分配输入格式

确定与数据匹配的输入格式后，可以通过调用 IWMWriter：：SetInputProps 来设置它供编写器使用。

对于视频流，必须在输入样本中设置帧的大小。 以下示例代码演示如何配置和设置视频输入。 它使用在“枚举输入格式”部分中定义的 FindInputFormat 函数获取 24 位 RGB 视频的输入格式。 有关使用此代码的详细信息，请参阅 使用代码示例。

HRESULT ConfigureVideoInput(IWMWriter* pWriter,
                            DWORD dwInput,
                            GUID guidSubType,
                            LONG lFrameWidth,
                            LONG lFrameHeight)
{
    DWORD   cbSize = 0;
    LONG    lStride = 0;

    IWMInputMediaProps* pProps  = NULL;
    WM_MEDIA_TYPE*      pType   = NULL;
    WMVIDEOINFOHEADER*  pVidHdr = NULL;
    BITMAPINFOHEADER*   pbmi    = NULL;

    // Get the base input format for the required subtype.
    HRESULT hr = FindInputFormat(pWriter, dwInput, guidSubType, &pProps);
    if (FAILED(hr))
    {
        goto Exit;
    }

    // Get the size of the media type structure.
    hr = pProps->GetMediaType(NULL, &cbSize);
    if (FAILED(hr))
    {
        goto Exit;
    }

    // Allocate memory for the media type structure.
    pType = (WM_MEDIA_TYPE*) new (std::nothrow) BYTE[cbSize];
    if (pType == NULL)
    {
        hr = E_OUTOFMEMORY;
        goto Exit;
    }
    
    // Get the media type structure.
    hr = pProps->GetMediaType(pType, &cbSize);
    if (FAILED(hr))
    {
        goto Exit;
    }

    // Adjust the format to match your source images.

    // First set pointers to the video structures.
    pVidHdr = (WMVIDEOINFOHEADER*) pType->pbFormat;
    pbmi  = &(pVidHdr->bmiHeader);
        
    pbmi->biWidth  = lFrameWidth;  
    pbmi->biHeight = lFrameHeight;
    
    // Stride = (width * bytes/pixel), rounded to the next DWORD boundary.
    lStride = (lFrameWidth * (pbmi->biBitCount / 8) + 3) & ~3;


    // Image size = stride * height. 
    pbmi->biSizeImage = lFrameHeight * lStride;

    // Apply the adjusted type to the video input. 
    hr = pProps->SetMediaType(pType);
    if (FAILED(hr))
    {
        goto Exit;
    }

    hr = pWriter->SetInputProps(dwInput, pProps);

Exit:
    delete [] pType;
    SAFE_RELEASE(pProps);
    return hr;
}

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