ios - 如何从 vImage_Buffer 到 CVPixelBufferRef

Question

我正在我的 iOS 应用程序中录制实时视频。在另一个 Stack Overflow page ，我发现您可以使用 vImage_Buffer 处理我的帧。

问题是我不知道如何从输出的 vImage_buffer 返回到 CVPixelBufferRef。

这是另一篇文章中给出的代码:

NSInteger cropX0 = 100,
          cropY0 = 100,
          cropHeight = 100,
          cropWidth = 100,
          outWidth = 480,
          outHeight = 480;

CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);                   
CVPixelBufferLockBaseAddress(imageBuffer,0);
void *baseAddress = CVPixelBufferGetBaseAddress(imageBuffer);
size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);

vImage_Buffer inBuff;                       
inBuff.height = cropHeight;
inBuff.width = cropWidth;
inBuff.rowBytes = bytesPerRow;

int startpos = cropY0 * bytesPerRow + 4 * cropX0;
inBuff.data = baseAddress + startpos;

unsigned char *outImg = (unsigned char*)malloc(4 * outWidth * outHeight);
vImage_Buffer outBuff = {outImg, outHeight, outWidth, 4 * outWidth};

vImage_Error err = vImageScale_ARGB8888(&inBuff, &outBuff, NULL, 0);
if (err != kvImageNoError) NSLog(@" error %ld", err);

现在我需要将 outBuff 转换为 CVPixelBufferRef。

我假设我需要使用 vImageBuffer_CopyToCVPixelBuffer，但我不确定如何使用。

我的第一次尝试失败了 EXC_BAD_ACCESS: CVPixelBufferUnlockBaseAddress(imageBuffer, 0);

CVPixelBufferRef pixelBuffer;
CVPixelBufferCreate(kCFAllocatorSystemDefault, 480, 480, kCVPixelFormatType_32BGRA, NULL, &pixelBuffer);
    
CVPixelBufferLockBaseAddress(pixelBuffer, 0);
    
vImage_CGImageFormat format = {
    .bitsPerComponent = 8,
    .bitsPerPixel = 32,
    .bitmapInfo = kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipFirst,  //BGRX8888
    .colorSpace = NULL,  //sRGB
};
    
vImageBuffer_CopyToCVPixelBuffer(&outBuff,
                                 &format,
                                 pixelBuffer,
                                 NULL,
                                 NULL,
                                 kvImageNoFlags);  // Here is the crash!
    
    
CVPixelBufferUnlockBaseAddress(pixelBuffer, 0);

有什么想法吗？

Answer 1

NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
    [NSNumber numberWithBool : YES], kCVPixelBufferCGImageCompatibilityKey,
    [NSNumber numberWithBool : YES], kCVPixelBufferCGBitmapContextCompatibilityKey,
    [NSNumber numberWithInt : 480], kCVPixelBufferWidthKey,
    [NSNumber numberWithInt : 480], kCVPixelBufferHeightKey,
    nil];

status = CVPixelBufferCreateWithBytes(kCFAllocatorDefault,
                                      480,
                                      480,
                                      kCVPixelFormatType_32BGRA,
                                      outImg,
                                      bytesPerRow,
                                      NULL,
                                      NULL,
                                      (__bridge CFDictionaryRef)options,
                                      &pixbuffer);

您应该像上面那样生成一个新的 pixelBuffer。