<AVCaptureDevice *> *)captureDevices {
#if defined(WEBRTC_IOS) && defined(__IPHONE_10_0) && \
    __IPHONE_OS_VERSION_MIN_REQUIRED >= __IPHONE_10_0
  AVCaptureDeviceDiscoverySession *session = [AVCaptureDeviceDiscoverySession
      discoverySessionWithDeviceTypes:@[ AVCaptureDeviceTypeBuiltInWideAngleCamera ]
                            mediaType:AVMediaTypeVideo
                             position:AVCaptureDevicePositionUnspecified];
  return session.devices;
#else
  return [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
#endif
}

+ (NSArray<AVCaptureDeviceFormat *> *)supportedFormatsForDevice:(AVCaptureDevice *)device {
  // Support opening the device in any format. We make sure it's converted to a format we
  // can handle, if needed, in the method `-setupVideoDataOutput`.
  return device.formats;
}

- (FourCharCode)preferredOutputPixelFormat {
  return _preferredOutputPixelFormat;
}

- (void)startCaptureWithDevice:(AVCaptureDevice *)device
                        format:(AVCaptureDeviceFormat *)format
                           fps:(NSInteger)fps {
  [self startCaptureWithDevice:device format:format fps:fps completionHandler:nil];
}

- (void)stopCapture {
  [self stopCaptureWithCompletionHandler:nil];
}

- (void)startCaptureWithDevice:(AVCaptureDevice *)device
                        format:(AVCaptureDeviceFormat *)format
                           fps:(NSInteger)fps
             completionHandler:(nullable void (^)(NSError *))completionHandler {
  _willBeRunning = YES;
  [RTCDispatcher
      dispatchAsyncOnType:RTCDispatcherTypeCaptureSession
                    block:^{
                      RTCLogInfo("startCaptureWithDevice %@ @ %ld fps", format, (long)fps);

#if TARGET_OS_IPHONE
                      dispatch_async(dispatch_get_main_queue(), ^{
                        if (!self->_generatingOrientationNotifications) {
                          [[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];
                          self->_generatingOrientationNotifications = YES;
                        }
                      });
#endif

                      self.currentDevice = device;

                      NSError *error = nil;
                      if (![self.currentDevice lockForConfiguration:&error]) {
                        RTCLogError(@"Failed to lock device %@. Error: %@",
                                    self.currentDevice,
                                    error.userInfo);
                        if (completionHandler) {
                          completionHandler(error);
                        }
                        self.willBeRunning = NO;
                        return;
                      }
                      [self reconfigureCaptureSessionInput];
                      [self updateOrientation];
                      [self updateDeviceCaptureFormat:format fps:fps];
                      [self updateVideoDataOutputPixelFormat:format];
                      [self.captureSession startRunning];
                      [self.currentDevice unlockForConfiguration];
                      self.isRunning = YES;
                      if (completionHandler) {
                        completionHandler(nil);
                      }
                    }];
}

- (void)stopCaptureWithCompletionHandler:(nullable void (^)(void))completionHandler {
  _willBeRunning = NO;
  [RTCDispatcher
      dispatchAsyncOnType:RTCDispatcherTypeCaptureSession
                    block:^{
                      RTCLogInfo("Stop");
                      self.currentDevice = nil;
                      for (AVCaptureDeviceInput *oldInput in [self.captureSession.inputs copy]) {
                        [self.captureSession removeInput:oldInput];
                      }
                      [self.captureSession stopRunning];

#if TARGET_OS_IPHONE
                      dispatch_async(dispatch_get_main_queue(), ^{
                        if (self->_generatingOrientationNotifications) {
                          [[UIDevice currentDevice] endGeneratingDeviceOrientationNotifications];
                          self->_generatingOrientationNotifications = NO;
                        }
                      });
#endif
                      self.isRunning = NO;
                      if (completionHandler) {
                        completionHandler();
                      }
                    }];
}

#pragma mark iOS notifications

#if TARGET_OS_IPHONE
- (void)deviceOrientationDidChange:(NSNotification *)notification {
  [RTCDispatcher dispatchAsyncOnType:RTCDispatcherTypeCaptureSession
                               block:^{
                                 [self updateOrientation];
                               }];
}
#endif

#pragma mark AVCaptureVideoDataOutputSampleBufferDelegate

//- (void)captureOutput:(AVCaptureOutput *)captureOutput
//    didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
//           fromConnection:(AVCaptureConnection *)connection {
//  NSParameterAssert(captureOutput == _videoDataOutput);
//
//  if (CMSampleBufferGetNumSamples(sampleBuffer) != 1 || !CMSampleBufferIsValid(sampleBuffer) ||
//      !CMSampleBufferDataIsReady(sampleBuffer)) {
//    return;
//  }
//
//  CVPixelBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
//  if (pixelBuffer == nil) {
//    return;
//  }
//
//#if TARGET_OS_IPHONE
//  // Default to portrait orientation on iPhone.
//  BOOL usingFrontCamera = NO;
//  // Check the image's EXIF for the camera the image came from as the image could have been
//  // delayed as we set alwaysDiscardsLateVideoFrames to NO.
//
//    AVCaptureDeviceInput *deviceInput =
//        (AVCaptureDeviceInput *)((AVCaptureInputPort *)connection.inputPorts.firstObject).input;
//    usingFrontCamera = AVCaptureDevicePositionFront == deviceInput.device.position;
//
//    switch (_orientation) {
//    case UIDeviceOrientationPortrait:
//      _rotation = RTCVideoRotation_90;
//      break;
//    case UIDeviceOrientationPortraitUpsideDown:
//      _rotation = RTCVideoRotation_270;
//      break;
//    case UIDeviceOrientationLandscapeLeft:
//      _rotation = usingFrontCamera ? RTCVideoRotation_180 : RTCVideoRotation_0;
//      break;
//    case UIDeviceOrientationLandscapeRight:
//      _rotation = usingFrontCamera ? RTCVideoRotation_0 : RTCVideoRotation_180;
//      break;
//    case UIDeviceOrientationFaceUp:
//    case UIDeviceOrientationFaceDown:
//    case UIDeviceOrientationUnknown:
//      // Ignore.
//      break;
//  }
//#else
//  // No rotation on Mac.
//  _rotation = RTCVideoRotation_0;
//#endif
//
//    if (self.delegate && [self.delegate respondsToSelector:@selector(rtcCameraVideoCapturer:didOutputSampleBuffer:)]) {
//        [self.delegate rtcCameraVideoCapturer:self didOutputSampleBuffer:sampleBuffer];
//    }
//}

#pragma mark - AVCaptureSession notifications

- (void)handleCaptureSessionInterruption:(NSNotification *)notification {
  NSString *reasonString = nil;
#if TARGET_OS_IPHONE
  NSNumber *reason = notification.userInfo[AVCaptureSessionInterruptionReasonKey];
  if (reason) {
    switch (reason.intValue) {
      case AVCaptureSessionInterruptionReasonVideoDeviceNotAvailableInBackground:
        reasonString = @"VideoDeviceNotAvailableInBackground";
        break;
      case AVCaptureSessionInterruptionReasonAudioDeviceInUseByAnotherClient:
        reasonString = @"AudioDeviceInUseByAnotherClient";
        break;
      case AVCaptureSessionInterruptionReasonVideoDeviceInUseByAnotherClient:
        reasonString = @"VideoDeviceInUseByAnotherClient";
        break;
      case AVCaptureSessionInterruptionReasonVideoDeviceNotAvailableWithMultipleForegroundApps:
        reasonString = @"VideoDeviceNotAvailableWithMultipleForegroundApps";
        break;
    }
  }
#endif
  RTCLog(@"Capture session interrupted: %@", reasonString);
}

- (void)handleCaptureSessionInterruptionEnded:(NSNotification *)notification {
  RTCLog(@"Capture session interruption ended.");
}

- (void)handleCaptureSessionRuntimeError:(NSNotification *)notification {
  NSError *error = [notification.userInfo objectForKey:AVCaptureSessionErrorKey];
  RTCLogError(@"Capture session runtime error: %@", error);

  [RTCDispatcher dispatchAsyncOnType:RTCDispatcherTypeCaptureSession
                               block:^{
#if TARGET_OS_IPHONE
                                 if (error.code == AVErrorMediaServicesWereReset) {
                                   [self handleNonFatalError];
                                 } else {
                                   [self handleFatalError];
                                 }
#else
                                [self handleFatalError];
#endif
                               }];
}

- (void)handleCaptureSessionDidStartRunning:(NSNotification *)notification {
  RTCLog(@"Capture session started.");

  [RTCDispatcher dispatchAsyncOnType:RTCDispatcherTypeCaptureSession
                               block:^{
                                 // If we successfully restarted after an unknown error,
                                 // allow future retries on fatal errors.
                                 self.hasRetriedOnFatalError = NO;
                               }];
}

- (void)handleCaptureSessionDidStopRunning:(NSNotification *)notification {
  RTCLog(@"Capture session stopped.");
}

- (void)handleFatalError {
  [RTCDispatcher
      dispatchAsyncOnType:RTCDispatcherTypeCaptureSession
                    block:^{
                      if (!self.hasRetriedOnFatalError) {
                        RTCLogWarning(@"Attempting to recover from fatal capture error.");
                        [self handleNonFatalError];
                        self.hasRetriedOnFatalError = YES;
                      } else {
                        RTCLogError(@"Previous fatal error recovery failed.");
                      }
                    }];
}

- (void)handleNonFatalError {
  [RTCDispatcher dispatchAsyncOnType:RTCDispatcherTypeCaptureSession
                               block:^{
                                 RTCLog(@"Restarting capture session after error.");
                                 if (self.isRunning) {
                                   [self.captureSession startRunning];
                                 }
                               }];
}

#if TARGET_OS_IPHONE

#pragma mark - UIApplication notifications

- (void)handleApplicationDidBecomeActive:(NSNotification *)notification {
  [RTCDispatcher dispatchAsyncOnType:RTCDispatcherTypeCaptureSession
                               block:^{
                                 if (self.isRunning && !self.captureSession.isRunning) {
                                   RTCLog(@"Restarting capture session on active.");
                                   [self.captureSession startRunning];
                                 }
                               }];
}

#endif  // TARGET_OS_IPHONE

#pragma mark - Private

- (dispatch_queue_t)frameQueue {
  if (!_frameQueue) {
    _frameQueue =
        dispatch_queue_create("org.webrtc.cameravideocapturer.video", DISPATCH_QUEUE_SERIAL);
    dispatch_set_target_queue(_frameQueue,
                              dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0));
  }
  return _frameQueue;
}

- (BOOL)setupCaptureSession:(AVCaptureSession *)captureSession {
  NSAssert(_captureSession == nil, @"Setup capture session called twice.");
  _captureSession = captureSession;
#if defined(WEBRTC_IOS)
  _captureSession.sessionPreset = AVCaptureSessionPresetInputPriority;
  _captureSession.usesApplicationAudioSession = NO;
#endif
  [self setupVideoDataOutput];
  // Add the output.
  if (![_captureSession canAddOutput:_videoDataOutput]) {
    RTCLogError(@"Video data output unsupported.");
    return NO;
  }
  [_captureSession addOutput:_videoDataOutput];

  return YES;
}

- (void)setupVideoDataOutput {
  NSAssert(_videoDataOutput == nil, @"Setup video data output called twice.");
  AVCaptureVideoDataOutput *videoDataOutput = [[AVCaptureVideoDataOutput alloc] init];

  // `videoDataOutput.availableVideoCVPixelFormatTypes` returns the pixel formats supported by the
  // device with the most efficient output format first. Find the first format that we support.
  NSSet<NSNumber *> *supportedPixelFormats = [RTCCVPixelBuffer supportedPixelFormats];
  NSMutableOrderedSet *availablePixelFormats =
      [NSMutableOrderedSet orderedSetWithArray:videoDataOutput.availableVideoCVPixelFormatTypes];
  [availablePixelFormats intersectSet:supportedPixelFormats];
  NSNumber *pixelFormat = availablePixelFormats.firstObject;
  NSAssert(pixelFormat, @"Output device has no supported formats.");

  _preferredOutputPixelFormat = [pixelFormat unsignedIntValue];
  _outputPixelFormat = _preferredOutputPixelFormat;
//  videoDataOutput.videoSettings = @{(NSString *)kCVPixelBufferPixelFormatTypeKey : pixelFormat};
    
//    [videoDataOutput setAlwaysDiscardsLateVideoFrames:YES];
    videoDataOutput.videoSettings = @{(id)kCVPixelBufferPixelFormatTypeKey : @(kCVPixelFormatType_32BGRA)};
    videoDataOutput.alwaysDiscardsLateVideoFrames = YES;
    
  [videoDataOutput setSampleBufferDelegate:self queue:self.frameQueue];
  _videoDataOutput = videoDataOutput;
    
//    // 设置视频方向和旋转
//    AVCaptureConnection *connection = [videoDataOutput connectionWithMediaType:AVMediaTypeVideo];
//    [connection setVideoOrientation:AVCaptureVideoOrientationPortrait];
//    [connection setVideoMirrored:NO];
}

- (void)updateVideoDataOutputPixelFormat:(AVCaptureDeviceFormat *)format {
//  FourCharCode mediaSubType = CMFormatDescriptionGetMediaSubType(format.formatDescription);
//  if (![[RTCCVPixelBuffer supportedPixelFormats] containsObject:@(mediaSubType)]) {
//    mediaSubType = _preferredOutputPixelFormat;
//  }
//
//  if (mediaSubType != _outputPixelFormat) {
//    _outputPixelFormat = mediaSubType;
//    _videoDataOutput.videoSettings =
//        @{ (NSString *)kCVPixelBufferPixelFormatTypeKey : @(mediaSubType) };
//  }
}

#pragma mark - Private, called inside capture queue

- (void)updateDeviceCaptureFormat:(AVCaptureDeviceFormat *)format fps:(NSInteger)fps {
  NSAssert([RTCDispatcher isOnQueueForType:RTCDispatcherTypeCaptureSession],
           @"updateDeviceCaptureFormat must be called on the capture queue.");
  @try {
    _currentDevice.activeFormat = format;
    _currentDevice.activeVideoMinFrameDuration = CMTimeMake(1, fps);
  } @catch (NSException *exception) {
    RTCLogError(@"Failed to set active format!\n User info:%@", exception.userInfo);
    return;
  }
}

- (void)reconfigureCaptureSessionInput {
  NSAssert([RTCDispatcher isOnQueueForType:RTCDispatcherTypeCaptureSession],
           @"reconfigureCaptureSessionInput must be called on the capture queue.");
  NSError *error = nil;
  AVCaptureDeviceInput *input =
      [AVCaptureDeviceInput deviceInputWithDevice:_currentDevice error:&error];
  if (!input) {
    RTCLogError(@"Failed to create front camera input: %@", error.localizedDescription);
    return;
  }
  [_captureSession beginConfiguration];
  for (AVCaptureDeviceInput *oldInput in [_captureSession.inputs copy]) {
    [_captureSession removeInput:oldInput];
  }
  if ([_captureSession canAddInput:input]) {
    [_captureSession addInput:input];
  } else {
    RTCLogError(@"Cannot add camera as an input to the session.");
  }
  [_captureSession commitConfiguration];
}

- (void)updateOrientation {
  NSAssert([RTCDispatcher isOnQueueForType:RTCDispatcherTypeCaptureSession],
           @"updateOrientation must be called on the capture queue.");
#if TARGET_OS_IPHONE
  _orientation = [UIDevice currentDevice].orientation;
#endif
}

- (instancetype)initWithDevicePosition:(AVCaptureDevicePosition)iDevicePosition
                        sessionPresset:(AVCaptureSessionPreset)sessionPreset
                                   fps:(int)iFPS
                         needYuvOutput:(BOOL)needYuvOutput
{
    self = [super init];
    if (self) {
        
        self.bSessionPause = YES;
        
        self.bufferQueue = dispatch_queue_create("STCameraBufferQueue", NULL);
        
        self.session = [[AVCaptureSession alloc] init];
        
        self.videoDevice = [self cameraDeviceWithPosition:iDevicePosition];
        _devicePosition = iDevicePosition;
        NSError *error = nil;
        self.deviceInput = [AVCaptureDeviceInput deviceInputWithDevice:self.videoDevice
                                                                 error:&error];
        
        if (!self.deviceInput || error) {

            NSLog(@"create input error");

            return nil;
        }
        
        
        self.dataOutput = [[AVCaptureVideoDataOutput alloc] init];
        [self.dataOutput setAlwaysDiscardsLateVideoFrames:YES];
        self.dataOutput.videoSettings = @{(id)kCVPixelBufferPixelFormatTypeKey : @(needYuvOutput ? kCVPixelFormatType_420YpCbCr8BiPlanarFullRange : kCVPixelFormatType_32BGRA)};
        self.dataOutput.alwaysDiscardsLateVideoFrames = YES;
        [self.dataOutput setSampleBufferDelegate:self queue:self.bufferQueue];
        self.metaOutput = [[AVCaptureMetadataOutput alloc] init];
        [self.metaOutput setMetadataObjectsDelegate:self queue:self.bufferQueue];
        
        self.stillImageOutput = [[AVCaptureStillImageOutput alloc] init];
        self.stillImageOutput.outputSettings = @{AVVideoCodecKey : AVVideoCodecJPEG};
        if ([self.stillImageOutput respondsToSelector:@selector(setHighResolutionStillImageOutputEnabled:)]) {

            self.stillImageOutput.highResolutionStillImageOutputEnabled = YES;
        }
        
        
        [self.session beginConfiguration];
        
        if ([self.session canAddInput:self.deviceInput]) {
            [self.session addInput:self.deviceInput];
        }else{
            NSLog( @"Could not add device input to the session" );
            return nil;
        }
        
        if ([self.session canSetSessionPreset:sessionPreset]) {
            [self.session setSessionPreset:sessionPreset];
            _sessionPreset = sessionPreset;
        }else if([self.session canSetSessionPreset:AVCaptureSessionPreset1920x1080]){
            [self.session setSessionPreset:AVCaptureSessionPreset1920x1080];
            _sessionPreset = AVCaptureSessionPreset1920x1080;
        }else if([self.session canSetSessionPreset:AVCaptureSessionPreset1280x720]){
            [self.session setSessionPreset:AVCaptureSessionPreset1280x720];
            _sessionPreset = AVCaptureSessionPreset1280x720;
        }else{
            [self.session setSessionPreset:AVCaptureSessionPreset640x480];
            _sessionPreset = AVCaptureSessionPreset640x480;
        }
        
        if ([self.session canAddOutput:self.dataOutput]) {
            
            [self.session addOutput:self.dataOutput];
        }else{
            
            NSLog( @"Could not add video data output to the session" );
            return nil;
        }
        
        if ([self.session canAddOutput:self.metaOutput]) {
            [self.session addOutput:self.metaOutput];
            self.metaOutput.metadataObjectTypes = @[AVMetadataObjectTypeFace].copy;
        }
        
        if ([self.session canAddOutput:self.stillImageOutput]) {

            [self.session addOutput:self.stillImageOutput];
        }else {

            NSLog(@"Could not add still image output to the session");
        }
        
        self.videoConnection =  [self.dataOutput connectionWithMediaType:AVMediaTypeVideo];
        
        
        if ([self.videoConnection isVideoOrientationSupported]) {
            
            [self.videoConnection setVideoOrientation:AVCaptureVideoOrientationPortrait];
            self.videoOrientation = AVCaptureVideoOrientationPortrait;
        }
        
        
        if ([self.videoConnection isVideoMirroringSupported]) {
            
            [self.videoConnection setVideoMirrored:YES];
            self.needVideoMirrored = YES;
        }
        
        if ([_videoDevice lockForConfiguration:NULL] == YES) {
//            _videoDevice.activeFormat = bestFormat;
            _videoDevice.activeVideoMinFrameDuration = CMTimeMake(1, iFPS);
            _videoDevice.activeVideoMaxFrameDuration = CMTimeMake(1, iFPS);
            [_videoDevice unlockForConfiguration];
        }
        
        
        [self.session commitConfiguration];
        
        NSMutableDictionary *tmpSettings = [[self.dataOutput recommendedVideoSettingsForAssetWriterWithOutputFileType:AVFileTypeQuickTimeMovie] mutableCopy];
        if (!EFMachineVersion.isiPhone5sOrLater) {
            NSNumber *tmpSettingValue = tmpSettings[AVVideoHeightKey];
            tmpSettings[AVVideoHeightKey] = tmpSettings[AVVideoWidthKey];
            tmpSettings[AVVideoWidthKey] = tmpSettingValue;
        }
        self.videoCompressingSettings = [tmpSettings copy];
        
        self.iExpectedFPS = iFPS;
        
        [self addObservers];
    }
    
    return self;
}

- (void)rotateCamera {
    
    if (self.devicePosition == AVCaptureDevicePositionFront) {
        self.devicePosition = AVCaptureDevicePositionBack;
    }else{
        self.devicePosition = AVCaptureDevicePositionFront;
    }
}

- (void)rotateCamera:(BOOL)isUseFrontCamera {
    
    if (isUseFrontCamera) {
        self.devicePosition = AVCaptureDevicePositionFront;
    }else{
        self.devicePosition = AVCaptureDevicePositionBack;
    }
}

- (void)setExposurePoint:(CGPoint)point inPreviewFrame:(CGRect)frame {
    
    BOOL isFrontCamera = self.devicePosition == AVCaptureDevicePositionFront;
    float fX = point.y / frame.size.height;
    float fY = isFrontCamera ? point.x / frame.size.width : (1 - point.x / frame.size.width);
    
    [self focusWithMode:self.videoDevice.focusMode exposureMode:self.videoDevice.exposureMode atPoint:CGPointMake(fX, fY)];
}

- (void)focusWithMode:(AVCaptureFocusMode)focusMode exposureMode:(AVCaptureExposureMode)exposureMode atPoint:(CGPoint)point{
    NSError *error = nil;
    AVCaptureDevice * device = self.videoDevice;
    
    if ( [device lockForConfiguration:&error] ) {
        device.exposureMode = AVCaptureExposureModeContinuousAutoExposure;
//        - (void)setISOValue:(float)value{
        [self setISOValue:0];
//device.exposureTargetBias
        // Setting (focus/exposure)PointOfInterest alone does not initiate a (focus/exposure) operation
        // Call -set(Focus/Exposure)Mode: to apply the new point of interest
        if ( focusMode != AVCaptureFocusModeLocked && device.isFocusPointOfInterestSupported && [device isFocusModeSupported:focusMode] ) {
            device.focusPointOfInterest = point;
            device.focusMode = focusMode;
        }
        
        if ( exposureMode != AVCaptureExposureModeCustom && device.isExposurePointOfInterestSupported && [device isExposureModeSupported:exposureMode] ) {
            device.exposurePointOfInterest = point;
            device.exposureMode = exposureMode;
        }
        
        device.subjectAreaChangeMonitoringEnabled = YES;
        [device unlockForConfiguration];
        
        
    }
}

- (void)setWhiteBalance{
    [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) {
        if ([captureDevice isWhiteBalanceModeSupported:AVCaptureWhiteBalanceModeContinuousAutoWhiteBalance]) {
            [captureDevice setWhiteBalanceMode:AVCaptureWhiteBalanceModeContinuousAutoWhiteBalance];
        }
    }];
}

- (void)changeDeviceProperty:(void(^)(AVCaptureDevice *))propertyChange{
    AVCaptureDevice *captureDevice= self.videoDevice;
    NSError *error;
    if ([captureDevice lockForConfiguration:&error]) {
        propertyChange(captureDevice);
        [captureDevice unlockForConfiguration];
    }else{
        NSLog(@"设置设备属性过程发生错误，错误信息：%@",error.localizedDescription);
    }
}

- (void)setISOValue:(float)value exposeDuration:(int)duration{
    float currentISO = (value < self.videoDevice.activeFormat.minISO) ? self.videoDevice.activeFormat.minISO: value;
    currentISO = value > self.videoDevice.activeFormat.maxISO ? self.videoDevice.activeFormat.maxISO : value;
    NSError *error;
    if ([self.videoDevice lockForConfiguration:&error]){
        [self.videoDevice setExposureModeCustomWithDuration:AVCaptureExposureDurationCurrent ISO:currentISO completionHandler:nil];
        [self.videoDevice unlockForConfiguration];
    }
}

- (void)setISOValue:(float)value{
//    float newVlaue = (value - 0.5) * (5.0 / 0.5); // mirror [0,1] to [-8,8]
    NSLog(@"%f", value);
    NSError *error = nil;
    if ( [self.videoDevice lockForConfiguration:&error] ) {
        [self.videoDevice setExposureTargetBias:value completionHandler:nil];
        [self.videoDevice unlockForConfiguration];
    }
    else {
        NSLog( @"Could not lock device for configuration: %@", error );
    }
}

- (void)setDevicePosition:(AVCaptureDevicePosition)devicePosition
{
    if (_devicePosition != devicePosition && devicePosition != AVCaptureDevicePositionUnspecified) {
        
        if (_session) {
            
            AVCaptureDevice *targetDevice = [self cameraDeviceWithPosition:devicePosition];
            
            if (targetDevice && [self judgeCameraAuthorization]) {
                
                NSError *error = nil;
                AVCaptureDeviceInput *deviceInput = [[AVCaptureDeviceInput alloc] initWithDevice:targetDevice error:&error];
                
                if(!deviceInput || error) {
                    
                    NSLog(@"Error creating capture device input: %@", error.localizedDescription);
                    return;
                }
                
                _bSessionPause = YES;
                
                [_session beginConfiguration];
                
                [_session removeInput:_deviceInput];
                
                if ([_session canAddInput:deviceInput]) {
                    
                    [_session addInput:deviceInput];
                    
                    _deviceInput = deviceInput;
                    _videoDevice = targetDevice;
                    
                    _devicePosition = devicePosition;
                }
                
                _videoConnection =  [_dataOutput connectionWithMediaType:AVMediaTypeVideo];
                
                if ([_videoConnection isVideoOrientationSupported]) {
                    
                    [_videoConnection setVideoOrientation:_videoOrientation];
                }
                
                if ([_videoConnection isVideoMirroringSupported]) {
                    
                    [_videoConnection setVideoMirrored:devicePosition == AVCaptureDevicePositionFront];
                }
                
                [_session commitConfiguration];
                
                [self setSessionPreset:_sessionPreset];
                
                _bSessionPause = NO;
            }
        }
    }
}

- (void)setSessionPreset:(NSString *)sessionPreset
{
    if (_session && _sessionPreset) {
        
//        if (![sessionPreset isEqualToString:_sessionPreset]) {
        
        _bSessionPause = YES;
        
        [_session beginConfiguration];
        
        if ([_session canSetSessionPreset:sessionPreset]) {
            
            [_session setSessionPreset:sessionPreset];
            
            _sessionPreset = sessionPreset;
        }
        
        
        [_session commitConfiguration];
        
        self.videoCompressingSettings = [[self.dataOutput recommendedVideoSettingsForAssetWriterWithOutputFileType:AVFileTypeQuickTimeMovie] copy];
        
//        [self setIExpectedFPS:_iExpectedFPS];
        
        _bSessionPause = NO;
//        }
    }
}

- (void)setIExpectedFPS:(int)iExpectedFPS
{
    _iExpectedFPS = iExpectedFPS;
    
    if (iExpectedFPS <= 0 || !_dataOutput.videoSettings || !_videoDevice) {
        
        return;
    }
    
    CGFloat fWidth = [[_dataOutput.videoSettings objectForKey:@"Width"] floatValue];
    CGFloat fHeight = [[_dataOutput.videoSettings objectForKey:@"Height"] floatValue];
    
    AVCaptureDeviceFormat *bestFormat = nil;
    AVFrameRateRange *bestFrameRateRange = nil;
    
    for (AVCaptureDeviceFormat *format in [_videoDevice formats]) {
        
        CMFormatDescriptionRef description = format.formatDescription;
        
        if (CMFormatDescriptionGetMediaSubType(description) != kCVPixelFormatType_420YpCbCr8BiPlanarFullRange) {
            
            continue;
        }
        
        CMVideoDimensions videoDimension = CMVideoFormatDescriptionGetDimensions(description);
        if ((videoDimension.width == fWidth && videoDimension.height == fHeight)
            ||
            (videoDimension.height == fWidth && videoDimension.width == fHeight)) {
            
            for (AVFrameRateRange *range in format.videoSupportedFrameRateRanges) {
                
                if (range.maxFrameRate >= bestFrameRateRange.maxFrameRate) {
                    bestFormat = format;
                    bestFrameRateRange = range;
                }
            }
        }
    }
    
    if (bestFormat) {
        
        CMTime minFrameDuration;
        
        if (bestFrameRateRange.minFrameDuration.timescale / bestFrameRateRange.minFrameDuration.value < iExpectedFPS) {
            
            minFrameDuration = bestFrameRateRange.minFrameDuration;
        }else{
            
            minFrameDuration = CMTimeMake(1, iExpectedFPS);
        }
        
        if ([_videoDevice lockForConfiguration:NULL] == YES) {
            _videoDevice.activeFormat = bestFormat;
            _videoDevice.activeVideoMinFrameDuration = minFrameDuration;
            _videoDevice.activeVideoMaxFrameDuration = minFrameDuration;
            [_videoDevice unlockForConfiguration];
        }
    }
}

- (void)startRunning
{
    if (![self judgeCameraAuthorization]) {
        
        return;
    }
    
    if (!self.dataOutput) {

        return;
    }
    
    if (self.session && ![self.session isRunning]) {
        if (self.bufferQueue) {
            dispatch_async(self.bufferQueue, ^{
                [self.session startRunning];
            });
        }
        self.bSessionPause = NO;
    }
}


- (void)stopRunning
{
    if (self.session && [self.session isRunning]) {
        if (self.bufferQueue) {
            dispatch_async(self.bufferQueue, ^{
                [self.session stopRunning];
            });
        }
        self.bSessionPause = YES;
    }
}

- (CGRect)getZoomedRectWithRect:(CGRect)rect scaleToFit:(BOOL)bScaleToFit
{
    CGRect rectRet = rect;
    
    if (self.dataOutput.videoSettings) {
        
        CGFloat fWidth = [[self.dataOutput.videoSettings objectForKey:@"Width"] floatValue];
        CGFloat fHeight = [[self.dataOutput.videoSettings objectForKey:@"Height"] floatValue];
        
        float fScaleX = fWidth / CGRectGetWidth(rect);
        float fScaleY = fHeight / CGRectGetHeight(rect);
        float fScale = bScaleToFit ? fmaxf(fScaleX, fScaleY) : fminf(fScaleX, fScaleY);
        
        fWidth /= fScale;
        fHeight /= fScale;
        
        CGFloat fX = rect.origin.x - (fWidth - rect.size.width) / 2.0f;
        CGFloat fY = rect.origin.y - (fHeight - rect.size.height) / 2.0f;
        
        rectRet = CGRectMake(fX, fY, fWidth, fHeight);
    }
    
    return rectRet;
}

- (BOOL)judgeCameraAuthorization
{
    AVAuthorizationStatus authStatus = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];
    
    if (authStatus == AVAuthorizationStatusRestricted || authStatus == AVAuthorizationStatusDenied) {
        return NO;
    }
    
    return YES;
}

- (AVCaptureDevice *)cameraDeviceWithPosition:(AVCaptureDevicePosition)position
{
    AVCaptureDevice *deviceRet = nil;
    
    if (position != AVCaptureDevicePositionUnspecified) {
        
        NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
        
        for (AVCaptureDevice *device in devices) {
            
            if ([device position] == position) {
                
                deviceRet = device;
            }
        }
    }
    
    return deviceRet;
}

- (AVCaptureVideoPreviewLayer *)previewLayer
{
    if (!_previewLayer) {
        
        _previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.session];
    }
    
    return _previewLayer;
}

- (void)snapStillImageCompletionHandler:(void (^)(CMSampleBufferRef imageDataSampleBuffer, NSError *error))handler
{
    if ([self judgeCameraAuthorization]) {
        self.bSessionPause = YES;
        
        NSString *strSessionPreset = [self.sessionPreset mutableCopy];
        self.sessionPreset = AVCaptureSessionPresetPhoto;
        
        // 改变preset会黑一下
        [NSThread sleepForTimeInterval:0.3];
        
        dispatch_async(self.bufferQueue, ^{
            
            [self.stillImageOutput captureStillImageAsynchronouslyFromConnection:[self.stillImageOutput connectionWithMediaType:AVMediaTypeVideo] completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {
                
                self.bSessionPause = NO;
                self.sessionPreset = strSessionPreset;
                handler(imageDataSampleBuffer , error);
            }];
        } );
    }
}
BOOL updateExporureModel(STExposureModel model){
    if (currentExposureMode == model) return NO;
    currentExposureMode = model;
    return YES;
}

- (void)test:(AVCaptureExposureMode)model{
    if ([self.videoDevice lockForConfiguration:nil]) {
        if ([self.videoDevice  isExposureModeSupported:model]) {
            [self.videoDevice setExposureMode:model];
        }
        [self.videoDevice unlockForConfiguration];
    }
}

- (void)setExposureTime:(CMTime)time{
    if ([self.videoDevice lockForConfiguration:nil]) {
        if (@available(iOS 12.0, *)) {
            self.videoDevice.activeMaxExposureDuration = time;
        } else {
            // Fallback on earlier versions
        }
        [self.videoDevice unlockForConfiguration];
    }
}
- (void)setFPS:(float)fps{
    if ([_videoDevice lockForConfiguration:NULL] == YES) {
//            _videoDevice.activeFormat = bestFormat;
        _videoDevice.activeVideoMinFrameDuration = CMTimeMake(1, fps);
        _videoDevice.activeVideoMaxFrameDuration = CMTimeMake(1, fps);
        [_videoDevice unlockForConfiguration];
    }
}

- (void)updateExposure:(CMSampleBufferRef)sampleBuffer{
    CFDictionaryRef metadataDict = CMCopyDictionaryOfAttachments(NULL,sampleBuffer, kCMAttachmentMode_ShouldPropagate);
    NSDictionary * metadata = [[NSMutableDictionary alloc] initWithDictionary:(__bridge NSDictionary *)metadataDict];
    CFRelease(metadataDict);
    NSDictionary *exifMetadata = [[metadata objectForKey:(NSString *)kCGImagePropertyExifDictionary] mutableCopy];
    float brightnessValue = [[exifMetadata objectForKey:(NSString *)kCGImagePropertyExifBrightnessValue] floatValue];
    
    if(brightnessValue > 2 && updateExporureModel(STExposureModelPositive2)){
        [self setISOValue:500 exposeDuration:30];
        [self test:AVCaptureExposureModeContinuousAutoExposure];
        [self setFPS:30];
    }else if(brightnessValue > 1 && brightnessValue < 2 && updateExporureModel(STExposureModelPositive1)){
        [self setISOValue:500 exposeDuration:30];
        [self test:AVCaptureExposureModeContinuousAutoExposure];
        [self setFPS:30];
    }else if(brightnessValue > 0 && brightnessValue < 1 && updateExporureModel(STExposureModel0)){
        [self setISOValue:500 exposeDuration:30];
        [self test:AVCaptureExposureModeContinuousAutoExposure];
        [self setFPS:30];
    }else if (brightnessValue > -1 && brightnessValue < 0 && updateExporureModel(STExposureModelNegative1)){
        [self setISOValue:self.videoDevice.activeFormat.maxISO - 200 exposeDuration:40];
        [self test:AVCaptureExposureModeContinuousAutoExposure];
    }else if (brightnessValue > -2 && brightnessValue < -1 && updateExporureModel(STExposureModelNegative2)){
        [self setISOValue:self.videoDevice.activeFormat.maxISO - 200 exposeDuration:35];
        [self test:AVCaptureExposureModeContinuousAutoExposure];
    }else if (brightnessValue > -2.5 && brightnessValue < -2 && updateExporureModel(STExposureModelNegative3)){
        [self setISOValue:self.videoDevice.activeFormat.maxISO - 200 exposeDuration:30];
        [self test:AVCaptureExposureModeContinuousAutoExposure];
    }else if (brightnessValue > -3 && brightnessValue < -2.5 && updateExporureModel(STExposureModelNegative4)){
        [self setISOValue:self.videoDevice.activeFormat.maxISO - 200 exposeDuration:25];
        [self test:AVCaptureExposureModeContinuousAutoExposure];
    }else if (brightnessValue > -3.5 && brightnessValue < -3 && updateExporureModel(STExposureModelNegative5)){
        [self setISOValue:self.videoDevice.activeFormat.maxISO - 200 exposeDuration:20];
        [self test:AVCaptureExposureModeContinuousAutoExposure];
    }else if (brightnessValue > -4 && brightnessValue < -3.5 && updateExporureModel(STExposureModelNegative6)){
        [self setISOValue:self.videoDevice.activeFormat.maxISO - 250 exposeDuration:15];
        [self test:AVCaptureExposureModeContinuousAutoExposure];
    }else if (brightnessValue > -5 && brightnessValue < -4 && updateExporureModel(STExposureModelNegative7)){
        [self setISOValue:self.videoDevice.activeFormat.maxISO - 200 exposeDuration:10];
        [self test:AVCaptureExposureModeContinuousAutoExposure];
    }else if(brightnessValue < -5 && updateExporureModel(STExposureModelNegative8)){
        [self setISOValue:self.videoDevice.activeFormat.maxISO - 150 exposeDuration:5];
        [self test:AVCaptureExposureModeContinuousAutoExposure];
    }

//    NSLog(@"current brightness %f min iso %f max iso %f min exposure %f max exposure %f", brightnessValue, self.videoDevice.activeFormat.minISO, self.videoDevice.activeFormat.maxISO, CMTimeGetSeconds(self.videoDevice.activeFormat.minExposureDuration),   CMTimeGetSeconds(self.videoDevice.activeFormat.maxExposureDuration));
}

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection
{
    if (!self.bSessionPause) {
        if (self.delegate && [self.delegate respondsToSelector:@selector(rtcCameraVideoCapturer:didOutputSampleBuffer:)]) {
            [self.delegate rtcCameraVideoCapturer:self didOutputSampleBuffer:sampleBuffer];
        }
//        if (self.delegate && [self.delegate respondsToSelector:@selector(captureOutput:didOutputSampleBuffer:fromConnection:)]) {
//            //[connection setVideoOrientation:AVCaptureVideoOrientationPortrait];
//            [self.delegate captureOutput:captureOutput didOutputSampleBuffer:sampleBuffer fromConnection:connection];
//        }
    }
//    [self updateExposure:sampleBuffer];
}


- (void)captureOutput:(AVCaptureOutput *)output didOutputMetadataObjects:(NSArray<__kindof AVMetadataObject *> *)metadataObjects fromConnection:(AVCaptureConnection *)connection{
    AVMetadataFaceObject *faceObject = nil;
    for(AVMetadataObject *object  in metadataObjects){
        if (AVMetadataObjectTypeFace == object.type) {
            faceObject = (AVMetadataFaceObject*)object;
        }
    }
    static BOOL hasFace = NO;
    if (!hasFace && faceObject.faceID) {
        hasFace = YES;
    }
    if (!faceObject.faceID) {
        hasFace = NO;
    }
}

#pragma mark - Notifications
- (void)addObservers {
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(appWillResignActive) name:UIApplicationWillResignActiveNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(appDidBecomeActive) name:UIApplicationDidBecomeActiveNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self
               selector:@selector(dealCaptureSessionRuntimeError:)
                   name:AVCaptureSessionRuntimeErrorNotification
                 object:self.session];
}

- (void)removeObservers {
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}

#pragma mark - Notification
- (void)appWillResignActive {
    RTCLogInfo("SDCustomRTCCameraCapturer appWillResignActive");
}

- (void)appDidBecomeActive {
    RTCLogInfo("SDCustomRTCCameraCapturer appDidBecomeActive");
    [self startRunning];
}

- (void)dealCaptureSessionRuntimeError:(NSNotification *)notification {
    NSError *error = [notification.userInfo objectForKey:AVCaptureSessionErrorKey];
    RTCLogError(@"SDCustomRTCCameraCapturer dealCaptureSessionRuntimeError error: %@", error);

    if (error.code == AVErrorMediaServicesWereReset) {
        [self startRunning];
    }
}

#pragma mark - Dealloc
- (void)dealloc {
    DebugLog(@"SDCustomRTCCameraCapturer dealloc");
    [self removeObservers];

    if (self.session) {
        self.bSessionPause = YES;
        [self.session beginConfiguration];
        [self.session removeOutput:self.dataOutput];
        [self.session removeInput:self.deviceInput];
        [self.session commitConfiguration];
        if ([self.session isRunning]) {
            [self.session stopRunning];
        }
        self.session = nil;
    }
}

@end

三、实现WebRTC结合ossrs视频通话功能

iOS端WebRTC调用ossrs相关，实现直播视频通话功能请查看：
https://blog.csdn.net/gloryFlow/article/details/132262724

这里列出来需要改动的地方

在createVideoTrack中使用SDCustomRTCCameraCapturer类

- (RTCVideoTrack *)createVideoTrack {
    RTCVideoSource *videoSource = [self.factory videoSource];
    self.localVideoSource = videoSource;

    // 如果是模拟器
    if (TARGET_IPHONE_SIMULATOR) {
        if (@available(iOS 10, *)) {
            self.videoCapturer = [[RTCFileVideoCapturer alloc] initWithDelegate:self];
        } else {
            // Fallback on earlier versions
        }
    } else{
        self.videoCapturer = [[SDCustomRTCCameraCapturer alloc] initWithDevicePosition:AVCaptureDevicePositionFront sessionPresset:AVCaptureSessionPreset1920x1080 fps:20 needYuvOutput:NO];
        
//        self.videoCapturer = [[SDCustomRTCCameraCapturer alloc] initWithDelegate:self];
    }
    
    RTCVideoTrack *videoTrack = [self.factory videoTrackWithSource:videoSource trackId:@"video0"];
    
    return videoTrack;
}

当需要渲染到界面上的时候，需要设置startCaptureLocalVideo，为 localVideoTrack添加渲染的界面View，renderer是一个RTCMTLVideoView

self.localRenderer = [[RTCMTLVideoView alloc] initWithFrame:CGRectZero];
    self.localRenderer.delegate = self;

- (void)startCaptureLocalVideo:(id<RTCVideoRenderer>)renderer {
    if (!self.isPublish) {
        return;
    }
    
    if (!renderer) {
        return;
    }
    
    if (!self.videoCapturer) {
        return;
    }
    
    [self setDegradationPreference:RTCDegradationPreferenceMaintainResolution];
    
    RTCVideoCapturer *capturer = self.videoCapturer;
    if ([capturer isKindOfClass:[SDCustomRTCCameraCapturer class]]) {
        AVCaptureDevice *camera = [self findDeviceForPosition:self.usingFrontCamera?AVCaptureDevicePositionFront:AVCaptureDevicePositionBack];
        
        SDCustomRTCCameraCapturer *cameraVideoCapturer = (SDCustomRTCCameraCapturer *)capturer;
        [cameraVideoCapturer setISOValue:0.0];
        [cameraVideoCapturer rotateCamera:self.usingFrontCamera];
        self.videoCapturer.delegate = self;

        AVCaptureDeviceFormat *formatNilable = [self selectFormatForDevice:camera];;
        
        if (!formatNilable) {
            return;
        }
        
        DebugLog(@"formatNilable:%@", formatNilable);
        
        NSInteger fps = [self selectFpsForFormat:formatNilable];
        
        CMVideoDimensions videoVideoDimensions = CMVideoFormatDescriptionGetDimensions(formatNilable.formatDescription);
        float width = videoVideoDimensions.width;
        float height = videoVideoDimensions.height;
                
        DebugLog(@"videoVideoDimensions width:%f,height:%f", width, height);
        [cameraVideoCapturer startRunning];
//        [cameraVideoCapturer startCaptureWithDevice:camera format:formatNilable fps:fps completionHandler:^(NSError *error) {
//            DebugLog(@"startCaptureWithDevice error:%@", error);
//        }];
        [self changeResolution:width height:height fps:(int)fps];
    }
    
    if (@available(iOS 10, *)) {
        if ([capturer isKindOfClass:[RTCFileVideoCapturer class]]) {
            RTCFileVideoCapturer *fileVideoCapturer = (RTCFileVideoCapturer *)capturer;
            [fileVideoCapturer startCapturingFromFileNamed:@"beautyPicture.mp4" onError:^(NSError * _Nonnull error) {
                DebugLog(@"startCaptureLocalVideo startCapturingFromFileNamed error:%@", error);
            }];
        }
    } else {
        // Fallback on earlier versions
    }
    
    [self.localVideoTrack addRenderer:renderer];
}

获得相机采集的画面- (void)rtcCameraVideoCapturer:(RTCVideoCapturer *)capturer didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer;

具体代码如下

- (void)rtcCameraVideoCapturer:(RTCVideoCapturer *)capturer didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer {

    CVPixelBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);

    RTCCVPixelBuffer *rtcPixelBuffer =
    [[RTCCVPixelBuffer alloc] initWithPixelBuffer:videoPixelBufferRef];
    RTCCVPixelBuffer *rtcPixelBuffer = [[RTCCVPixelBuffer alloc] initWithPixelBuffer:pixelBuffer];
    int64_t timeStampNs = CMTimeGetSeconds(CMSampleBufferGetPresentationTimeStamp(sampleBuffer)) *
    1000000000;
    RTCVideoFrame *rtcVideoFrame = [[RTCVideoFrame alloc] initWithBuffer:rtcPixelBuffer     

    
    [self.localVideoSource capturer:capturer didCaptureVideoFrame:rtcVideoFrame];
}

WebRTCClient完整代码如下

WebRTCClient.h

#import <Foundation/Foundation.h>
#import <WebRTC/WebRTC.h>
#import <UIKit/UIKit.h>
#import "SDCustomRTCCameraCapturer.h"

#define kSelectedResolution @"kSelectedResolutionIndex"
#define kFramerateLimit 30.0

@protocol WebRTCClientDelegate;
@interface WebRTCClient : NSObject

@property (nonatomic, weak) id<WebRTCClientDelegate> delegate;

/**
 connect工厂
 */
@property (nonatomic, strong) RTCPeerConnectionFactory *factory;

/**
 是否push
 */
@property (nonatomic, assign) BOOL isPublish;

/**
 connect
 */
@property (nonatomic, strong) RTCPeerConnection *peerConnection;

/**
 RTCAudioSession
 */
@property (nonatomic, strong) RTCAudioSession *rtcAudioSession;

/**
 DispatchQueue
 */
@property (nonatomic) dispatch_queue_t audioQueue;

/**
 mediaConstrains
 */
@property (nonatomic, strong) NSDictionary *mediaConstrains;

/**
 publishMediaConstrains
 */
@property (nonatomic, strong) NSDictionary *publishMediaConstrains;

/**
 playMediaConstrains
 */
@property (nonatomic, strong) NSDictionary *playMediaConstrains;

/**
 optionalConstraints
 */
@property (nonatomic, strong) NSDictionary *optionalConstraints;

/**
 RTCVideoCapturer摄像头采集器
 */
@property (nonatomic, strong) RTCVideoCapturer *videoCapturer;

/**
 local语音localAudioTrack
 */
@property (nonatomic, strong) RTCAudioTrack *localAudioTrack;

/**
 localVideoTrack
 */
@property (nonatomic, strong) RTCVideoTrack *localVideoTrack;

/**
 remoteVideoTrack
 */
@property (nonatomic, strong) RTCVideoTrack *remoteVideoTrack;

/**
 RTCVideoRenderer
 */
@property (nonatomic, weak) id<RTCVideoRenderer> remoteRenderView;

/**
 localDataChannel
 */
@property (nonatomic, strong) RTCDataChannel *localDataChannel;

/**
 localDataChannel
 */
@property (nonatomic, strong) RTCDataChannel *remoteDataChannel;

/**
 RTCVideoSource
 */
@property (nonatomic, strong) RTCVideoSource *localVideoSource;


- (instancetype)initWithPublish:(BOOL)isPublish;

- (void)startCaptureLocalVideo:(id<RTCVideoRenderer>)renderer;

- (void)addIceCandidate:(RTCIceCandidate *)candidate;

- (void)answer:(void (^)(RTCSessionDescription *sdp))completionHandler;

- (void)offer:(void (^)(RTCSessionDescription *sdp))completionHandler;

- (void)setRemoteSdp:(RTCSessionDescription *)remoteSdp completion:(void (^)(NSError *error))completion;

- (void)setRemoteCandidate:(RTCIceCandidate *)remoteCandidate;

- (BOOL)changeResolution:(int)width height:(int)height fps:(int)fps;

- (NSArray<NSString *> *)availableVideoResolutions;

#pragma mark - switchCamera
- (void)switchCamera:(id<RTCVideoRenderer>)renderer;

#pragma mark - Hiden or show Video
- (void)hidenVideo;

- (void)showVideo;

#pragma mark - Hiden or show Audio
- (void)muteAudio;

- (void)unmuteAudio;

- (void)speakOff;

- (void)speakOn;

#pragma mark - 设置视频码率BitrateBps
- (void)setMaxBitrate:(int)maxBitrate;

- (void)setMinBitrate:(int)minBitrate;

#pragma mark - 设置视频帧率
- (void)setMaxFramerate:(int)maxFramerate;

- (void)close;

@end


@protocol WebRTCClientDelegate <NSObject>

// 处理美颜设置
- (RTCVideoFrame *)webRTCClient:(WebRTCClient *)client didCaptureSampleBuffer:(CMSampleBufferRef)sampleBuffer;

- (void)webRTCClient:(WebRTCClient *)client didDiscoverLocalCandidate:(RTCIceCandidate *)candidate;
- (void)webRTCClient:(WebRTCClient *)client didChangeConnectionState:(RTCIceConnectionState)state;
- (void)webRTCClient:(WebRTCClient *)client didReceiveData:(NSData *)data;

@end

WebRTCClient.m

#import "WebRTCClient.h"


@interface WebRTCClient ()<RTCPeerConnectionDelegate, RTCDataChannelDelegate, RTCVideoCapturerDelegate, SDCustomRTCCameraCapturerDelegate>

@property (nonatomic, assign) BOOL usingFrontCamera;

@end

@implementation WebRTCClient

- (instancetype)initWithPublish:(BOOL)isPublish {
    self = [super init];
    if (self) {
        self.isPublish = isPublish;
        self.usingFrontCamera = YES;
                                        
        RTCMediaConstraints *constraints = [[RTCMediaConstraints alloc] initWithMandatoryConstraints:self.publishMediaConstrains optionalConstraints:self.optionalConstraints];
        
        RTCConfiguration *newConfig = [[RTCConfiguration alloc] init];
        newConfig.sdpSemantics = RTCSdpSemanticsUnifiedPlan;
        newConfig.continualGatheringPolicy = RTCContinualGatheringPolicyGatherContinually;

        self.peerConnection = [self.factory peerConnectionWithConfiguration:newConfig constraints:constraints delegate:nil];
        
        [self createMediaSenders];
        
        [self createMediaReceivers];
        
        // srs not support data channel.
        // self.createDataChannel()
        [self configureAudioSession];
        
        self.peerConnection.delegate = self;
    }
    return self;
}


- (void)createMediaSenders {
    if (!self.isPublish) {
        return;
    }
    
    NSString *streamId = @"stream";
    
    // Audio
    RTCAudioTrack *audioTrack = [self createAudioTrack];
    self.localAudioTrack = audioTrack;
    
    RTCRtpTransceiverInit *audioTrackTransceiver = [[RTCRtpTransceiverInit alloc] init];
    audioTrackTransceiver.direction = RTCRtpTransceiverDirectionSendOnly;
    audioTrackTransceiver.streamIds = @[streamId];
    
    [self.peerConnection addTransceiverWithTrack:audioTrack init:audioTrackTransceiver];
    
    // Video
    RTCRtpEncodingParameters *encodingParameters = [[RTCRtpEncodingParameters alloc] init];
    encodingParameters.maxBitrateBps = @(6000000);
//    encodingParameters.bitratePriority = 1.0;
    
    RTCVideoTrack *videoTrack = [self createVideoTrack];
    self.localVideoTrack = videoTrack;
    RTCRtpTransceiverInit *videoTrackTransceiver = [[RTCRtpTransceiverInit alloc] init];
    videoTrackTransceiver.direction = RTCRtpTransceiverDirectionSendOnly;
    videoTrackTransceiver.streamIds = @[streamId];
    
    // 设置该属性后，SRS服务无法播放视频画面
//    videoTrackTransceiver.sendEncodings = @[encodingParameters];
    [self.peerConnection addTransceiverWithTrack:videoTrack init:videoTrackTransceiver];
    
    [self setDegradationPreference:RTCDegradationPreferenceBalanced];
    [self setMaxBitrate:6000000];
}

- (void)createMediaReceivers {
    if (!self.isPublish) {
        return;
    }
    
    if (self.peerConnection.transceivers.count > 0) {
        RTCRtpTransceiver *transceiver = self.peerConnection.transceivers.firstObject;
        if (transceiver.mediaType == RTCRtpMediaTypeVideo) {
            RTCVideoTrack *track = (RTCVideoTrack *)transceiver.receiver.track;
            self.remoteVideoTrack = track;
        }
    }
}

- (void)configureAudioSession {
    [self.rtcAudioSession lockForConfiguration];
    @try {
        RTCAudioSessionConfiguration *configuration =
            [[RTCAudioSessionConfiguration alloc] init];
        configuration.category = AVAudioSessionCategoryPlayAndRecord;
        configuration.categoryOptions = AVAudioSessionCategoryOptionDefaultToSpeaker;
        configuration.mode = AVAudioSessionModeDefault;
        BOOL hasSucceeded = NO;
        NSError *error = nil;
        if (self.rtcAudioSession.isActive) {
          hasSucceeded = [self.rtcAudioSession setConfiguration:configuration error:&error];
        } else {
          hasSucceeded = [self.rtcAudioSession setConfiguration:configuration
                                            active:YES
                                             error:&error];
        }
        if (!hasSucceeded) {
            DebugLog(@"Error setting configuration: %@", error.localizedDescription);
        }
    } @catch (NSException *exception) {
        DebugLog(@"configureAudioSession exception:%@", exception);
    }
    
    [self.rtcAudioSession unlockForConfiguration];
}

- (RTCAudioTrack *)createAudioTrack {
    /// enable google 3A algorithm.
    NSDictionary *mandatory = @{
        @"googEchoCancellation": kRTCMediaConstraintsValueTrue,
        @"googAutoGainControl": kRTCMediaConstraintsValueTrue,
        @"googNoiseSuppression": kRTCMediaConstraintsValueTrue,
    };
    
    RTCMediaConstraints *audioConstrains = [[RTCMediaConstraints alloc] initWithMandatoryConstraints:mandatory optionalConstraints:self.optionalConstraints];
    RTCAudioSource *audioSource = [self.factory audioSourceWithConstraints:audioConstrains];
    
    RTCAudioTrack *audioTrack = [self.factory audioTrackWithSource:audioSource trackId:@"audio0"];
    
    return audioTrack;
}

- (RTCVideoTrack *)createVideoTrack {
    RTCVideoSource *videoSource = [self.factory videoSource];
    self.localVideoSource = videoSource;

    // 如果是模拟器
    if (TARGET_IPHONE_SIMULATOR) {
        if (@available(iOS 10, *)) {
            self.videoCapturer = [[RTCFileVideoCapturer alloc] initWithDelegate:self];
        } else {
            // Fallback on earlier versions
        }
    } else{
        self.videoCapturer = [[SDCustomRTCCameraCapturer alloc] initWithDevicePosition:AVCaptureDevicePositionFront sessionPresset:AVCaptureSessionPreset1920x1080 fps:20 needYuvOutput:NO];
        
//        self.videoCapturer = [[SDCustomRTCCameraCapturer alloc] initWithDelegate:self];
    }
    
    RTCVideoTrack *videoTrack = [self.factory videoTrackWithSource:videoSource trackId:@"video0"];
    
    return videoTrack;
}

- (void)addIceCandidate:(RTCIceCandidate *)candidate {
    [self.peerConnection addIceCandidate:candidate];
}

- (void)offer:(void (^)(RTCSessionDescription *sdp))completion {
    if (self.isPublish) {
        self.mediaConstrains = self.publishMediaConstrains;
    } else {
        self.mediaConstrains = self.playMediaConstrains;
    }
    
    RTCMediaConstraints *constrains = [[RTCMediaConstraints alloc] initWithMandatoryConstraints:self.mediaConstrains optionalConstraints:self.optionalConstraints];
    DebugLog(@"peerConnection:%@",self.peerConnection);
    __weak typeof(self) weakSelf = self;
    [weakSelf.peerConnection offerForConstraints:constrains completionHandler:^(RTCSessionDescription * _Nullable sdp, NSError * _Nullable error) {
        if (error) {
            DebugLog(@"offer offerForConstraints error:%@", error);
        }
        
        if (sdp) {
            [weakSelf.peerConnection setLocalDescription:sdp completionHandler:^(NSError * _Nullable error) {
                if (error) {
                    DebugLog(@"offer setLocalDescription error:%@", error);
                }
                if (completion) {
                    completion(sdp);
                }
            }];
        }
    }];
}

- (void)answer:(void (^)(RTCSessionDescription *sdp))completion {
    RTCMediaConstraints *constrains = [[RTCMediaConstraints alloc] initWithMandatoryConstraints:self.mediaConstrains optionalConstraints:self.optionalConstraints];
    __weak typeof(self) weakSelf = self;
    [weakSelf.peerConnection answerForConstraints:constrains completionHandler:^(RTCSessionDescription * _Nullable sdp, NSError * _Nullable error) {
        if (error) {
            DebugLog(@"answer answerForConstraints error:%@", error);
        }
        
        if (sdp) {
            [weakSelf.peerConnection setLocalDescription:sdp completionHandler:^(NSError * _Nullable error) {
                if (error) {
                    DebugLog(@"answer setLocalDescription error:%@", error);
                }
                if (completion) {
                    completion(sdp);
                }
            }];
        }
    }];
}

- (void)setRemoteSdp:(RTCSessionDescription *)remoteSdp completion:(void (^)(NSError *error))completion {
    [self.peerConnection setRemoteDescription:remoteSdp completionHandler:completion];
}

- (void)setRemoteCandidate:(RTCIceCandidate *)remoteCandidate {
    [self.peerConnection addIceCandidate:remoteCandidate];
}

- (void)setMaxBitrate:(int)maxBitrate {
    if (self.peerConnection.senders.count > 0) {
        RTCRtpSender *videoSender = self.peerConnection.senders.firstObject;
        RTCRtpParameters *parametersToModify = videoSender.parameters;
        for (RTCRtpEncodingParameters *encoding in parametersToModify.encodings) {
            encoding.maxBitrateBps = @(maxBitrate);
        }
        [videoSender setParameters:parametersToModify];
    }
}

- (void)setDegradationPreference:(RTCDegradationPreference)degradationPreference {
    // RTCDegradationPreferenceMaintainResolution
    NSMutableArray *videoSenders = [NSMutableArray arrayWithCapacity:0];
    for (RTCRtpSender *sender in self.peerConnection.senders) {
        if (sender.track && [kRTCMediaStreamTrackKindVideo isEqualToString:sender.track.kind]) {
            // [videoSenders addObject:sender];
            RTCRtpParameters *parameters = sender.parameters;
            parameters.degradationPreference = [NSNumber numberWithInteger:degradationPreference];
            [sender setParameters:parameters];
            
            [videoSenders addObject:sender];
        }
    }
    
    for (RTCRtpSender *sender in videoSenders) {
        RTCRtpParameters *parameters = sender.parameters;
        parameters.degradationPreference = [NSNumber numberWithInteger:degradationPreference];
        [sender setParameters:parameters];
    }
}

- (void)setMinBitrate:(int)minBitrate {
    if (self.peerConnection.senders.count > 0) {
        RTCRtpSender *videoSender = self.peerConnection.senders.firstObject;
        RTCRtpParameters *parametersToModify = videoSender.parameters;
        for (RTCRtpEncodingParameters *encoding in parametersToModify.encodings) {
            encoding.minBitrateBps = @(minBitrate);
        }
        [videoSender setParameters:parametersToModify];
    }
}

- (void)setMaxFramerate:(int)maxFramerate {
    if (self.peerConnection.senders.count > 0) {
        RTCRtpSender *videoSender = self.peerConnection.senders.firstObject;
        RTCRtpParameters *parametersToModify = videoSender.parameters;
        // 该版本暂时没有maxFramerate，需要更新到最新版本
        for (RTCRtpEncodingParameters *encoding in parametersToModify.encodings) {
            encoding.maxFramerate = @(maxFramerate);
        }
        [videoSender setParameters:parametersToModify];
    }
}

#pragma mark - Private
- (AVCaptureDevice *)findDeviceForPosition:(AVCaptureDevicePosition)position {
  NSArray<AVCaptureDevice *> *captureDevices =
      [SDCustomRTCCameraCapturer captureDevices];
  for (AVCaptureDevice *device in captureDevices) {
    if (device.position == position) {
      return device;
    }
  }
  return captureDevices[0];
}

- (NSArray<NSString *> *)availableVideoResolutions {
  NSMutableSet<NSArray<NSNumber *> *> *resolutions =
      [[NSMutableSet<NSArray<NSNumber *> *> alloc] init];
  for (AVCaptureDevice *device in [SDCustomRTCCameraCapturer captureDevices]) {
    for (AVCaptureDeviceFormat *format in
         [SDCustomRTCCameraCapturer supportedFormatsForDevice:device]) {
      CMVideoDimensions resolution =
          CMVideoFormatDescriptionGetDimensions(format.formatDescription);
      NSArray<NSNumber *> *resolutionObject = @[@(resolution.width), @(resolution.height) ];
      [resolutions addObject:resolutionObject];
    }
  }

  NSArray<NSArray<NSNumber *> *> *sortedResolutions =
      [[resolutions allObjects] sortedArrayUsingComparator:^NSComparisonResult(
                                    NSArray<NSNumber *> *obj1, NSArray<NSNumber *> *obj2) {
        NSComparisonResult cmp = [obj1.firstObject compare:obj2.firstObject];
        if (cmp != NSOrderedSame) {
          return cmp;
        }
        return [obj1.lastObject compare:obj2.lastObject];
      }];

  NSMutableArray<NSString *> *resolutionStrings = [[NSMutableArray<NSString *> alloc] init];
  for (NSArray<NSNumber *> *resolution in sortedResolutions) {
    NSString *resolutionString =
        [NSString stringWithFormat:@"%@x%@", resolution.firstObject, resolution.lastObject];
    [resolutionStrings addObject:resolutionString];
  }

  return [resolutionStrings copy];
}


- (int)videoResolutionComponentAtIndex:(int)index inString:(NSString *)resolution {
    if (index != 0 && index != 1) {
        return 0;
    }
    NSArray<NSString *> *components = [resolution componentsSeparatedByString:@"x"];
    if (components.count != 2) {
        return 0;
    }
    return components[index].intValue;
}

- (AVCaptureDeviceFormat *)selectFormatForDevice:(AVCaptureDevice *)device {
    RTCVideoCapturer *capturer = self.videoCapturer;
    if ([capturer isKindOfClass:[SDCustomRTCCameraCapturer class]]) {
        SDCustomRTCCameraCapturer *cameraVideoCapturer = (SDCustomRTCCameraCapturer *)capturer;
        NSArray *availableVideoResolutions = [self availableVideoResolutions];
        NSString *selectedIndexStr = [[NSUserDefaults standardUserDefaults] objectForKey:kSelectedResolution];
        int selectedIndex = 0;
        if (selectedIndexStr && selectedIndexStr.length > 0) {
            selectedIndex = [selectedIndexStr intValue];
        }
        
        NSString *videoResolution = [availableVideoResolutions objectAtIndex:selectedIndex];
        DebugLog(@"availableVideoResolutions:%@, videoResolution:%@", availableVideoResolutions, videoResolution);
        NSArray<AVCaptureDeviceFormat *> *formats =
          [SDCustomRTCCameraCapturer supportedFormatsForDevice:device];
        int targetWidth = [self videoResolutionComponentAtIndex:0 inString:videoResolution];
        int targetHeight = [self videoResolutionComponentAtIndex:1 inString:videoResolution];
        AVCaptureDeviceFormat *selectedFormat = nil;
        int currentDiff = INT_MAX;

        for (AVCaptureDeviceFormat *format in formats) {
            CMVideoDimensions dimension = CMVideoFormatDescriptionGetDimensions(format.formatDescription);
            FourCharCode pixelFormat = CMFormatDescriptionGetMediaSubType(format.formatDescription);
            int diff = abs(targetWidth - dimension.width) + abs(targetHeight - dimension.height);
            if (diff < currentDiff) {
              selectedFormat = format;
              currentDiff = diff;
            } else if (diff == currentDiff && pixelFormat == [cameraVideoCapturer preferredOutputPixelFormat]) {
              selectedFormat = format;
            }
        }

        return selectedFormat;
    }
    
    return nil;
}

- (NSInteger)selectFpsForFormat:(AVCaptureDeviceFormat *)format {
    Float64 maxSupportedFramerate = 0;
    for (AVFrameRateRange *fpsRange in format.videoSupportedFrameRateRanges) {
        maxSupportedFramerate = fmax(maxSupportedFramerate, fpsRange.maxFrameRate);
    }
//    return fmin(maxSupportedFramerate, kFramerateLimit);
    return 20;
}

- (void)startCaptureLocalVideo:(id<RTCVideoRenderer>)renderer {
    if (!self.isPublish) {
        return;
    }
    
    if (!renderer) {
        return;
    }
    
    if (!self.videoCapturer) {
        return;
    }
    
    [self setDegradationPreference:RTCDegradationPreferenceMaintainResolution];
    
    RTCVideoCapturer *capturer = self.videoCapturer;
    if ([capturer isKindOfClass:[SDCustomRTCCameraCapturer class]]) {
        AVCaptureDevice *camera = [self findDeviceForPosition:self.usingFrontCamera?AVCaptureDevicePositionFront:AVCaptureDevicePositionBack];
        
        SDCustomRTCCameraCapturer *cameraVideoCapturer = (SDCustomRTCCameraCapturer *)capturer;
        [cameraVideoCapturer setISOValue:0.0];
        [cameraVideoCapturer rotateCamera:self.usingFrontCamera];
        self.videoCapturer.delegate = self;

        AVCaptureDeviceFormat *formatNilable = [self selectFormatForDevice:camera];;
        
        if (!formatNilable) {
            return;
        }
        
        DebugLog(@"formatNilable:%@", formatNilable);
        
        NSInteger fps = [self selectFpsForFormat:formatNilable];
        
        CMVideoDimensions videoVideoDimensions = CMVideoFormatDescriptionGetDimensions(formatNilable.formatDescription);
        float width = videoVideoDimensions.width;
        float height = videoVideoDimensions.height;
                
        DebugLog(@"videoVideoDimensions width:%f,height:%f", width, height);
        [cameraVideoCapturer startRunning];
//        [cameraVideoCapturer startCaptureWithDevice:camera format:formatNilable fps:fps completionHandler:^(NSError *error) {
//            DebugLog(@"startCaptureWithDevice error:%@", error);
//        }];
        [self changeResolution:width height:height fps:(int)fps];
    }
    
    if (@available(iOS 10, *)) {
        if ([capturer isKindOfClass:[RTCFileVideoCapturer class]]) {
            RTCFileVideoCapturer *fileVideoCapturer = (RTCFileVideoCapturer *)capturer;
            [fileVideoCapturer startCapturingFromFileNamed:@"beautyPicture.mp4" onError:^(NSError * _Nonnull error) {
                DebugLog(@"startCaptureLocalVideo startCapturingFromFileNamed error:%@", error);
            }];
        }
    } else {
        // Fallback on earlier versions
    }
    
    [self.localVideoTrack addRenderer:renderer];
}

- (void)renderRemoteVideo:(id<RTCVideoRenderer>)renderer {
    if (!self.isPublish) {
        return;
    }
    
    self.remoteRenderView = renderer;
}

- (RTCDataChannel *)createDataChannel {
    RTCDataChannelConfiguration *config = [[RTCDataChannelConfiguration alloc] init];
    RTCDataChannel *dataChannel = [self.peerConnection dataChannelForLabel:@"WebRTCData" configuration:config];
    if (!dataChannel) {
        return nil;
    }
    
    dataChannel.delegate = self;
    self.localDataChannel = dataChannel;
    return dataChannel;
}

- (void)sendData:(NSData *)data {
    RTCDataBuffer *buffer = [[RTCDataBuffer alloc] initWithData:data isBinary:YES];
    [self.remoteDataChannel sendData:buffer];
}

#pragma mark - switchCamera
- (void)switchCamera:(id<RTCVideoRenderer>)renderer {
    self.usingFrontCamera = !self.usingFrontCamera;
    [self startCaptureLocalVideo:renderer];
}

#pragma mark - 更改分辨率
- (BOOL)changeResolution:(int)width height:(int)height fps:(int)fps {
    if (!self.localVideoSource) {
        RTCVideoSource *videoSource = [self.factory videoSource];
        [videoSource adaptOutputFormatToWidth:width height:height fps:fps];
    } else {
        [self.localVideoSource adaptOutputFormatToWidth:width height:height fps:fps];
    }
    return YES;
}

#pragma mark - Hiden or show Video
- (void)hidenVideo {
    [self setVideoEnabled:NO];
    self.localVideoTrack.isEnabled = NO;
}

- (void)showVideo {
    [self setVideoEnabled:YES];
    self.localVideoTrack.isEnabled = YES;
}

- (void)setVideoEnabled:(BOOL)isEnabled {
    [self setTrackEnabled:[RTCVideoTrack class] isEnabled:isEnabled];
}

- (void)setTrackEnabled:(Class)track isEnabled:(BOOL)isEnabled {
    for (RTCRtpTransceiver *transceiver in self.peerConnection.transceivers) {
        if (transceiver && [transceiver isKindOfClass:track]) {
            transceiver.sender.track.isEnabled = isEnabled;
        }
    }
}


#pragma mark - Hiden or show Audio
- (void)muteAudio {
    [self setAudioEnabled:NO];
    self.localAudioTrack.isEnabled = NO;
}

- (void)unmuteAudio {
    [self setAudioEnabled:YES];
    self.localAudioTrack.isEnabled = YES;
}

- (void)speakOff {
    __weak typeof(self) weakSelf = self;
    dispatch_async(self.audioQueue, ^{
        [weakSelf.rtcAudioSession lockForConfiguration];
        @try {
            
            NSError *error;
            [self.rtcAudioSession setCategory:AVAudioSessionCategoryPlayAndRecord withOptions:AVAudioSessionCategoryOptionDefaultToSpeaker error:&error];
            
            NSError *ooapError;
            [self.rtcAudioSession overrideOutputAudioPort:AVAudioSessionPortOverrideNone error:&ooapError];
            DebugLog(@"speakOff error:%@, ooapError:%@", error, ooapError);
        } @catch (NSException *exception) {
            DebugLog(@"speakOff exception:%@", exception);
        }
        [weakSelf.rtcAudioSession unlockForConfiguration];
    });
}

- (void)speakOn {
    __weak typeof(self) weakSelf = self;
    dispatch_async(self.audioQueue, ^{
        [weakSelf.rtcAudioSession lockForConfiguration];
        @try {
            
            NSError *error;
            [self.rtcAudioSession setCategory:AVAudioSessionCategoryPlayAndRecord withOptions:AVAudioSessionCategoryOptionDefaultToSpeaker error:&error];
            
            NSError *ooapError;
            [self.rtcAudioSession overrideOutputAudioPort:AVAudioSessionPortOverrideSpeaker error:&ooapError];
            
            NSError *activeError;
            [self.rtcAudioSession setActive:YES error:&activeError];
            
            DebugLog(@"speakOn error:%@, ooapError:%@, activeError:%@", error, ooapError, activeError);
        } @catch (NSException *exception) {
            DebugLog(@"speakOn exception:%@", exception);
        }
        [weakSelf.rtcAudioSession unlockForConfiguration];
    });
}

- (void)setAudioEnabled:(BOOL)isEnabled {
    [self setTrackEnabled:[RTCAudioTrack class] isEnabled:isEnabled];
}

- (void)close {
    RTCVideoCapturer *capturer = self.videoCapturer;
    if ([capturer isKindOfClass:[SDCustomRTCCameraCapturer class]]) {
        SDCustomRTCCameraCapturer *cameraVideoCapturer = (SDCustomRTCCameraCapturer *)capturer;
        [cameraVideoCapturer stopRunning];
    }
    [self.peerConnection close];
    self.peerConnection = nil;
    self.videoCapturer = nil;
}

#pragma mark - RTCPeerConnectionDelegate
/** Called when the SignalingState changed. */
- (void)peerConnection:(RTCPeerConnection *)peerConnection
didChangeSignalingState:(RTCSignalingState)stateChanged {
    DebugLog(@"peerConnection didChangeSignalingState:%ld", (long)stateChanged);
}

/** Called when media is received on a new stream from remote peer. */
- (void)peerConnection:(RTCPeerConnection *)peerConnection didAddStream:(RTCMediaStream *)stream {
    DebugLog(@"peerConnection didAddStream");
    if (self.isPublish) {
        return;
    }
    
    NSArray *videoTracks = stream.videoTracks;
    if (videoTracks && videoTracks.count > 0) {
        RTCVideoTrack *track = videoTracks.firstObject;
        self.remoteVideoTrack = track;
    }
    
    if (self.remoteVideoTrack && self.remoteRenderView) {
        id<RTCVideoRenderer> remoteRenderView = self.remoteRenderView;
        RTCVideoTrack *remoteVideoTrack = self.remoteVideoTrack;
        [remoteVideoTrack addRenderer:remoteRenderView];
    }
    
    /**
     if let audioTrack = stream.audioTracks.first{
     print("audio track faund")
     audioTrack.source.volume = 8
     }
     */
}

/** Called when a remote peer closes a stream.
 *  This is not called when RTCSdpSemanticsUnifiedPlan is specified.
 */
- (void)peerConnection:(RTCPeerConnection *)peerConnection didRemoveStream:(RTCMediaStream *)stream {
    DebugLog(@"peerConnection didRemoveStream");
}

/** Called when negotiation is needed, for example ICE has restarted. */
- (void)peerConnectionShouldNegotiate:(RTCPeerConnection *)peerConnection {
    DebugLog(@"peerConnection peerConnectionShouldNegotiate");
}

/** Called any time the IceConnectionState changes. */
- (void)peerConnection:(RTCPeerConnection *)peerConnection
    didChangeIceConnectionState:(RTCIceConnectionState)newState {
    DebugLog(@"peerConnection didChangeIceConnectionState:%ld", newState);
    if (self.delegate && [self.delegate respondsToSelector:@selector(webRTCClient:didChangeConnectionState:)]) {
        [self.delegate webRTCClient:self didChangeConnectionState:newState];
    }
    
    if (RTCIceConnectionStateConnected == newState || RTCIceConnectionStateChecking == newState) {
        [self setDegradationPreference:RTCDegradationPreferenceMaintainResolution];
    }
}

/** Called any time the IceGatheringState changes. */
- (void)peerConnection:(RTCPeerConnection *)peerConnection
    didChangeIceGatheringState:(RTCIceGatheringState)newState {
    DebugLog(@"peerConnection didChangeIceGatheringState:%ld", newState);
}

/** New ice candidate has been found. */
- (void)peerConnection:(RTCPeerConnection *)peerConnection
    didGenerateIceCandidate:(RTCIceCandidate *)candidate {
    DebugLog(@"peerConnection didGenerateIceCandidate:%@", candidate);
    if (self.delegate && [self.delegate respondsToSelector:@selector(webRTCClient:didDiscoverLocalCandidate:)]) {
        [self.delegate webRTCClient:self didDiscoverLocalCandidate:candidate];
    }
}

/** Called when a group of local Ice candidates have been removed. */
- (void)peerConnection:(RTCPeerConnection *)peerConnection
    didRemoveIceCandidates:(NSArray<RTCIceCandidate *> *)candidates {
    DebugLog(@"peerConnection didRemoveIceCandidates:%@", candidates);
}

/** New data channel has been opened. */
- (void)peerConnection:(RTCPeerConnection *)peerConnection
    didOpenDataChannel:(RTCDataChannel *)dataChannel {
    DebugLog(@"peerConnection didOpenDataChannel:%@", dataChannel);
    self.remoteDataChannel = dataChannel;
}

/** Called when signaling indicates a transceiver will be receiving media from
 *  the remote endpoint.
 *  This is only called with RTCSdpSemanticsUnifiedPlan specified.
 */
- (void)peerConnection:(RTCPeerConnection *)peerConnection
    didStartReceivingOnTransceiver:(RTCRtpTransceiver *)transceiver {
    DebugLog(@"peerConnection didStartReceivingOnTransceiver:%@", transceiver);
}

/** Called when a receiver and its track are created. */
- (void)peerConnection:(RTCPeerConnection *)peerConnection
        didAddReceiver:(RTCRtpReceiver *)rtpReceiver
               streams:(NSArray<RTCMediaStream *> *)mediaStreams {
    DebugLog(@"peerConnection didAddReceiver");
}

/** Called when the receiver and its track are removed. */
- (void)peerConnection:(RTCPeerConnection *)peerConnection
     didRemoveReceiver:(RTCRtpReceiver *)rtpReceiver {
    DebugLog(@"peerConnection didRemoveReceiver");
}

#pragma mark - RTCDataChannelDelegate
/** The data channel state changed. */
- (void)dataChannelDidChangeState:(RTCDataChannel *)dataChannel {
    DebugLog(@"dataChannelDidChangeState:%@", dataChannel);
}

/** The data channel successfully received a data buffer. */
- (void)dataChannel:(RTCDataChannel *)dataChannel
didReceiveMessageWithBuffer:(RTCDataBuffer *)buffer {
    if (self.delegate && [self.delegate respondsToSelector:@selector(webRTCClient:didReceiveData:)]) {
        [self.delegate webRTCClient:self didReceiveData:buffer.data];
    }
}

#pragma mark - RTCVideoCapturerDelegate处理代理
- (void)capturer:(RTCVideoCapturer *)capturer didCaptureVideoFrame:(RTCVideoFrame *)frame {
//    DebugLog(@"capturer:%@ didCaptureVideoFrame:%@", capturer, frame);
//    RTCVideoFrame *aFilterVideoFrame;
//    if (self.delegate && [self.delegate respondsToSelector:@selector(webRTCClient:didCaptureVideoFrame:)]) {
//        aFilterVideoFrame = [self.delegate webRTCClient:self didCaptureVideoFrame:frame];
//    }
    
    //  操作C 需要手动释放  否则内存暴涨
//      CVPixelBufferRelease(_buffer)
    //    拿到pixelBuffersampleBuffer
//        ((RTCCVPixelBuffer*)frame.buffer).pixelBuffer
    
//    if (!aFilterVideoFrame) {
//        aFilterVideoFrame = frame;
//    }
//
//    [self.localVideoSource capturer:capturer didCaptureVideoFrame:frame];
}

- (void)rtcCameraVideoCapturer:(RTCVideoCapturer *)capturer didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer {

    CVPixelBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);

    RTCCVPixelBuffer *rtcPixelBuffer =
    [[RTCCVPixelBuffer alloc] initWithPixelBuffer:videoPixelBufferRef];
    RTCCVPixelBuffer *rtcPixelBuffer = [[RTCCVPixelBuffer alloc] initWithPixelBuffer:pixelBuffer];
    int64_t timeStampNs = CMTimeGetSeconds(CMSampleBufferGetPresentationTimeStamp(sampleBuffer)) *
    1000000000;
    RTCVideoFrame *rtcVideoFrame = [[RTCVideoFrame alloc] initWithBuffer:rtcPixelBuffer     

    
    [self.localVideoSource capturer:capturer didCaptureVideoFrame:rtcVideoFrame];
}

#pragma mark - Lazy
- (RTCPeerConnectionFactory *)factory {
    if (!_factory) {
        RTCInitializeSSL();
        RTCDefaultVideoEncoderFactory *videoEncoderFactory = [[RTCDefaultVideoEncoderFactory alloc] init];
        
        RTCDefaultVideoDecoderFactory *videoDecoderFactory = [[RTCDefaultVideoDecoderFactory alloc] init];
        _factory = [[RTCPeerConnectionFactory alloc] initWithEncoderFactory:videoEncoderFactory decoderFactory:videoDecoderFactory];
    }
    return _factory;
}

- (dispatch_queue_t)audioQueue {
    if (!_audioQueue) {
        _audioQueue = dispatch_queue_create("cn.dface.webrtc", NULL);
    }
    return _audioQueue;
}

- (RTCAudioSession *)rtcAudioSession {
    if (!_rtcAudioSession) {
        _rtcAudioSession = [RTCAudioSession sharedInstance];
    }
    
    return _rtcAudioSession;
}

- (NSDictionary *)mediaConstrains {
    if (!_mediaConstrains) {
        _mediaConstrains = [[NSDictionary alloc] initWithObjectsAndKeys:
                            kRTCMediaConstraintsValueFalse, kRTCMediaConstraintsOfferToReceiveAudio,
                            kRTCMediaConstraintsValueFalse, kRTCMediaConstraintsOfferToReceiveVideo,
                            kRTCMediaConstraintsValueTrue, @"IceRestart",
                            nil];
    }
    return _mediaConstrains;
}

- (NSDictionary *)publishMediaConstrains {
    if (!_publishMediaConstrains) {
        _publishMediaConstrains = [[NSDictionary alloc] initWithObjectsAndKeys:
                                   kRTCMediaConstraintsValueFalse, kRTCMediaConstraintsOfferToReceiveAudio,
                                   kRTCMediaConstraintsValueFalse, kRTCMediaConstraintsOfferToReceiveVideo,
                                   kRTCMediaConstraintsValueTrue, @"IceRestart",
                                   kRTCMediaConstraintsValueTrue, @"googCpuOveruseDetection",
                                   kRTCMediaConstraintsValueFalse, @"googBandwidthLimitedResolution",
//                                   @"2160", kRTCMediaConstraintsMinWidth,
//                                   @"3840", kRTCMediaConstraintsMinHeight,
//                                   @"0.25", kRTCMediaConstraintsMinAspectRatio,
//                                   @"1", kRTCMediaConstraintsMaxAspectRatio,
                                   nil];
    }
    return _publishMediaConstrains;
}

- (NSDictionary *)playMediaConstrains {
    if (!_playMediaConstrains) {
        _playMediaConstrains = [[NSDictionary alloc] initWithObjectsAndKeys:
                                kRTCMediaConstraintsValueTrue, kRTCMediaConstraintsOfferToReceiveAudio,
                                kRTCMediaConstraintsValueTrue, kRTCMediaConstraintsOfferToReceiveVideo,
                                kRTCMediaConstraintsValueTrue, @"IceRestart",
                                kRTCMediaConstraintsValueTrue, @"googCpuOveruseDetection",
                                kRTCMediaConstraintsValueFalse, @"googBandwidthLimitedResolution",
//                                @"2160", kRTCMediaConstraintsMinWidth,
//                                @"3840", kRTCMediaConstraintsMinHeight,
//                                @"0.25", kRTCMediaConstraintsMinAspectRatio,
//                                @"1", kRTCMediaConstraintsMaxAspectRatio,
                                nil];
    }
    return _playMediaConstrains;
}

- (NSDictionary *)optionalConstraints {
    if (!_optionalConstraints) {
        _optionalConstraints = [[NSDictionary alloc] initWithObjectsAndKeys:
                                kRTCMediaConstraintsValueTrue, @"DtlsSrtpKeyAgreement",
                                kRTCMediaConstraintsValueTrue, @"googCpuOveruseDetection",
                                nil];
    }
    return _optionalConstraints;
}

- (void)dealloc {
    [self.peerConnection close];
    self.peerConnection = nil;
}

@end

至此WebRTC视频自定义RTCVideoCapturer相机完毕。

其他
之前搭建ossrs服务，可以查看：https://blog.csdn.net/gloryFlow/article/details/132257196
之前实现iOS端调用ossrs音视频通话，可以查看：https://blog.csdn.net/gloryFlow/article/details/132262724
之前WebRTC音视频通话高分辨率不显示画面问题，可以查看：https://blog.csdn.net/gloryFlow/article/details/132240952
修改SDP中的码率Bitrate，可以查看：https://blog.csdn.net/gloryFlow/article/details/132263021
GPUImage视频通话视频美颜滤镜，可以查看：https://blog.csdn.net/gloryFlow/article/details/132265842
RTC直播本地视频或相册视频，可以查看：https://blog.csdn.net/gloryFlow/article/details/132267068

四、小结

WebRTC音视频通话-WebRTC视频自定义RTCVideoCapturer相机。主要获得相机采集的画面CVPixelBufferRef，将处理后的CVPixelBufferRef生成RTCVideoFrame，通过调用WebRTC的localVideoSource中实现的didCaptureVideoFrame方法。内容较多，描述可能不准确，请见谅。

https://blog.csdn.net/gloryFlow/article/details/132308673

学习记录，每天不停进步。