QVideoFrame yuv444 转yuv420p 代码写法

下面是一个简单的示例代码，展示了如何使用Qt中的QVideoFrame类将yuv444数据转换为yuv420p数据：

QVideoFrame yuv444Frame; // 原始yuv444数据帧
QVideoFrame yuv420pFrame(QSize(width, height), QVideoFrame::Format_YUV420P); // 新的yuv420p数据帧

if (yuv444Frame.map(QAbstractVideoBuffer::ReadOnly)) {
    // 获取yuv444数据帧的指针和步长
    uchar *yData = yuv444Frame.bits(0);
    uchar *uData = yuv444Frame.bits(1);
    uchar *vData = yuv444Frame.bits(2);
    int yStride = yuv444Frame.bytesPerLine(0);
    int uStride = yuv444Frame.bytesPerLine(1);
    int vStride = yuv444Frame.bytesPerLine(2);

    if (yuv420pFrame.map(QAbstractVideoBuffer::WriteOnly)) {
        // 获取yuv420p数据帧的指针和步长
        uchar *yuv420pData = yuv420pFrame.bits();
        int yuv420pStride = yuv420pFrame.bytesPerLine();

        // 调用转换函数将yuv444数据转换为yuv420p数据
        yuv444_to_yuv420p(yData, uData, vData, yStride, uStride, vStride, yuv420pData, yuv420pStride, width, height);

        yuv420pFrame.unmap();
    }

    yuv444Frame.unmap();
}

上述代码中的`yuv444_to_yuv420p`函数是实现yuv444转yuv420p的具体算法，这里不再赘述。需要注意的是，该函数需要根据实际情况进行修改，以保证转换后的图像质量和准确性。