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Guest

Hi all,

I'm trying to capture a frame and store it to a TBitmap, so that I can
process it later.
(needs to be Tbitmap). The main problem lies inside the callback funciton
"myYieldCallbackProc".
Stealing from a previous post, I've read that the data is in uyvy format.

I managed to steal another bit of code ( written by Andrew Tridgell 2000)
but to no avail.
All I get is a black background with red little dots scattered everywhere,
and nothing
like the captured picture.

Anyone know how to solve this beast??

------------------------BITS OF
CODE---------------------------------------------------------------
LRESULT FAR PASCAL myYieldCallbackProc(HWND hWnd,LPVIDEOHDR lpVHdr)
{
LPBITMAPINFO lpbi;
LPBITMAPINFOHEADER lpdata;
int sz;
// char lpStatusText[50];
CAPSTATUS cs;

sz = (int)capGetVideoFormatSize(hWnd);
lpbi = (LPBITMAPINFO)LocalAlloc(LPTR, sz);
lpdata = (LPBITMAPINFOHEADER)lpVHdr->lpData;
if (lpbi)
{
capGetVideoFormat(hWnd, lpbi, sz);
frmmain->Caption = DateTimeToStr(Now());

char * MyImage = lpVHdr->lpData; // is buffer contained video in format
avi uyvy
//***************************************
Graphics::TBitmap * SrcBitmap;
SrcBitmap = new Graphics::TBitmap;
SrcBitmap->PixelFormat = pf24bit;
SrcBitmap->Width = lpbi->bmiHeader.biWidth;
SrcBitmap->Height = lpbi->bmiHeader.biHeight;
char * thisptr = MyImage;
yuv_convert(MyImage,thisptr,320,200);

for (int y = 0;y< 200;y++)
{
for (int x = 0;x< 320;x++)
{
SrcBitmap->Canvas->Pixels[x][y] = thisptr[ (y*320) + x];
}
}
frmmain->Image2->Canvas->Draw(0,0,SrcBitmap);
SrcBitmap->SaveToFile("c:\temp.bmp");
SrcBitmap->Free();
//****************************************
}
LocalFree(lpbi);
return (LRESULT) TRUE;
}

void __fastcall Tfrmmain::Button11Click(TObject *Sender)
{
hwnd = capCreateCaptureWindow( NULL, WS_CHILD | WS_VISIBLE, 0, 0,
640, 400, this->Handle,100 );
SendMessage(hwnd,WM_CAP_DRIVER_CONNECT,0,0);
capOverlay(hwnd,TRUE);
capSetCallbackOnVideoStream( hwnd, myYieldCallbackProc );
capCaptureSequenceNoFile(hwnd);
}

void yuvtorgb(int Y, int U, int V, char* rgb)
{ int r, g, b;
static short L1[256], L2[256], L3[256], L4[256], L5[256];

static int initialised;
if (!initialised)
{
int i;
initialised=1;
for (i=0;i<256;i++) {
L1[i] = 1.164*(i-16);
L2[i] = 1.596*(i-128);
L3[i] = -0.813*(i-128);
L4[i] = 2.018*(i-128);
L5[i] = -0.391*(i-128);
}
}
#if 0
r = 1.164*(Y-16) + 1.596*(V-128);
g = 1.164*(Y-16) - 0.813*(U-128) - 0.391*(V-128);
b = 1.164*(Y-16) + 2.018*(U-128);
#endif r = L1[Y] + L2[V]; g = L1[Y] + L3[U] + L5[V]; b = L1[Y] + L4[U];
if (r < 0) r = 0; if (g < 0) g = 0; if (b < 0) b = 0; if (r > 255) r = 255;
if (g > 255) g = 255; if (b > 255) b = 255; rgb[0] = r;
rgb[1] = g;
rgb[2] = b;
}

void yuv_convert(char* buf, char * rgb, int xsize, int ysize)
{ int i;
for (i=0;i int Y1, Y2, U, V;
Y1 = buf[2*i+0];
Y2 = buf[2*i+2];
U = buf[2*i+1];
V = buf[2*i+3];
yuvtorgb(Y1, U, V, &rgb[3*i]);
yuvtorgb(Y2, U, V, &rgb[3*(i+1)]);
}
}

Edward · Guest

Maqn i have thew same problem but i use this code

CAPSTATUS CapStatus;
char str[12];

TimerRefresh->Enabled = false;
if(!FileExists("SAIR.DAT"))
{
if(ctImg>=20)
{
ctImg=0;
}
ctImg++;
sprintf(str,"web%03d.bmp",ctImg);

try
{
capGetStatus(hWndC, &CapStatus, sizeof (CAPSTATUS));
capFileSaveDIB(hWndC, str);

Graphics::TBitmap *bmpOld = new Graphics::TBitmap();
Graphics::TBitmap *bmpNew = new Graphics::TBitmap();

bmpOld->LoadFromFile(str);
bmpNew->Width = tamXVL;
bmpNew->Height = tamYVL;
bmpNew->Canvas->StretchDraw(bmpNew->Canvas->ClipRect, bmpOld);

bmpNew->Assign(bmpNew);
bmpNew->SaveToFile(str);

delete bmpOld;
delete bmpNew;

}
catch (Exception &Ex)
{
MessageDlg("Exception type " + Ex.ClassName() + " returned error
message: " + Ex.Message + "r" + " in form " + this->ClassName(), mtError,
TMsgDlgButtons() << mbOK, 0);
abort();
}
}
else
{
capDriverDisconnect(hWndC);
FreeLibrary(AVICapDllHandle);
Close();
}
TimerRefresh->Enabled = true;

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