AVFoundation框架

1.AVAsset：用于獲取一個多媒體文件的信息挠进，相當(dāng)于獲取一個視頻或音頻文件，是一個抽象類誊册，不能直接使用领突。

2.AVURLAsset：AVAsset的子類，通過URL路徑創(chuàng)建一個包含多媒體信息的對象案怯。

NSURL *url = <#A URL that identifies an audiovisual asset such as a movie file#>;
AVURLAsset *anAsset = [[AVURLAsset alloc] initWithURL:url options:nil];

3.AVCaptureSession：用于捕捉視頻和音頻攘须，負(fù)責(zé)協(xié)調(diào)視頻和音頻的輸入流和輸出流。

AVCaptureSession *captureSession = [[AVCaptureSession alloc] init]; 
if ([_captureSession canSetSessionPreset:AVCaptureSessionPreset1280x720]) _captureSession.sessionPreset = AVCaptureSessionPreset1280x720;

4.AVCaptureDevice：表示輸入設(shè)備殴泰，如照相機(jī)或麥克風(fēng)于宙。

AVCaptureDevice *device = [self getCameraDeviceWithPosition:AVCaptureDevicePositionBack];

- (AVCaptureDevice *)getCameraDeviceWithPosition:(AVCaptureDevicePosition)position {
    NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    for (AVCaptureDevice *device in devices) {
        if ([device position] == position) {
            if ([device supportsAVCaptureSessionPreset:AVCaptureSessionPreset1280x720]) return device;
            return nil;
        }
    }
    return nil;
}

5.AVCaptureDeviceInput：視頻或音頻的輸入流，把該對象添加到AVCaptureSession對象中管理悍汛。

NSError *error;
AVCaptureDeviceInput *input =
        [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
if (!input) {
    // Handle the error appropriately.
}
if ([captureSession canAddInput:captureDeviceInput]) {
    [captureSession addInput:captureDeviceInput];
}

6.AVCaptureOutput：視頻或音頻的輸出流捞魁，通常使用它的子類：AVCaptureAudioDataOutput，AVCaptureVideoDataOutput离咐，AVCaptureStillImageOutput谱俭，AVCaptureFileOutput等，把該對象添加到AVCaptureSession對象中管理宵蛀。

AVCaptureMovieFileOutput *movieOutput = [[AVCaptureMovieFileOutput alloc] init];
if ([captureSession canAddOutput:movieOutput]) {
    [captureSession addOutput:movieOutput];
}

7.AVCaptureVideoPreviewLayer：預(yù)覽圖層昆著，實(shí)時查看攝像頭捕捉的畫面。

AVCaptureVideoPreviewLayer *captureVideoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:captureSession];
captureVideoPreviewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
captureVideoPreviewLayer.frame = <#Set layer frame#>;

8.AVCaptureConnection：AVCaptureSession和輸入輸出流之間的連接术陶，可以用來調(diào)節(jié)一些設(shè)置凑懂，如光學(xué)防抖。

AVCaptureConnection *captureConnection = [movieOutput connectionWithMediaType:AVMediaTypeVideo];
// 打開影院級光學(xué)防抖
captureConnection.preferredVideoStabilizationMode = AVCaptureVideoStabilizationModeCinematic;

9.AVCaptureDeviceFormat：輸入設(shè)備的一些設(shè)置梧宫，可以用來修改一些設(shè)置接谨，如ISO摆碉，慢動作，防抖等脓豪。

AVCaptureDevice *captureDevice = [self.captureDeviceInput device];
NSError *error;
if ([captureDevice lockForConfiguration:&error]) {
    CGFloat minISO = captureDevice.activeFormat.minISO;
    CGFloat maxISO = captureDevice.activeFormat.maxISO;
    // 調(diào)節(jié)ISO為全范圍的70%
    CGFloat currentISO = (maxISO - minISO) * 0.7 + minISO;
    [captureDevice setExposureModeCustomWithDuration:AVCaptureExposureDurationCurrent ISO:currentISO completionHandler:nil];
    [captureDevice unlockForConfiguration];
}else{
    // Handle the error appropriately.
}

初始化相機(jī)

/// 負(fù)責(zé)輸入和輸出設(shè)備之間的數(shù)據(jù)傳遞
@property (nonatomic, strong) AVCaptureSession *captureSession;
/// 負(fù)責(zé)從AVCaptureDevice獲得視頻輸入流
@property (nonatomic, strong) AVCaptureDeviceInput *captureDeviceInput;
/// 負(fù)責(zé)從AVCaptureDevice獲得音頻輸入流
@property (nonatomic, strong) AVCaptureDeviceInput *audioCaptureDeviceInput;
/// 視頻輸出流
@property (nonatomic, strong) AVCaptureMovieFileOutput *captureMovieFileOutput;
/// 相機(jī)拍攝預(yù)覽圖層
@property (nonatomic, strong) AVCaptureVideoPreviewLayer *captureVideoPreviewLayer;

... 公用方法

/// 獲取攝像頭設(shè)備
- (AVCaptureDevice *)getCameraDeviceWithPosition:(AVCaptureDevicePosition)position {
    NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    for (AVCaptureDevice *device in devices) {
        if ([device position] == position) {
            if ([device supportsAVCaptureSessionPreset:AVCaptureSessionPreset1280x720]) return device;
            return nil;
        }
    }
    return nil;
}

... 創(chuàng)建自定義相機(jī)

// 創(chuàng)建AVCaptureSession
_captureSession = [[AVCaptureSession alloc] init];
if ([_captureSession canSetSessionPreset:AVCaptureSessionPreset1280x720]) _captureSession.sessionPreset = AVCaptureSessionPreset1280x720;

// 獲取攝像設(shè)備
AVCaptureDevice *videoCaptureDevice = [self getCameraDeviceWithPosition:AVCaptureDevicePositionBack];
if (!videoCaptureDevice)  {
    // Handle the error appropriately.
}

// 獲取視頻輸入流
NSError *error = nil;
_captureDeviceInput = [AVCaptureDeviceInput deviceInputWithDevice:videoCaptureDevice error:&error];
if (error) {
    // Handle the error appropriately.
}

// 獲取錄音設(shè)備
AVCaptureDevice *audioCaptureDevice = [[AVCaptureDevice devicesWithMediaType:AVMediaTypeAudio] firstObject];

// 獲取音頻輸入流
_audioCaptureDeviceInput = [AVCaptureDeviceInput deviceInputWithDevice:audioCaptureDevice error:&error];
if (error) {
    // Handle the error appropriately.
}

// 將視頻和音頻輸入添加到AVCaptureSession
if ([_captureSession canAddInput:_captureDeviceInput] && [_captureSession canAddInput:_audioCaptureDeviceInput]) {
    [_captureSession addInput:_captureDeviceInput];
    [_captureSession addInput:_audioCaptureDeviceInput];
}

// 創(chuàng)建輸出流
_captureMovieFileOutput = [[AVCaptureMovieFileOutput alloc] init];

// 將輸出流添加到AVCaptureSession
if ([_captureSession canAddOutput:_captureMovieFileOutput]) {
    [_captureSession addOutput:_captureMovieFileOutput];
    // 根據(jù)設(shè)備輸出獲得連接
    AVCaptureConnection *captureConnection = [_captureMovieFileOutput connectionWithMediaType:AVMediaTypeVideo];
    // 判斷是否支持光學(xué)防抖
    if ([videoCaptureDevice.activeFormat isVideoStabilizationModeSupported:AVCaptureVideoStabilizationModeCinematic]) {
        // 如果支持防抖就打開防抖
        captureConnection.preferredVideoStabilizationMode = AVCaptureVideoStabilizationModeCinematic;
    }
}

// 保存默認(rèn)的AVCaptureDeviceFormat
// 之所以保存是因?yàn)樾薷臄z像頭捕捉頻率之后巷帝，防抖就無法再次開啟，試了下只能夠用這個默認(rèn)的format才可以扫夜，所以把它存起來楞泼，關(guān)閉慢動作拍攝后在設(shè)置會默認(rèn)的format開啟防抖
_defaultFormat = videoCaptureDevice.activeFormat;
_defaultMinFrameDuration = videoCaptureDevice.activeVideoMinFrameDuration;
_defaultMaxFrameDuration = videoCaptureDevice.activeVideoMaxFrameDuration;

// 創(chuàng)建預(yù)覽圖層
_captureVideoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:_captureSession];
_captureVideoPreviewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;//填充模式
_captureVideoPreviewLayer.frame = self.bounds;

// 相機(jī)的預(yù)覽圖層是一個CALayer，所以可以創(chuàng)建一個UIView笤闯，在view的layer上addSublayer就可以
// 因?yàn)檫@里是寫在view的init方法里堕阔，所以直接調(diào)用了self.layer的addSublayer方法
[self.layer addSublayer:_captureVideoPreviewLayer];

// 開始捕獲
[self.captureSession startRunning];

配置操作界面

可以在相機(jī)的預(yù)覽圖層所在的view上面直接addSubview我們需要的視圖，我的做法是直接創(chuàng)建一個和當(dāng)前預(yù)覽圖層一樣大的UIView做控制面板望侈，背景色為透明。然后整體蓋在相機(jī)預(yù)覽圖層上面勋桶，所有的手勢方法脱衙，按鈕點(diǎn)擊等都在我們的控制面板上作響應(yīng)，具體代碼其實(shí)就是通過代理傳遞控制面板的操作讓相機(jī)界面去做對應(yīng)的處理例驹，這里就不貼無用代碼了痴突。

相機(jī)設(shè)置

1.切換到后攝像頭

#pragma mark - 切換到后攝像頭
- (void)cameraBackgroundDidClickChangeBack {
    AVCaptureDevice *toChangeDevice;
    AVCaptureDevicePosition toChangePosition = AVCaptureDevicePositionBack;
    toChangeDevice = [self getCameraDeviceWithPosition:toChangePosition];
    AVCaptureDeviceInput *toChangeDeviceInput = [AVCaptureDeviceInput deviceInputWithDevice:toChangeDevice error:nil];
    [self.captureSession beginConfiguration];
    [self.captureSession removeInput:self.captureDeviceInput];
    if ([self.captureSession canAddInput:toChangeDeviceInput]) {
        [self.captureSession addInput:toChangeDeviceInput];
        self.captureDeviceInput = toChangeDeviceInput;
    }
    [self.captureSession commitConfiguration];
}

2.切換到前攝像頭

- (void)cameraBackgroundDidClickChangeFront {
    AVCaptureDevice *toChangeDevice;
    AVCaptureDevicePosition toChangePosition = AVCaptureDevicePositionFront;
    toChangeDevice = [self getCameraDeviceWithPosition:toChangePosition];
    AVCaptureDeviceInput *toChangeDeviceInput = [AVCaptureDeviceInput deviceInputWithDevice:toChangeDevice error:nil];
    [self.captureSession beginConfiguration];
    [self.captureSession removeInput:self.captureDeviceInput];
    if ([self.captureSession canAddInput:toChangeDeviceInput]) {
        [self.captureSession addInput:toChangeDeviceInput];
        self.captureDeviceInput = toChangeDeviceInput;
    }
    [self.captureSession commitConfiguration];
}

3.打開閃光燈

- (void)cameraBackgroundDidClickOpenFlash {
    AVCaptureDevice *captureDevice = [self.captureDeviceInput device];
    NSError *error;
    if ([captureDevice lockForConfiguration:&error]) {
        if ([captureDevice isTorchModeSupported:AVCaptureTorchModeOn]) [captureDevice setTorchMode:AVCaptureTorchModeOn];
    }else{
        // Handle the error appropriately.
    }
}

4.關(guān)閉閃光燈

- (void)cameraBackgroundDidClickCloseFlash {
    AVCaptureDevice *captureDevice = [self.captureDeviceInput device];
    NSError *error;
    if ([captureDevice lockForConfiguration:&error]) {
        if ([captureDevice isTorchModeSupported:AVCaptureTorchModeOff]) [captureDevice setTorchMode:AVCaptureTorchModeOff];
    }else{
        // Handle the error appropriately.
    }
}

5.調(diào)節(jié)焦距

// 焦距范圍0.0-1.0
- (void)cameraBackgroundDidChangeFocus:(CGFloat)focus {
    AVCaptureDevice *captureDevice = [self.captureDeviceInput device];
    NSError *error;
    if ([captureDevice lockForConfiguration:&error]) {
        if ([captureDevice isFocusModeSupported:AVCaptureFocusModeContinuousAutoFocus]) [captureDevice setFocusModeLockedWithLensPosition:focus completionHandler:nil];
    }else{
        // Handle the error appropriately.
    }
}

6.數(shù)碼變焦

// 數(shù)碼變焦 1-3倍
- (void)cameraBackgroundDidChangeZoom:(CGFloat)zoom {
    AVCaptureDevice *captureDevice = [self.captureDeviceInput device];
    NSError *error;
    if ([captureDevice lockForConfiguration:&error]) {
        [captureDevice rampToVideoZoomFactor:zoom withRate:50];
    }else{
        // Handle the error appropriately.
    }
}

7.調(diào)節(jié)ISO狸驳，光感度

// 調(diào)節(jié)ISO，光感度 0.0-1.0
- (void)cameraBackgroundDidChangeISO:(CGFloat)iso {
    AVCaptureDevice *captureDevice = [self.captureDeviceInput device];
    NSError *error;
    if ([captureDevice lockForConfiguration:&error]) {
        CGFloat minISO = captureDevice.activeFormat.minISO;
        CGFloat maxISO = captureDevice.activeFormat.maxISO;
        CGFloat currentISO = (maxISO - minISO) * iso + minISO;
        [captureDevice setExposureModeCustomWithDuration:AVCaptureExposureDurationCurrent ISO:currentISO completionHandler:nil];
        [captureDevice unlockForConfiguration];
    }else{
        // Handle the error appropriately.
    }
}

8.點(diǎn)擊屏幕自動對焦

// 當(dāng)前屏幕上點(diǎn)擊的點(diǎn)坐標(biāo)
- (void)cameraBackgroundDidTap:(CGPoint)point {
    AVCaptureDevice *captureDevice = [self.captureDeviceInput device];
    NSError *error;
    if ([captureDevice lockForConfiguration:&error]) {
        CGPoint location = point;
        CGPoint pointOfInerest = CGPointMake(0.5, 0.5);
        CGSize frameSize = self.captureVideoPreviewLayer.frame.size;
        if ([captureDevice position] == AVCaptureDevicePositionFront) location.x = frameSize.width - location.x;
        pointOfInerest = CGPointMake(location.y / frameSize.height, 1.f - (location.x / frameSize.width));
        [self focusWithMode:AVCaptureFocusModeAutoFocus exposureMode:AVCaptureExposureModeAutoExpose atPoint:pointOfInerest];
        
        [[self.captureDeviceInput device] addObserver:self forKeyPath:@"ISO" options:NSKeyValueObservingOptionNew context:NULL];
    }else{
        // Handle the error appropriately.
    }
}

-(void)focusWithMode:(AVCaptureFocusMode)focusMode exposureMode:(AVCaptureExposureMode)exposureMode atPoint:(CGPoint)point{
    AVCaptureDevice *captureDevice = [self.captureDeviceInput device];
    NSError *error;
    if ([captureDevice lockForConfiguration:&error]) {
        if ([captureDevice isFocusModeSupported:focusMode]) [captureDevice setFocusMode:AVCaptureFocusModeAutoFocus];
        if ([captureDevice isFocusPointOfInterestSupported]) [captureDevice setFocusPointOfInterest:point];
        if ([captureDevice isExposureModeSupported:exposureMode]) [captureDevice setExposureMode:AVCaptureExposureModeAutoExpose];
        if ([captureDevice isExposurePointOfInterestSupported]) [captureDevice setExposurePointOfInterest:point];
    }else{
        // Handle the error appropriately.
    }
}

9.獲取錄制時視頻的方向
因?yàn)橄鄼C(jī)的特殊性，不能夠用常規(guī)的控制器的方向來獲取當(dāng)前的方向船逮，因?yàn)橛脩艨赡荜P(guān)閉屏幕旋轉(zhuǎn)，這里用重力感應(yīng)來計算當(dāng)前手機(jī)的放置狀態(tài)窑邦。

@property (nonatomic, strong) CMMotionManager *motionManager;
@property (nonatomic, assign) UIDeviceOrientation deviceOrientation;
...

_motionManager = [[CMMotionManager alloc] init];
_motionManager.deviceMotionUpdateInterval = 1/15.0;
if (_motionManager.deviceMotionAvailable) {
    [_motionManager startDeviceMotionUpdatesToQueue:[NSOperationQueue currentQueue] withHandler:^(CMDeviceMotion * _Nullable motion, NSError * _Nullable error) {
        [self performSelectorOnMainThread:@selector(handleDeviceMotion:) withObject:motion waitUntilDone:YES];
    }];
} else {
    NSLog(@"No device motion on device");
}

...

/// 重力感應(yīng)回調(diào)
- (void)handleDeviceMotion:(CMDeviceMotion *)deviceMotion{
    double x = deviceMotion.gravity.x;
    double y = deviceMotion.gravity.y;

    CGAffineTransform videoTransform;
    
    if (fabs(y) >= fabs(x)) {
        if (y >= 0) {
            videoTransform = CGAffineTransformMakeRotation(M_PI);
            _deviceOrientation = UIDeviceOrientationPortraitUpsideDown;
        } else {
            videoTransform = CGAffineTransformMakeRotation(0);
            _deviceOrientation = UIDeviceOrientationPortrait;
        }
    } else {
        if (x >= 0) {
            videoTransform = CGAffineTransformMakeRotation(-M_PI_2);
            _deviceOrientation = UIDeviceOrientationLandscapeRight;    // Home鍵左側(cè)水平拍攝
        } else {
            videoTransform = CGAffineTransformMakeRotation(M_PI_2);
            _deviceOrientation = UIDeviceOrientationLandscapeLeft;     // Home鍵右側(cè)水平拍攝
        }
    }
    // 告訴操作界面當(dāng)前屏幕的方向拜英，做按鈕跟隨屏幕方向旋轉(zhuǎn)的操作
    [self.backgroundView setOrientation:_deviceOrientation];
}

11.慢動作拍攝

- (void)cameraBackgroundDidClickOpenSlow {
    [self.captureSession stopRunning];
    CGFloat desiredFPS = 240.0;
    AVCaptureDevice *videoDevice = self.captureDeviceInput.device;
    AVCaptureDeviceFormat *selectedFormat = nil;
    int32_t maxWidth = 0;
    AVFrameRateRange *frameRateRange = nil;
    for (AVCaptureDeviceFormat *format in [videoDevice formats]) {
        for (AVFrameRateRange *range in format.videoSupportedFrameRateRanges) {
            CMFormatDescriptionRef desc = format.formatDescription;
            CMVideoDimensions dimensions = CMVideoFormatDescriptionGetDimensions(desc);
            int32_t width = dimensions.width;
            if (range.minFrameRate <= desiredFPS && desiredFPS <= range.maxFrameRate && width >= maxWidth) {
                selectedFormat = format;
                frameRateRange = range;
                maxWidth = width;
            }
        }
    }
    if (selectedFormat) {
        if ([videoDevice lockForConfiguration:nil]) {
            NSLog(@"selected format: %@", selectedFormat);
            videoDevice.activeFormat = selectedFormat;
            videoDevice.activeVideoMinFrameDuration = CMTimeMake(1, (int32_t)desiredFPS);
            videoDevice.activeVideoMaxFrameDuration = CMTimeMake(1, (int32_t)desiredFPS);
            [videoDevice unlockForConfiguration];
        }
    }
    [self.captureSession startRunning];
}

12.慢動作拍攝關(guān)

- (void)cameraBackgroundDidClickCloseSlow {
    [self.captureSession stopRunning];
    CGFloat desiredFPS = 60.0;
    AVCaptureDevice *videoDevice = self.captureDeviceInput.device;
    AVCaptureDeviceFormat *selectedFormat = nil;
    int32_t maxWidth = 0;
    AVFrameRateRange *frameRateRange = nil;
    for (AVCaptureDeviceFormat *format in [videoDevice formats]) {
        for (AVFrameRateRange *range in format.videoSupportedFrameRateRanges) {
            CMFormatDescriptionRef desc = format.formatDescription;
            CMVideoDimensions dimensions = CMVideoFormatDescriptionGetDimensions(desc);
            int32_t width = dimensions.width;
            if (range.minFrameRate <= desiredFPS && desiredFPS <= range.maxFrameRate && width >= maxWidth) {
                selectedFormat = format;
                frameRateRange = range;
                maxWidth = width;
            }
        }
    }
    if (selectedFormat) {
        if ([videoDevice lockForConfiguration:nil]) {
            NSLog(@"selected format: %@", selectedFormat);
            videoDevice.activeFormat = _defaultFormat;
            videoDevice.activeVideoMinFrameDuration = _defaultMinFrameDuration;
            videoDevice.activeVideoMaxFrameDuration = _defaultMaxFrameDuration;
            [videoDevice unlockForConfiguration];
        }
    }
    [self.captureSession startRunning];
}

13.防抖開啟

- (void)cameraBackgroundDidClickOpenAntiShake {
    AVCaptureConnection *captureConnection = [_captureMovieFileOutput connectionWithMediaType:AVMediaTypeVideo];
    NSLog(@"change captureConnection: %@", captureConnection);
    AVCaptureDevice *videoDevice = self.captureDeviceInput.device;
    NSLog(@"set format: %@", videoDevice.activeFormat);
    if ([videoDevice.activeFormat isVideoStabilizationModeSupported:AVCaptureVideoStabilizationModeCinematic]) {
        captureConnection.preferredVideoStabilizationMode = AVCaptureVideoStabilizationModeCinematic;
    }
}

14.防抖關(guān)閉

#pragma mark - 防抖關(guān)
- (void)cameraBackgroundDidClickCloseAntiShake {
    AVCaptureConnection *captureConnection = [_captureMovieFileOutput connectionWithMediaType:AVMediaTypeVideo];
    NSLog(@"change captureConnection: %@", captureConnection);
    AVCaptureDevice *videoDevice = self.captureDeviceInput.device;
    if ([videoDevice.activeFormat isVideoStabilizationModeSupported:AVCaptureVideoStabilizationModeOff]) {
        captureConnection.preferredVideoStabilizationMode = AVCaptureVideoStabilizationModeOff;
    }
}

15.錄制視頻

#pragma mark - 錄制
- (void)cameraBackgroundDidClickPlay {
    // 根據(jù)設(shè)備輸出獲得連接
    AVCaptureConnection *captureConnection = [self.captureMovieFileOutput connectionWithMediaType:AVMediaTypeVideo];
    // 根據(jù)連接取得設(shè)備輸出的數(shù)據(jù)
    if (![self.captureMovieFileOutput isRecording]) {
        captureConnection.videoOrientation = (AVCaptureVideoOrientation)_deviceOrientation; // 視頻方向和手機(jī)方向一致
        NSString *outputFilePath = [kCachePath stringByAppendingPathComponent:[self movieName]];
        NSURL *fileURL = [NSURL fileURLWithPath:outputFilePath];
        [self.captureMovieFileOutput startRecordingToOutputFileURL:fileURL recordingDelegate:self];
        _currentMoviePath = outputFilePath;
    }
}

- (void)captureOutput:(AVCaptureFileOutput *)captureOutput didStartRecordingToOutputFileAtURL:(NSURL *)fileURL fromConnections:(NSArray *)connections {
    NSLog(@"開始錄制");
}

- (void)captureOutput:(AVCaptureFileOutput *)captureOutput didFinishRecordingToOutputFileAtURL:(NSURL *)outputFileURL fromConnections:(NSArray *)connections error:(NSError *)error {
    NSLog(@"錄制完成");
}

16.暫停錄制

[self.captureMovieFileOutput stopRecording];

17.調(diào)節(jié)視頻的速度
慢動作拍攝的時候要調(diào)節(jié)攝像頭的捕捉頻率，快速的時候直接調(diào)節(jié)視頻速度就可以了盆驹。
慢動作下拍攝的視頻視頻的播放時長還是實(shí)際拍攝的時間圆丹，這里根據(jù)設(shè)置的慢速倍率，把視頻的時長拉長躯喇。

/// 處理速度視頻
- (void)setSpeedWithVideo:(NSDictionary *)video completed:(void(^)())completed {
    dispatch_async(dispatch_get_global_queue(0, 0), ^{
        NSLog(@"video set thread: %@", [NSThread currentThread]);
        // 獲取視頻
        AVURLAsset* videoAsset = [[AVURLAsset alloc]initWithURL:[NSURL fileURLWithPath:video[kMoviePath]] options:nil];
        // 視頻混合
        AVMutableComposition* mixComposition = [AVMutableComposition composition];
        // 視頻軌道
        AVMutableCompositionTrack *compositionVideoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
        // 音頻軌道
        AVMutableCompositionTrack *compositionAudioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
        
        // 視頻的方向
        CGAffineTransform videoTransform = [videoAsset tracksWithMediaType:AVMediaTypeVideo].lastObject.preferredTransform;
        if (videoTransform.a == 0 && videoTransform.b == 1.0 && videoTransform.c == -1.0 && videoTransform.d == 0) {
            NSLog(@"垂直拍攝");
            videoTransform = CGAffineTransformMakeRotation(M_PI_2);
        }else if (videoTransform.a == 0 && videoTransform.b == -1.0 && videoTransform.c == 1.0 && videoTransform.d == 0) {
            NSLog(@"倒立拍攝");
            videoTransform = CGAffineTransformMakeRotation(-M_PI_2);
        }else if (videoTransform.a == 1.0 && videoTransform.b == 0 && videoTransform.c == 0 && videoTransform.d == 1.0) {
            NSLog(@"Home鍵右側(cè)水平拍攝");
            videoTransform = CGAffineTransformMakeRotation(0);
        }else if (videoTransform.a == -1.0 && videoTransform.b == 0 && videoTransform.c == 0 && videoTransform.d == -1.0) {
            NSLog(@"Home鍵左側(cè)水平拍攝");
            videoTransform = CGAffineTransformMakeRotation(M_PI);
        }
        // 根據(jù)視頻的方向同步視頻軌道方向
        compositionVideoTrack.preferredTransform = videoTransform;
        compositionVideoTrack.naturalTimeScale = 600;
        
        // 插入視頻軌道
        [compositionVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, CMTimeMake(videoAsset.duration.value, videoAsset.duration.timescale)) ofTrack:[[videoAsset tracksWithMediaType:AVMediaTypeVideo] firstObject] atTime:kCMTimeZero error:nil];
        // 插入音頻軌道
        [compositionAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, CMTimeMake(videoAsset.duration.value, videoAsset.duration.timescale)) ofTrack:[[videoAsset tracksWithMediaType:AVMediaTypeAudio] firstObject] atTime:kCMTimeZero error:nil];
        
        // 適配視頻速度比率
        CGFloat scale = 1.0;
        if([video[kMovieSpeed] isEqualToString:kMovieSpeed_Fast]){
            scale = 0.2f;  // 快速 x5
        } else if ([video[kMovieSpeed] isEqualToString:kMovieSpeed_Slow]) {
            scale = 4.0f;  // 慢速 x4
        }
        
        // 根據(jù)速度比率調(diào)節(jié)音頻和視頻
        [compositionVideoTrack scaleTimeRange:CMTimeRangeMake(kCMTimeZero, CMTimeMake(videoAsset.duration.value, videoAsset.duration.timescale)) toDuration:CMTimeMake(videoAsset.duration.value * scale , videoAsset.duration.timescale)];
        [compositionAudioTrack scaleTimeRange:CMTimeRangeMake(kCMTimeZero, CMTimeMake(videoAsset.duration.value, videoAsset.duration.timescale)) toDuration:CMTimeMake(videoAsset.duration.value * scale, videoAsset.duration.timescale)];
        
        // 配置導(dǎo)出
        AVAssetExportSession* _assetExport = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPreset1280x720];
        // 導(dǎo)出視頻的臨時保存路徑
        NSString *exportPath = [kCachePath stringByAppendingPathComponent:[self movieName]];
        NSURL *exportUrl = [NSURL fileURLWithPath:exportPath];
        
        // 導(dǎo)出視頻的格式 .MOV
        _assetExport.outputFileType = AVFileTypeQuickTimeMovie;
        _assetExport.outputURL = exportUrl;
        _assetExport.shouldOptimizeForNetworkUse = YES;
        
        // 導(dǎo)出視頻
        [_assetExport exportAsynchronouslyWithCompletionHandler:
         ^(void ) {
             dispatch_async(dispatch_get_main_queue(), ^{
                 [_processedVideoPaths addObject:exportPath];
                 // 將導(dǎo)出的視頻保存到相冊
                 ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
                 if (![library videoAtPathIsCompatibleWithSavedPhotosAlbum:[NSURL URLWithString:exportPath]]){
                     NSLog(@"cache can't write");
                     completed();
                     return;
                 }
                 [library writeVideoAtPathToSavedPhotosAlbum:[NSURL URLWithString:exportPath] completionBlock:^(NSURL *assetURL, NSError *error) {
                     if (error) {
                         completed();
                         NSLog(@"cache write error");
                     } else {
                         completed();
                         NSLog(@"cache write success");
                     }
                 }];
             });
         }];
    });
}

18.將多個視頻合并為一個視頻

- (void)mergeVideosWithPaths:(NSArray *)paths completed:(void(^)(NSString *videoPath))completed {
    if (!paths.count) return;
    
    dispatch_async(dispatch_get_main_queue(), ^{
        AVMutableComposition* mixComposition = [[AVMutableComposition alloc] init];
        AVMutableCompositionTrack *audioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
        AVMutableCompositionTrack *videoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
        videoTrack.preferredTransform = CGAffineTransformRotate(CGAffineTransformIdentity, M_PI_2);
        
        CMTime totalDuration = kCMTimeZero;
        
//        NSMutableArray<AVMutableVideoCompositionLayerInstruction *> *instructions = [NSMutableArray array];
        
        for (int i = 0; i < paths.count; i++) {
            AVURLAsset *asset = [AVURLAsset assetWithURL:[NSURL fileURLWithPath:paths[i]]];
            
            
            AVAssetTrack *assetAudioTrack = [[asset tracksWithMediaType:AVMediaTypeAudio] firstObject];
            AVAssetTrack *assetVideoTrack = [[asset tracksWithMediaType:AVMediaTypeVideo]firstObject];
            
            NSLog(@"%lld", asset.duration.value/asset.duration.timescale);
            
            NSError *erroraudio = nil;
            BOOL ba = [audioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, asset.duration) ofTrack:assetAudioTrack atTime:totalDuration error:&erroraudio];
            NSLog(@"erroraudio:%@--%d", erroraudio, ba);
            
            NSError *errorVideo = nil;

            BOOL bl = [videoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, asset.duration) ofTrack:assetVideoTrack atTime:totalDuration error:&errorVideo];
            NSLog(@"errorVideo:%@--%d",errorVideo,bl);
            
//            AVMutableVideoCompositionLayerInstruction *instruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoTrack];
//            UIImageOrientation assetOrientation = UIImageOrientationUp;
//            BOOL isAssetPortrait = NO;
//            // 根據(jù)視頻的實(shí)際拍攝方向來調(diào)整視頻的方向
//            CGAffineTransform videoTransform = assetVideoTrack.preferredTransform;
//            if (videoTransform.a == 0 && videoTransform.b == 1.0 && videoTransform.c == -1.0 && videoTransform.d == 0) {
//                NSLog(@"垂直拍攝");
//                assetOrientation = UIImageOrientationRight;
//                isAssetPortrait = YES;
//            }else if (videoTransform.a == 0 && videoTransform.b == -1.0 && videoTransform.c == 1.0 && videoTransform.d == 0) {
//                NSLog(@"倒立拍攝");
//                assetOrientation = UIImageOrientationLeft;
//                isAssetPortrait = YES;
//            }else if (videoTransform.a == 1.0 && videoTransform.b == 0 && videoTransform.c == 0 && videoTransform.d == 1.0) {
//                NSLog(@"Home鍵右側(cè)水平拍攝");
//                assetOrientation = UIImageOrientationUp;
//            }else if (videoTransform.a == -1.0 && videoTransform.b == 0 && videoTransform.c == 0 && videoTransform.d == -1.0) {
//                NSLog(@"Home鍵左側(cè)水平拍攝");
//                assetOrientation = UIImageOrientationDown;
//            }
//            CGFloat assetScaleToFitRatio = 720.0 / assetVideoTrack.naturalSize.width;
//            if (isAssetPortrait) {
//                assetScaleToFitRatio = 720.0 / assetVideoTrack.naturalSize.height;
//                CGAffineTransform assetSacleFactor = CGAffineTransformMakeScale(assetScaleToFitRatio, assetScaleToFitRatio);
//                [instruction setTransform:CGAffineTransformConcat(assetVideoTrack.preferredTransform, assetSacleFactor) atTime:totalDuration];
//            } else {
//                /**
//                 豎直方向視頻尺寸：720*1280
//                 水平方向視頻尺寸：720*405
//                 水平方向視頻需要劇中的y值：（1280 － 405）／ 2 ＝ 437.5
//                 **/
//                CGAffineTransform assetSacleFactor = CGAffineTransformMakeScale(assetScaleToFitRatio, assetScaleToFitRatio);
//                [instruction setTransform:CGAffineTransformConcat(CGAffineTransformConcat(assetVideoTrack.preferredTransform, assetSacleFactor), CGAffineTransformMakeTranslation(0, 437.5)) atTime:totalDuration];
//            }
//            // 把新的插入到最上面辫封，最后是按照數(shù)組順序播放的。
//            [instructions insertObject:instruction atIndex:0];
//            totalDuration = CMTimeAdd(totalDuration, asset.duration);
//            // 在當(dāng)前視頻時間點(diǎn)結(jié)束后需要清空尺寸廉丽，否則如果第二個視頻尺寸比第一個小倦微，它會顯示在第二個視頻的下方。
//            [instruction setCropRectangle:CGRectZero atTime:totalDuration];
        }
        
//        AVMutableVideoCompositionInstruction *mixInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
//        mixInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, totalDuration);
//        mixInstruction.layerInstructions = instructions;
        
//        AVMutableVideoComposition *mixVideoComposition = [AVMutableVideoComposition videoComposition];
//        mixVideoComposition.instructions = [NSArray arrayWithObject:mixInstruction];
//        mixVideoComposition.frameDuration = CMTimeMake(1, 25);
//        mixVideoComposition.renderSize = CGSizeMake(720.0, 1280.0);
//
        NSString *outPath = [kVideoPath stringByAppendingPathComponent:[self movieName]];
        NSURL *mergeFileURL = [NSURL fileURLWithPath:outPath];
        
        AVAssetExportSession *exporter = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetHighestQuality];
        exporter.outputURL = mergeFileURL;
        exporter.outputFileType = AVFileTypeQuickTimeMovie;
//        exporter.videoComposition = mixVideoComposition;
        exporter.shouldOptimizeForNetworkUse = YES;
        [exporter exportAsynchronouslyWithCompletionHandler:^{
             dispatch_async(dispatch_get_main_queue(), ^{
                 completed(outPath);
             });
         }];
    });
}

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