Question

我正在寻找DirectShow中的接口，它只允许我推送一个频率。 IAMTVTuner界面允许您put_channel，但这需要预调卡。我想指定调到的频率。模拟调谐可以实现吗？（然而，您可以使用数字流接口轻松完成）。

Answer 1

I think this codeproject link should help you

以下是代码：

// It is assumed that you have constructed the complete TV tuner Graph 
// of your Device.And will use this function to set custom frequencies 
// or to fine tune a tuned TV channel.Please also make sure to set the 
// appropriate Video standard and contry code before calling this function.

#define INSTANCEDATA_OF_PROPERTY_PTR(x) ((PKSPROPERTY((x))) + 1)
#define INSTANCEDATA_OF_PROPERTY_SIZE(x) (sizeof((x)) - sizeof(KSPROPERTY))

HRESULT SetFrequency(long Freq)
{ 
    HRESULT hr;
    DWORD dwSupported=0;  

    // Query the IKsPropertySet on your Device TV Tuner Filter.
    // m_pTvtuner is IBaseFilter Pointer of your TV Tuner Filter.   

    CComPtr m_pKSProp;
    hr = m_pTvtuner->QueryInterface(IID_IKsPropertySet, (void**)&m_pKSProp); 
    if (FAILED(hr))
        return E_FAIL;

    KSPROPERTY_TUNER_MODE_CAPS_S ModeCaps;
    KSPROPERTY_TUNER_FREQUENCY_S Frequency;
    memset(&ModeCaps,0,sizeof(KSPROPERTY_TUNER_MODE_CAPS_S));
    memset(&Frequency,0,sizeof(KSPROPERTY_TUNER_FREQUENCY_S));
    ModeCaps.Mode = AMTUNER_MODE_TV; 

    // Check either the Property is supported or not by the Tuner drivers 

    hr = m_pKSProp->QuerySupported(PROPSETID_TUNER, 
          KSPROPERTY_TUNER_MODE_CAPS,&dwSupported);
    if(SUCCEEDED(hr) && dwSupported&KSPROPERTY_SUPPORT_GET)
    {
        DWORD cbBytes=0;
        hr = m_pKSProp->Get(PROPSETID_TUNER,KSPROPERTY_TUNER_MODE_CAPS,
            INSTANCEDATA_OF_PROPERTY_PTR(&ModeCaps),
            INSTANCEDATA_OF_PROPERTY_SIZE(ModeCaps),
            &ModeCaps,
            sizeof(ModeCaps),
            &cbBytes);  
    }
    else
        return E_FAIL; 

    Frequency.Frequency=Freq;
    if(ModeCaps.Strategy==KS_TUNER_STRATEGY_DRIVER_TUNES)
        Frequency.TuningFlags=KS_TUNER_TUNING_FINE;
    else
        Frequency.TuningFlags=KS_TUNER_TUNING_EXACT;

    // Here the real magic starts

    if(Freq>=ModeCaps.MinFrequency && Freq<=ModeCaps.MaxFrequency)
    {
        hr = m_pKSProp->Set(PROPSETID_TUNER,
            KSPROPERTY_TUNER_FREQUENCY,
            INSTANCEDATA_OF_PROPERTY_PTR(&Frequency),
            INSTANCEDATA_OF_PROPERTY_SIZE(Frequency),
            &Frequency,
            sizeof(Frequency));
        if(FAILED(hr))
            return E_FAIL;  
    }
    else
        return E_FAIL;

    return S_OK;
}

DirectShow API用于模拟调频以放置频率？

1 个答案: