用于模拟调谐的DirectShow API提供频率？

Question

我正在寻找DirectShow中的接口，它可以让我仅推送一个频率。 IAMTVTuner界面允许你put_channel，但这需要预先调整你的卡。我只想指定要调整的频率。模拟调谐可能吗？ （但是，用数字流的接口你可以轻松完成）。

Answer 1

I think this codeproject link should help you

下面是代码：

// 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; 
}