在上兩篇文章的基礎上，我們初步認識了AV Foundation框架，並且可以利用它完成一些特定的需求，今天，繼續我們的小小的研究。日進一步，不求速成。
通過了解我們知道，AV Foundation可以用來播放和建立基於時間的音視訊資源，並可以精確的處理基於時間的音視訊媒體資料（查詢、建立、編輯及二次編碼），當然也可以在硬體裝置上獲取實時的視訊輸入流或視訊回放等。AV Foundation可以滿足您對媒體資料的大部分處理。
在處理之前，我們需要大致的瞭解下媒體工程軟體裡的相關類。一個工程檔案中有很多軌道，如音訊軌道1，音訊軌道2 …，視訊軌道1，視訊軌道2等，每個軌道里有許多素材，對於每個視訊素材，它可以進行縮放、旋轉等操作，素材庫中的視訊拖到軌道中會分為視訊軌和音訊軌兩個軌道。大致分為以下幾個：
AVAsset：素材庫裡的素材；
AVAssetTrack：素材的軌道；
AVMutableComposition ：一個用來合成視訊的工程檔案；
AVMutableCompositionTrack ：工程檔案中的軌道，有音訊軌、視訊軌等，裡面可以插入各種對應的素材；
AVMutableVideoCompositionLayerInstruction：視訊軌道中的一個視訊，可以縮放、旋轉等；
AVMutableVideoCompositionInstruction：一個視訊軌道，包含了這個軌道上的所有視訊素材；
AVMutableVideoComposition：管理所有視訊軌道，可以決定最終視訊的尺寸，裁剪需要在這裡進行；
AVAssetExportSession：配置渲染引數並渲染。
AVAsset
AVFoundation使用AVAsset類來表示一個媒體資源，一個AVAsset例項是一個或多個音視訊媒體資料的集合，是一個抽象類。可以使用子類用URL來建立一個asset物件，也可以基於現有的媒體資源創造一個新的媒體資源。下面是AVAsset中的一些屬性，分別對應著視訊的基本資訊，如時長，建立時間等。
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@property (nonatomic, readonly) CMTime duration; @property (nonatomic, readonly) float preferredRate;// 預設速度 @property (nonatomic, readonly) float preferredVolume;// 音量 @property (nonatomic, readonly, nullable) AVMetadataItem *creationDate NS_AVAILABLE(10_8, 5_0);// 視訊的建立時間 |
程式碼是最好的老師，建立一個AVAsset：
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AVAsset *asset = [AVAsset assetWithURL:...]; |
為了建立一個由URL標識的代表任何資源的assert物件，可以使用AVURLAssert，最簡單的是從檔案裡建立一個assert物件：
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NSURL *url = ...; AVURLAsset *anAsset = [[AVURLAsset alloc] initWithURL:url options:nil]; |
AVURLAsset初始化方法的第二個引數使用一個dictionary，這個dictionary裡的唯一一個key是 AVURLAssetPreferPreciseDurationAndTimingKey，它的value是一個boolean型別（用NSValue包裝的物件），這個值表示asset是否提供一個精確的duration。
AVURLAssetPreferPreciseDurationAndTimingKey值為NO(不傳預設為NO)，duration會取一個估計值，計算量比較小。反之如果為YES，duration需要返回一個精確值，計算量會比較大，耗時比較長。使用一個預估的duration效率比較高並且對播放來說足夠。如果你想要播放asset，初始化方法傳nil就行了，而不是一個dictionry，或者傳一個以AVURLAssetPreferPreciseDurationAndTimingKeydictionary為key，值為NO的一個dictionary；如果你想把asset加到一個composition中，你需要一個精確的訪問許可權，這時你可以傳一個dictionary，這個dictionary的一組鍵值對為AVURLAssetPreferPreciseDurationAndTimingKey和YES。
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NSURL *url = ...; NSDictionary *options = @{ AVURLAssetPreferPreciseDurationAndTimingKey : @YES }; AVURLAsset *anAssetToUseInAComposition = [[AVURLAsset alloc] initWithURL:url options:options]; |
從asset中獲取靜態圖片（比如說縮圖），你可以用AVAssetImageGenerator物件。可以用asset初始化一個AVAssetImageGenerator物件，即使asset在初始化的時候沒有可見的track也能成功，所以需要使用tracksWithMediaCharacteristic檢測asset是否有track。generateCGImagesAsynchronouslyForTimes:completionHandler: 方法可以生成一系列圖片，第一個引數是一個包含NSValue型別的陣列，陣列裡每一個物件都是CMTime結構體，表示你想要生成的圖片在視訊中的時間點，第二個引數是一個block，每生成一張圖片都會回撥這個block，這個block提供一個result的引數告訴你圖片是否成功生成或者圖片生成操作是否取消。
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AVURLAsset *asset = [AVURLAsset alloc] initWithURL:... options:nil]; if ([asset tracksWithMediaType:[AVMediaTypeVideo ] count] > 0 ) { AVAssetImageGenerator *generator = [[AVAssetImageGenerator alloc]initWithAsset:asset]; generator.appliesPreferredTrackTransform = YES; CMTime time = CMTimeMakeWithSeconds(0, 25); NSValue *timeValue = [NSValue valueWithCMTime:time]; [generator generateCGImagesAsynchronouslyForTimes:@[timeValue] completionHandler:^ (CMTime requestedTime, CGImageRef image, CMTime actualTime, AVAssetImageGeneratorResult result, NSError *error) { if (result == AVAssetImageGeneratorSucceeded) { UIImage *captureImage = [UIImage imageWithCGImage:image]; // 成功 do something } else { // 失敗 } }]; } |
AVAssetTrack
一般的視訊至少有2個軌道，一個播放聲音，一個播放畫面。在AVAsset中，可以通過trackId，獲得特定的track。
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- (nullable AVAssetTrack *)trackWithTrackID:(CMPersistentTrackID)trackID; |
除了通過trackID獲得track之外，AVAsset中還提供了其他3中方式獲得track：
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@property (nonatomic, readonly) NSArray *tracks; |
tracks中包含了當前Asset中的所有track，通過遍歷我們可以獲得想要的track。
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- (NSArray *)tracksWithMediaType:(NSString *)mediaType; |
-tracksWithMediaType:方法會根據指定的媒體型別返回一個track陣列，陣列中包含著Asset中所有指定媒體型別的track。如果Asset中沒有這個媒體型別的track，返回一個空陣列。AVMediaFormat中一共定義了8種媒體型別: AVMediaTypeVideo、AVMediaTypeAudio、AVMediaTypeText、AVMediaTypeClosedCaption、AVMediaTypeSubtitle、AVMediaTypeTimecode、AVMediaTypeMetadata、AVMediaTypeMuxed。
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- (NSArray *)tracksWithMediaCharacteristic:(NSString *)mediaCharacteristic; |
-tracksWithMediaCharacteristic:方法會根據指定的媒體特徵返回track陣列，陣列的特性與-tracksWithMediaType:類似，如果Asset中沒有這個媒體特徵的track，返回一個空陣列。AVMediaFormat中一共定義了15種媒體特徵: AVMediaTypeMetadataObject、AVMediaCharacteristicVisual、AVMediaCharacteristicAudible、AVMediaCharacteristicLegible、AVMediaCharacteristicFrameBased、AVMediaCharacteristicIsMainProgramContent、AVMediaCharacteristicIsAuxiliaryContent、AVMediaCharacteristicContainsOnlyForcedSubtitles、AVMediaCharacteristicTranscribesSpokenDialogForAccessibility、AVMediaCharacteristicDescribesMusicAndSoundForAccessibility、AVMediaCharacteristicEasyToRead、AVMediaCharacteristicDescribesVideoForAccessibility、AVMediaCharacteristicLanguageTranslation、AVMediaCharacteristicDubbedTranslation、AVMediaCharacteristicVoiceOverTranslation。
程式碼實現：
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AVAsset *asset = [AVAsset assetWithURL:...]; NSArray* allVideoTracks = [asset tracksWithMediaType:AVMediaTypeVideo]; if ([allVideoTracks count] > 0) { AVAssetTrack* track = [[asset tracksWithMediaType:AVMediaTypeVideo]objectAtIndex:0]; CGSize size = [track naturalSize];// 本視訊的解析度 } |
下面看一個小例：
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AVAsset *asset = [AVAsset assetWithURL:...]; AVAssetTrack *videoAssetTrack = [[asset tracksWithMediaType:AVMediaTypeVideo]objectAtIndex:0];//素材的視訊軌 AVAssetTrack *audioAssertTrack = [[asset tracksWithMediaType:AVMediaTypeAudio]objectAtIndex:0];//素材的音訊軌 //將素材的視訊插入視訊軌，音訊插入音訊軌 AVMutableComposition *composition = [AVMutableComposition composition];//這是工程檔案 AVMutableCompositionTrack *videoCompositionTrack = [composition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];//視訊軌道 [videoCompositionTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAssetTrack.timeRange.duration) ofTrack:videoAssetTrack atTime:kCMTimeZero error:nil];//在視訊軌道插入一個時間段的視訊 AVMutableCompositionTrack *audioCompositionTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];//音訊軌道 [audioCompositionTrack insertTimeRange: CMTimeRangeMake(kCMTimeZero, videoAssetTrack.timeRange.duration) ofTrack:audioAssertTrack atTime:kCMTimeZero error:nil];//插入音訊資料，否則沒有聲音 // 裁剪視訊 AVMutableVideoCompositionLayerInstruction *videoCompositionLayerIns = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoAssetTrack]; [videoCompositionLayerIns setTransform:videoAssetTrack.preferredTransform atTime:kCMTimeZero];//得到視訊素材 AVMutableVideoCompositionInstruction *videoCompositionIns = [AVMutableVideoCompositionInstruction videoCompositionInstruction]; [videoCompositionIns setTimeRange:CMTimeRangeMake(kCMTimeZero, videoAssetTrack.timeRange.duration)];//得到視訊軌道 AVMutableVideoComposition *videoComposition = [AVMutableVideoComposition videoComposition]; videoComposition.instructions = @[videoCompositionIns];videoComposition.renderSize = CGSizeMake(...);//裁剪出對應的大小 videoComposition.frameDuration = CMTimeMake(1, 30); // 匯出 AVAssetExportSession *exporter = [[AVAssetExportSession alloc] initWithAsset:composition presetName:AVAssetExportPresetMediumQuality]; exporter.videoComposition = videoComposition; exporter.outputURL = [NSURL fileURLWithPath:... isDirectory:YES]; exporter.outputFileType = AVFileTypeMPEG4; exporter.shouldOptimizeForNetworkUse = YES; [exporter exportAsynchronouslyWithCompletionHandler:^{ if (exporter.error) { // 失敗處理 }else{ // 成功 } }]; |
補充上篇錄製視訊的示例：
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#import "ViewController.h" #import #import typedef void(^PropertyChangeBlock) (AVCaptureDevice *captureDevice); @interface ViewController () /** 負責輸入和輸出裝置之間的資料傳遞 */ @property (nonatomic,strong) AVCaptureSession *captureSession; /** 負責從AVCaptureDevice獲得輸入資料 */ @property (nonatomic,strong) AVCaptureDeviceInput *captureDeviceInput; /** 視訊輸出流 */ @property (nonatomic,strong) AVCaptureMovieFileOutput *captureMovieFileOutput; /** 相機拍攝預覽圖層 */ @property (nonatomic,strong) AVCaptureVideoPreviewLayer *captureVideoPreviewLayer; /** 是否允許螢幕旋轉(在錄製螢幕中禁止旋轉) */ @property (nonatomic,assign) BOOL enableRotation; /** 旋轉前大小 */ @property (nonatomic,assign) CGRect *lastBounds; /** 後臺任務標識 */ @property (nonatomic,assign) UIBackgroundTaskIdentifier backgroundTaskIdentifier; @property (weak, nonatomic) IBOutlet UIView *viewContainer; /** 自動閃光按鈕 */ @property (weak, nonatomic) IBOutlet UIButton *flashAutoButton; /** 開啟閃光按鈕 */ @property (weak, nonatomic) IBOutlet UIButton *flashOnButton; /** 關閉閃光按鈕 */ @property (weak, nonatomic) IBOutlet UIButton *flashOffButton; /** 聚焦框 */ @property (weak, nonatomic) IBOutlet UIImageView *focusCursor; /** 拍照按鈕 */ @property (weak, nonatomic) IBOutlet UIButton *takeButton1; @end @implementation ViewController - (void)viewDidLoad { [super viewDidLoad]; } - (void)viewWillAppear:(BOOL)animated { [super viewWillAppear:animated]; // 初始化會話 _captureSession = [[AVCaptureSession alloc] init]; if ([_captureSession canSetSessionPreset:AVCaptureSessionPreset1280x720]) { // 設定解析度 _captureSession.sessionPreset = AVCaptureSessionPreset1280x720; } // 獲得輸入裝置 AVCaptureDevice *captureDevice = [self getCameraDeviceWithPosition:AVCaptureDevicePositionBack]; // 得道後置攝像頭 if (!captureDevice) { NSLog(@"取得後置攝像頭出現錯誤"); return; } // 新增一個音訊輸入裝置 AVCaptureDevice *audioCaptureDevice = [[AVCaptureDevice devicesWithMediaType:AVMediaTypeAudio] firstObject]; NSError *error = nil; // 根據輸入裝置初始化輸入物件，用於獲得輸入資料 _captureDeviceInput = [[AVCaptureDeviceInput alloc] initWithDevice:captureDevice error:&error]; if (error) { NSLog(@"取得裝置輸入物件時出錯，錯誤原因：%@",error.localizedDescription); return; } AVCaptureDeviceInput *audioCaptureDeviceInput = [[AVCaptureDeviceInput alloc] initWithDevice:audioCaptureDevice error:&error]; if (error) { NSLog(@"取得裝置輸入物件時出錯，錯誤原因：%@",error.localizedDescription); return; } // 初始化輸出裝置物件，用於獲得輸出資料 _captureMovieFileOutput = [[AVCaptureMovieFileOutput alloc] init]; // 將裝置輸入新增到會話中 if ([_captureSession canAddInput:_captureDeviceInput]) { [_captureSession addInput:_captureDeviceInput]; [_captureSession addInput:audioCaptureDeviceInput]; AVCaptureConnection *captureConnection=[_captureMovieFileOutput connectionWithMediaType:AVMediaTypeVideo]; if ([captureConnection isVideoStabilizationSupported ]) { captureConnection.preferredVideoStabilizationMode=AVCaptureVideoStabilizationModeAuto;//視訊防抖 } } // 將裝置輸出新增到會話中 if ([_captureSession canAddOutput:_captureMovieFileOutput]) { [_captureSession addOutput:_captureMovieFileOutput]; } // 建立視訊預覽層，用於時實展示攝像頭狀態 _captureVideoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.captureSession]; CALayer *layer = self.viewContainer.layer; layer.masksToBounds = YES; // 設定圖層的圓角屬性 _captureVideoPreviewLayer.frame = layer.bounds; _captureVideoPreviewLayer.videoGravity = AVLayerVideoGravityResize; // 填充模式顯示在layer上 // 將視訊預覽層新增到介面中 [layer insertSublayer:_captureVideoPreviewLayer below:self.focusCursor.layer]; _enableRotation=YES; [self addNotificationToCaptureDevice:captureDevice]; // 給輸入裝置新增通知 [self addGenstureRecognizer]; // 新增手勢 [self setFlashModeButtonStatus]; // 設定閃光燈按鈕狀態 } // 在控制器檢視展示和檢視離開介面時啟動，停止會話 - (void)viewDidAppear:(BOOL)animated { [super viewDidAppear:animated]; [self.captureSession startRunning]; } - (void)viewDidDisappear:(BOOL)animated { [super viewDidDisappear:animated]; [self.captureSession stopRunning]; } - (BOOL)shouldAutorotate { return self.enableRotation; } // 旋轉螢幕時調整視訊預覽圖層的方向 - (void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration { AVCaptureConnection *captureConnection = [self.captureVideoPreviewLayer connection]; captureConnection.videoOrientation = (AVCaptureVideoOrientation)toInterfaceOrientation; } // 旋轉後重新設定大小 - (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation { _captureVideoPreviewLayer.frame = self.viewContainer.bounds; } -(void)dealloc{ [self removeNotification]; } #pragma -mark 通知 /** * 給輸入裝置新增通知 * */ - (void)addNotificationToCaptureDevice:(AVCaptureDevice *)captureDevice { //注意新增區域改變捕獲通知必須首先設定裝置允許捕獲 [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) { captureDevice.subjectAreaChangeMonitoringEnabled = YES; }]; NSNotificationCenter *notificationCenter = [NSNotificationCenter defaultCenter]; // 捕獲區域發生改變 [notificationCenter addObserver:self selector:@selector(areaChange:) name:AVCaptureDeviceSubjectAreaDidChangeNotification object:captureDevice]; } - (void)removeNotificationFromCaptureDevice:(AVCaptureDevice *)captureDevice { NSNotificationCenter *notificationCenter = [NSNotificationCenter defaultCenter]; [notificationCenter removeObserver:self name:AVCaptureDeviceSubjectAreaDidChangeNotification object:captureDevice]; } /** * 移除所有通知 */ -(void)removeNotification{ NSNotificationCenter *notificationCenter= [NSNotificationCenter defaultCenter]; [notificationCenter removeObserver:self]; } -(void)addNotificationToCaptureSession:(AVCaptureSession *)captureSession{ NSNotificationCenter *notificationCenter= [NSNotificationCenter defaultCenter]; //會話出錯 [notificationCenter addObserver:self selector:@selector(sessionRuntimeError:) name:AVCaptureSessionRuntimeErrorNotification object:captureSession]; } /** * 裝置連線成功 * * @param notification 通知物件 */ -(void)deviceConnected:(NSNotification *)notification{ NSLog(@"裝置已連線..."); } /** * 裝置連線斷開 * * @param notification 通知物件 */ -(void)deviceDisconnected:(NSNotification *)notification{ NSLog(@"裝置已斷開."); } /** * 捕獲區域改變 * * @param notification 通知物件 */ -(void)areaChange:(NSNotification *)notification{ NSLog(@"捕獲區域改變..."); } /** * 會話出錯 * * @param notification 通知物件 */ -(void)sessionRuntimeError:(NSNotification *)notification{ NSLog(@"會話發生錯誤."); } #pragma -mark 私有方法 /** * 取得指定位置的攝像頭 * * @param position 攝像頭位置 * * @return 攝像頭裝置 */ -(AVCaptureDevice *)getCameraDeviceWithPosition:(AVCaptureDevicePosition )position{ NSArray *cameras= [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo]; for (AVCaptureDevice *camera in cameras) { if ([camera position] == position) { return camera; } } return nil; } /** * 改變裝置屬性的統一操作方法 * @param propertyChange 屬性改變操作 */ - (void)changeDeviceProperty:(PropertyChangeBlock)propertyChange { AVCaptureDevice *captureDevice = [self.captureDeviceInput device]; NSError *error; //注意改變裝置屬性前一定要首先呼叫lockForConfiguration:呼叫完之後使用unlockForConfiguration方法解鎖 if ([captureDevice lockForConfiguration:&error]) { propertyChange(captureDevice); [captureDevice unlockForConfiguration]; }else{ NSLog(@"設定裝置屬性過程發生錯誤，錯誤資訊：%@",error.localizedDescription); } } /** * 設定閃光燈模式 * * @param flashMode 閃光燈模式 */ -(void)setFlashMode:(AVCaptureFlashMode )flashMode{ [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) { if ([captureDevice isFlashModeSupported:flashMode]) { [captureDevice setFlashMode:flashMode]; } }]; } /** * 設定聚焦模式 * * @param focusMode 聚焦模式 */ -(void)setFocusMode:(AVCaptureFocusMode )focusMode{ [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) { if ([captureDevice isFocusModeSupported:focusMode]) { [captureDevice setFocusMode:focusMode]; } }]; } /** * 設定曝光模式 * * @param exposureMode 曝光模式 */ -(void)setExposureMode:(AVCaptureExposureMode)exposureMode{ [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) { if ([captureDevice isExposureModeSupported:exposureMode]) { [captureDevice setExposureMode:exposureMode]; } }]; } /** * 設定聚焦點 * * @param point 聚焦點 */ -(void)focusWithMode:(AVCaptureFocusMode)focusMode exposureMode:(AVCaptureExposureMode)exposureMode atPoint:(CGPoint)point{ [self changeDeviceProperty:^(AVCaptureDevice *captureDevice) { 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]; } }]; } /** * 新增手勢：點按時聚焦 * */ - (void)addGenstureRecognizer { UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapScreen:)]; [self.viewContainer addGestureRecognizer:tapGesture]; } - (void)tapScreen:(UITapGestureRecognizer *)tapGesture { CGPoint point= [tapGesture locationInView:self.viewContainer]; NSLog(@"(%f,%f)",point.x,point.y); //將UI座標轉化為攝像頭座標 CGPoint cameraPoint= [self.captureVideoPreviewLayer captureDevicePointOfInterestForPoint:point]; [self setFocusCursorWithPoint:point]; [self focusWithMode:AVCaptureFocusModeAutoFocus exposureMode:AVCaptureExposureModeAutoExpose atPoint:cameraPoint]; } /** * 設定聚焦游標位置 * * @param point 游標位置 */ -(void)setFocusCursorWithPoint:(CGPoint)point{ self.focusCursor.center=point; self.focusCursor.transform=CGAffineTransformMakeScale(1.5, 1.5); self.focusCursor.alpha=1.0; [UIView animateWithDuration:1.0 animations:^{ self.focusCursor.transform=CGAffineTransformIdentity; } completion:^(BOOL finished) { self.focusCursor.alpha=0; }]; } /** * 設定閃光燈按鈕狀態 */ -(void)setFlashModeButtonStatus{ AVCaptureDevice *captureDevice=[self.captureDeviceInput device]; AVCaptureFlashMode flashMode=captureDevice.flashMode; if([captureDevice isFlashAvailable]){ // 如果當前閃光可用（後置攝像頭時閃光燈可用，前置攝像頭時閃光燈不可用） self.flashAutoButton.hidden=NO; self.flashOnButton.hidden=NO; self.flashOffButton.hidden=NO; self.flashAutoButton.enabled=YES; self.flashOnButton.enabled=YES; self.flashOffButton.enabled=YES; switch (flashMode) { case AVCaptureFlashModeAuto: self.flashAutoButton.enabled=NO; break; case AVCaptureFlashModeOn: self.flashOnButton.enabled=NO; break; case AVCaptureFlashModeOff: self.flashOffButton.enabled=NO; break; default: break; } }else{ self.flashAutoButton.hidden=YES; self.flashOnButton.hidden=YES; self.flashOffButton.hidden=YES; } } #pragma mark -按鈕處理 #pragma mark 切換前後攝像頭 - (IBAction)toggleButtonClick1:(UIButton *)sender { // 得到當前的輸入裝置並刪除其上面的通知 AVCaptureDevice *currentDevice=[self.captureDeviceInput device]; AVCaptureDevicePosition currentPosition=[currentDevice position]; [self removeNotificationFromCaptureDevice:currentDevice]; AVCaptureDevice *toChangeDevice; AVCaptureDevicePosition toChangePosition=AVCaptureDevicePositionFront; if (currentPosition==AVCaptureDevicePositionUnspecified||currentPosition==AVCaptureDevicePositionFront) { // 如果當前輸入裝置不是前置攝像頭 toChangePosition=AVCaptureDevicePositionBack; } toChangeDevice=[self getCameraDeviceWithPosition:toChangePosition]; // 取得攝像頭裝置 [self addNotificationToCaptureDevice:toChangeDevice]; // 給裝置加入通知 //獲得要調整的裝置輸入物件 AVCaptureDeviceInput *toChangeDeviceInput=[[AVCaptureDeviceInput alloc]initWithDevice:toChangeDevice error:nil]; //改變會話的配置前一定要先開啟配置，配置完成後提交配置改變 [self.captureSession beginConfiguration]; //移除原有輸入物件 [self.captureSession removeInput:self.captureDeviceInput]; //新增新的輸入物件 if ([self.captureSession canAddInput:toChangeDeviceInput]) { [self.captureSession addInput:toChangeDeviceInput]; self.captureDeviceInput=toChangeDeviceInput; } //提交會話配置 [self.captureSession commitConfiguration]; [self setFlashModeButtonStatus]; } #pragma mark 錄製視訊 - (IBAction)takeButtonClick11:(UIButton *)sender { //根據裝置輸出獲得連線 AVCaptureConnection *captureConnection=[self.captureMovieFileOutput connectionWithMediaType:AVMediaTypeVideo]; //根據連線取得裝置輸出的資料 if (![self.captureMovieFileOutput isRecording]) { // 如果此時沒有在錄屏 self.enableRotation=NO; //如果支援多工則則開始多工 if ([[UIDevice currentDevice] isMultitaskingSupported]) { self.backgroundTaskIdentifier=[[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:nil]; } //預覽圖層和視訊方向保持一致 captureConnection.videoOrientation=[self.captureVideoPreviewLayer connection].videoOrientation; NSString *outputFielPath=[NSTemporaryDirectory() stringByAppendingString:@"myMovie.mov"]; NSLog(@"save path is :%@",outputFielPath); NSURL *fileUrl=[NSURL fileURLWithPath:outputFielPath]; NSLog(@"fileUrl:%@",fileUrl); [self.captureMovieFileOutput startRecordingToOutputFileURL:fileUrl recordingDelegate:self]; } else{ [self.captureMovieFileOutput stopRecording];//停止錄製 } } #pragma mark 自動閃光燈開啟 - (IBAction)flashAutoClick1:(UIButton *)sender { [self setFlashMode:AVCaptureFlashModeAuto]; [self setFlashModeButtonStatus]; } #pragma mark 開啟閃光燈 - (IBAction)flashOnClick1:(UIButton *)sender { [self setFlashMode:AVCaptureFlashModeOn]; [self setFlashModeButtonStatus]; } #pragma mark 關閉閃光燈 - (IBAction)flashOffClick1:(UIButton *)sender { [self setFlashMode:AVCaptureFlashModeOff]; [self setFlashModeButtonStatus]; } #pragma mark -AVCaptureFileOutputRecordingDelegate 視訊輸出代理中的方法 // optional // 當資料開始寫入檔案的時候呼叫,如果資料寫入錯誤，則該方法不會被呼叫 - (void)captureOutput:(AVCaptureFileOutput *)captureOutput didStartRecordingToOutputFileAtURL:(NSURL *)fileURL fromConnections:(NSArray *)connections { NSLog(@"開始錄製"); } // required // 當資料寫入完成時呼叫該方法 - (void)captureOutput:(AVCaptureFileOutput *)captureOutput didFinishRecordingToOutputFileAtURL:(NSURL *)outputFileURL fromConnections:(NSArray *)connections error:(NSError *)error { NSLog(@"視訊錄製完成"); //視訊錄製完成之後在後臺將視訊儲存到相簿 self.enableRotation = YES; UIBackgroundTaskIdentifier lastBackgroundTaskIdentifier = self.backgroundTaskIdentifier; self.backgroundTaskIdentifier = UIBackgroundTaskInvalid; ALAssetsLibrary *assetsLibrary = [[ALAssetsLibrary alloc] init]; [assetsLibrary writeVideoAtPathToSavedPhotosAlbum:outputFileURL completionBlock:^(NSURL *assetURL, NSError *error) { if (error) { NSLog(@"儲存視訊到相簿的過程發生錯誤，錯誤資訊：%@",error.localizedDescription); } NSLog(@"outputURL:%@",outputFileURL); [[NSFileManager defaultManager] removeItemAtURL:outputFileURL error:nil]; if (lastBackgroundTaskIdentifier != UIBackgroundTaskInvalid) { [[UIApplication sharedApplication] endBackgroundTask:lastBackgroundTaskIdentifier]; } NSLog(@"成功儲存視訊到相簿"); }]; } @end |