the question of mfxExtScreenCaptureParam when using screen capture plu-in

Hello, thank you very much for checking this question. When I use screen capture plu-in, the mfxExtScreenCaptureParam parameter is not added, and when I add the mfxExtScreenCaptureParam parameter and set it, it will report an error.

without  mfxExtScreenCaptureParam :

//...........mfxExtScreenCaptureParam..............

mfxVideoParam par;

.........................

 mfxExtScreenCaptureParam extScPar;
 mfxExtBuffer *mfxextbuf,*dirtymfxextbuf;
 mfxExtDirtyRect mfxexdirRect;
 memset(&mfxexdirRect, 0, sizeof(mfxexdirRect));
 memset(&mfxextbuf, 0, sizeof(mfxextbuf));
 memset(&extScPar, 0, sizeof(extScPar));
 extScPar.Header.BufferId = MFX_EXTBUFF_SCREEN_CAPTURE_PARAM;
 extScPar.Header.BufferSz = sizeof(mfxExtScreenCaptureParam);
 extScPar.EnableDirtyRect = 1;
 extScPar.DisplayIndex = 0;
 extScPar.EnableCursorCapture = 0;
 mfxextbuf= (mfxExtBuffer*)&extScPar;
 //mfxexdirRect = &mfxextbuf;
 mfxexdirRect.Header.BufferId = MFX_EXTBUFF_DIRTY_RECTANGLES;
 mfxexdirRect.Header.BufferSz = sizeof(mfxExtScreenCaptureParam);
 dirtymfxextbuf = (mfxExtBuffer*)&mfxexdirRect;

// par.NumExtParam = 1;
 //par.ExtParam = &mfxextbuf;
 //...........mfxExtScreenCaptureParam..............
 

 mfxSts = MFXVideoDECODE_Init(mfxSes, &par);

36704 2018-9-12 19:28:26:399     par.Protected=0
36704 2018-9-12 19:28:26:399     par.IOPattern=MFX_IOPATTERN_OUT_VIDEO_MEMORY
36704 2018-9-12 19:28:26:399     par.NumExtParam=0
36704 2018-9-12 19:28:26:399     par.ExtParam=0000000000000000

36704 2018-9-12 19:28:26:399     par.reserved2=0
36704 2018-9-12 19:28:26:399 function: MFXVideoDECODE_Init(84.0707 msec, status=MFX_WRN_PARTIAL_ACCELERATION) -

using  mfxExtScreenCaptureParam :

mfxVideoParam par;

..........................

//...........mfxExtScreenCaptureParam..............
 mfxExtScreenCaptureParam extScPar;
 mfxExtBuffer *mfxextbuf,*dirtymfxextbuf;
 mfxExtDirtyRect mfxexdirRect;
 memset(&mfxexdirRect, 0, sizeof(mfxexdirRect));
 memset(&mfxextbuf, 0, sizeof(mfxextbuf));
 memset(&extScPar, 0, sizeof(extScPar));
 extScPar.Header.BufferId = MFX_EXTBUFF_SCREEN_CAPTURE_PARAM;
 extScPar.Header.BufferSz = sizeof(mfxExtScreenCaptureParam);
 extScPar.EnableDirtyRect = 1;
 extScPar.DisplayIndex = 0;
 extScPar.EnableCursorCapture = 0;
 mfxextbuf= (mfxExtBuffer*)&extScPar;
 //mfxexdirRect = &mfxextbuf;
 mfxexdirRect.Header.BufferId = MFX_EXTBUFF_DIRTY_RECTANGLES;
 mfxexdirRect.Header.BufferSz = sizeof(mfxExtScreenCaptureParam);
 dirtymfxextbuf = (mfxExtBuffer*)&mfxexdirRect;

 par.NumExtParam = 1;
 par.ExtParam = &mfxextbuf;
 //...........mfxExtScreenCaptureParam..............
 

 mfxSts = MFXVideoDECODE_Init(mfxSes, &par);

43912 2018-9-12 19:37:54:239     par.Protected=0
43912 2018-9-12 19:37:54:239     par.IOPattern=MFX_IOPATTERN_OUT_VIDEO_MEMORY
43912 2018-9-12 19:37:54:239     par.NumExtParam=1
43912 2018-9-12 19:37:54:239     par.ExtParam=00000070B0CFC7A8
43912 2018-9-12 19:37:54:239     par.ExtParam[0]=00000070B0CFC750
43912 2018-9-12 19:37:54:239     par.ExtParam[0].BufferId=1095779155
43912 2018-9-12 19:37:54:239     par.ExtParam[0].BufferSz=64

43912 2018-9-12 19:37:54:239     par.reserved2=0
43912 2018-9-12 19:37:54:239 function: MFXVideoDECODE_Init(0.0306667 msec, status=MFX_ERR_INVALID_VIDEO_PARAM) -

how can i to solve this problem??thankyou for your help!best wishes for u!