- (uint8_t *)convertVideoSmapleBufferToYuvData:(CMSampleBufferRef) videoSample{

// 获取yuv数据

// 通过CMSampleBufferGetImageBuffer方法，获得CVImageBufferRef。

// 这里面就包含了yuv420(NV12)数据的指针

CVImageBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(videoSample);

//表示开始操作数据

CVPixelBufferLockBaseAddress(pixelBuffer, 0);

//图像宽度（像素）

size_t pixelWidth = CVPixelBufferGetWidth(pixelBuffer);

//图像高度（像素）

size_t pixelHeight = CVPixelBufferGetHeight(pixelBuffer);

//yuv中的y所占字节数

size_t y_size = pixelWidth * pixelHeight;

//yuv中的uv所占的字节数

size_t uv_size = y_size / 2;

//    uint8_t *yuv_frame = malloc(uv_size + y_size);

//获取CVImageBufferRef中的y数据

uint8_t *y_frame = CVPixelBufferGetBaseAddressOfPlane(pixelBuffer, 0);

memcpy(yuv_frame, y_frame, y_size);

//获取CMVImageBufferRef中的uv数据

uint8_t *uv_frame = CVPixelBufferGetBaseAddressOfPlane(pixelBuffer, 1);

memcpy(yuv_frame + y_size, uv_frame, uv_size);

CVPixelBufferUnlockBaseAddress(pixelBuffer, 0);

return yuv_frame;

//返回数据

//    return [NSData dataWithBytesNoCopy:yuv_frame length:y_size + uv_size];

}