我正在使用AVCaptureVideoDataOutput并希望将CMSampleBufferRef转换为UI
Image.许多答案都是一样的,比如
UIImage created from CMSampleBufferRef not displayed in UIImageView?和
AVCaptureSession with multiple previews
如果我将VideoDataOutput颜色空间设置为BGRA,则可以正常工作(记入此答案CGBitmapContextCreateImage error)
NSString* key = (NSString*)kCVPixelBufferPixelFormatTypeKey; NSNumber* value = [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA]; NSDictionary* videoSettings = [NSDictionary dictionaryWithObject:value forKey:key]; [dataOutput setVideoSettings:videoSettings];
如果没有上述视频设置,我将收到以下错误
CGBitmapContextCreate: invalid data bytes/row: should be at least 2560 for 8 integer bits/component,3 components,kCGImageAlphaPremultipliedFirst. <Error>: CGBitmapContextCreateImage: invalid context 0x0
使用BGRA不是一个好选择,因为从YUV(默认AVCaptureSession颜色空间)到BGRA的转换开销,如Brad和Codo在How to get the Y component from CMSampleBuffer resulted from the AVCaptureSession?所述
那么有没有办法将CMSampleBufferRef转换为UIImage并使用YUV颜色空间？
解决方法
经过大量研究并阅读了苹果文档和wikipedis.我想出了答案,它对我来说非常有效.因此,对于未来的读者,当视频像素类型设置为kCVPixelFormatType_420YpCbCr8BiPlanarFullRange时,我将共享代码以将CMSampleBufferRef转换为UIImage
// Create a UIImage from sample buffer data
// Works only if pixel format is kCVPixelFormatType_420YpCbCr8BiPlanarFullRange
-(UIImage *) imageFromSamplePlanerPixelBuffer:(CMSampleBufferRef) sampleBuffer{
@autoreleasepool {
// 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 plane pixel buffer
void *baseAddress = CVPixelBufferGetBaseAddressOfPlane(imageBuffer,0);
// Get the number of bytes per row for the plane pixel buffer
size_t bytesPerRow = CVPixelBufferGetBytesPerRowOfPlane(imageBuffer,0);
// Get the pixel buffer width and height
size_t width = CVPixelBufferGetWidth(imageBuffer);
size_t height = CVPixelBufferGetHeight(imageBuffer);
// Create a device-dependent gray color space
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray();
// Create a bitmap graphics context with the sample buffer data
CGContextRef context = CGBitmapContextCreate(baseAddress,width,height,8,bytesPerRow,colorSpace,kCGImageAlphaNone);
// 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);
}
}
