自定义相机（三） -- 视频流数据 AND 预览 拍照 变焦

实现功能：

　　1. 视频流数据

　　2. 预览和拍照变焦， 所见即所得。

运行环境：

　　1.  XCODE 5.1.1

　　2.  真机（IPHONE5  ,  IOS6.1.4）

#import <UIKit/UIKit.h>
#import <AVFoundation/AVFoundation.h>       //导入 - "视频流"

@interface MCViewController : UIViewController<AVCaptureVideoDataOutputSampleBufferDelegate>

@property (strong, nonatomic) AVCaptureSession * captureSession;            //AVCaptureSession实例
@property (strong, nonatomic) AVCaptureDeviceInput * videoInput;            //持有视频输入实例

@property (strong, nonatomic) AVCaptureStillImageOutput * stillImageOutput;  //持有静态图像输出实例

@end

//
//  MCViewController.m
//  MyCamera

#import "MCViewController.h"

@interface MCViewController ()

@end

@implementation MCViewController

#pragma mark - life cycle

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];

    //开始扑捉会话
    [self.captureSession startRunning];
}

- (void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];

    //停止扑捉会话
    [self.captureSession stopRunning];
}

- (void)viewDidLoad
{
    [super viewDidLoad];

    //初始化视频流
    [self initAv];

    //添加拍照按钮
    [self addCaptureButton];
}

#pragma mark - 初始化视频流

- (void) initAv
{
    //1.1 创建AVCaptureSession
    self.captureSession = [[AVCaptureSession alloc] init];
    //1.2 指定输入设备。这里使用后摄像头。
    AVCaptureDevice * device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    //1.3 创建AVCaptureDeviceInput的实例，将所选设备作为扑捉会话的输入。
    //      此外，在将是其添加到回话前请创建好输入，这里需要做个检查。
    NSError * error = nil;
    self.videoInput = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
    if (self.videoInput) {
        [self.captureSession addInput:self.videoInput];
    }
    else
    {
        NSLog(@"input error : %@", error);
    }

    //4. 视频流帧数据
    AVCaptureVideoDataOutput * output = [[AVCaptureVideoDataOutput alloc] init];
    [self.captureSession addOutput:output];

    dispatch_queue_t queue = dispatch_queue_create("myQueue", NULL);
    [output setSampleBufferDelegate:self queue:queue];
    //dispatch_release(queue);

    //    output.videoSettings = [NSDictionary dictionaryWithObject:
    //                                                       [NSNumber numberWithInt:kCVPixelFormatType_32BGRA]
    //                                                       forKey:(id)kCVPixelBufferPixelFormatTypeKey];

    output.videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                            [NSNumber numberWithInt:kCVPixelFormatType_32BGRA], kCVPixelBufferPixelFormatTypeKey,
                            [NSNumber numberWithInt: 320], (id)kCVPixelBufferWidthKey,
                            [NSNumber numberWithInt: 240], (id)kCVPixelBufferHeightKey,
                            nil];
    //output.minFrameDuration = CMTimeMake(1, 15);

    //2. 创建预览层
    AVCaptureVideoPreviewLayer * previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:self.captureSession];
    UIView * aView = self.view;
    previewLayer.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);
    previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
    [aView.layer addSublayer:previewLayer];
    [previewLayer setAffineTransform:CGAffineTransformMakeScale(5.0, 5.0)]; //3. 实现拍照
    self.stillImageOutput = [[AVCaptureStillImageOutput alloc] init];
    NSDictionary * stillImageOutputSettings = [[NSDictionary alloc] initWithObjectsAndKeys:AVVideoCodecJPEG,AVVideoCodecKey, nil];
    [self.stillImageOutput setOutputSettings:stillImageOutputSettings];
    [self.captureSession addOutput:self.stillImageOutput];

//    //4. 拍照变焦
//    AVCaptureConnection * stillImageConnection = [self connectionWithMediaType:AVMediaTypeVideo fromConnections:[self.stillImageOutput connections]];
//
//    [stillImageConnection setVideoScaleAndCropFactor:5.0];  

}

#pragma  mark -
- (AVCaptureConnection *)connectionWithMediaType:(NSString *)mediaType fromConnections:(NSArray *)connections
{
    for ( AVCaptureConnection *connection in connections )
    {
        for ( AVCaptureInputPort *port in [connection inputPorts] )
        {
            if ( [[port mediaType] isEqual:mediaType] )
            {
                return connection;
            }
        }
    }
    return nil;
}

#pragma mark -  delegate -  AVCaptureVideoDataOutputSampleBufferDelegate

- (void)captureOutput:(AVCaptureOutput *)captureOutput
didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
       fromConnection:(AVCaptureConnection *)connection
{
    //视频流一帧数据(UIImage类型)
    UIImage * image =  [self imageFromSampleBuffer:sampleBuffer];

    NSLog(@"视频流， 宽：(%f)  高：(%f)", image.size.width, image.size.height);
    //IPHONE4  720  * 1280
    //IPHONE5  1080 * 1920

    //或：视频流一帧数据(NSData类型)
    //NSData * imageData = UIImageJPEGRepresentation(image, 0.5);

    //Code...

}

// Create a UIImage from sample buffer data
- (UIImage *) imageFromSampleBuffer:(CMSampleBufferRef) sampleBuffer
{
    // Get a CMSampleBuffer‘s Core Video image buffer for the media data
    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
    // Lock the base address of the pixel buffer
    CVPixelBufferLockBaseAddress(imageBuffer, 0);

    // Get the number of bytes per row for the pixel buffer
    void *baseAddress = CVPixelBufferGetBaseAddress(imageBuffer);

    // Get the number of bytes per row for the pixel buffer
    size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
    // Get the pixel buffer width and height
    size_t width = CVPixelBufferGetWidth(imageBuffer);
    size_t height = CVPixelBufferGetHeight(imageBuffer);

    // Create a device-dependent RGB color space
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

    // Create a bitmap graphics context with the sample buffer data
    CGContextRef context = CGBitmapContextCreate(baseAddress, width, height, 8,
                                                 bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);
    // Create a Quartz image from the pixel data in the bitmap graphics context
    CGImageRef quartzImage = CGBitmapContextCreateImage(context);
    // Unlock the pixel buffer
    CVPixelBufferUnlockBaseAddress(imageBuffer,0);

    // Free up the context and color space
    CGContextRelease(context);
    CGColorSpaceRelease(colorSpace);

    // Create an image object from the Quartz image
    //UIImage *image = [UIImage imageWithCGImage:quartzImage];
    UIImage *image = [UIImage imageWithCGImage:quartzImage scale:1.0f orientation:UIImageOrientationRight];

    // Release the Quartz image
    CGImageRelease(quartzImage);

    return (image);
}

#pragma mark - 添加按钮 AND 点击按钮事件

- (void)addCaptureButton
{
    CGRect frame = CGRectMake(0, 0, 100, 100);
    UIButton * btn = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    btn.frame = frame;
    [btn setTitle:@"拍照" forState:UIControlStateNormal];
    btn.backgroundColor = [UIColor clearColor];
    btn.tag = 1111;
    [btn addTarget:self action:@selector(onClickCaptureButton:) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:btn];
}

-(IBAction)onClickCaptureButton:(id)sender
{
    [self takePicture];
}

#pragma mark - 保持图像到相册

- (void)saveImageToPhotos:(UIImage*)savedImage
{
    UIImageWriteToSavedPhotosAlbum(savedImage, self, @selector(image:didFinishSavingWithError:contextInfo:), NULL);
}

// 指定回调方法
- (void)image: (UIImage *) image didFinishSavingWithError: (NSError *) error contextInfo: (void *) contextInfo
{
    NSString * msg = nil ;
    if(error != NULL)
    {
        msg = @"保存图片失败" ;
    }
    else
    {
        msg = @"保存图片成功" ;
    }

    UIAlertView * alert = [[UIAlertView alloc] initWithTitle:@"保存图片结果提示"
                                                    message:msg
                                                   delegate:self
                                          cancelButtonTitle:@"确定"
                                          otherButtonTitles:nil];
    [alert show];
}

#pragma mark - 拍照函数

//拍照
- (void) takePicture
{
    //1.
    AVCaptureConnection * stillImageConnection = [self.stillImageOutput.connections objectAtIndex:0];

    if ([stillImageConnection isVideoOrientationSupported]) {
        [stillImageConnection setVideoOrientation:AVCaptureVideoOrientationPortrait];
    }

    //2.
    [self.stillImageOutput captureStillImageAsynchronouslyFromConnection:stillImageConnection completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {

        if (imageDataSampleBuffer != NULL)
        {
            //图像数据类型转换
            NSData * imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];
            UIImage * image = [[UIImage alloc] initWithData:imageData];

            //保存图像
            [self saveImageToPhotos:image];

        }
        else
        {
            NSLog(@"Error capturing still image %@", error);
        }
    }];

}

@end

自定义相机（三） -- 视频流数据 AND 预览 拍照 变焦