将CMSampleBufferRef转换为UIImage

我用AVCaptureSession拍摄video。 但我想将捕获的图像转换为UIImage。

我在互联网上找到了一些代码：

- (UIImage *) imageFromSampleBuffer:(CMSampleBufferRef) sampleBuffer { NSLog(@"imageFromSampleBuffer: called"); // 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); } 

但是我遇到了一些错误：

 Jan 17 17:39:25 iPhone-4-de-XXX ThinkOutsideTheBox[2363] : CGBitmapContextCreate: invalid data bytes/row: should be at least 2560 for 8 integer bits/component, 3 components, kCGImageAlphaPremultipliedFirst. Jan 17 17:39:25 iPhone-4-de-XXX ThinkOutsideTheBox[2363] : CGBitmapContextCreateImage: invalid context 0x0 2013-01-17 17:39:25.896 ThinkOutsideTheBox[2363:907] image  Jan 17 17:39:25 iPhone-4-de-XXX ThinkOutsideTheBox[2363] : CGContextDrawImage: invalid context 0x0 Jan 17 17:39:25 iPhone-4-de-XXX ThinkOutsideTheBox[2363] : CGBitmapContextGetData: invalid context 0x0 

编辑：我也使用UIImage获取rgb颜色：

 -(void) captureOutput:(AVCaptureOutput*)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection*)connection { UIImage* image = [self imageFromSampleBuffer:sampleBuffer]; unsigned char* pixels = [image rgbaPixels]; double totalLuminance = 0.0; for(int p=0;p<image.size.width*image.size.height*4;p+=4) { totalLuminance += pixels[p]*0.299 + pixels[p+1]*0.587 + pixels[p+2]*0.114; } totalLuminance /= (image.size.width*image.size.height); totalLuminance /= 255.0; NSLog(@"totalLuminance %f",totalLuminance); } 

Answer 1

您最好的选择是将捕获video数据输出的videoSettings设置为指定所需像素格式的字典，您需要将其设置为CGBitmapContext可以处理的RGB的某些变体。

该文档包含Core Video可以处理的所有像素格式的列表 。 CGBitmapContext仅支持其中的一小部分。 您在互联网上找到的代码所期望的格式是kCVPixelFormatType_32BGRA ，但这可能是针对Macs-on iOS设备编写的， kCVPixelFormatType_32ARGB （big-endian）可能更快。 在设备上尝试它们，并比较帧速率。