放大NSData或CMSampleBufferRef
放大NSData或CMSampleBufferRef
提问于 2013-02-26 11:58:42
我正在用最新的SDK开发一个iOS应用程序。
这个应用程序将与OpenCV一起工作，我必须在相机上进行缩放，但是这个，它在iOS SDK上是不可用的，所以我想用编程的方式来实现它。
我必须对每一个视频帧进行“缩放”。这是我必须做的事情：
#pragma mark - AVCaptureSession delegate
- (void)captureOutput:(AVCaptureOutput *)captureOutput
didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
fromConnection:(AVCaptureConnection *)connection
{
CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
/*Lock the image buffer*/
CVPixelBufferLockBaseAddress(imageBuffer,0);
/*Get information about the image*/
uint8_t *baseAddress = (uint8_t *)CVPixelBufferGetBaseAddress(imageBuffer);
size_t width = CVPixelBufferGetWidth(imageBuffer);
size_t height = CVPixelBufferGetHeight(imageBuffer);
//size_t stride = CVPixelBufferGetBytesPerRow(imageBuffer);
//put buffer in open cv, no memory copied
cv::Mat image = cv::Mat(height, width, CV_8UC4, baseAddress);
// copy the image
//cv::Mat copied_image = image.clone();
_lastFrame = [NSData dataWithBytes:image.data
length:image.elemSize() * image.total()];
[DataExchanger postFrame];
/*We unlock the image buffer*/
CVPixelBufferUnlockBaseAddress(imageBuffer,0);
}NSData 您知道如何在或上放大
回答 1
Stack Overflow用户
发布于 2013-02-28 13:11:37
一种方法是将你的图片放入一个CGImageRef中，在该图片中选择一个正方形，然后再将它画成一个正常大小。像这样的东西(虽然可能有更好的方法)：
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);
CGContextRelease(context);
CGImageRef smallQuartzImage = CGImageCreateWithImageInRect(quartzImage, CGRectMake(200, 200, 600, 600));
cv::Mat image(height, width, CV_8UC4 );
CGContextRef contextRef = CGBitmapContextCreate( image.data, width, height, 8, cvMat.step[0], colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst );
CGContextDrawImage(contextRef, CGRectMake(0, 0, width, height), smallQuartzImage);
CGContextRelease( contextRef );
CGColorSpaceRelease( colorSpace );页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/15088561
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