c++ - 在 Windows 8 上使用 Media Engine 播放音乐

Question

我正在将 Windows Phone 8 应用程序移植到 Windows 8，似乎 Media Engine 库的工作方式有所不同。

这是我在 WP8 上运行的初始化代码:

DX::ThrowIfFailed(
    MFStartup(MF_VERSION)
    );
ComPtr<IMFMediaEngineClassFactory> mediaEngineFactory;
ComPtr<IMFAttributes> mediaEngineAttributes;

// Create the class factory for the Media Engine.
DX::ThrowIfFailed(
    CoCreateInstance(CLSID_MFMediaEngineClassFactory, nullptr, CLSCTX_INPROC_SERVER, IID_PPV_ARGS(&mediaEngineFactory))
    );

// Define configuration attributes.
DX::ThrowIfFailed(
    MFCreateAttributes(&mediaEngineAttributes, 1)
    );

ComPtr<MediaEngineNotify> notify = Make<MediaEngineNotify>();
ComPtr<IUnknown> unknownNotify;
DX::ThrowIfFailed(
    notify.As(&unknownNotify)
    );

DX::ThrowIfFailed(
    mediaEngineAttributes->SetUnknown(MF_MEDIA_ENGINE_CALLBACK, unknownNotify.Get())
    );

// Create the Media Engine.
DX::ThrowIfFailed(
    mediaEngineFactory->CreateInstance(0, mediaEngineAttributes.Get(), &m_mediaEngine)
    );

CreateInstance() 抛出 0xc00d36e6 异常 (MF_E_ATTRIBUTENOTFOUND)。

我尝试搜索 MP3 的媒体引擎播放示例，但只能找到视频播放示例。

有什么想法吗？

Answer 1

我找出了缺失的属性。我必须添加 MF_MEDIA_ENGINE_AUDIO_CATEGORY 来指定媒体引擎实际执行的操作。这是一个适用于 WP8 和 WIN8 的示例:

#if PLATFORM_WINDOWS8
    DX::ThrowIfFailed(
        MFStartup(MF_VERSION)
        );
#endif
    ComPtr<IMFMediaEngineClassFactory> mediaEngineFactory;
    ComPtr<IMFAttributes> mediaEngineAttributes;

    // Create the class factory for the Media Engine.
    DX::ThrowIfFailed(
        CoCreateInstance(CLSID_MFMediaEngineClassFactory, nullptr, CLSCTX_INPROC_SERVER, IID_PPV_ARGS(&mediaEngineFactory))
        );

    // Define configuration attributes.
    DX::ThrowIfFailed(
        MFCreateAttributes(&mediaEngineAttributes, 1)
        );

    ComPtr<MediaEngineNotify> notify = Make<MediaEngineNotify>();
    ComPtr<IUnknown> unknownNotify;
    DX::ThrowIfFailed(
        notify.As(&unknownNotify)
        );

    DX::ThrowIfFailed(
        mediaEngineAttributes->SetUnknown(MF_MEDIA_ENGINE_CALLBACK, unknownNotify.Get())
        );

    DWORD flags=0;

#if PLATFORM_WINDOWS8
    DX::ThrowIfFailed(
        mediaEngineAttributes->SetUINT32(MF_MEDIA_ENGINE_AUDIO_CATEGORY, AudioCategory_GameMedia)
        );
    flags = MF_MEDIA_ENGINE_AUDIOONLY | MF_MEDIA_ENGINE_REAL_TIME_MODE;
#endif

    // Create the Media Engine.
    DX::ThrowIfFailed(
        mediaEngineFactory->CreateInstance(flags, mediaEngineAttributes.Get(), &m_mediaEngine)
        );