iphone ios4 视频捕捉

要注意：初始化摄像头的时候，设置采集格式是rgb的，

numberWithInt:kCVPixelFormatType_32BGRA

所以，输出的时候可以用以下方法生成NSImage

见http://stackoverflow.com/questions/3152259/how-to-convert-a-cvimagebufferref-to-uiimage

第一步：初始化AVCaptureSession，添加输入，输出源 

#import <AVFoundation/AVFoundation.h>    // Create and configure a capture session and start it running  - (void)setupCaptureSession   {      NSError *error = nil;        // Create the session      AVCaptureSession *session = [[AVCaptureSession alloc] init];        // Configure the session to produce lower resolution video frames, if your       // processing algorithm can cope. We'll specify medium quality for the      // chosen device.      session.sessionPreset = AVCaptureSessionPresetMedium;        // Find a suitable AVCaptureDevice      AVCaptureDevice *device = [AVCaptureDevice                               defaultDeviceWithMediaType:AVMediaTypeVideo];        // Create a device input with the device and add it to the session.      AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device                                                                       error:&error];      if (!input) {          // Handling the error appropriately.      }      [session addInput:input];        // Create a VideoDataOutput and add it to the session      AVCaptureVideoDataOutput *output = [[[AVCaptureVideoDataOutput alloc] init] autorelease];      [session addOutput:output];        // Configure your output.      dispatch_queue_t queue = dispatch_queue_create("myQueue", NULL);      [output setSampleBufferDelegate:self queue:queue];      dispatch_release(queue);        // Specify the pixel format      output.videoSettings =                   [NSDictionary dictionaryWithObject:                      [NSNumber numberWithInt:kCVPixelFormatType_32BGRA]                       forKey:(id)kCVPixelBufferPixelFormatTypeKey];          // If you wish to cap the frame rate to a known value, such as 15 fps, set       // minFrameDuration.      output.minFrameDuration = CMTimeMake(1, 15);        // Start the session running to start the flow of data      [session startRunning];        // Assign session to an ivar.      [self setSession:session];  }  

第二步：实现AVCaptureVideoDataOutputSampleBufferDelegate协议方法 

// Delegate routine that is called when a sample buffer was written  - (void)captureOutput:(AVCaptureOutput *)captureOutput            didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer            fromConnection:(AVCaptureConnection *)connection  {       // Create a UIImage from the sample buffer data      UIImage *image = [self imageFromSampleBuffer:sampleBuffer];         < Add your code here that uses the image >    }    // Create a UIImage from sample buffer data  - (UIImage *) imageFromSampleBuffer:(CMSampleBufferRef) sampleBuffer   {      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      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();       if (!colorSpace)       {          NSLog(@"CGColorSpaceCreateDeviceRGB failure");          return nil;      }        // Get the base address of the pixel buffer      void *baseAddress = CVPixelBufferGetBaseAddress(imageBuffer);      // Get the data size for contiguous planes of the pixel buffer.      size_t bufferSize = CVPixelBufferGetDataSize(imageBuffer);         // Create a Quartz direct-access data provider that uses data we supply      CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, baseAddress, bufferSize,                                                               NULL);      // Create a bitmap image from data supplied by our data provider      CGImageRef cgImage =           CGImageCreate(width,                          height,                          8,                          32,                          bytesPerRow,                          colorSpace,                          kCGImageAlphaNoneSkipFirst | kCGBitmapByteOrder32Little,                          provider,                          NULL,                          true,                          kCGRenderingIntentDefault);      CGDataProviderRelease(provider);      CGColorSpaceRelease(colorSpace);        // Create and return an image object representing the specified Quartz image      UIImage *image = [UIImage imageWithCGImage:cgImage];      CGImageRelease(cgImage);        CVPixelBufferUnlockBaseAddress(imageBuffer, 0);        return image;  }  

好了，现在就可以自由的显示和分析获取的UIImage了，再也不用使用私有API了