图文详解YUV420数据格式

-(void)YUVPixelBuffer2RGB:(CMSampleBufferRef)sampleBuffer
{
    CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
    CVPixelBufferLockBaseAddress(imageBuffer, 0);
    
    int width = (int) CVPixelBufferGetWidth(imageBuffer);
    int height = (int) CVPixelBufferGetHeight(imageBuffer);
    
    uint8_t *yBuffer =(uint8_t *) CVPixelBufferGetBaseAddressOfPlane(imageBuffer, 0);;
    size_t yPitch = CVPixelBufferGetBytesPerRowOfPlane(imageBuffer, 0);
    uint8_t *cbCrBuffer =(uint8_t *) CVPixelBufferGetBaseAddressOfPlane(imageBuffer, 1);
    size_t cbCrPitch = CVPixelBufferGetBytesPerRowOfPlane(imageBuffer, 1);
    
    if (yBuffer == NULL)
    {
        NSLog(@"yBuffer is NULL");
        return ;
    }
    int bytesPerPixel = 4;
    
    for(int y = 0; y < height; y++) {// height
        uint8_t *rgbBufferLine = &rgbBuffer[y * width * bytesPerPixel];
        uint8_t *yBufferLine = &yBuffer[y* yPitch];
        uint8_t *cbCrBufferLine = &cbCrBuffer[(y >> 1) * cbCrPitch];
        
        for(int x = 0; x < width; x++) {//width
            int16_t y = yBufferLine[x];
            int16_t cb = cbCrBufferLine[x & ~1] - 128;
            int16_t cr = cbCrBufferLine[x | 1] - 128;
            
            uint8_t *rgbOutput = &rgbBufferLine[x*bytesPerPixel];
            
            int16_t r = (int16_t)roundf( y + cr *  1.4 );
            int16_t g = (int16_t)roundf( y + cb * -0.343 + cr * -0.711 );
            int16_t b = (int16_t)roundf( y + cb *  1.765);
            
            rgbOutput[0] = 0xff;
            rgbOutput[1] = clamp(r);
            rgbOutput[2] = clamp(g);
            rgbOutput[3] = clamp(b);
        }
    }
    CVPixelBufferUnlockBaseAddress(imageBuffer,0);
}