Converting a Buffer to a Bitmap

edit

I found something! And I must say I was very blind.

CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
CVPixelBufferLockBaseAddress(imageBuffer,0);

size_t width = CVPixelBufferGetWidth(imageBuffer);
size_t height = CVPixelBufferGetHeight(imageBuffer);
void *baseAddress = CVPixelBufferGetBaseAddress(imageBuffer);

cv::Mat frame(height, width, CV_8UC4, (void*)baseAddress);

CVPixelBufferUnlockBaseAddress(imageBuffer, 0);

cv::cvtColor(frame, frame, CV_BGRA2RGB);

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *filePath = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"ocv%d.BMP", picNum]];
const char* cPath = [filePath cStringUsingEncoding:NSMacOSRomanStringEncoding];

const cv::string newPaths = (const cv::string)cPath;

cv::imwrite(newPaths, frame);

I just have to use the imwrite function from opencv. This way I get BMP-files around 24 MB directly after the bayer-filter!