将 CMSampleBuffer 转换为 UIImage

Question

这是一个将 CMSampleBuffer 转换为 UIImage 的函数（来自 Apple 文档的代码）

func imageFromSampleBuffer(sampleBuffer: CMSampleBuffer) -> UIImage {
    // Get a CMSampleBuffer's Core Video image buffer for the media data
    var 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
    var baseAddress = CVPixelBufferGetBaseAddress(imageBuffer)

    // Get the number of bytes per row for the pixel buffer
    var bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer)
    // Get the pixel buffer width and height
    var width = CVPixelBufferGetWidth(imageBuffer)
    var height = CVPixelBufferGetHeight(imageBuffer)

    // Create a device-dependent RGB color space
    var colorSpace = CGColorSpaceCreateDeviceRGB()

    // Create a bitmap graphics context with the sample buffer data
    let bitmapInfo = CGBitmapInfo(CGImageAlphaInfo.NoneSkipLast.rawValue)
    var context = CGBitmapContextCreate(baseAddress, width, height, 8, bytesPerRow, colorSpace, bitmapInfo)
    // Create a Quartz image from the pixel data in the bitmap graphics context
    var quartzImage = CGBitmapContextCreateImage(context);
    // Unlock the pixel buffer
    CVPixelBufferUnlockBaseAddress(imageBuffer,0);

    // Create an image object from the Quartz image
    var image = UIImage(CGImage: quartzImage)!

    return image
}

当我尝试使用 UIImageView 可视化 UIImage 时，我什么也得不到。
有什么想法吗？

Answer 1

我刚刚在我当前的项目中完成了完全相同的功能，这就是我如何让它工作的（通过大量的谷歌搜索和一些试验和错误）：

let bitmapInfo = CGBitmapInfo(CGImageAlphaInfo.NoneSkipFirst.rawValue | CGBitmapInfo.ByteOrder32Little.rawValue)

另外，请确保您在主线程中呈现 UIImageView（您可能在相机会话线程中获取 CMSampleBuffer），因为 UIKit 只能在主线程中执行。否则，您将不得不等待很长时间才能显示图像。

Answer 2

@Zigglzworth 需要为 captureVideoDataOutput 设置 kCVPixelFormatType_32BGRA

        let videoOutput = AVCaptureVideoDataOutput()
        videoOutput.videoSettings = [kCVPixelBufferPixelFormatTypeKey as String: kCVPixelFormatType_32BGRA]

Answer 3

这是 Swift 3.0 的解决方案，其中扩展了 CMSampleBuffer，创建一个变量，为您提供可选的 UIImage。

import AVFoundation

extension CMSampleBuffer {
    var uiImage: UIImage? {
        guard let imageBuffer = CMSampleBufferGetImageBuffer(self) else { return nil }

        CVPixelBufferLockBaseAddress(imageBuffer, CVPixelBufferLockFlags(rawValue: 0))
        let baseAddress = CVPixelBufferGetBaseAddress(imageBuffer)
        let bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer)
        let width = CVPixelBufferGetWidth(imageBuffer)
        let height = CVPixelBufferGetHeight(imageBuffer)
        let colorSpace = CGColorSpaceCreateDeviceRGB()
        let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.noneSkipFirst.rawValue | CGBitmapInfo.byteOrder32Little.rawValue)
        guard let context = CGContext(data: baseAddress,
                                      width: width,
                                      height: height,
                                      bitsPerComponent: 8,
                                      bytesPerRow: bytesPerRow,
                                      space: colorSpace,
                                      bitmapInfo: bitmapInfo.rawValue) else { return nil }
        guard let cgImage = context.makeImage() else { return nil }

        CVPixelBufferUnlockBaseAddress(imageBuffer,CVPixelBufferLockFlags(rawValue: 0));

        return UIImage(cgImage: cgImage)
    }
}