UIImage z AVCaptureVideoPreviewLayer

Question

Próbuję pobrać obraz z kanału wideo (w zasadzie funkcjonalność pauzy lub migawki). Mój projekt został skonfigurowany przy użyciu Benjamin Loulier's template. Mój problem polega na tym, że mimo że wyświetlam kolorowe wideo na ekranie poprzez prevLayer (AVCaptureVideoPreviewLayer), ustawiłem ustawienia wideo na skalę szarości, więc nie mogę uzyskać UIImage z customLayer (zwykłego CALayer).

Próbowałem użyć tej funkcji podając here, ale to nie działa dla AVCaptureVideoPreviewLayer z jakiegoś głupiego powodu (pokazuje jasne/przejrzyste). Czy ktoś wie metody zapisywania zawartości AVCaptureVideoPreviewLayer jako UIImage?

Answer 1

Ok to jest moja odpowiedź, dzięki uprzejmości https://developer.apple.com/library/ios/#qa/qa1702/_index.html

Jedna uwaga. minFrameDuration jest przestarzałe od iOS 5.0. Nie jestem pewien powodu ani czy jest wymiana.

#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); 
}