Resolution of WebCam

[chris-evans]

Hi Sam,

I have found this code sample / library really useful, but have been struggling to add one feature to the code base. I am trying to add support for detecting resolutions supported by the WebCam. I have some code previously that was leveraging DirectShowLib, but I much prefer the simplicity of this code base (I feel like I can understand it). Any ideas/thoughts would be greatly appreciated.

Code Sample:: so after getting the capture pin from the output filter... I am calling the below method I wrote. All looks good, but the data I get back from GetNumberOfCapabilities makes no sense. capabilitiesCount is random (but huge) and capabilitiesResultStructureSize is zero. Also, GetStreamCaps throws a memory error.
private void SelectWebcamResolution(IPin sourcePin)
{
var cfg = sourcePin as IAMStreamConfig;

int capsCount = 0;
int capsStructSize = 0;
var result = cfg.GetNumberOfCapabilities(out capsCount, out capsStructSize);

if (result == 0 && capabilitiesResultStructureSize > 0)
{
    var ptr = Marshal.AllocCoTaskMem(capabilitiesResultStructureSize);
    try
    {
        for (int i = 0; i != capabilitiesCount; ++i)
        {
            AMMediaType capabilityInfo = null;
            result = cfg.GetStreamCaps(0, out capabilityInfo, ptr); // this throws mem error
        }
    }
    finally
    { Marshal.Release(ptr); }
}

}

Thanks in advance,
Chris Evans