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我需要创建 a 的副本，CVPixelBufferRef以便能够使用副本中的值以逐位方式操作原始像素缓冲区。我似乎无法用CVPixelBufferCreate或实现这一点CVPixelBufferCreateWithBytes。

根据这个问题，它也可以用 memcpy() 来完成。但是，没有说明如何实现这一点，以及无论如何都需要调用哪些 Core Video 库。

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3 回答 3

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这似乎有效：

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {

    CVPixelBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);

    // Get pixel buffer info
    const int kBytesPerPixel = 4;
    CVPixelBufferLockBaseAddress(pixelBuffer, 0);
    int bufferWidth = (int)CVPixelBufferGetWidth(pixelBuffer);
    int bufferHeight = (int)CVPixelBufferGetHeight(pixelBuffer);
    size_t bytesPerRow = CVPixelBufferGetBytesPerRow(pixelBuffer); 
    uint8_t *baseAddress = CVPixelBufferGetBaseAddress(pixelBuffer);

    // Copy the pixel buffer
    CVPixelBufferRef pixelBufferCopy = NULL;
    CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault, bufferWidth, bufferHeight, kCVPixelFormatType_32BGRA, NULL, &pixelBufferCopy);
    CVPixelBufferLockBaseAddress(pixelBufferCopy, 0);
    uint8_t *copyBaseAddress = CVPixelBufferGetBaseAddress(pixelBufferCopy);
    memcpy(copyBaseAddress, baseAddress, bufferHeight * bytesPerRow);

    // Do what needs to be done with the 2 pixel buffers

}
于 2016-05-30T09:06:41.533 回答
3

ooOlly 的代码在所有情况下都不适用于 YUV 像素缓冲区（底部的绿线和 memcpy 中的 sig 陷阱），因此这对于来自相机的 YUV 像素缓冲区迅速有效：

var copyOut: CVPixelBuffer?
let status = CVPixelBufferCreate(kCFAllocatorDefault, CVPixelBufferGetWidth(pixelBuffer), CVPixelBufferGetHeight(pixelBuffer), CVPixelBufferGetPixelFormatType(pixelBuffer), nil, &copyOut)
let copy = copyOut!

CVPixelBufferLockBaseAddress(copy, [])
CVPixelBufferLockBaseAddress(pixelBuffer, [])

let ydestPlane = CVPixelBufferGetBaseAddressOfPlane(copy, 0)
let ysrcPlane = CVPixelBufferGetBaseAddressOfPlane(pixelBuffer, 0)
memcpy(ydestPlane, ysrcPlane, CVPixelBufferGetBytesPerRowOfPlane(pixelBuffer, 0) * CVPixelBufferGetHeightOfPlane(pixelBuffer, 0))

let uvdestPlane = CVPixelBufferGetBaseAddressOfPlane(copy, 1)
let uvsrcPlane = CVPixelBufferGetBaseAddressOfPlane(pixelBuffer, 1)
memcpy(uvdestPlane, uvsrcPlane, CVPixelBufferGetBytesPerRowOfPlane(pixelBuffer, 1) * CVPixelBufferGetHeightOfPlane(pixelBuffer, 1))

CVPixelBufferUnlockBaseAddress(copy, [])
CVPixelBufferUnlockBaseAddress(pixelBuffer, [])

当然，强烈建议使用比强制解包更好的错误处理。

于 2019-03-08T20:08:26.307 回答
1

Maxi Mus 的代码仅适用于 RGB/BGR 缓冲区。所以对于 YUV 缓冲区下面的代码应该可以工作。

// Copy the pixel buffer
    CVPixelBufferRef pixelBufferCopy = NULL;
    CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault, bufferWidth, bufferHeight, pixelFormat, NULL, &pixelBufferCopy);
    CVPixelBufferLockBaseAddress(pixelBufferCopy, 0);
    //BGR
//    uint8_t *copyBaseAddress = CVPixelBufferGetBaseAddress(pixelBufferCopy);
//    memcpy(copyBaseAddress, baseAddress, bufferHeight * bytesPerRow);
    uint8_t *yDestPlane = CVPixelBufferGetBaseAddressOfPlane(pixelBufferCopy, 0);
    //YUV
    uint8_t *yPlane = CVPixelBufferGetBaseAddressOfPlane(pixelBuffer, 0);
    memcpy(yDestPlane, yPlane, bufferWidth * bufferHeight);
    uint8_t *uvDestPlane = CVPixelBufferGetBaseAddressOfPlane(pixelBufferCopy, 1);
    uint8_t *uvPlane = CVPixelBufferGetBaseAddressOfPlane(pixelBuffer, 1);
    memcpy(uvDestPlane, uvPlane, bufferWidth * bufferHeight/2);
    CVPixelBufferUnlockBaseAddress(pixelBufferCopy, 0);
于 2018-08-31T12:47:19.467 回答