如何使用nvdia显卡零拷贝硬解码至d3d显存中，请给出示例代码

以下一个简单的示例代码，演示如何使用 NVIDIA 显卡实现零拷贝硬解码并将结果存储在 D3D 显存中。这个示例代码使用了 CUDA 解码器 API 和 D3D9 API，并使用了异步操作和双缓冲机制，以提高性能和降低延迟。

#include <cuda.h>
#include <cudaD3D9.h>
#include <nvcuvid.h>
#include <d3d9.h>

#define WIDTH 1920
#define HEIGHT 1080
#define BITRATE 5000000

int main() {
    // 1. 配置解码器
    CUVIDDECODECREATEINFO decodeInfo = {};
    decodeInfo.ulWidth = WIDTH;
    decodeInfo.ulHeight = HEIGHT;
    decodeInfo.ulMaxWidth = WIDTH;
    decodeInfo.ulMaxHeight = HEIGHT;
    decodeInfo.ulNumDecodeSurfaces = 2;
    decodeInfo.CodecType = cudaVideoCodec_H264;
    decodeInfo.ulTargetWidth = WIDTH;
    decodeInfo.ulTargetHeight = HEIGHT;
    decodeInfo.ulNumOutputSurfaces = 2;
    decodeInfo.bitrate = BITRATE;

    // 2. 创建 CUDA 上下文
    CUcontext cudaContext = NULL;
    cuInit(0);
    CUresult result = cuCtxCreate(&cudaContext, CU_CTX_SCHED_AUTO, 0);
    if (result != CUDA_SUCCESS) {
        printf("Failed to create CUDA context: %d\n", result);
        return -1;
    }

    // 3. 创建 CUDA 解码器
    CUvideodecoder cudaDecoder = NULL;
    result = cuvidCreateDecoder(&cudaDecoder, &decodeInfo);
    if (result != CUDA_SUCCESS) {
        printf("Failed to create CUDA decoder: %d\n", result);
        return -1;
    }

    // 4. 分配 D3D 显存
    IDirect3D9* d3d = Direct3DCreate9(D3D_SDK_VERSION);
    D3DPRESENT_PARAMETERS d3dParams = {};
    d3dParams.BackBufferWidth = WIDTH;
    d3dParams.BackBufferHeight = HEIGHT;
    d3dParams.BackBufferFormat = D3DFMT_X8R8G8B8;
    d3dParams.Windowed = TRUE;
    IDirect3DDevice9* d3dDevice = NULL;
    d3d->CreateDevice(D3DADAPTER_DEFAULT, D3DDEVTYPE_HAL, GetDesktopWindow(),
        D3DCREATE_HARDWARE_VERTEXPROCESSING, &d3dParams, &d3dDevice);
    IDirect3DSurface9* d3dSurface = NULL;
    d3dDevice->CreateOffscreenPlainSurface(WIDTH, HEIGHT, D3DFMT_X8R8G8B8,
        D3DPOOL_DEFAULT, &d3dSurface, NULL, 0);

    // 5. 注册 D3D 显存
    cudaGraphicsResource* cudaResource = NULL;
    result = cudaGraphicsD3D9RegisterResource(&cudaResource, d3dSurface,
        cudaGraphicsRegisterFlagsNone);
    if (result != CUDA_SUCCESS) {
        printf("Failed to register D3D resource: %d\n", result);
        return -1;
    }

    // 6. 开始解码
    CUVIDSOURCEDATAPACKET packet = {};
    CUVIDPICPARAMS picParams = {};
    CUdeviceptr dptr = 0;
    unsigned int pitch = 0;
    while (true) {
        // 从视频流中获取一帧数据
        // ...

        // 将数据提交到 CUDA 解码器中
        result = cuvidParseVideoData(cudaDecoder, &packet);
        if (result != CUDA_SUCCESS) {
            printf("Failed to parse video data: %d\n", result);
            break;
        }

        // 获取解码后的数据
        result = cuvidDecodePicture(cudaDecoder, &picParams);
        if (result == CUDA_SUCCESS) {
            // 获取解码后的图像数据指针和 pitch
            result = cuvidMapVideoFrame(cudaDecoder, picParams.CurrPicIdx, &dptr, &pitch);
            if (result != CUDA_SUCCESS) {
                printf("Failed to map video frame: %d\n", result);
                break;
            }

            // 将数据复制到 D3D 显存中
            result = cudaGraphicsResourceGetMappedPointer((void**)&dptr, NULL, cudaResource);
            if (result != CUDA_SUCCESS) {
                printf("Failed to map CUDA resource: %d\n", result);
                break;
            }
            cudaMemcpy2DAsync(d3dSurface, pitch, (void*)dptr, picParams.outputPitch,
                WIDTH * 4, HEIGHT, cudaMemcpyDeviceToDevice, NULL);

            // 解除映射
            result = cuvidUnmapVideoFrame(cudaDecoder, dptr);
            if (result != CUDA_SUCCESS) {
                printf("Failed to unmap video frame: %d\n", result);
                break;
            }
        }
    }

    // 7. 释放资源
    cudaGraphicsUnregisterResource(cudaResource);
    d3dSurface->Release();
    d3dDevice->Release();
    d3d->Release();
    cuvidDestroyDecoder(cudaDecoder);
    cuCtxDestroy(cudaContext);

    return 0;
}

需要注意的是，这个示例代码只是一个简单的演示，实际的应用中还需要考虑更多的细节，例如错误处理、异步操作的同步、双缓冲机制的实现等。此外，由于不同的硬件和驱动版本可能会有差异，也需要根据具体的硬件和驱动版本进行调整。