Error capturing still. Error 31

Feb 3, 2008 at 7:00 AM
I managed to get hold of a USB Video standard specification webcam from a Chinese market, the camera contains a Vimicro 301V chip.
This camera requires no driver under XP and works fine using the Control Panel->Scanners and Cameras app.
But now, there is a new problem which is about the test application "CamTest2007". There is no error message when I run it. It would pop-up window but can't get any image. When I do "Get Still Image", it shows me the error: "Error capturing still. Error 31". Does anyone know what's wrong? I have rebuild CamTest2007 and WebCam_100, My OS is WinCE 5.0.
I debug the test application and driver and find where is the error happened? the test application call f = DeviceIoControl (pcs->hCam, IOCTLCAMERADEVICE_STARTVIDEOSTREAM, (LPVOID)&svStruct, sizeof (STARTVIDSTRUCT), (LPVOID)sz1, 0, &dwBytes, NULL);
-->enter WebCam Driver "case IOCTLCAMERADEVICE_STARTVIDEOSTREAM:
err = mdd_SetVideoFormat (pDrv, pIn, dwIn, pdwBytesWritten); "
-->"rc = pdd_StartVidStream (pDrv, (BYTE)vsData.wFormatIndex, (BYTE)vsData.wFrameIndex, pVid, vsData.dwInterval); "
-->"rc = NegotiateQuality (pDrv, bFormatIndex, bFrameIndex, dwValidInterval);"
-->"rc = GetMinMaxQuality (pDrv, bFormatIndex, bFrameIndex, dwValidInterval,&wQualityMin,&wQualityMax,
&wQualityInc);"
-->"rc = DoVendorTransfer (pDrv, USBVIDGETMIN, USBVIDEOVSCSPROBE_CTL, bInterface, bUnit, (PBYTE)p, wProbeLen);"
-->"dw = IssueVendorTransfer (pDrv->lpUsbFuncs, pDrv->hDevice, DefaultTransferComplete, pPDD->hVendorEvent,(fSet ? USBOUTTRANSFER : USBINTRANSFER) | USBSHORTTRANSFER_OK,
&req, fSet && (req.wLength < sizeof (bTBuff)) ? pVal : bTBuff,
NULL, &dwBytes, 2000, &dwErr);"
then get a error 31.