IOS音视频（二）AVFoundation视频捕捉

// Create the capture session.
let captureSession = AVCaptureSession()
// Find the default audio device.
guard let audioDevice = AVCaptureDevice.default(for: .audio) else { return }
do {
    // Wrap the audio device in a capture device input.
    let audioInput = try AVCaptureDeviceInput(device: audioDevice)
    // If the input can be added, add it to the session.
    if captureSession.canAddInput(audioInput) {
        captureSession.addInput(audioInput)
} catch {
    // Configuration failed. Handle error.
}

 self.captureVideoInput = [AVCaptureDeviceInput deviceInputWithDevice:self.activeVideoDevice error:&videoError];
    if (self.captureVideoInput) {
        if ([self.captureSession canAddInput:self.captureVideoInput]){
            [self.captureSession addInput:self.captureVideoInput];
    } else if (videoError) {
    }

#import <AVFoundation/AVFoundation.h>
extern NSString *const THThumbnailCreatedNotification;
@protocol THCameraControllerDelegate <NSObject>
// 1发生错误事件是，需要在对象委托上调用一些方法来处理
- (void)deviceConfigurationFailedWithError:(NSError *)error;
- (void)mediaCaptureFailedWithError:(NSError *)error;
- (void)assetLibraryWriteFailedWithError:(NSError *)error;
@interface THCameraController : NSObject
@property (weak, nonatomic) id<THCameraControllerDelegate> delegate;
@property (nonatomic, strong, readonly) AVCaptureSession *captureSession;
// 2 用于设置、配置视频捕捉会话
- (BOOL)setupSession:(NSError **)error;
- (void)startSession;
- (void)stopSession;
// 3 切换不同的摄像头
- (BOOL)switchCameras;
- (BOOL)canSwitchCameras;
@property (nonatomic, readonly) NSUInteger cameraCount;
@property (nonatomic, readonly) BOOL cameraHasTorch; //手电筒
@property (nonatomic, readonly) BOOL cameraHasFlash; //闪光灯
@property (nonatomic, readonly) BOOL cameraSupportsTapToFocus; //聚焦
@property (nonatomic, readonly) BOOL cameraSupportsTapToExpose;//曝光
@property (nonatomic) AVCaptureTorchMode torchMode; //手电筒模式
@property (nonatomic) AVCaptureFlashMode flashMode; //闪光灯模式
// 4 聚焦、曝光、重设聚焦、曝光的方法
- (void)focusAtPoint:(CGPoint)point;
- (void)exposeAtPoint:(CGPoint)point;
- (void)resetFocusAndExposureModes;
// 5 实现捕捉静态图片 & 视频的功能
//捕捉静态图片
- (void)captureStillImage;
//视频录制
//开始录制
- (void)startRecording;
//停止录制
- (void)stopRecording;
//获取录制状态
- (BOOL)isRecording;
//录制时间
- (CMTime)recordedDuration;
@end

/// 检测 AVAuthorization 权限
/// 传入待检查的 AVMediaType，AVMediaTypeVideo or AVMediaTypeAudio
/// 返回是否权限可用
- (BOOL)ifAVAuthorizationValid:(NSString *)targetAVMediaType grantedCallback:(void (^)())grantedCallback
    NSString *mediaType = targetAVMediaType;
    BOOL result = NO;
    if ([AVCaptureDevice respondsToSelector:@selector(authorizationStatusForMediaType:)]) {
        AVAuthorizationStatus authStatus = [AVCaptureDevice authorizationStatusForMediaType:mediaType];
        switch (authStatus) {
            case AVAuthorizationStatusNotDetermined: { // 尚未请求授权
                [AVCaptureDevice requestAccessForMediaType:targetAVMediaType completionHandler:^(BOOL granted) {
                    dispatch_async(dispatch_get_main_queue(), ^{
                        if (granted) {
                            grantedCallback();
                break;
            case AVAuthorizationStatusDenied: { // 明确拒绝
                if ([mediaType isEqualToString:AVMediaTypeVideo]) {
                    [METSettingPermissionAlertView showAlertViewWithPermissionType:METSettingPermissionTypeCamera];// 申请相机权限
                } else if ([mediaType isEqualToString:AVMediaTypeAudio]) {
                    [METSettingPermissionAlertView showAlertViewWithPermissionType:METSettingPermissionTypeMicrophone];// 申请麦克风权限
                break;
            case AVAuthorizationStatusRestricted: { // 限制权限更改
                break;
            case AVAuthorizationStatusAuthorized: { // 已授权
                result = YES;
                break;
            default: // 兜底
                break;
    return result;
}

    self.previewLayer = [[AVCaptureVideoPreviewLayer alloc] init];
    [self.previewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
    [self.previewLayer setSession:self.cameraHelper.captureSession];
    self.previewLayer.frame = CGRectMake(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT - 50);
    [self.previewImageView.layer addSublayer:self.previewLayer];

+ (Class)layerClass {
    return [AVCaptureVideoPreviewLayer class];
- (AVCaptureSession*)session {
    return [(AVCaptureVideoPreviewLayer*)self.layer session];
- (void)setSession:(AVCaptureSession *)session {
    [(AVCaptureVideoPreviewLayer*)self.layer setSession:session];
}

    self.captureSession = [[AVCaptureSession alloc]init];
    [self.captureSession setSessionPreset:(self.isVideoMode)?AVCaptureSessionPreset1280x720:AVCaptureSessionPresetPhoto];

- (void)configSessionInput
    // 摄像头输入
    NSError *videoError = [[NSError alloc] init];
    self.activeVideoDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    self.flashMode = self.activeVideoDevice.flashMode;
    self.captureVideoInput = [AVCaptureDeviceInput deviceInputWithDevice:self.activeVideoDevice error:&videoError];
    if (self.captureVideoInput) {
        if ([self.captureSession canAddInput:self.captureVideoInput]){
            [self.captureSession addInput:self.captureVideoInput];
    } else if (videoError) {
    if (self.isVideoMode) {
        // 麦克风输入
        NSError *audioError = [[NSError alloc] init];
        AVCaptureDeviceInput




    
 *audioInput = [AVCaptureDeviceInput deviceInputWithDevice:[AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeAudio] error:&audioError];
        if (audioInput) {
            if ([self.captureSession canAddInput:audioInput]) {
                [self.captureSession addInput:audioInput];
        } else if (audioError) {
}

- (void)configSessionOutput
    if (self.isVideoMode) {
        // 视频输出
        self.movieFileOutput = [[AVCaptureMovieFileOutput alloc] init];
        if ([self.captureSession canAddOutput:self.movieFileOutput]) {
            [self.captureSession addOutput:self.movieFileOutput];
    } else {
        // 图片输出
        self.imageOutput = [[AVCaptureStillImageOutput alloc] init];
        self.imageOutput.outputSettings = @{AVVideoCodecKey:AVVideoCodecJPEG};// 配置 outputSetting 属性，表示希望捕捉 JPEG 格式的图片
        if ([self.captureSession canAddOutput:self.imageOutput]) {
            [self.captureSession addOutput:self.imageOutput];
}

- (BOOL)setupSession:(NSError **)error {
    //创建捕捉会话。AVCaptureSession 是捕捉场景的中心枢纽
    self.captureSession = [[AVCaptureSession alloc]init];
     AVCaptureSessionPresetHigh
     AVCaptureSessionPresetMedium
     AVCaptureSessionPresetLow
     AVCaptureSessionPreset640x480
     AVCaptureSessionPreset1280x720
     AVCaptureSessionPresetPhoto
    //设置图像的分辨率
    self.captureSession.sessionPreset = AVCaptureSessionPresetHigh;
    //拿到默认视频捕捉设备 iOS系统返回后置摄像头
    AVCaptureDevice *videoDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    //将捕捉设备封装成AVCaptureDeviceInput
    //注意：为会话添加捕捉设备，必须将设备封装成AVCaptureDeviceInput对象
    AVCaptureDeviceInput *videoInput = [AVCaptureDeviceInput deviceInputWithDevice:videoDevice error:error];
    //判断videoInput是否有效
    if (videoInput)
        //canAddInput：测试是否能被添加到会话中
        if ([self.captureSession canAddInput:videoInput])
            //将videoInput 添加到 captureSession中
            [self.captureSession addInput:videoInput];
            self.activeVideoInput = videoInput;
    }else
        return NO;
    //选择默认音频捕捉设备 即返回一个内置麦克风
    AVCaptureDevice *audioDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeAudio];
    //为这个设备创建一个捕捉设备输入
    AVCaptureDeviceInput *audioInput = [AVCaptureDeviceInput deviceInputWithDevice:audioDevice error:error];
    //判断audioInput是否有效
    if (audioInput) {
        //canAddInput：测试是否能被添加到会话中
        if ([self.captureSession canAddInput:audioInput])
            //将audioInput 添加到 captureSession中
            [self.captureSession addInput:audioInput];
    }else
        return NO;
    //AVCaptureStillImageOutput 实例 从摄像头捕捉静态图片
    self.imageOutput = [[AVCaptureStillImageOutput alloc]init];
    //配置字典：希望捕捉到JPEG格式的图片
    self.imageOutput.outputSettings = @{AVVideoCodecKey:AVVideoCodecJPEG};
    //输出连接 判断是否可用，可用则添加到输出连接中去
    if ([self.captureSession canAddOutput:self.imageOutput])
        [self.captureSession addOutput:self.imageOutput];
    //创建一个AVCaptureMovieFileOutput 实例，用于将Quick Time 电影录制到文件系统
    self.movieOutput = [[AVCaptureMovieFileOutput alloc]init];
    //输出连接 判断是否可用，可用则添加到输出连接中去
    if ([self.captureSession canAddOutput:self.movieOutput])
        [self.captureSession addOutput:self.movieOutput];
    self.videoQueue = dispatch_queue_create("com.kongyulu.VideoQueue", NULL);
    return YES;
}

- (void)startSession {
    //检查是否处于运行状态
    if (![self.captureSession isRunning])
        //使用同步调用会损耗一定的时间，则用异步的方式处理
        dispatch_async(self.videoQueue, ^{
            [self.captureSession startRunning];
- (void)stopSession {
    //检查是否处于运行状态
    if ([self.captureSession isRunning])
        //使用异步方式，停止运行
        dispatch_async(self.videoQueue, ^{
            [self.captureSession stopRunning];
}

typedef NS_ENUM(NSInteger, AVCaptureDevicePosition) {
    AVCaptureDevicePositionUnspecified = 0, // 未知
    AVCaptureDevicePositionBack        = 1, // 后置摄像头
    AVCaptureDevicePositionFront       = 2, // 前置摄像头
}

- (AVCaptureDevice *)activeCamera {
    //返回当前捕捉会话对应的摄像头的device 属性
    return self.activeVideoInput.device;
//返回当前未激活的摄像头
- (AVCaptureDevice *)inactiveCamera {
    //通过查找当前激活摄像头的反向摄像头获得，如果设备只有1个摄像头，则返回nil
       AVCaptureDevice *device = nil;
      if (self.cameraCount > 1)
          if ([self activeCamera].position == AVCaptureDevicePositionBack) {
               device = [self cameraWithPosition:AVCaptureDevicePositionFront];
         }else
             device = [self cameraWithPosition:AVCaptureDevicePositionBack];
    return device;
}

//判断是否有超过1个摄像头可用
- (BOOL)canSwitchCameras {
    return self.cameraCount > 1;
}

//可用视频捕捉设备的数量
- (NSUInteger)cameraCount {
     return [[AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo] count];
}

#pragma mark - Device Configuration   配置摄像头支持的方法
- (AVCaptureDevice *)cameraWithPosition:(AVCaptureDevicePosition)position {
    //获取可用视频设备
    NSArray *devicess = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    //遍历可用的视频设备 并返回position 参数值
    for (AVCaptureDevice *device in devicess)
        if (device.position == position) {
            return device;
    return nil;
}

//切换摄像头
- (BOOL)switchCameras {
    //判断是否有多个摄像头
    if (![self canSwitchCameras])
        return NO;
    //获取当前设备的反向设备
    NSError *error;
    AVCaptureDevice *videoDevice = [self inactiveCamera];
    //将输入设备封装成AVCaptureDeviceInput
    AVCaptureDeviceInput *videoInput = [AVCaptureDeviceInput deviceInputWithDevice:videoDevice error:&error];
    //判断videoInput 是否为nil
    if (videoInput)
        //标注原配置变化开始
        [self.captureSession beginConfiguration];
        //将捕捉会话中，原本的捕捉输入设备移除
        [self.captureSession removeInput:self.activeVideoInput];
        //判断新的设备是否能加入
        if ([self.captureSession




    
 canAddInput:videoInput])
            //能加入成功，则将videoInput 作为新的视频捕捉设备
            [self.captureSession addInput:videoInput];
            //将获得设备 改为 videoInput
            self.activeVideoInput = videoInput;
        }else
            //如果新设备，无法加入。则将原本的视频捕捉设备重新加入到捕捉会话中
            [self.captureSession addInput:self.activeVideoInput];
        //配置完成后， AVCaptureSession commitConfiguration 会分批的将所有变更整合在一起。
        [self.captureSession commitConfiguration];
    }else
        //创建AVCaptureDeviceInput 出现错误，则通知委托来处理该错误
        [self.delegate deviceConfigurationFailedWithError:error];
        return NO;
    return YES;
}

//这里 beginConfiguration 和 commitConfiguration 可以使修改操作成为原子性操作，保证设备运行安全。
            [self.captureSession beginConfiguration];// 开始配置新的视频输入
            [self.captureSession removeInput:self.captureVideoInput]; // 首先移除旧的 input，才能加入新的 input
            if ([self.captureSession canAddInput:newInput]) {
                [self.captureSession addInput:newInput];
                self.activeVideoDevice = newActiveDevice;
                self.captureVideoInput = newInput;
            } else {
                [self.captureSession addInput:self.captureVideoInput];
            [self.captureSession commitConfiguration];

#pragma mark - Focus Methods 点击聚焦方法的实现
- (BOOL)cameraSupportsTapToFocus {
    //询问激活中的摄像头是否支持兴趣点对焦
    return [[self activeCamera]isFocusPointOfInterestSupported];
- (void)focusAtPoint:(CGPoint)point {
    AVCaptureDevice *device = [self activeCamera];
    //是否支持兴趣点对焦 & 是否自动对焦模式
    if (device.isFocusPointOfInterestSupported && [device isFocusModeSupported:AVCaptureFocusModeAutoFocus]) {
        NSError *error;
        //锁定设备准备配置，如果获得了锁
        if ([device lockForConfiguration:&error]) {
            //将focusPointOfInterest属性设置CGPoint
            device.focusPointOfInterest = point;
            //focusMode 设置为AVCaptureFocusModeAutoFocus
            device.focusMode = AVCaptureFocusModeAutoFocus;
            //释放该锁定
            [device unlockForConfiguration];
        }else{
            //错误时，则返回给错误处理代理
            [self.delegate deviceConfigurationFailedWithError:error];
}

- (BOOL)cameraSupportsTapToExpose {
    //询问设备是否支持对一个兴趣点进行曝光
    return [[self activeCamera] isExposurePointOfInterestSupported];
}

static const NSString *THCameraAdjustingExposureContext;
- (void)exposeAtPoint:(CGPoint)point {
    AVCaptureDevice *device = [self activeCamera];
    AVCaptureExposureMode exposureMode =AVCaptureExposureModeContinuousAutoExposure;
    //判断是否支持 AVCaptureExposureModeContinuousAutoExposure 模式
    if (device.isExposurePointOfInterestSupported && [device isExposureModeSupported:exposureMode]) {
        [device isExposureModeSupported:exposureMode];
        NSError *error;
        //锁定设备准备配置
        if ([device lockForConfiguration:&error])
            //配置期望值
            device.exposurePointOfInterest = point;
            device.exposureMode = exposureMode;
            //判断设备是否支持锁定曝光的模式。
            if ([device isExposureModeSupported:AVCaptureExposureModeLocked]) {
                //支持，则使用kvo确定设备的adjustingExposure属性的状态。
                [device addObserver:self forKeyPath:@"adjustingExposure" options:NSKeyValueObservingOptionNew context:&THCameraAdjustingExposureContext];
            //释放该锁定
            [device unlockForConfiguration];
        }else
            [self.delegate deviceConfigurationFailedWithError:error];
}

typedef NS_ENUM(NSInteger, AVCaptureFlashMode) {
    AVCaptureFlashModeOff  = 0,
    AVCaptureFlashModeOn   = 1,
    AVCaptureFlashModeAuto = 2,
typedef NS_ENUM(NSInteger, AVCaptureTorchMode) {
    AVCaptureTorchModeOff  = 0,
    AVCaptureTorchModeOn   = 1,
    AVCaptureTorchModeAuto = 2,
}

//判断是否有闪光灯
- (BOOL)cameraHasFlash {
    return [[self activeCamera] hasFlash];
//闪光灯模式
- (AVCaptureFlashMode)flashMode {
    return [[self activeCamera] flashMode];
//设置闪光灯
- (void)setFlashMode:(AVCaptureFlashMode)flashMode {
    //获取会话
    AVCaptureDevice *device = [self activeCamera];
    //判断是否支持闪光灯模式
    if ([device isFlashModeSupported:flashMode]) {
        //如果支持，则锁定设备
        NSError *error;
        if ([device lockForConfiguration:&error]) {
            //修改闪光灯模式
            device.flashMode = flashMode;
            //修改完成，解锁释放设备
            [device unlockForConfiguration];
        }else
            [self.delegate deviceConfigurationFailedWithError:error];
}

//是否支持手电筒
- (BOOL)cameraHasTorch {
    return [[self activeCamera]hasTorch];
}

//手电筒模式
- (AVCaptureTorchMode)torchMode {
    return [[self activeCamera]torchMode];
//设置是否打开手电筒
- (void)setTorchMode:(AVCaptureTorchMode)torchMode {
    AVCaptureDevice *device = [self activeCamera];
    if ([device isTorchModeSupported:torchMode]) {
        NSError *error;
        if ([device lockForConfiguration:&error]) {
            device.torchMode = torchMode;
            [device unlockForConfiguration];
        }else
            [self.delegate deviceConfigurationFailedWithError:error];
}

    AVCaptureConnection *connection = [self.cameraHelper.imageOutput connectionWithMediaType:AVMediaTypeVideo];
    if ([connection isVideoOrientationSupported]) {
        [connection setVideoOrientation:self.cameraHelper.videoOrientation];
    if (!connection.enabled || !connection.isActive) { // connection 不可用
        // 处理非法情况
        return;
    }

    // 监测重力感应器并调整 orientation
    CMMotionManager *motionManager = [[CMMotionManager alloc] init];
    motionManager.deviceMotionUpdateInterval = 1/15.0;
    if (motionManager.deviceMotionAvailable) {
        [motionManager startDeviceMotionUpdatesToQueue:[NSOperationQueue currentQueue]
                                           withHandler: ^(CMDeviceMotion *motion, NSError *error){
                                               double x = motion.gravity.x;
                                               double y = motion.gravity.y;
                                               if (fabs(y) >= fabs(x)) { // y 轴分量大于 x 轴
                                                   if (y >= 0) { // 顶部向下
                                                       self.videoOrientation = AVCaptureVideoOrientationPortraitUpsideDown; // UIDeviceOrientationPortraitUpsideDown;
                                                   } else { // 顶部向上
                                                       self.videoOrientation = AVCaptureVideoOrientationPortrait; // UIDeviceOrientationPortrait;
                                               } else {
                                                   if (x >= 0) { // 顶部向右
                                                       self.videoOrientation = AVCaptureVideoOrientationLandscapeLeft; // UIDeviceOrientationLandscapeRight;
                                                   } else { // 顶部向左
                                                       self.videoOrientation = AVCaptureVideoOrientationLandscapeRight; // UIDeviceOrientationLandscapeLeft;
        self.motionManager = motionManager;
    } else {
        self.videoOrientation = AVCaptureVideoOrientationPortrait;
    }

    @weakify(self)
    [self.cameraHelper.imageOutput captureStillImageAsynchronouslyFromConnection:connection completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {
        @strongify(self)
        if (!error && imageDataSampleBuffer) {
            NSData *imageData = [AVCaptureStillImageOutput




    
 jpegStillImageNSDataRepresentation:imageDataSampleBuffer];
            if (!imageData) {return;}
            UIImage *image = [UIImage imageWithData:imageData];
            if (!image) {return;}
    }];

    [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
        PHAssetChangeRequest *changeRequest = [PHAssetChangeRequest creationRequestForAssetFromImage:targetImage];
        NSString *imageIdentifier = changeRequest.placeholderForCreatedAsset.localIdentifier;
    } completionHandler:^( BOOL success, NSError * _Nullable error ) {
    }];

#pragma mark - Image Capture Methods 拍摄静态图片
    AVCaptureStillImageOutput 是AVCaptureOutput的子类。用于捕捉图片
- (void)captureStillImage {
    //获取连接
    AVCaptureConnection *connection = [self.imageOutput connectionWithMediaType:AVMediaTypeVideo];
    //程序只支持纵向，但是如果用户横向拍照时，需要调整结果照片的方向
    //判断是否支持设置视频方向
    if (connection.isVideoOrientationSupported) {
        //获取方向值
        connection.videoOrientation = [self currentVideoOrientation];
    //定义一个handler 块，会返回1个图片的NSData数据
    id handler = ^(CMSampleBufferRef sampleBuffer,NSError *error)
                    if (sampleBuffer != NULL) {
                        NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:sampleBuffer];
                        UIImage *image = [[UIImage alloc]initWithData:imageData];
                        //重点：捕捉图片成功后，将图片传递出去
                        [self writeImageToAssetsLibrary:image];
                    }else
                        NSLog(@"NULL sampleBuffer:%@",[error localizedDescription]);
    //捕捉静态图片
    [self.imageOutput captureStillImageAsynchronouslyFromConnection:connection completionHandler:handler];
//获取方向值
- (AVCaptureVideoOrientation)currentVideoOrientation {
    AVCaptureVideoOrientation orientation;
    //获取UIDevice 的 orientation
    switch ([UIDevice currentDevice].orientation) {
        case UIDeviceOrientationPortrait:
            orientation = AVCaptureVideoOrientationPortrait;
            break;
        case UIDeviceOrientationLandscapeRight:
            orientation = AVCaptureVideoOrientationLandscapeLeft;
            break;
        case UIDeviceOrientationPortraitUpsideDown:
            orientation = AVCaptureVideoOrientationPortraitUpsideDown;
            break;
        default:
            orientation = AVCaptureVideoOrientationLandscapeRight;
            break;
    return orientation;
    return 0;
    Assets Library 框架 
    用来让开发者通过代码方式访问iOS photo
    注意：会访问到相册，需要修改plist 权限。否则会导致项目崩溃
- (void)writeImageToAssetsLibrary:(UIImage *)image {
    //创建ALAssetsLibrary  实例
    ALAssetsLibrary *library = [[ALAssetsLibrary alloc]init];
    //参数1:图片（参数为CGImageRef 所以image.CGImage）
    //参数2:方向参数 转为NSUInteger
    //参数3:写入成功、失败处理
    [library writeImageToSavedPhotosAlbum:image.CGImage
                             orientation:(NSUInteger)image.imageOrientation
                         completionBlock:^(NSURL *assetURL, NSError *error) {
                             //成功后，发送捕捉图片通知。用于绘制程序的左下角的缩略图
                             if (!error)
                                 [self postThumbnailNotifification:image];
                             }else
                                 //失败打印错误信息
                                 id message = [error localizedDescription];
                                 NSLog(@"%@",message);
//发送缩略图通知
- (void)postThumbnailNotifification:(UIImage *)image {
    //回到主队列
    dispatch_async(dispatch_get_main_queue(), ^{
        //发送请求
        NSNotificationCenter *nc = [NSNotificationCenter defaultCenter];
        [nc postNotificationName:THThumbnailCreatedNotification object:image];
}

    AVCaptureConnection *videoConnection = [self.cameraHelper.movieFileOutput connectionWithMediaType:AVMediaTypeVideo];
    if ([videoConnection isVideoOrientationSupported]) {
        [videoConnection setVideoOrientation:self.cameraHelper.videoOrientation];
    if ([videoConnection isVideoStabilizationSupported]) {
        [videoConnection setPreferredVideoStabilizationMode:AVCaptureVideoStabilizationModeAuto];
    [videoConnection setVideoScaleAndCropFactor:1.0];
    if (![self.cameraHelper.movieFileOutput isRecording] && videoConnection.isActive && videoConnection.isEnabled) {
        // 判断视频连接是否可用
        self.countTimer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(refreshTimeLabel) userInfo:nil repeats:YES];
        NSString *urlString = [NSTemporaryDirectory() stringByAppendingString:[NSString stringWithFormat:@"%.0f.mov", [[NSDate date] timeIntervalSince1970] * 1000]];
        NSURL *url = [NSURL fileURLWithPath:urlString];
        [self.cameraHelper.movieFileOutput startRecordingToOutputFileURL:url recordingDelegate:self];
        [self.captureButton setTitle:@"结束" forState:UIControlStateNormal];
    } else {
    }

- (void)saveVideo:(NSURL *)videoURL
    __block NSString *imageIdentifier;
    @weakify(self)
    [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
        // 保存视频
        PHAssetChangeRequest *changeRequest = [PHAssetChangeRequest creationRequestForAssetFromVideoAtFileURL:videoURL];
        imageIdentifier = changeRequest.placeholderForCreatedAsset.localIdentifier;
    } completionHandler:^( BOOL success, NSError * _Nullable error ) {
        @strongify(self)
        dispatch_async(dispatch_get_main_queue(), ^{
            @strongify(self)
            [self resetTimeCounter];
            if (!success) {
                // 错误处理
            } else {
                PHAsset *asset = [PHAsset fetchAssetsWithLocalIdentifiers:@[imageIdentifier] options:nil].firstObject;
                if (asset && asset.mediaType == PHAssetMediaTypeVideo) {
                    PHVideoRequestOptions *options = [[PHVideoRequestOptions alloc] init];
                    options.version = PHImageRequestOptionsVersionCurrent;
                    options.deliveryMode = PHVideoRequestOptionsDeliveryModeAutomatic;
                    [[PHImageManager defaultManager] requestAVAssetForVideo:asset options:options resultHandler:^(AVAsset * _Nullable obj, AVAudioMix * _Nullable audioMix, NSDictionary * _Nullable info) {
                        @strongify(self)
                        [self resolveAVAsset:obj identifier:asset.localIdentifier];
- (void)resolveAVAsset:(AVAsset *)asset identifier:(NSString *)identifier
    if (!asset) {
        return;
    if (![asset isKindOfClass:[AVURLAsset class]]) {
        return;
    AVURLAsset *urlAsset = (AVURLAsset *)asset;
    NSURL *url = urlAsset.URL;
    NSData *data = [NSData dataWithContentsOfURL:url];
    AVAssetImageGenerator *generator = [AVAssetImageGenerator assetImageGeneratorWithAsset:asset];
    generator.appliesPreferredTrackTransform = YES; //捕捉缩略图时考虑视频 orientation 变化，避免错误的缩略图方向
    CMTime snaptime = kCMTimeZero;
    CGImageRef cgImageRef = [generator copyCGImageAtTime:snaptime actualTime:NULL error:nil];
    UIImage *assetImage = [UIImage imageWithCGImage:cgImageRef];
    CGImageRelease(cgImageRef);
}

//判断是否录制状态
- (BOOL)isRecording {
    return self.movieOutput.isRecording;
}

//开始录制
- (void)startRecording {
    if (![self isRecording]) {
        //获取当前视频捕捉连接信息，用于捕捉视频数据配置一些核心属性
        AVCaptureConnection * videoConnection = [self.movieOutput connectionWithMediaType:AVMediaTypeVideo];
        //判断是否支持设置videoOrientation 属性。
        if([videoConnection isVideoOrientationSupported])
            //支持则修改当前视频的方向
            videoConnection.videoOrientation = [self currentVideoOrientation];
        //判断是否支持视频稳定 可以显著提高视频的质量。只会在录制视频文件涉及
        if([videoConnection isVideoStabilizationSupported])
            videoConnection.enablesVideoStabilizationWhenAvailable = YES;
        AVCaptureDevice *device = [self activeCamera];
        //摄像头可以进行平滑对焦模式操作。即减慢摄像头镜头对焦速度。当用户移动拍摄时摄像头会尝试快速自动对焦。
        if (device.isSmoothAutoFocusEnabled) {
            NSError *error;
            if ([device lockForConfiguration:&error]) {
                device.smoothAutoFocusEnabled = YES;
                [device unlockForConfiguration];
            }else
                [self.delegate deviceConfigurationFailedWithError:error];
        //查找写入捕捉视频的唯一文件系统URL.
        self.outputURL = [self uniqueURL];
        //在捕捉输出上调用方法 参数1:录制保存路径  参数2:代理
        [self.movieOutput startRecordingToOutputFileURL:self.outputURL recordingDelegate:self];
- (CMTime)recordedDuration {
    return self.movieOutput.recordedDuration;
//写入视频唯一文件系统URL
- (NSURL *)uniqueURL {
    NSFileManager *fileManager = [NSFileManager defaultManager];
    //temporaryDirectoryWithTemplateString  可以将文件写入的目的创建一个唯一命名的目录；
    NSString *dirPath = [fileManager temporaryDirectoryWithTemplateString:@"kamera.XXXXXX"];
    if (dirPath) {
        NSString *filePath = [dirPath stringByAppendingPathComponent:@"kamera_movie.mov"];
        return  [NSURL fileURLWithPath:filePath];
    return nil;
}

//停止录制
- (void)stopRecording {
    //是否正在录制
    if ([self isRecording]) {
        [self.movieOutput stopRecording];
}

#pragma mark - AVCaptureFileOutputRecordingDelegate
- (void)captureOutput:(AVCaptureFileOutput *)captureOutput
didFinishRecordingToOutputFileAtURL:(NSURL *)outputFileURL
      fromConnections:(NSArray *)connections
                error:(NSError *)error {
    if (error) {
        [self.delegate mediaCaptureFailedWithError:error];
    }else
        [self writeVideoToAssetsLibrary:[self.outputURL copy]];
    self.outputURL = nil;
}

//写入捕捉到的视频
- (void)writeVideoToAssetsLibrary:(NSURL *)videoURL {
    //ALAssetsLibrary 实例 提供写入视频的接口
    ALAssetsLibrary *library = [[ALAssetsLibrary alloc]init];
    //写资源库写入前，检查视频是否可被写入 （写入前尽量养成判断的习惯）
    if ([library videoAtPathIsCompatibleWithSavedPhotosAlbum:videoURL]) {
        //创建block块
        ALAssetsLibraryWriteVideoCompletionBlock completionBlock;
        completionBlock = ^(NSURL *assetURL,NSError *error)




    

            if (error) {
                [self.delegate assetLibraryWriteFailedWithError:error];
            }else
                //用于界面展示视频缩略图
                [self generateThumbnailForVideoAtURL:videoURL];
        //执行实际写入资源库的动作
        [library writeVideoAtPathToSavedPhotosAlbum:videoURL completionBlock:completionBlock];
}

//获取视频左下角缩略图
- (void)generateThumbnailForVideoAtURL:(NSURL *)videoURL {
    //在videoQueue 上，
    dispatch_async(self.videoQueue, ^{
        //建立新的AVAsset & AVAssetImageGenerator
        AVAsset *asset = [AVAsset assetWithURL:videoURL];
        AVAssetImageGenerator *imageGenerator = [AVAssetImageGenerator assetImageGeneratorWithAsset:asset];
        //设置maximumSize 宽为100，高为0 根据视频的宽高比来计算图片的高度
        imageGenerator.maximumSize = CGSizeMake(100.0f, 0.0f);
        //捕捉视频缩略图会考虑视频的变化（如视频的方向变化），如果不设置，缩略图的方向可能出错
        imageGenerator.appliesPreferredTrackTransform = YES;
        //获取CGImageRef图片 注意需要自己管理它的创建和释放
        CGImageRef imageRef = [imageGenerator copyCGImageAtTime:kCMTimeZero actualTime:NULL error:nil];
        //将图片转化为UIImage
        UIImage *image = [UIImage imageWithCGImage:imageRef];
        //释放CGImageRef imageRef 防止内存泄漏
        CGImageRelease(imageRef);
        //回到主线程
        dispatch_async(dispatch_get_main_queue(), ^{
            //发送通知，传递最新的image
            [self postThumbnailNotifification:image];
}

- (BOOL)cameraSupportsZoom
    return self.cameraHelper.activeVideoDevice.activeFormat.videoMaxZoomFactor > 1.0f;
}

// 在 iphone6s 和 iphone8plus 上测试得到此值为 2.0左右
self.cameraHelper.activeVideoDevice.activeFormat.videoZoomFactorUpscaleThreshold;

{
    [self.slider addTarget:self action:@selector(sliderValueChange:) forControlEvents:UIControlEventValueChanged];
- (void)sliderValueChange:(id)sender
    UISlider *slider = (UISlider *)sender;
    [self setZoomValue:slider.value];
- (CGFloat)maxZoomFactor
    return MIN(self.cameraHelper.activeVideoDevice.activeFormat.videoMaxZoomFactor, 4.0f);
- (void)setZoomValue:(CGFloat)zoomValue
    if (!self.cameraHelper.activeVideoDevice.isRampingVideoZoom) {
        NSError *error;
        if ([self.cameraHelper.activeVideoDevice lockForConfiguration:&error]) {
            CGFloat zoomFactor = pow([self maxZoomFactor], zoomValue);
            self.cameraHelper.activeVideoDevice.videoZoomFactor = zoomFactor;
            [self.cameraHelper.activeVideoDevice unlockForConfiguration];
}

- (void)rampZoomToValue:(CGFloat)zoomValue {
    CGFloat zoomFactor = pow([self maxZoomFactor], zoomValue);
    NSError *error;
    if ([self.activeCamera lockForConfiguration:&error]) {
        [self.activeCamera rampToVideoZoomFactor:zoomFactor
                                        withRate:THZoomRate];
        [self.activeCamera unlockForConfiguration];
    } else {
- (void)cancelZoom {
    NSError *error;
    if ([self.activeCamera lockForConfiguration:&error]) {
        [self.activeCamera cancelVideoZoomRamp];
        [self.activeCamera unlockForConfiguration];
    } else {
}

    [RACObserve(self, activeVideoDevice.videoZoomFactor) subscribeNext:^(id x) {
        NSLog(@"videoZoomFactor: %f", self.activeVideoDevice.videoZoomFactor);
    }];

    [RACObserve(self, activeVideoDevice.rampingVideoZoom) subscribeNext:^(id x) {
        NSLog(@"rampingVideoZoom : %@", (self.activeVideoDevice.rampingVideoZoom)?@"true":@"false");
    }];

- (void)captureOutput:(AVCaptureOutput *)output didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection; // 有新的视频帧写入时调用，数据会基于 output 的 videoSetting 进行解码或重新编码
- (void)captureOutput:(AVCaptureOutput *)output didDropSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection; // 有迟到的视频帧被丢弃时调用，通常是因为在上面一个方法里进行了比较耗时的操作

    int BYTES_PER_PIXEL = 4;
    CVPixelBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer); //CVPixelBufferRef 在主内存中保存像素数据
    CVPixelBufferLockBaseAddress(pixelBuffer, 0); // 获取相应内存块的锁
    size_t bufferWidth = CVPixelBufferGetWidth(pixelBuffer);
    size_t bufferHeight = CVPixelBufferGetHeight(pixelBuffer);// 获取像素宽高
    unsigned char *pixel = (unsigned char *)CVPixelBufferGetBaseAddress(pixelBuffer); // 获取像素 buffer 的起始位置
    unsigned char grayPixel;
    for (int row = 0; row < bufferHeight; row++) {
        for (int column = 0; column < bufferWidth; column ++) { // 遍历每一个像素点
            grayPixel = (pixel[0] + pixel[1] + pixel[2])/3.0;
            pixel[0] = pixel[1] = pixel[2] = grayPixel;
            pixel += BYTES_PER_PIXEL;
    CIImage *ciImage = [CIImage imageWithCVPixelBuffer:pixelBuffer]; // 通过 buffer 生成对应的 CIImage
    CVPixelBufferUnlockBaseAddress(pixelBuffer, 0); // 解除锁

    CMFormatDescriptionRef formatDescription = CMSampleBufferGetFormatDescription(sampleBuffer);
    CMMediaType mediaType = CMFormatDescriptionGetMediaType(formatDescription);

    CMTime presentation = CMSampleBufferGetPresentationTimeStamp(sampleBuffer); // 获取帧样本的原始时间戳
    CMTime decode = CMSampleBufferGetDecodeTimeStamp(sampleBuffer); // 获取帧样本的解码时间戳

    CFDictionaryRef exif = (CFDictionaryRef)CMGetAttachment(sampleBuffer, kCGImagePropertyExifDictionary, NULL);

    self.videoDataOutput = [[AVCaptureVideoDataOutput alloc] init];
    self.videoDataOutput.videoSettings = @{(id)kCVPixelBufferPixelFormatTypeKey: @(kCVPixelFormatType_32BGRA)}; // 摄像头的初始格式为双平面 420v，这是一个 YUV 格式，而 OpenGL ES 常用 BGRA 格式
    if ([self.captureSession canAddOutput:self.videoDataOutput]) {
        [self.captureSession addOutput:self.videoDataOutput];
        [self.videoDataOutput setSampleBufferDelegate:self queue:dispatch_get_main_queue()];
    }

    AVCaptureDeviceFormat *maxFormat = nil;
    AVFrameRateRange *maxFrameRateRange = nil;
    for (AVCaptureDeviceFormat *format in self.formats) {
        FourCharCode codecType = CMVideoFormatDescriptionGetCodecType(format.formatDescription);
        //codecType 是一个无符号32位的数据类型，但是是由四个字符对应的四个字节组成，一般可能值为 "420v" 或 "420f"，这里选取 420v 格式来配置。
        if (codecType == kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange) {
            NSArray *frameRateRanges = format.videoSupportedFrameRateRanges;
            for (AVFrameRateRange *range in frameRateRanges) {
                if (range.maxFrameRate > maxFrameRateRange.maxFrameRate) {
                    maxFormat = format;
                    maxFrameRateRange = range;
        } else {
    }

- (BOOL)isHighFrameRate {
    return self.frameRateRange.maxFrameRate > 30.0f;
}

    if ([self hasMediaType:AVMediaTypeVideo] && [self lockForConfiguration:error] && [self.activeCamera supportsHighFrameRateCapture]) {
        CMTime minFrameDuration = self.frameRateRange.minFrameDuration;
        self.activeFormat = self.format;
        self.activeVideoMinFrameDuration = minFrameDuration;
        self.activeVideoMaxFrameDuration = minFrameDuration;
        [self unlockForConfiguration];
    }

    self.metaDataOutput




    
 = [[AVCaptureMetadataOutput alloc] init];
    if ([self.captureSession canAddOutput:self.metaDataOutput]) {
        [self.captureSession addOutput:self.metaDataOutput];
        NSArray *metaDataObjectType = @[AVMetadataObjectTypeFace];
        self.metaDataOutput.metadataObjectTypes = metaDataObjectType;
        [self.metaDataOutput setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
    }

- (void)captureOutput:(AVCaptureOutput *)output didOutputMetadataObjects:(NSArray<__kindof AVMetadataObject *> *)metadataObjects fromConnection:(AVCaptureConnection *)connection
    if (self.detectFaces) {
        self.detectFaces(metadataObjects);
}

        @weakify(self)
        self.cameraHelper.detectFaces = ^(NSArray *faces) {
            @strongify(self)
            NSMutableArray *transformedFaces = [NSMutableArray array];
            for (AVMetadataFaceObject *face in faces) {
                AVMetadataObject *transformedFace = [self.previewLayer transformedMetadataObjectForMetadataObject:face];
                [transformedFaces addObject:transformedFace];
            NSMutableArray *lostFaces = [self.faceLayers.allKeys mutableCopy];
            for (AVMetadataFaceObject *face in transformedFaces) {
                NSNumber *faceId = @(face.faceID);
                [lostFaces removeObject:faceId];
                CALayer *layer = self.faceLayers[faceId];
                if (!layer) {
                    layer = [CALayer layer];
                    layer.borderWidth = 5.0f;
                    layer.borderColor = [UIColor colorWithRed:0.188 green:0.517 blue:0.877 alpha:1.000].CGColor;
                    [self.previewLayer addSublayer:layer];
                    self.faceLayers[faceId] = layer;
                layer.transform = CATransform3DIdentity;
                layer.frame = face.bounds;
                if (face.hasRollAngle) {
                    layer.transform = CATransform3DConcat(layer.transform, [self transformForRollAngle:face.rollAngle]);
                if (face.hasYawAngle) {
                    NSLog(@"%f", face.yawAngle);
                    layer.transform = CATransform3DConcat(layer.transform, [self transformForYawAngle:face.yawAngle]);
            for (NSNumber *faceID in lostFaces) {
                CALayer *layer = self.faceLayers[faceID];
                [layer removeFromSuperlayer];
                [self.faceLayers removeObjectForKey:faceID];
// Rotate around Z-axis
- (CATransform3D)transformForRollAngle:(CGFloat)rollAngleInDegrees {        // 3
    CGFloat rollAngleInRadians = THDegreesToRadians(rollAngleInDegrees);
    return CATransform3DMakeRotation(rollAngleInRadians, 0.0f, 0.0f, 1.0f);
// Rotate around Y-axis
- (CATransform3D)transformForYawAngle:(CGFloat)yawAngleInDegrees {          // 5
    CGFloat yawAngleInRadians = THDegreesToRadians(yawAngleInDegrees);
    CATransform3D yawTransform = CATransform3DMakeRotation(yawAngleInRadians, 0.0f, -1.0f, 0.0f);
    return CATransform3DConcat(yawTransform, [self orientationTransform]);
- (CATransform3D)orientationTransform {                                     // 6
    CGFloat angle = 0.0;
    switch ([UIDevice currentDevice].orientation) {
        case UIDeviceOrientationPortraitUpsideDown:
            angle = M_PI;
            break;
        case UIDeviceOrientationLandscapeRight:
            angle = -M_PI / 2.0f;
            break;
        case UIDeviceOrientationLandscapeLeft:
            angle = M_PI / 2.0f;
            break;
        default: // as UIDeviceOrientationPortrait
            angle = 0.0;
            break;
    return CATransform3DMakeRotation(angle, 0.0f, 0.0f, 1.0f);
static CGFloat THDegreesToRadians(CGFloat degrees) {
    return degrees * M_PI / 180;
}

    self.metaDataOutput = [[AVCaptureMetadataOutput alloc] init];
    if ([self.captureSession canAddOutput:self.metaDataOutput]) {
        [self.captureSession addOutput:self.metaDataOutput];
        [self.metaDataOutput setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
        NSArray *types = @[AVMetadataObjectTypeQRCode];
        self.metaDataOutput.metadataObjectTypes = types;
    }

- (void)captureOutput:(AVCaptureOutput *)output didOutputMetadataObjects:(NSArray<__kindof AVMetadataObject *> *)metadataObjects fromConnection:(AVCaptureConnection *)connection
    [metadataObjects enumerateObjectsUsingBlock:^(__kindof AVMetadataObject * _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
        if ([obj isKindOfClass:[AVMetadataMachineReadableCodeObject class]]) {
            NSLog(@"%@", ((AVMetadataMachineReadableCodeObject*)obj).stringValue);
}

- (NSArray *)transformedCodesFromCodes:(NSArray *)codes {
    NSMutableArray *transformedCodes = [NSMutableArray array];
    [codes enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
        AVMetadataObject *transformedCode = [self.previewLayer transformedMetadataObjectForMetadataObject:obj];
        [transformedCodes addObject:transformedCode];
    return [transformedCodes copy];
}

- (UIBezierPath *)bezierPathForBounds:(CGRect)bounds {
    return [UIBezierPath bezierPathWithRect:bounds];
}

- (UIBezierPath *)bezierPathForCorners:(NSArray *)corners {
    UIBezierPath *path = [UIBezierPath bezierPath];
    for (int i = 0; i < corners.count; i++) {
        CGPoint point = [self pointForCorner:corners[I]];
        if (i == 0) {
            [path moveToPoint:point];
        } else {
            [path addLineToPoint:point];
    [path closePath];
    return path;
- (CGPoint)pointForCorner:(NSDictionary *)corner {
    CGPoint point;
    CGPointMakeWithDictionaryRepresentation((CFDictionaryRef)corner, &point);
    return point;
}

 private let session = AVCaptureSession()

switch currentPosition {
case .unspecified, .front:
    preferredPosition = .back
    preferredDeviceType = .builtInDualCamera
case .back:
    preferredPosition = .front
    preferredDeviceType = .builtInTrueDepthCamera
@unknown default:
    print("Unknown capture position. Defaulting to back, dual-camera.")
    preferredPosition = .back
    preferredDeviceType = .builtInDualCamera
}

// Remove the existing device input first, because AVCaptureSession doesn't support
// simultaneous use of the rear and front cameras.
self.session.removeInput(self.videoDeviceInput)
if self.session.canAddInput(videoDeviceInput) {
    NotificationCenter.default.removeObserver(self, name: .AVCaptureDeviceSubjectAreaDidChange, object: currentVideoDevice)
    NotificationCenter.default.addObserver(self, selector: #selector(self.subjectAreaDidChange), name: .AVCaptureDeviceSubjectAreaDidChange, object: videoDeviceInput.device)
    self.session.addInput(videoDeviceInput)
    self.videoDeviceInput = videoDeviceInput
} else {
    self.session.addInput(self.videoDeviceInput)

NotificationCenter.default.addObserver(self,
                                       selector: #selector(sessionWasInterrupted),
                                       name: .AVCaptureSessionWasInterrupted,
                                       object: session)
NotificationCenter.default.addObserver(self,
                                       selector: #selector(sessionInterruptionEnded),
                                       name: .AVCaptureSessionInterruptionEnded,
                                       object: session)

if reason == .audioDeviceInUseByAnotherClient || reason == .videoDeviceInUseByAnotherClient {
    showResumeButton = true
} else if reason == .videoDeviceNotAvailableWithMultipleForegroundApps {
    // Fade-in a label to inform the user that the camera is unavailable.
    cameraUnavailableLabel.alpha = 0
    cameraUnavailableLabel.isHidden = false
    UIView.animate(withDuration: 0.25) {
        self.cameraUnavailableLabel.alpha = 1
} else if reason == .videoDeviceNotAvailableDueToSystemPressure {
    print("Session stopped running due to shutdown system pressure level.")
}

NotificationCenter.default.addObserver(self,
                                       selector: #selector(sessionRuntimeError),
                                       name: .AVCaptureSessionRuntimeError,
                                       object: session)

// If media services were reset, and the last start succeeded, restart the session.
if error.code == .mediaServicesWereReset {
    sessionQueue.async {
        if self.isSessionRunning {
            self.session.startRunning()
            self.isSessionRunning = self.session.isRunning
        } else {
            DispatchQueue.main.async {
                self.resumeButton.isHidden = false
} else {
    resumeButton.isHidden = false

let pressureLevel = systemPressureState.level
if pressureLevel == .serious || pressureLevel == .critical {
    if self.movieFileOutput == nil || self.movieFileOutput?.isRecording == false {
        do {
            try self.videoDeviceInput.device.lockForConfiguration()
            print("WARNING: Reached elevated system pressure level: \(pressureLevel). Throttling frame rate.")
            self.videoDeviceInput.device.activeVideoMinFrameDuration = CMTime(value: 1, timescale: 20)




    

            self.videoDeviceInput.device.activeVideoMaxFrameDuration = CMTime(value: 1, timescale: 15)
            self.videoDeviceInput.device.unlockForConfiguration()
        } catch {
            print("Could not lock device for configuration: \(error)")
} else if pressureLevel == .shutdown {
    print("Session stopped running due to shutdown system pressure level.")
}

if let photoOutputConnection = self.photoOutput.connection(with: .video) {
    photoOutputConnection.videoOrientation = videoPreviewLayerOrientation!
}

var photoSettings = AVCapturePhotoSettings()
// Capture HEIF photos when supported. Enable auto-flash and high-resolution photos.
if  self.photoOutput.availablePhotoCodecTypes.contains(.hevc) {
    photoSettings = AVCapturePhotoSettings(format: [AVVideoCodecKey: AVVideoCodecType.hevc])
if self.videoDeviceInput.device.isFlashAvailable {
    photoSettings.flashMode = .auto
photoSettings.isHighResolutionPhotoEnabled = true
if !photoSettings.__availablePreviewPhotoPixelFormatTypes.isEmpty {
    photoSettings.previewPhotoFormat = [kCVPixelBufferPixelFormatTypeKey as String: photoSettings.__availablePreviewPhotoPixelFormatTypes.first!]
// Live Photo capture is not supported in movie mode.
if self.livePhotoMode == .on && self.photoOutput.isLivePhotoCaptureSupported {
    let livePhotoMovieFileName = NSUUID().uuidString
    let livePhotoMovieFilePath = (NSTemporaryDirectory() as NSString).appendingPathComponent((livePhotoMovieFileName as NSString).appendingPathExtension("mov")!)
    photoSettings.livePhotoMovieFileURL = URL(fileURLWithPath: livePhotoMovieFilePath)
photoSettings.isDepthDataDeliveryEnabled = (self.depthDataDeliveryMode == .on
    && self.photoOutput.isDepthDataDeliveryEnabled)
photoSettings.isPortraitEffectsMatteDeliveryEnabled = (self.portraitEffectsMatteDeliveryMode == .on
    && self.photoOutput.isPortraitEffectsMatteDeliveryEnabled)
if photoSettings.isDepthDataDeliveryEnabled {
    if !self.photoOutput.availableSemanticSegmentationMatteTypes.isEmpty {
        photoSettings.enabledSemanticSegmentationMatteTypes = self.selectedSemanticSegmentationMatteTypes
photoSettings.photoQualityPrioritization = self.photoQualityPrioritizationMode

self.photoOutput.capturePhoto(with: photoSettings, delegate: photoCaptureProcessor)

self.sessionQueue.async {
    if capturing {
        self.inProgressLivePhotoCapturesCount += 1
    } else {
        self.inProgressLivePhotoCapturesCount -= 1
    let inProgressLivePhotoCapturesCount = self.inProgressLivePhotoCapturesCount
    DispatchQueue.main.async {
        if inProgressLivePhotoCapturesCount > 0 {
            self.capturingLivePhotoLabel.isHidden = false
        } else if inProgressLivePhotoCapturesCount == 0 {
            self.capturingLivePhotoLabel.isHidden = true
        } else {
            print("Error: In progress Live Photo capture count is less than 0.")

// Flash the screen to signal that AVCam took a photo.
DispatchQueue.main.async {
    self.previewView.videoPreviewLayer.opacity = 0
    UIView.animate(withDuration: 0.25) {
        self.previewView.videoPreviewLayer.opacity = 1
}

self.sessionQueue.async {
    self.inProgressPhotoCaptureDelegates[photoCaptureProcessor.requestedPhotoSettings.uniqueID] = nil
}

if error != nil {
    print("Error processing Live Photo companion movie: \(String(describing: error))")
    return
livePhotoCompanionMovieURL = outputFileURL

if self.photoOutput.isDepthDataDeliverySupported {
               self.photoOutput.isDepthDataDeliveryEnabled = true
               DispatchQueue.main.async {
                   self.depthDataDeliveryButton.isEnabled = true
           if self.photoOutput.isPortraitEffectsMatteDeliverySupported {
               self.photoOutput.isPortraitEffectsMatteDeliveryEnabled = true
               DispatchQueue.main.async {
                   self.portraitEffectsMatteDeliveryButton.isEnabled = true
           if !self.photoOutput.availableSemanticSegmentationMatteTypes.isEmpty {
self.photoOutput.enabledSemanticSegmentationMatteTypes = self.photoOutput.availableSemanticSegmentationMatteTypes
               self.selectedSemanticSegmentationMatteTypes = self.photoOutput.availableSemanticSegmentationMatteTypes
               DispatchQueue.main.async {
                   self.semanticSegmentationMatteDeliveryButton.isEnabled = (self.depthDataDeliveryMode == .on) ? true : false
           DispatchQueue.main.async {
               self.livePhotoModeButton.isHidden = false
               self.depthDataDeliveryButton.isHidden = false
               self.portraitEffectsMatteDeliveryButton.isHidden = false
               self.semanticSegmentationMatteDeliveryButton.isHidden = false
               self.photoQualityPrioritizationSegControl.isHidden = false
               self.photoQualityPrioritizationSegControl.isEnabled = true
           }

if var portraitEffectsMatte = photo.portraitEffectsMatte {
    if let orientation = photo.metadata[String(kCGImagePropertyOrientation)] as? UInt32 {
        portraitEffectsMatte = portraitEffectsMatte.applyingExifOrientation(CGImagePropertyOrientation(rawValue: orientation)!)
    let portraitEffectsMattePixelBuffer = portraitEffectsMatte.mattingImage

// Capture all available semantic segmentation matte types.
photoOutput.enabledSemanticSegmentationMatteTypes = 
    photoOutput.availableSemanticSegmentationMatteTypes

// Find the semantic segmentation matte image for the specified type.
guard var segmentationMatte = photo.semanticSegmentationMatte(for: ssmType) else { return }
// Retrieve the photo orientation and apply it to the matte image.
if let orientation = photo.metadata[String(kCGImagePropertyOrientation)] as? UInt32,
    let exifOrientation = CGImagePropertyOrientation(rawValue: orientation) {
    // Apply the Exif orientation to the matte image.
    segmentationMatte = segmentationMatte.applyingExifOrientation(exifOrientation)
var imageOption: CIImageOption!
// Switch on the AVSemanticSegmentationMatteType value.
switch ssmType {
case .hair:
    imageOption = .auxiliarySemanticSegmentationHairMatte
case .skin:
    imageOption = .auxiliarySemanticSegmentationSkinMatte
case .teeth:
    imageOption = .auxiliarySemanticSegmentationTeethMatte
default:
    print("This semantic segmentation type is not supported!")
    return
guard let perceptualColorSpace = CGColorSpace(name: CGColorSpace.sRGB) else { return }
// Create a new CIImage from the matte's underlying CVPixelBuffer.
let ciImage = CIImage( cvImageBuffer: segmentationMatte.mattingImage,
                       options: [imageOption: true,
                                 .colorSpace: perceptualColorSpace])
// Get the HEIF representation of this image.
guard let imageData = context.heifRepresentation(of: ciImage,
                                                 format: .RGBA8,
                                                 colorSpace: perceptualColorSpace,
                                                 options: [.depthImage: ciImage]) else { return }
// Add the image data to the SSM data array for writing to the photo library.
semanticSegmentationMatteDataArray.append(imageData)

if let dualCameraDevice = AVCaptureDevice.default(.builtInDualCamera, for: .video, position: .back) {
    defaultVideoDevice = dualCameraDevice
} else if let backCameraDevice = AVCaptureDevice.default(.builtInWideAngleCamera, for: .video, position: .back) {
    // If a rear dual camera is not available, default to the rear wide angle camera.
    defaultVideoDevice = backCameraDevice
} else if let frontCameraDevice = AVCaptureDevice.default(.builtInWideAngleCamera, for: .video, position: .front) {
    // If the rear wide angle camera isn't available, default to the front wide angle camera.
    defaultVideoDevice = frontCameraDevice

movieFileOutput.startRecording(to: URL(fileURLWithPath: outputFilePath), recordingDelegate: self)

DispatchQueue.main.async {
    self.recordButton.isEnabled = true
    self.recordButton.setImage(#imageLiteral(resourceName: "CaptureStop"), for: [])

PHPhotoLibrary.shared().performChanges({
    let options = PHAssetResourceCreationOptions()
    options.shouldMoveFile = true
    let creationRequest = PHAssetCreationRequest.forAsset()
    creationRequest.addResource(with: .video, fileURL: outputFileURL, options: options)
}, completionHandler: { success, error in
    if !success {
        print("AVCam couldn't save the movie to your photo library: \(String(describing: error))")
    cleanup()
)

self.backgroundRecordingID = UIApplication.shared.beginBackgroundTask(expirationHandler: nil)

let movieFileOutput = AVCaptureMovieFileOutput()
if self.session.canAddOutput(movieFileOutput) {
    self.session.beginConfiguration()
    self.session.addOutput(movieFileOutput)
    self.session.sessionPreset = .high
    if let connection = movieFileOutput.connection(with: .video) {
        if connection.isVideoStabilizationSupported {
            connection.preferredVideoStabilizationMode = .auto
    self.session.commitConfiguration()
    DispatchQueue.main.async {
        captureModeControl.isEnabled = true
    self.movieFileOutput = movieFileOutput
    DispatchQueue.main.async {
        self.recordButton.isEnabled = true
         For photo captures during movie recording, Speed quality photo processing is prioritized