在没有压缩的情况下捕获仍然是UIImage(来自CMSampleBufferRef)？

Question

我需要从CMSampleBufferRef 获取UIImage来自未压缩的图像数据.我正在使用代码:

captureStillImageOutput captureStillImageAsynchronouslyFromConnection:connection
 completionHandler:^(CMSampleBufferRef imageSampleBuffer, NSError *error) 
{
    // that famous function from Apple docs found on a lot of websites
    // does NOT work for still images
    UIImage *capturedImage = [self imageFromSampleBuffer:imageSampleBuffer]; 
}

http://developer.apple.com/library/ios/#qa/qa1702/_index.html是imageFromSampleBuffer功能链接.

但它不能正常工作.:(

有一种jpegStillImageNSDataRepresentation:imageSampleBuffer方法,但它提供压缩数据(好吧,因为JPEG).

UIImage捕获静止图像后,如何使用最原始的非压缩数据创建？

也许,我应该为视频输出指定一些设置？我目前正在使用这些:

captureStillImageOutput = [[AVCaptureStillImageOutput alloc] init];
captureStillImageOutput.outputSettings = @{ (id)kCVPixelBufferPixelFormatTypeKey : @(kCVPixelFormatType_32BGRA) };

我注意到,输出有一个默认值AVVideoCodecKey,即AVVideoCodecJPEG.是否可以以任何方式避免,或者甚至在拍摄静止图像时是否重要？

我在那里找到了一些东西:来自相机的原始图像数据,如"645 PRO",但我只需要一个UIImage,而不使用OpenCV或OGLES或其他第三方.

Answer 1

该方法imageFromSampleBuffer确实有效,我正在使用它的更改版本,但如果我没记错,你需要设置outputSettings.我认为您需要将键设置为kCVPixelBufferPixelFormatTypeKey和值kCVPixelFormatType_32BGRA.

例如:

NSString* key = (NSString*)kCVPixelBufferPixelFormatTypeKey;                                 
NSNumber* value = [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA];                
NSDictionary* outputSettings = [NSDictionary dictionaryWithObject:value forKey:key];

[newStillImageOutput setOutputSettings:outputSettings];

编辑

我正在使用这些设置来拍摄静态图像而非视频.你的sessionPreset AVCaptureSessionPresetPhoto？可能存在问题

AVCaptureSession *newCaptureSession = [[AVCaptureSession alloc] init];
[newCaptureSession setSessionPreset:AVCaptureSessionPresetPhoto];

编辑2

关于将其保存到UIImage的部分与文档中的部分相同.这就是我要问问题的其他根源的原因,但我想这只是抓住了吸管.我知道另一种方式,但这需要OpenCV.

- (UIImage *) imageFromSampleBuffer:(CMSampleBufferRef) sampleBuffer{
CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);

CVPixelBufferLockBaseAddress(imageBuffer, 0);

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);

}

我想这对你没有帮助,抱歉.我不知道你的问题的其他起源.