How to set amcap's default color space to YUY2?

Question

Hi,

AMcap is a app for capturing video or to preview from webcam. Its source code comes with Microsoft Windows SDK as sample.

I want to (bypass the following process of user interaction in amcap code or say want to) set it as default:

Ampcap menu

  Options

    Video Capture Pin ...

        Color Space/Compression: YUY2

        Output size: 1600x1200

I have a compatible webcam and works fine on changing manually to YUY2 and 1600x1200 in AMcap app.

By default it is:

    Color Space/Compression: MJPG

    Output size: 160x120

I tried to find 'YUY2' string in whole project, but I could not find it, so that I could hardcode it. It seems it is created dynamically and then operated; refer: in the file amcap.cpp nearby line no 3395.

Please help.

-Rahul

Answer 1

I have some code that uses an IID_IAMStreamConfig interface to set the camera image size. I didn't use it to set the image format, but I added the code that I think will do the job. It is untested however.

   // get the number of formats and make sure the strutucre size matches
   int count;
   int size;
   VIDEO_STREAM_CONFIG_CAPS caps;
   pSC->GetNumberOfCapabilities(&count, &size);
   if( sizeof(caps) != size )
   {
    // Error
   }

   AM_MEDIA_TYPE* mt_p = NULL;
   hr = pSC->GetStreamCaps(0, &mt_p, (BYTE*)&caps);
   if (hr != S_OK)
   {
    // Error
   }

   if ((mt_p->majortype != MEDIATYPE_Video) || (mt_p->formattype != FORMAT_VideoInfo))
   {
    // Error
   }

   VIDEOINFOHEADER* video_info_header_p = (VIDEOINFOHEADER *)mt_p->pbFormat;
      video_info_header_p->bmiHeader.biWidth = 1600;
   video_info_header_p->bmiHeader.biHeight = 1200;
   // Code to change video format 
   // I think 16 is the right value for biBitCount, but I am not sure!!!!
   video_info_header_p->bmiHeader.biCompression = MAKEFOURCC('Y','U','Y','2');
   video_info_header_p->bmiHeader.biBitCount = 16;

   hr = pSC->SetFormat(mt_p);
   if (hr != S_OK)
   {
    // Error
   }

   if (mt_p->cbFormat != 0)
   {
    CoTaskMemFree((PVOID)mt_p->pbFormat);
    mt_p->cbFormat = 0;
    mt_p->pbFormat = NULL;
   }
   if (mt_p->pUnk != NULL)
   {
    // Unecessary because pUnk should not be used, but safest.
    mt_p->pUnk->Release();
    mt_p->pUnk = NULL;
   }

You should place the code after the following block in amcap:

    if(hr != NOERROR)
        hr = gcap.pBuilder->FindInterface(&PIN_CATEGORY_CAPTURE,
            &MEDIATYPE_Video, gcap.pVCap,
            IID_IAMStreamConfig, (void **)&pSC);

Again, this is untested code, but you can try it and I hope it helps.

Answer 2

Hey @Dani van der Meer: Thanks for the Pointer ... I have done it by: In the function BOOL InitCapFilters()

after

 if(hr != NOERROR)
{

    hr = gcap.pBuilder->FindInterface(&PIN_CATEGORY_CAPTURE,
                                      &MEDIATYPE_Video, gcap.pVCap,
                                      IID_IAMStreamConfig, (void **)&gcap.pVSC);

    if(hr != NOERROR)
    {
        // this means we can't set frame rate (non-DV only)
        ErrMsg(TEXT("Error %x: Cannot find VCapture:IAMStreamConfig"), hr);
    }
}

gcap.fCapAudioIsRelevant = TRUE;

Paste:

CMediaType *pmt;
// default capture format
if(gcap.pVSC && gcap.pVSC->GetFormat((AM_MEDIA_TYPE**)&pmt) == S_OK)
{
    // DV capture does not use a VIDEOINFOHEADER
    if(pmt->formattype == FORMAT_VideoInfo)
    {
  pmt->SetType(&MEDIATYPE_Video);
  pmt->SetFormatType(&FORMAT_VideoInfo);
  pmt->SetSubtype(&MEDIASUBTYPE_YUY2);
  pmt->SetTemporalCompression(FALSE);

     VIDEOINFOHEADER* lpvihin = (VIDEOINFOHEADER*) pmt->pbFormat;

  {

             //DWORD fccYUY2 =  'YUY2' ;
    //lpvihin->bmiHeader.biCompression  =fccYUY2;
   //'YUY2';// MAKEFOURCC('Y','U','Y','2');
   //lpvihin->bmiHeader.biBitCount = 16; 
   lpvihin->bmiHeader.biWidth =  1600;// 960; //1600;
   lpvihin->bmiHeader.biHeight =  1200;//  720; //1200;
   lpvihin->bmiHeader.biSizeImage =   1600*1200*3; 

   hr = gcap.pVSC->SetFormat(pmt);

   ResizeWindow(HEADER(pmt->pbFormat)->biWidth,
                     ABS(HEADER(pmt->pbFormat)->biHeight));
        }
    }
    if(pmt->majortype != MEDIATYPE_Video)
    {
        // This capture filter captures something other that pure video.
        // Maybe it's DV or something?  Anyway, chances are we shouldn't
        // allow capturing audio separately, since our video capture
        // filter may have audio combined in it already!
        gcap.fCapAudioIsRelevant = FALSE;
        gcap.fCapAudio = FALSE;
    }
    DeleteMediaType(pmt);
}

Thanks a lot