Make an UIImage from a CMSampleBuffer

Question

This is not the same as the countless questions about converting a CMSampleBuffer to a UIImage. I\'m simply wondering why I can\'t convert it like

Answer 1

TO ALL: don't use methods like:

    private let context = CIContext()

    private func imageFromSampleBuffer2(_ sampleBuffer: CMSampleBuffer) -> UIImage? {
        guard let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else { return nil }
        let ciImage = CIImage(cvPixelBuffer: imageBuffer)
        guard let cgImage = context.createCGImage(ciImage, from: ciImage.extent) else { return nil }
        return UIImage(cgImage: cgImage)
    }

they eat much more cpu, more time to convert

use solution from https://stackoverflow.com/a/40193359/7767664

don't forget to set next setting for AVCaptureVideoDataOutput

    videoOutput = AVCaptureVideoDataOutput()

    videoOutput.videoSettings = [(kCVPixelBufferPixelFormatTypeKey as String) : NSNumber(value: kCVPixelFormatType_32BGRA as UInt32)]
    //videoOutput.alwaysDiscardsLateVideoFrames = true

    videoOutput.setSampleBufferDelegate(self, queue: DispatchQueue(label: "MyQueue"))

convert method

    func imageFromSampleBuffer(_ sampleBuffer : CMSampleBuffer) -> UIImage {
        // Get a CMSampleBuffer's Core Video image buffer for the media data
        let  imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
        // Lock the base address of the pixel buffer
        CVPixelBufferLockBaseAddress(imageBuffer!, CVPixelBufferLockFlags.readOnly);


    // Get the number of bytes per row for the pixel buffer
    let baseAddress = CVPixelBufferGetBaseAddress(imageBuffer!);

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

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

    // Create a bitmap graphics context with the sample buffer data
    var bitmapInfo: UInt32 = CGBitmapInfo.byteOrder32Little.rawValue
    bitmapInfo |= CGImageAlphaInfo.premultipliedFirst.rawValue & CGBitmapInfo.alphaInfoMask.rawValue
    //let bitmapInfo: UInt32 = CGBitmapInfo.alphaInfoMask.rawValue
    let context = CGContext.init(data: baseAddress, width: width, height: height, bitsPerComponent: 8, bytesPerRow: bytesPerRow, space: colorSpace, bitmapInfo: bitmapInfo)
    // Create a Quartz image from the pixel data in the bitmap graphics context
    let quartzImage = context?.makeImage();
    // Unlock the pixel buffer
    CVPixelBufferUnlockBaseAddress(imageBuffer!, CVPixelBufferLockFlags.readOnly);

    // Create an image object from the Quartz image
    let image = UIImage.init(cgImage: quartzImage!);

    return (image);
}