AVCaptureVideoPreviewLayerのUIImage

Question

ビデオフィード（基本的には一時停止または「スナップショット」機能）から静止画像を取得しようとしています。私のプロジェクトはBenjamin Loulier's templateを使ってセットアップされています。私の問題は、prevLayer（AVCaptureVideoPreviewLayer）経由で画面にカラービデオを表示しているにもかかわらず、ビデオ設定をグレースケールに設定しているため、UIImageをcustomLayer（通常のCALayer）から取得できないということです。

hereという名前のこの機能を使用しようとしましたが、これはAVCaptureVideoPreviewLayerでは愚かな理由では機能しません（クリア/トランスペアレントに表示されます）。誰もAVCaptureVideoPreviewLayerのコンテンツをUIImageとして保存する方法を知っていますか？

Answer 1

[OK]を、これは私の答え、https://developer.apple.com/library/ios/#qa/qa1702/_index.html

ワンノートの礼儀です。 minFrameDurationはiOS 5.0以降廃止予定です。理由がわからない場合や交換品がある場合。

#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]; 
} 

// 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 
{ 
    // 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]; 

    // Release the Quartz image 
    CGImageRelease(quartzImage); 

    return (image); 
}