将CMSampleBufferRef转换为带有YUV颜色空间的UIImage？

Question

将CMSampleBufferRef转换为带有YUV颜色空间的UIImage？

8

我正在使用 AVCaptureVideoDataOutput 并希望将 CMSampleBufferRef 转换为 UIImage。许多答案都相同，例如 CMSampleBufferRef 创建的 UIImage 无法在 UIImageView 中显示？和具有多个预览的 AVCaptureSession。

如果我将 VideoDataOutput 的颜色空间设置为 BGRA，它就可以正常工作（感谢这个答案 CGBitmapContextCreateImage 错误）。

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

没有上述videoSettings，我将会收到以下错误。

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并不是一个好的选择，因为存在从YUV（默认AVCaptureSession颜色空间）转换为BGRA的开销，正如Brad和Codo在How to get the Y component from CMSampleBuffer resulted from the AVCaptureSession?中所述。

那么有没有一种方法将CMSampleBufferRef转换为UIImage并使用YUV颜色空间？

- onmyway133

有什么解决方案吗？ - Adarsh V C

@AdarshVC，为什么不投票支持这个问题，让它更加引人注目呢？ - onmyway133

请查看此问题：https://dev59.com/13A75IYBdhLWcg3wboUz - Basheer_CAD

@entropy 我已经投票了，很久以前就投了 :) - Adarsh V C

2个回答

-1

// 这对我有效。

var image: CGImage?
VTCreateCGImageFromCVPixelBuffer(pixelBuffer, options: nil, imageOut: &image)
DispatchQueue.main.async {
    self.imageView.image = UIImage(cgImage: image!)
}

- Jobs

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- Bluewings · Accepted Answer

经过大量研究和阅读苹果文档及维基百科，我找到了答案，并且它对我非常有效。所以为了未来的读者们，我分享一下将视频像素类型设置为kCVPixelFormatType_420YpCbCr8BiPlanarFullRange时，将 CMSampleBufferRef 转换为 UIImage 的代码:

// 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);
    }
}