Thread: Setting camera resolution through DirectShow

I want to set the resolution on my camera to 640x480 without using the filter pin dialog. Since the logitech quickcam software can do this, i know its possible, but they wont budge on supplying this information. I woudl prefer a general solution that woudl work with all capture devices, not just logitech cameras. Currently I can call up the filter pin dialog, but I need something that will do it at application startup without user intervention.

Assuming you're using DirectShow, a quick google suggests that the IAMStreamConfig interface is involved.

gg

That interface just lets you set the media type, not the resolution.

Another google search suggests otherwise.....

Found this from the WiMoBot source code: http://garage.wimobot.com/

Code:

// Sets up the capture filter to capture pictures at the specified 
// resolution.  the resolution is specified using an id.
HRESULT SetCameraResolution(HANDLE hCamera, DWORD dwId)
{
    HRESULT hr = S_OK;
    CameraInfo *pci = (CameraInfo*)hCamera;

    // get the IAMStreamConfig interface so that we can set the resolution
    CComPtr<IAMStreamConfig>        pConfig;
    hr = pci->pCaptureBuilder->FindInterface(
        &PIN_CATEGORY_STILL,
        &MEDIATYPE_Video,
        pci->pVideoCaptureFilter,
        IID_IAMStreamConfig,
        (void**)&pConfig);

    int iCount = 0;
    int iSize = 0;
    // get the number of different resolutions possible
    hr = pConfig->GetNumberOfCapabilities(&iCount, &iSize);

    if (SUCCEEDED(hr) && 
        iSize == sizeof(VIDEO_STREAM_CONFIG_CAPS) && 
        dwId < iCount)
    {
        VIDEO_STREAM_CONFIG_CAPS scc;
        AM_MEDIA_TYPE *pmtConfig;
        // make sure we can set the capture format to the resolution we want
        hr = pConfig->GetStreamCaps(dwId, &pmtConfig, (BYTE*)&scc);
        if (SUCCEEDED(hr))
        {
            // That resolution is available, now we set the capture format to the resolution we want.
            pConfig->SetFormat(pmtConfig);

            DeleteMediaType(pmtConfig);
        }
    }
    else
    {
        hr = E_FAIL;
    }


    return hr;
}

So they seem to be using the SetFormat() method to change resolutions.

gg