DirectShow 摄像头流驱动程序

Question

我是 DirectShow 编程的新手，我正在尝试创建一个示例抓取器应用程序，以便频繁地从视频捕获设备抓取帧（即每 100 毫秒）。

我的源代码基于 Windows SDK 示例中提供的 SampleGrabber 应用程序。

一般来说，驱动程序使用我的 PC 网络摄像头工作得很好。但是，我在使用华硕 T100 平板电脑时确实遇到了一些问题。在这种情况下，我在设置相机分辨率后尝试使用 ConnectFilters 功能时收到错误“libtbd 错误数据未正确标记”。我试图为相机设置的分辨率是 1280x720，我知道该设备可以支持它。

下面我附上我关于捕获功能的部分代码：

ICreateDevEnum *pSysDevEnum = 0;
IEnumMoniker *pEnumCams = 0;
IMoniker *pMon = 0;
IBaseFilter *CameraF = 0;

IGraphBuilder *pGraph = NULL;
IMediaControl *pControl = NULL;
IMediaEventEx *pEvent = NULL;
IBaseFilter *pGrabberF = NULL;
ISampleGrabber *pSGrabber = NULL;
IBaseFilter *pSourceF = NULL;
IEnumPins *pEnum = NULL;
IPin *pPin = NULL;
IBaseFilter *pNullF = NULL;

BYTE *pBuffer = NULL;
HRESULT hr;
AM_MEDIA_TYPE mt;
int count = 0;

printf("Statting with capturing\n");
//Device list
hr = CoCreateInstance(CLSID_SystemDeviceEnum, NULL, CLSCTX_INPROC_SERVER,
    IID_ICreateDevEnum, (void **)&pSysDevEnum);
if (FAILED(hr)) 
    return false;

// Obtain a class enumerator for the video compressor category.
hr = pSysDevEnum->CreateClassEnumerator(CLSID_VideoInputDeviceCategory,
    &pEnumCams, 0);
if (hr != S_OK)
    return false;

// Enumerate the monikers. to desired device (0,1,2,...)
for (int i = 0; i <= cur_cam; ++i)
{
    hr = pEnumCams->Next(1, &pMon, NULL);
    if (hr != S_OK)
        return false;
}
//Get BaseFilter of chosen camera
hr = pMon->BindToObject(0, 0, IID_IBaseFilter, (void**)&CameraF);
if (hr != S_OK)
    return false;

//Create the Filter Graph Manager 
hr = CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC_SERVER, IID_PPV_ARGS(&pGraph));
if (FAILED(hr))
    return false;

//Query for the IMediaControl and IMediaEventEx interfaces
hr = pGraph->QueryInterface(IID_PPV_ARGS(&pControl));
if (FAILED(hr))
    return false;

hr = pGraph->QueryInterface(IID_PPV_ARGS(&pEvent));
if (FAILED(hr))
    return false;

// Add web camera to graph as source filter (because first?)
hr = pGraph->AddFilter(CameraF, L"Capture Source");
if (hr != S_OK)
    return false;

// Create an instance of the Sample Grabber Filter
hr = CoCreateInstance(CLSID_SampleGrabber, NULL, CLSCTX_INPROC_SERVER,
    IID_PPV_ARGS(&pGrabberF));
if (FAILED(hr))
    return false;

// Add it to the filter graph.
hr = pGraph->AddFilter(pGrabberF, L"Sample Grabber");
if (FAILED(hr))
    return false;

hr = pGrabberF->QueryInterface(IID_PPV_ARGS(&pSGrabber));
if (FAILED(hr))
    return false;

//Set the Media Type
ZeroMemory(&mt, sizeof(mt));
mt.majortype = MEDIATYPE_Video;
mt.subtype = MEDIASUBTYPE_RGB24 ;

hr = pSGrabber->SetMediaType(&mt);
if (FAILED(hr))
    return false;

//Building graph. Connecting Source (CameraF) and Sample Grabber
hr = CameraF->EnumPins(&pEnum);
if (FAILED(hr))
    return false;

while (S_OK == pEnum->Next(1, &pPin, NULL))
{
    hr = SetResolution(width_, height_, pPin);

    if (FAILED(hr))
        std::cout << "Failed to set resolution" << std::endl;

    hr = ConnectFilters(pGraph, pPin, pGrabberF);

    if (SUCCEEDED(hr))
    {
        std::cout << "Success to Connect Filter Graphs" << std::endl;
        break;
    }
    else{
        std::cout << "Failed to Connect Filter Graphs" << std::endl;
    }
}

if (FAILED(hr)){
    std::cout << "Failed A" << std::endl;
    return false;
}


SafeRelease(pPin);

//The following code connects the Sample Grabber to the Null Renderer filter:
hr = CoCreateInstance(CLSID_NullRenderer, NULL, CLSCTX_INPROC_SERVER, IID_PPV_ARGS(&pNullF));
if (FAILED(hr))
    return false;

hr = pGraph->AddFilter(pNullF, L"Null Filter");
if (FAILED(hr))
    return false;

//ConnectFilters SamplerGrabber and Null Filter
hr = ConnectFilters(pGraph, pGrabberF, pNullF);
if (FAILED(hr))
    return false;

hr = pSGrabber->SetBufferSamples(TRUE);
if (FAILED(hr))
    return false;

hr = pSGrabber->SetOneShot(TRUE);//Halt after sample received
if (FAILED(hr))
    return false;

hr = pControl->Run();//Run filter graph
if (FAILED(hr))
    return false;

printf("Wait for a seconds to let cam sensor adopt to light\n");
Sleep(3000);//Wait 3 seconds
printf("OK\n");

//char filename[50];
printf("Go for the  loop");

for (;;){

    long evCode;
    while (1)
    {
        hr = pEvent->WaitForCompletion(INFINITE, &evCode);//Wait for frame
        if (evCode == EC_COMPLETE || evCode == EC_SYSTEMBASE)
            break;
        printf("Not complete. event: %d\n", evCode);
        pControl->Pause();//pause the Graph
        pSGrabber->SetOneShot(TRUE);//Set to halt after first frame
        hr = pControl->Run();//resume filter graph
        if (FAILED(hr))
            return false;
        Sleep(1000);//wait for a second
    }
    printf("out of while  loop");
    //if (hr != S_OK)
    //  return false;
    Sleep(100);
    //there frame got. Graph still running, but Sample Grabber halted

    // Find the required buffer size.
    long cbBufSize;
    hr = pSGrabber->GetCurrentBuffer(&cbBufSize, NULL);
    if (FAILED(hr))
        return false;

    pBuffer = (BYTE*)CoTaskMemAlloc(cbBufSize);
    if (!pBuffer)
    {
        hr = E_OUTOFMEMORY;
        return false;
    }

    hr = pSGrabber->GetCurrentBuffer(&cbBufSize, (long*)pBuffer);
    if (FAILED(hr))
        return false;


    hr = pSGrabber->GetConnectedMediaType(&mt);
    if (FAILED(hr))
        return false;


    // Examine the format block.
    if ((mt.formattype == FORMAT_VideoInfo) &&
        (mt.cbFormat >= sizeof(VIDEOINFOHEADER)) && (mt.pbFormat != NULL))
    {
        VIDEOINFOHEADER *pVih = (VIDEOINFOHEADER*)mt.pbFormat;
        //sprintf_s(filename, sizeof(filename), "photo%d.bmp",++count);
        time_t t1 = time(NULL);
        SYSTEMTIME st;
        GetSystemTime(&st);

        printf("Save frame to file: %s - %02ld,%02ld.%03ld seconds\n", FileName, st.wMinute,st.wSecond, st.wMilliseconds );
        hr = WriteBitmap(FileName, &pVih->bmiHeader, mt.cbFormat - SIZE_PREHEADER,pBuffer, cbBufSize);
    }
    else
    {
        // Invalid format.
        hr = VFW_E_INVALIDMEDIATYPE;
        printf("Invalid frame format\n");
    }

    CoTaskMemFree(pBuffer);

    if ((GetAsyncKeyState(VK_ESCAPE) & 0x01))
        break;
    else if ((GetAsyncKeyState(VK_SPACE) & 0x01))
        CameraProperties(CameraF);

}

SafeRelease(pEnum);
SafeRelease(pNullF);
SafeRelease(pSourceF);
SafeRelease(pSGrabber);
SafeRelease(pGrabberF);
SafeRelease(pControl);
SafeRelease(pEvent);
SafeRelease(pGraph);

下面是设置相机分辨率的函数：

// Set the grabbing size
// First we iterate through the available media types and 
// store the first one that fits the requested size.
// If we have found one, we set it.
// In any case we query the size of the current media type
// to have this information for clients of this class.

HRESULT hr;

IAMStreamConfig *pConfig;
IEnumMediaTypes *pMedia;
AM_MEDIA_TYPE *pmt = NULL, *pfnt = NULL;

hr = pPin->EnumMediaTypes(&pMedia);
if (SUCCEEDED(hr))
{

    while (pMedia->Next(1, &pmt, 0) == S_OK)
    {
        if (pmt->formattype == FORMAT_VideoInfo)
        {
            VIDEOINFOHEADER *vih = (VIDEOINFOHEADER *)pmt->pbFormat;
            // printf("Size %i  %i\n", vih->bmiHeader.biWidth, vih->bmiHeader.biHeight );
            if (vih->bmiHeader.biWidth == width_ && vih->bmiHeader.biHeight == height_)
            {
                pfnt = pmt;
                printf("found mediatype with %i %i\n", vih->bmiHeader.biWidth, vih->bmiHeader.biHeight );
                break;
            }
            DeleteMediaType(pmt);
        }
    }
    pMedia->Release();
}
hr = pPin->QueryInterface(IID_IAMStreamConfig, (void **)&pConfig);
if (SUCCEEDED(hr))
{
    if (pfnt != NULL)
    {
        hr = pConfig->SetFormat(pfnt);
        DeleteMediaType(pfnt);
    }
    hr = pConfig->GetFormat(&pfnt);
    if (SUCCEEDED(hr))
    {

        m_nWidth = ((VIDEOINFOHEADER *)pfnt->pbFormat)->bmiHeader.biWidth;
        m_nHeight = ((VIDEOINFOHEADER *)pfnt->pbFormat)->bmiHeader.biHeight;

        DeleteMediaType(pfnt);
    }
}

以前有人遇到过这种问题吗？捕获过滤器设置是否有任何错误？

任何想法都会非常有帮助。

更新 1

我正在添加应用程序执行输出的屏幕截图。 Output

更新 2

我尝试使用 OpenCV 3.1 设置分辨率，但我遇到了完全相同的问题。平板电脑正在使用 Intel(R) Imaging Signal Processor 2400 驱动程序用于摄像头，这就是问题所在。奇怪的想法是，使用AmCap 我既可以设置相机分辨率，又可以毫无问题地处理相机设备。可以请人帮忙吗？有谁知道 AmCap 使用什么接口与相机通信？

Answer 1

我设法解决了这个问题。似乎报告的 libdbd 错误与分辨率更改无关。

问题是我试图通过在 SetFormat() 函数中传递不受支持的视频格式来设置分辨率。详细来说，新的工作 SetResolution() 函数变成了：

// Set the grabbing size
// First we iterate through the available media types and 
// store the first one that fits the requested size.
// If we have found one, we set it.
// In any case we query the size of the current media type
// to have this information for clients of this class.

HRESULT hr;

IAMStreamConfig *pConfig=NULL;
//IEnumMediaTypes *pMedia;
BYTE *pSCC = NULL;
AM_MEDIA_TYPE *pmt = NULL, *pfnt = NULL, *mfnt=NULL;

//hr = pPin->EnumMediaTypes(&pMedia);
int iCount, iSize;

hr = pPin->QueryInterface(IID_IAMStreamConfig, (void **)&pConfig);

hr = pConfig->GetNumberOfCapabilities(&iCount, &iSize);
pSCC = new BYTE[iSize];
int i = 0;
if (SUCCEEDED(hr))
{
    while (i<=iCount)
    {
        pConfig->GetStreamCaps(i++, &pfnt, pSCC);

        VIDEOINFOHEADER *vih = (VIDEOINFOHEADER *)pfnt->pbFormat;
        printf("Size %i  %i\n", vih->bmiHeader.biWidth, vih->bmiHeader.biHeight );
        if (vih->bmiHeader.biWidth == width_ && vih->bmiHeader.biHeight == height_)
        {
            //pfnt = mfnt;
            printf("Found mediatype with %i %i - %x\n", vih->bmiHeader.biWidth, vih->bmiHeader.biHeight, pfnt->formattype );
            hr = pConfig->SetFormat(pfnt);
            //break;
        }

    }
}

//DeleteMediaType(pfnt);
delete[] pSCC;
pConfig->Release();
return hr;