iOS AVFoundation之自定义相机AVCaptureS

作者: 床前明月_光 | 来源:发表于2017-08-01 11:06 被阅读450次

    要自定义一个相机,涉及的类有很多, 这也是AVFounation的重要学习内容之一, 音视频的捕获方面的知识更是重中之重,大概涉及的类有AVCaptureSessionAVCaptureConnectionAVCaptureDeviceAVCaptureDeviceInputAVCapturePhotoOutputAVCaptureMovieFileOutput等, 下面来一一介绍

    AVCaptureSession

    这个就是充当会话者的角色, 我们可以理解为平时生活中的插线板, 有输入, 有输出。其中AVCaptureDeviceInput为输入, AVCapturePhotoOutputAVCaptureMovieFileOutput等为输出它们之间的关系我们可以看一下下面这幅图

    输入, 输出与会话者之间的关系
    这里的AVCaptureStillImageOutPutAVCapturePhotoOutput是类似的, iOS10之前用AVCaptureStillImageOutPut, iOS10之后用AVCapturePhotoOutput

    其中输入源有:AVCaptureDeviceInput(video)AVCaptureDeviceInput(audio)
    输出源有:AVCaptureVideoDataOutput, AVCaptureAudioDataOutput, AVCaptureMovieFileOutput, AVCaptureStillImageOutput(AVCapturePhotoOutput), AVCaptureMetadataOutput,

    简单的创建一个会话者

    AVCaptureSession *session = [[AVCaptureSession alloc] init];
    
    // 添加输入与输出
    
    [session startRunning];
    

    AVCaptureSession可以拥有一个或多个输入源, 当你想获取一张图片的时候你只需要AVCaptureDeviceInput(video)也就是图像的输入源就可以了, 当你想获取一段有声的视频时,则需要两个输入源AVCaptureDeviceInput(video)AVCaptureDeviceInput(audio),你还可以只获取声音数据的时候, 只要AVCaptureDeviceInput(audio)就可以了。
    在创建AVCaptureSession时我们一般会设定一个预设来获取不同规格的数据:

    NSString *const AVCaptureSessionPresetPhoto; //一般在获取静态图片的时候用
    NSString *const AVCaptureSessionPresetHigh; 
    NSString *const AVCaptureSessionPresetMedium;
    NSString *const AVCaptureSessionPresetLow; 
    NSString *const AVCaptureSessionPreset352x288;
    NSString *const AVCaptureSessionPreset640x480;  //  VGA.
    NSString *const AVCaptureSessionPreset1280x720;  // 720p HD.
    NSString *const AVCaptureSessionPreset1920x1080;
    NSString *const AVCaptureSessionPresetiFrame960x540;
    NSString *const AVCaptureSessionPresetiFrame1280x720;
    NSString *const AVCaptureSessionPresetInputPriority; //通过已连接的捕获设备的 activeFormat 来反过来控制 capture session 的输出质量等级
    

    在配置AVCaptureSession, 需要注意的是:
    1、在输入输出或配置它的时候, 线程是阻塞的, 所以最后是创建一条串行队列异步执行。
    2、在改变或配置输入, 输出, 预设(sessionPreset)的时候, 在AVCaptureSession所在线程在修改或配置之前调用- (void)beginConfiguration; 修改完之后, 或修改失败之后调用- (void)commitConfiguration;, 这样可以提高流畅性等不必要的BUG。

    AVCaptureConnection

    AVCaptureSession中, 可能存在着很多的AVCaptureConnectionAVCaptureConnection代表着一条连接通道, 例如: 获取一张图片, 输入是AVCaptureDeviceInput(video) 输出是 AVCaptureStillImageOutput(AVCapturePhotoOutput), 在输入到输出这个过程中, 就有一个AVCaptureConnection对象去管理者这个流程。AVCaptureConnection可以有多个输入和输出,例如:获取视视频的时候, 就有视频和音频的输入, 输出也可以分视频数据和音频数据, 还可以获取图片数据。一般这个对象在你AVCaptureSession中加入输入输出的时候就会自动的帮你创建了。

    AVCaptureConnection与输入输出的关系
    所以我们一般是去获取使用:
    AVCaptureConnection *connection = [movieFileOutput connectionWithMediaType:AVMediaTypeAudio];
    

    我们一般用它来管理视频或图片输出的方向格式等问题, 还有音频输出的音量、声道等, 控制输入或输出

    //图片输出朝向问题
           AVCaptureConnection *photoOutputConnection = [self.photoOutput connectionWithMediaType:AVMediaTypeVideo];
            photoOutputConnection.videoOrientation = videoPreviewLayerVideoOrientation;
    

    其中朝向问题, 这里整理出来然大家有个很好的对比

    [UIApplication sharedApplication].statusBarOrientation; 状态栏的方向跟视频的方向是一致的, 还有对比设备的朝向
    typedef NS_ENUM(NSInteger, UIInterfaceOrientation) {
        UIInterfaceOrientationUnknown                                                           = UIDeviceOrientationUnknown, 
        UIInterfaceOrientationPortrait            =  AVCaptureVideoOrientationPortrait          = UIDeviceOrientationPortrait,              //home button on the bottom.
        UIInterfaceOrientationPortraitUpsideDown  = AVCaptureVideoOrientationPortraitUpsideDown = UIDeviceOrientationPortraitUpsideDown,    //home button on the top.
        UIInterfaceOrientationLandscapeLeft       = AVCaptureVideoOrientationLandscapeRight     = UIDeviceOrientationLandscapeRight,        //home button on the right.
        UIInterfaceOrientationLandscapeRight      = AVCaptureVideoOrientationLandscapeLeft      = UIDeviceOrientationLandscapeLeft          //home button on the left.  
    } __TVOS_PROHIBITED;
    
    

    AVCaptureDeviceInput

    这个类代表着AVCaptureSession中的输入, 其中会根据AVCaptureDevice中的是视频设备(摄像头)还是音频设备(麦克风),的不同而不同,创建出来之后充当输入的角色添加到AVCaptureSession

        //配置session输入输出, 或输入输出属性, sessionPreset时,需要用到-beginConfiguration, -commitConfiguration
        [self.session beginConfiguration];
        self.session.sessionPreset = AVCaptureSessionPresetPhoto;
        //添加视频输入
        AVCaptureDevice *videoDevice = [AVCaptureDevice defaultDeviceWithDeviceType:AVCaptureDeviceTypeBuiltInWideAngleCamera mediaType:AVMediaTypeVideo position:AVCaptureDevicePositionUnspecified];
        AVCaptureDeviceInput *videoDeviceInput = [AVCaptureDeviceInput deviceInputWithDevice:videoDevice error:&error];
        if (!videoDeviceInput) {
            NSLog(@"视频设备输出创建错误--%@", error);
            self.setupResult = AVCamManualSetupResultSessionConfigurationFailed;
            [self.session commitConfiguration];
            return;
        }
        if ([self.session canAddInput:videoDeviceInput]) {
            [self.session addInput:videoDeviceInput];
            self.videoDeviceInput = videoDeviceInput;
            self.videoDevice = videoDevice;
            dispatch_async(dispatch_get_main_queue(), ^{//调整视频输入方向
                UIInterfaceOrientation statusBarOriebtation = [UIApplication sharedApplication].statusBarOrientation;
                AVCaptureVideoOrientation initialVideoOrientation = AVCaptureVideoOrientationPortrait;
                if (statusBarOriebtation != UIInterfaceOrientationUnknown) {
                    initialVideoOrientation = (AVCaptureVideoOrientation)statusBarOriebtation;
                }
                
                AVCaptureVideoPreviewLayer *previewLayer = (AVCaptureVideoPreviewLayer *)self.previewView.layer;
                previewLayer.connection.videoOrientation = initialVideoOrientation;
            });
        }else {
            NSLog(@"不能添加视频输入到session");
            self.setupResult = AVCamManualSetupResultSessionConfigurationFailed;
            [self.session commitConfiguration];
            return;
        
        }
        
        //添加音频输入
        AVCaptureDevice *audioDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeAudio];
        AVCaptureDeviceInput *audioDeviceInput = [AVCaptureDeviceInput deviceInputWithDevice:audioDevice error:&error];
        if (!audioDeviceInput) {
            NSLog(@"音频设备输出创建错误--%@", error);
            
        }
        
        if ([self.session canAddInput:audioDeviceInput]) {
            [self.session addInput:audioDeviceInput];
        }else {
         
            NSLog(@"不能添加音频输入到session");
        }
    
    

    需要注意的是:
    1、摄像头的聚焦(AVCaptureFocusMode)、曝光(AVCaptureExposureMode)、白平衡(AVCaptureWhiteBalanceMode)和感光度(ISO)等等一些参数设置都是在AVCaptureDevice(video)里面配置完成的。
    2、AVCaptureDevice配置参数或修改参数的时候都要注意先调用 - (BOOL)lockForConfiguration:(NSError **)outError; 配置完成后调用 - (void)unlockForConfiguration;

    下面是一下参数的配置:

    //改变聚焦模式
    - (IBAction)changeFocusMode:(id)sender
    {
        UISegmentedControl *control = sender;
        AVCaptureFocusMode mode = (AVCaptureFocusMode)[self.focusModes[control.selectedSegmentIndex] intValue];
        NSError *error = nil;
        if ([self.videoDevice lockForConfiguration:&error]) {
            if ([self.videoDevice isFocusModeSupported:mode]) {
                self.videoDevice.focusMode = mode;
            }
            else {
               NSLog( @"Focus mode %@ is not supported. Focus mode is %@.", [self stringFromFocusMode:mode], [self stringFromFocusMode:self.videoDevice.focusMode] );
                self.focusModeControl.selectedSegmentIndex = [self.focusModes indexOfObject:@(self.videoDevice.focusMode)];
                [self.videoDevice unlockForConfiguration];
            }
           
        }
        else {
             NSLog( @"Could not lock device for configuration: %@", error );
        }
        
    }
    
    //手动模式下, 改变镜头聚焦位置
    - (IBAction)changeLensPosition:(id)sender
    {
        UISlider *control = sender;
        NSError *error = nil;
        if ([self.videoDevice lockForConfiguration:&error]) {
            [self.videoDevice setFocusModeLockedWithLensPosition:control.value completionHandler:nil];//手动聚焦
            [self.videoDevice unlockForConfiguration];
        }
        else {
            NSLog( @"Could not lock device for configuration: %@", error );
        }
    }
    
    //设置输入设备的聚焦和曝光的模式和点
    - (void)focusWithMode:(AVCaptureFocusMode)focusMode exposeWithMode:(AVCaptureExposureMode)exposureMode atDevicePoint:(CGPoint)point monitorSubjectAreaChange:(BOOL)monitorSubjectAreaChange
    {
        dispatch_async(self.sessionQueue, ^{
            AVCaptureDevice *device = self.videoDevice;
            NSError *error = nil;
            if ([device lockForConfiguration:&error]) {
                if (focusMode != AVCaptureFocusModeLocked && device.isFocusPointOfInterestSupported && [device isFocusModeSupported:focusMode]) {
                    device.focusPointOfInterest = point;
                    device.focusMode = focusMode;
                }
                
                if (exposureMode != AVCaptureExposureModeCustom && device.isExposurePointOfInterestSupported && [device isExposureModeSupported:exposureMode]) {
                    device.exposurePointOfInterest = point;
                    device.exposureMode = exposureMode;
                }
                
                device.subjectAreaChangeMonitoringEnabled = monitorSubjectAreaChange;
                [device unlockForConfiguration];
            }else {
              NSLog( @"Could not lock device for configuration: %@", error );
            }
        });
    }
    
    //根据点击的位置, 进行聚焦和曝光
    - (IBAction)focusAndExposeTap:(UIGestureRecognizer *)gestureRecognizer
    {
        CGPoint devicePoint = [(AVCaptureVideoPreviewLayer *)self.previewView.layer captureDevicePointOfInterestForPoint:[gestureRecognizer locationInView:[gestureRecognizer view]]];
        [self focusWithMode:self.videoDevice.focusMode exposeWithMode:self.videoDevice.exposureMode atDevicePoint:devicePoint monitorSubjectAreaChange:YES];
        
    }
    
    //改变曝光模式
    - (IBAction)changeExposureMode:(id)sender
    {
        UISegmentedControl *control = sender;
        AVCaptureExposureMode mode = (AVCaptureExposureMode)[self.exposureModes[control.selectedSegmentIndex] intValue];
        NSError *error = nil;
        if ([self.videoDevice lockForConfiguration:&error]) {
            if ([self.videoDevice isExposureModeSupported:mode]) {
                self.videoDevice.exposureMode = mode;
            }
            else {
              NSLog( @"Exposure mode %@ is not supported. Exposure mode is %@.", [self stringFromExposureMode:mode], [self stringFromExposureMode:self.videoDevice.exposureMode] );
                self.exposureModeControl.selectedSegmentIndex = [self.exposureModes indexOfObject:@(self.videoDevice.exposureMode)];
            }
            [self.videoDevice unlockForConfiguration];
        }
        else {
           NSLog( @"Could not lock device for configuration: %@", error );
        }
    }
    
    //手动模式下的设置曝光时间
    - (IBAction)changeExposureDuration:(id)sender
    {
        UISlider *control = sender;
        NSError *error = nil;
        
        double p = pow( control.value, kExposureDurationPower ); // Apply power function to expand slider's low-end range
        double minDurationSeconds = MAX( CMTimeGetSeconds( self.videoDevice.activeFormat.minExposureDuration ), kExposureMinimumDuration );
        double maxDurationSeconds = CMTimeGetSeconds( self.videoDevice.activeFormat.maxExposureDuration );
        double newDurationSeconds = p * ( maxDurationSeconds - minDurationSeconds ) + minDurationSeconds; // Scale from 0-1 slider range to actual duration
        if ([self.videoDevice lockForConfiguration:&error]) {
            [self.videoDevice setExposureModeCustomWithDuration:CMTimeMakeWithSeconds(newDurationSeconds, 1000*1000*1000) ISO:AVCaptureISOCurrent completionHandler:nil];
            [self.videoDevice unlockForConfiguration];
        }
        else {
        
          NSLog( @"Could not lock device for configuration: %@", error );
        }
    }
    

    AVCaptureOutput

    一般是用他们的子类AVCaptureVideoDataOutput, AVCaptureAudioDataOutput, AVCaptureMovieFileOutput, AVCaptureStillImageOutput(AVCapturePhotoOutput), AVCaptureMetadataOutput, 他们都用相对应的代理, 其中数据输出都是通过代理来实现的,
    下面的是视频的数据输出和存储

    - (IBAction)toggleMovieRecording:(id)sender
    {
        self.recordButton.enabled = NO;
        self.cameraButton.enabled = NO;
        self.captureModeControl.enabled = NO;
        
        AVCaptureVideoPreviewLayer *previewLayer = (AVCaptureVideoPreviewLayer *)self.previewView.layer;
        AVCaptureVideoOrientation previewLayerVideoOrientation = previewLayer.connection.videoOrientation;
        dispatch_async(self.sessionQueue, ^{
            if (!self.movieFileOutput.isRecording) {
                
                if ([UIDevice currentDevice].isMultitaskingSupported) {
                    self.backgroundRecordingID = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:nil];
                }
                AVCaptureConnection *moviceConnection = [self.movieFileOutput connectionWithMediaType:AVMediaTypeVideo];
                moviceConnection.videoOrientation = previewLayerVideoOrientation;
                //保存到相册
                NSString *outputFileName = [NSProcessInfo processInfo].globallyUniqueString;
                NSString *outputFilePath = [NSTemporaryDirectory() stringByAppendingPathComponent:[outputFileName stringByAppendingPathExtension:@"mov"]];
                [self.movieFileOutput startRecordingToOutputFileURL:[NSURL fileURLWithPath:outputFilePath] recordingDelegate:self];
            }
            else {
                [self.movieFileOutput stopRecording];
            
            }
            
        });
    }
    
    - (void)captureOutput:(AVCaptureFileOutput *)captureOutput didStartRecordingToOutputFileAtURL:(NSURL *)fileURL fromConnections:(NSArray *)connections
    {
        dispatch_async( dispatch_get_main_queue(), ^{
            self.recordButton.enabled = YES;
            [self.recordButton setTitle:NSLocalizedString( @"Stop", @"Recording button stop title" ) forState:UIControlStateNormal];
        });
    }
    
    - (void)captureOutput:(AVCaptureFileOutput *)captureOutput didFinishRecordingToOutputFileAtURL:(NSURL *)outputFileURL fromConnections:(NSArray *)connections error:(NSError *)error
    {
        UIBackgroundTaskIdentifier  currentBackgroundRecordingID = self.backgroundRecordingID;
        self.backgroundRecordingID = UIBackgroundTaskInvalid;
        dispatch_block_t cleanup = ^{
            if ([[NSFileManager defaultManager] fileExistsAtPath:outputFileURL.path]) {
                [[NSFileManager defaultManager] removeItemAtPath:outputFileURL.path error:nil];
            }
            if (currentBackgroundRecordingID != UIBackgroundTaskInvalid) {
                [[UIApplication sharedApplication] endBackgroundTask:currentBackgroundRecordingID];
            }
        
        };
        BOOL success = YES;
        if (error) {
            NSLog( @"Error occurred while capturing movie: %@", error );
            success = [error.userInfo[AVErrorRecordingSuccessfullyFinishedKey] boolValue];
        }
        if (success) {
            [PHPhotoLibrary requestAuthorization:^(PHAuthorizationStatus status) {
                if (status == PHAuthorizationStatusAuthorized) {
                    [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
                        PHAssetResourceCreationOptions *options = [[PHAssetResourceCreationOptions alloc] init];
                        options.shouldMoveFile = YES;
                        PHAssetCreationRequest *changeRequest = [PHAssetCreationRequest creationRequestForAsset];
                        [changeRequest addResourceWithType:PHAssetResourceTypeVideo fileURL:outputFileURL options:options];
                    } completionHandler:^(BOOL success, NSError * _Nullable error) {
                        if (!success) {
                            NSLog( @"Could not save movie to photo library: %@", error);
                        }
                        cleanup();
                    }];
                }else {
                    cleanup();
                }
            }];
        }
        else {
            cleanup();
        }
        dispatch_async(dispatch_get_main_queue(), ^{
            self.cameraButton.enabled = (self.videoDeviceDiscoverySession.devices.count > 1);
            self.recordButton.enabled = self.captureModeControl.selectedSegmentIndex == AVCamManualCaptureModeMovie;
            [self.recordButton setTitle:NSLocalizedString( @"Record", @"Recording button record title" ) forState:UIControlStateNormal];
            self.captureModeControl.enabled = YES;
        });
    }
    

    参考

    文章代码都是官方代码DEMO
    大家还可以参考另外一篇比较好的文章iOS-AVFoundation自定义相机详解

    相关文章

      网友评论

      • 西叶lv:- (void)lightSensitive {

        // 1.获取硬件设备
        AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

        // 2.创建输入流
        AVCaptureDeviceInput *input = [[AVCaptureDeviceInput alloc]initWithDevice:device error:nil];

        // 3.创建设备输出流
        AVCaptureVideoDataOutput *output = [[AVCaptureVideoDataOutput alloc] init];
        [output setSampleBufferDelegate:self queue:dispatch_get_main_queue()];


        // AVCaptureSession属性
        AVCaptureSession *session = [[AVCaptureSession alloc]init];
        // 设置为高质量采集率
        [session setSessionPreset:AVCaptureSessionPresetHigh];
        // 添加会话输入和输出
        if ([session canAddInput:input]) {
        [session addInput:input];
        }
        if ([session canAddOutput:output]) {
        [session addOutput:output];
        }

        // 9.启动会话
        [session startRunning];

        }
        我这样写,AVCaptureSession对象被提前释放了,[session startRunning];无效,只能把AVCaptureSession对象定义成属性,才行.为啥AVCaptureSession对象会被提前释放呢??求解答
        西叶lv:@床前明月_光 嗯,这个我知道。我现在明白了,Session必须一直存在,才能保证会话的正常进行,一旦出了这个方法,因为session不存在了,所以会话不能正常运行
        床前明月_光:@郝嘉律 过了这个方法大括号,对象就被释放啦, 这是作用域和内存管理的知识

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