如何解析 KLV 数据

如何解析KLV数据？下面有一些代码。我想使用 klv 元数据制作地图。但是怎么做呢？

我知道纬度和经度在 klv 的第 13 和第 14 个键中。但是我如何使用它们并制作地图。

ILMMpgDmx *CMainFrame::GetMPEG2DemuxInterface()
{
    IUnknown *pSplitter;
    HRESULT hr = m_player->GetSubObject(ltmmPlay_Object_Splitter, &pSplitter);
    if (SUCCEEDED(hr))
    {
        ILMMpgDmx *pMpgDmx;
        hr = pSplitter->QueryInterface(IID_ILMMpgDmx, (void **)&pMpgDmx);
        if (SUCCEEDED(hr))
        {
            pSplitter->Release();
            return pMpgDmx;
        }
        pSplitter->Release();
    }
    return NULL;
}
void CMainFrame::EnableMPEG2DemuxCallback()
{
    HRESULT hr;
    ILMMpgDmx *pMpgDmx = GetMPEG2DemuxInterface();
    if (pMpgDmx)
    {
        // make sure the demux is not using the callback I am about to destroy
        pMpgDmx->put_CallbackObj(NULL);
        DeleteCallbackClass();
        m_pCallback = new CMPEG2DemuxCallback(pMpgDmx);
        // Force the callback to be called in the main thread. C++ applications in general can handle data in another thread, but our app is using MFC
        // Our callback will display data in a window and MFC doesn't work well when you use windows from threads other than the main thread
        // So, for simplicity, we will ask the demux to send the data to the main thread
        hr = pMpgDmx->put_CallInSameThread(VARIANT_TRUE);
        hr = pMpgDmx->put_CallbackObj(m_pCallback);
        pMpgDmx->Release();
    }
}

被调用的 DataAvailable(( 函数如下所示：

HRESULT STDMETHODCALLTYPE CMPEG2DemuxCallback::DataAvailable
( 
    /* [in] */ VARIANT *pData,
    /* [in] */ long lDataSize,
    /* [in] */ FileTypeConstants fileType,
    /* [in] */ long streamPID,
    /* [in] */ long streamType,
    /* [in] */ PTSTypeConstants PTSType,
    /* [in] */ double PTS,
    /* [in] */ long flags
)
{
    // skip small (most likely invalid) data chunks
    if(lDataSize <= 1)
        return S_OK;
    //refresh control
    { 
        static const DWORD MIN_REFRESH_TIME = 1000 ;//1 second
        static DWORD dwLastTime = 0 ;//allow first data to be displayed
        DWORD dwCurTime = GetTickCount ( ) ;
        if ( dwCurTime - dwLastTime < MIN_REFRESH_TIME )
        {         
            return S_OK ;
        }
        else
        {
            dwLastTime = dwCurTime ;
        }
    }
    CPrivateDataView* pDataView = CPrivateDataViewManager::GetPrivateDataListView ( ) ;
    if(!pDataView)
        return S_OK;//skip
    pDataView->SetRedraw ( FALSE ) ;
    pDataView->GetListCtrl ( ).DeleteAllItems ( ) ;
    {
        HRESULT hr;
        if(flags & DataFlag_IsKLV)
        {
            ILMKlvParser* pParser;
            hr = m_pMpgDmx->GetKlvParser(streamPID, &pParser);
            if(FAILED(hr))
                return hr;
            hr = EnumKlvKeys(pParser, pDataView, NULL, pData, lDataSize, flags);
            if(FAILED(hr)) 
            { 
                pParser->Release() ;
                return hr;
            }
            pParser->Release();
        }
        else if(flags & DataFlag_IsAscii)
        {
            CString str;
            hr = DumpVariantAsAscii(str, pData, lDataSize);
            if(FAILED(hr))
                return hr;
            pDataView->AddValue (str) ;
        }
        else if(flags & DataFlag_IsBinary)
        {
            CString str;
            hr = DumpVariantAsBinary(str, pData, lDataSize);
            if(FAILED(hr))
                return hr;
            pDataView->AddValue (str) ;
        }
        else
        {
            ASSERT ( FALSE ) ;      
            return E_UNEXPECTED;
        }
    }
    pDataView->SetRedraw ( TRUE ) ;
    pDataView->RedrawWindow ( ) ;
    return S_OK ;
}

这些都是我找到的代码。我也找到了这个klv库。我需要一条路径。

https://github.com/Hunter522/libklv