exception at 0x65100c40 (QtGuid4.dll)

[sabeesh]

Hi,
I create a test program in Qt4.3 and compile it using Visual Studio 2005.
At the time of compiling, there has no errors. But when I run that program
, the program start running and after some 2 sec it display an error and crash. The error is like this. Any one know why this error?

First-chance exception at 0x65100c40 (QtGuid4.dll) in Test.exe: 0xC0000005: Access violation reading location 0x00000000


Please help me to find the reason of this error?

[jacek]

It looks like you have a null pointer somewhere. Post the backtrace and we will try to find where it is.

[sabeesh]

Hi,
When I run that program, V.S print these values at the output window

'Test.exe'': Loaded 'D:\svnserver\ccmanager\windows\debug\Test.exe'', Symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\ntdll.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\kernel32.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\Qt\4.3.0\bin\Qt3Supportd4.dll', Symbols loaded.
'Test.exe': Loaded 'C:\WINDOWS\system32\advapi32.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\rpcrt4.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\shell32.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\gdi32.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\user32.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\msvcrt.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\shlwapi.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\comdlg32.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\comctl32.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\ws2_32.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\ws2help.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\Qt\4.3.0\bin\QtSqld4.dll', Symbols loaded.
'Test.exe'': Loaded 'C:\Qt\4.3.0\bin\QtCored4.dll', Symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\ole32.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\WinSxS\x86_Microsoft.VC80.DebugCRT_1fc 8b3b9a1e18e3b_8.0.50727.42_x-ww_f75eb16c\msvcp80d.dll', Symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\WinSxS\x86_Microsoft.VC80.DebugCRT_1fc 8b3b9a1e18e3b_8.0.50727.42_x-ww_f75eb16c\msvcr80d.dll', Symbols loaded.
'Test.exe'': Loaded 'C:\Qt\4.3.0\bin\QtXmld4.dll', Symbols loaded.
'Test.exe'': Loaded 'C:\Qt\4.3.0\bin\QtGuid4.dll', Symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\oleaut32.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\imm32.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\winmm.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\winspool.drv', No symbols loaded.
'Test.exe'': Loaded 'C:\Qt\4.3.0\bin\QtNetworkd4.dll', Symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\sqlite3.dll', Binary was not built with debug information.
'Test.exe'': Loaded 'C:\WINDOWS\system32\avicap32.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\version.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\msvfw32.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\WinSxS\x86_Microsoft.Windows.Common-Controls_6595b64144ccf1df_6.0.2600.2982_x-ww_ac3f9c03\comctl32.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\Syncor11.dll', Symbols loaded.
'Test.exe'': Loaded 'C:\Program Files\Common Files\Logitech\LVMVFM\LVPrcInj.dll', No symbols loaded.
The thread 'Win32 Thread' (0xddc) has exited with code 12058624 (0xb80000).
'Test.exe'': Loaded 'C:\WINDOWS\system32\MSCTF.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\MSCTFIME.IME', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\uxtheme.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\usp10.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\Qt\4.3.0\plugins\imageformats\qgifd4.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\Qt\4.3.0\plugins\imageformats\qjpegd4.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\Qt\4.3.0\plugins\imageformats\qmngd4.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\Qt\4.3.0\plugins\imageformats\qsvgd4.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\Qt\4.3.0\bin\QtSvgd4.dll', Symbols loaded.
'Test.exe'': Loaded 'C:\Qt\4.3.0\plugins\imageformats\qtiffd4.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\secur32.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\userenv.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\xpsp2res.dll', Binary was not built with debug information.
'Test.exe'': Loaded 'C:\WINDOWS\system32\dciman32.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\wdmaud.drv', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\setupapi.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\wintrust.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\crypt32.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\msasn1.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\imagehlp.dll', No symbols loaded.
'Test.exe'': Unloaded 'C:\WINDOWS\system32\setupapi.dll'
'Test.exe'': Unloaded 'C:\WINDOWS\system32\wdmaud.drv'
'Test.exe'': Loaded 'C:\WINDOWS\system32\wdmaud.drv', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\setupapi.dll', No symbols loaded.
'Test.exe'': Unloaded 'C:\WINDOWS\system32\setupapi.dll'
'Test.exe'': Loaded 'C:\WINDOWS\system32\msacm32.drv', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\msacm32.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\midimap.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\P1100bVf.dll', Binary was not built with debug information.
'Test.exe'': Loaded 'C:\WINDOWS\system32\cfgmgr32.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\setupapi.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\vfwwdm32.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\ksuser.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\clbcatq.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\comres.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\devenum.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\msdmo.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\ksproxy.ax', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\kswdmcap.ax', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\mfc42.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\P1100bDx.ax', Binary was not built with debug information.
'Test.exe'': Loaded 'C:\WINDOWS\system32\qcap.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\quartz.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\Program Files\Common Files\Logitech\LVMVFM\UMVPL.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\msvcr71.dll', Symbols loaded.
The thread 'Win32 Thread' (0x710) has exited with code 0 (0x0).
The thread 'Win32 Thread' (0x898) has exited with code -2147024637 (0x80070103).
The thread 'Win32 Thread' (0x830) has exited with code 0 (0x0).
'Test.exe'': Unloaded 'C:\WINDOWS\system32\vfwwdm32.dll'
'Test.exe'': Unloaded 'C:\WINDOWS\system32\P1100bVf.dll'
'Test.exe'': Unloaded 'C:\WINDOWS\system32\cfgmgr32.dll'
'Test.exe'': Unloaded 'C:\WINDOWS\system32\dciman32.dll'
'Test.exe'': Loaded 'C:\WINDOWS\system32\dciman32.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\P1100bVf.dll', Binary was not built with debug information.
'Test.exe'': Loaded 'C:\WINDOWS\system32\cfgmgr32.dll', No symbols loaded.
'Test.exe'': Loaded 'C:\WINDOWS\system32\vfwwdm32.dll', No symbols loaded.
CallbackStatus(500, "text")
CVideoDeviceWin32:umpCaptureStatus(00000000)
Image width : 176
Image height : 144
Live window? : T
Overlay window? : F
Scaled? : F
Scroll : (0,0)
Using def. palette? : T
Audio hardware? : T
Capture file exists?: T
Current video frame : 0
Video frames dropped: 0
Current wave samples: 0
Time elapsed (ms) : 0
Capturing now : F
# video buffers : 0
# audio buffers : 0
Setting video mode
m_ImageSize.width() 176
m_ImageSize.height() 144
Call TryPalette
CallbackStatus: Reset
CVideoDeviceWin32:umpCaptureStatus(00000000)
Image width : 176
Image height : 144
Live window? : T
Overlay window? : F
Scaled? : F
Scroll : (0,0)
Using def. palette? : T
Audio hardware? : T
Capture file exists?: T
Current video frame : 0
Video frames dropped: 0
Current wave samples: 0
Time elapsed (ms) : 0
Capturing now : F
# video buffers : 0
# audio buffers : 0
The thread 'Win32 Thread' (0x954) has exited with code 0 (0x0).
CallbackError(418, "text")
TryPalette(32) return F
CallbackError(0, "text")
TryPalette(24) return T
CVideoDeviceWin32:umpCaptureParms()
uSeconds per frame : 66667
User must hit OK? : F
Percent drop error : 10%
Yield? : F
Index size : 34952
Chunk Granularity : 0
Using DOS memory? : F
Buffers requested : 5
Capture Audio? : T
Audio buffers : 4
Abort key :x1b
Abort left mouse? : T
Abort right mouse? : T
Limit enabled? : F
Time limit : 0
MCI Controlled? : F
Step MCI device? : F
MCI start time : 0
MCI stop time : 0
Double resolution? : F
Average capture step: 0
Audio buffer size : 0
Disable write cache?: F
Stream Master : 0
First-chance exception at 0x65100c40 (QtGuid4.dll) in Test.exe': 0xC0000005: Access violation reading location 0x00000000.
Unhandled exception at 0x65100c40 (QtGuid4.dll) in Test.exe': 0xC0000005: Access violation reading location 0x00000000.
The program '[904] Test.exe': Native' has exited with code 0 (0x0).

Please help me...

[jpn]

What's the content of Debug->Windows->Call Stack?

[sabeesh]

Hi,
Please see the attachmenet file

[jpn]

In CCamPanel::paintEvent(), how is the image constructed you're attempting to paint?

[sabeesh]

Hi,
Yes, I create that image in another location and paste it in that location

[sabeesh]

Hi,
This is my code for capture the image from Web camera

m_Palette = 0;
   // Open handle in an invisible window
   m_CapHandle = capCreateCaptureWindow((LPTSTR)"Capture Window",
#if 1
                                        0,
                                        0, 0, 160, 120,
#else
                                        WS_BORDER | WS_VISIBLE,
                                        0, 0, 320, 240,
#endif
                                        (HWND) 0, 0);
 
 
 
   if (!m_CapHandle) {
     qWarning("Could not create capwindow handle.");
   }
   else {
     // Connect to capture device
     if (capDriverConnect(m_CapHandle, m_CapIndex)) {
 
       // Register; this will make sure we are being callbacked (if you will excuse the grammar...)
      CVideoCollector::Instance((QWidget *) m_CapHandle)->RegisterDevice(m_CapHandle, this);
 
       ret = true;
 
       // Get the size of the video format structure & allocate memory
       m_BMISize = capGetVideoFormatSize(m_CapHandle);
	    assert(m_BMISize > 0);
       m_pBMIBuf = new uchar[m_BMISize];
       m_pVideoInfo = (BITMAPINFO *)m_pBMIBuf;
 
       // Get the actual format structure; It contains width, height, and
       // 'compression' info
       if (capGetVideoFormat(m_CapHandle, m_pBMIBuf, m_BMISize)) {
         qDebug("Got VideoFormat, struct size = %d", m_BMISize);
         DumpVideoFormat(m_pVideoInfo);
       }
       else
         qDebug("capGetVideoFormat failed.");
 
       // Get initial capture status
       capGetStatus(m_CapHandle, &m_CaptureStatus, sizeof(m_CaptureStatus));
       m_ImageSize.setWidth(m_CaptureStatus.uiImageWidth);
       m_ImageSize.setHeight(m_CaptureStatus.uiImageHeight);
     }
     else {
       qWarning("Failed to connect to capDriver %d", m_CapIndex);
       DestroyWindow(m_CapHandle);
       m_CapHandle = 0;
     }
   }

m_Palette = 0;
   // Open handle in an invisible window
   m_CapHandle = capCreateCaptureWindow((LPTSTR)"Capture Window",
#if 1
                                        0,
                                        0, 0, 160, 120,
#else
                                        WS_BORDER | WS_VISIBLE,
                                        0, 0, 320, 240,
#endif
                                        (HWND) 0, 0);



   if (!m_CapHandle) {
     qWarning("Could not create capwindow handle.");
   }
   else {
     // Connect to capture device
     if (capDriverConnect(m_CapHandle, m_CapIndex)) {
		 
       // Register; this will make sure we are being callbacked (if you will excuse the grammar...)
      CVideoCollector::Instance((QWidget *) m_CapHandle)->RegisterDevice(m_CapHandle, this);

       ret = true;

       // Get the size of the video format structure & allocate memory
       m_BMISize = capGetVideoFormatSize(m_CapHandle);
	    assert(m_BMISize > 0);
       m_pBMIBuf = new uchar[m_BMISize];
       m_pVideoInfo = (BITMAPINFO *)m_pBMIBuf;

       // Get the actual format structure; It contains width, height, and
       // 'compression' info
       if (capGetVideoFormat(m_CapHandle, m_pBMIBuf, m_BMISize)) {
         qDebug("Got VideoFormat, struct size = %d", m_BMISize);
         DumpVideoFormat(m_pVideoInfo);
       }
       else
         qDebug("capGetVideoFormat failed.");

       // Get initial capture status
       capGetStatus(m_CapHandle, &m_CaptureStatus, sizeof(m_CaptureStatus));
       m_ImageSize.setWidth(m_CaptureStatus.uiImageWidth);
       m_ImageSize.setHeight(m_CaptureStatus.uiImageHeight);
     }
     else {
       qWarning("Failed to connect to capDriver %d", m_CapIndex);
       DestroyWindow(m_CapHandle);
       m_CapHandle = 0;
     }
   }

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With these date I need to create an image. How can I do it ?
Please help me...

[jpn]

I don't see a single reference to QImage. How is the QImage constructed?

PS. Use [code]-tags around code blocks, please.

[sabeesh]

Hi,
I need to create a QImage from that code. I can do it in Linux and the code in like is like this

struct video_window vwin;
    struct video_audio Audio;
    QSize RequestedSize;
    QDomNode v;
    uint i;
    const char * TEMP_NODENAME;
    TEMP_NODENAME = m_NodeName.toStdString( ).c_str( );
    m_CamFD = ::open((const char *) TEMP_NODENAME, O_RDWR);
 
    if (m_CamFD < 0)
      return false;
 
    /* Check for Philips cams */
    m_HasFramerate = false;
 
    if (m_IntfName.contains ("Philips", Qt::CaseInsensitive )) {
      m_HasFramerate = true;
    }
    else {
      struct pwc_probe Probe;
 
    if (ioctl(m_CamFD, VIDIOCPWCPROBE, &Probe) == 0) {
      if (m_IntfName == Probe.name) {
        m_HasFramerate = true;
    } }
    }
 
   /* Probe audio functionality */
    if (ioctl(m_CamFD, VIDIOCGAUDIO, &Audio) == 0) {
      m_Mutable = (Audio.flags & VIDEO_AUDIO_MUTABLE);
    if (m_Mutable)
      qDebug("Device can be muted (usually TV card).");
    }
    else
        qWarning("Cannot query audio capabilities of video device.");
   /* See if device has mmap(); */
    m_VMBuf.size = 0;
    m_VMBuf.frames = 0;
    vid_io_buffer_size = 0;
 
    if (ioctl(m_CamFD, VIDIOCGMBUF, &m_VMBuf) == 0) {
      vid_io_buffer_size = m_VMBuf.size;
    if (m_RequestedBuffers > 0) {
      // User specified a number of buffers; see if we can match that.
    if (m_VMBuf.frames < m_RequestedBuffers) {
          qWarning("There are more buffers requested than device can provide. Limiting to %d buffers.", m_Buffers);
    } else
     m_Buffers = m_RequestedBuffers;
    }
    else // We grab everything we can.
    m_Buffers = m_VMBuf.frames;
    }
    else {
      m_VMBuf.size = 0; // Just to be sure....
      m_VMBuf.frames = 0;
    }
 
    /* See if we can actually mmap() the memory */
    if (m_VMBuf.size > 0) {
        vid_io_buffer = (uchar *)mmap(NULL, vid_io_buffer_size, PROT_READ | PROT_WRITE, MAP_SHARED, m_CamFD, 0);
    if (vid_io_buffer == (uchar *)-1) {
        qWarning("mmap() failed (%d). Falling back to non-mmap()ed mode.", errno);
        m_VMBuf.size = 0;
        vid_io_buffer = NULL;
    }
    else {
      vid_io_offsets.resize(m_Buffers);
        for (i = 0; i < m_Buffers; i++)
            vid_io_offsets[i] = m_VMBuf.offsets[i]; 
    }  }
 
    if (m_VMBuf.size == 0) { // No mmap or failed: allocate a buffer
      m_Buffers = m_RequestedBuffers;
       if (m_Buffers < 0)
         m_Buffers = 4; // In case the user didn't specify a buffer size, we make one.
         vid_io_buffer_size = m_Buffers * m_MaxSize.width() * m_MaxSize.height() * 4;
         vid_io_buffer = new uchar[vid_io_buffer_size];
         vid_io_offsets.resize(m_Buffers);
           for (i = 0; i < m_Buffers; i++)
           vid_io_offsets[i] = i * m_MaxSize.width() * m_MaxSize.height() * 4;
     }
 
    if (vid_io_buffer == NULL) {
       qWarning("Failed to mmap/malloc memory!");
       return false;
    }
    // Try to set default image size (from config)
    memset(&vwin, 0, sizeof(vwin));
    RequestedSize = m_pSettings->GetSize();
 
    if (!RequestedSize.isNull()) {
      vwin.width = RequestedSize.width();
      vwin.height = RequestedSize.height();
         if (m_HasFramerate) {
      vwin.flags |= (m_pSettings->GetFramerate() << PWC_FPS_SHIFT) & PWC_FPS_FRMASK;
    }
 
    if (ioctl(m_CamFD, VIDIOCSWIN, &vwin) < 0) {
      qWarning("Failed to restore image size (%d, %d)", vwin.width, vwin.height);
    }
    }
 
    // Query current image size
    if (ioctl(m_CamFD, VIDIOCGWIN, &vwin) < 0) {
      qWarning("Failed to query current image size.");
    }
    else {
    m_ImageSize.setWidth(vwin.width);
    m_ImageSize.setHeight(vwin.height);
 if (m_HasFramerate)
    {
      m_Framerate = (vwin.flags & PWC_FPS_FRMASK) >> PWC_FPS_SHIFT;
      qDebug("Initial image size = (%d, %d), framerate = %d", vwin.width, vwin.height, m_Framerate);
    }
       }
 
    // Restore brightness, contrast, etc.
    m_VPic.brightness = m_pSettings->GetBrightness();
    m_VPic.contrast = m_pSettings->GetContrast();
    m_VPic.colour = m_pSettings->GetSaturation();
    m_VPic.hue = m_pSettings->GetHue();
    m_VPic.whiteness = m_pSettings->GetGamma();
 
    if (ioctl(m_CamFD, VIDIOCSPICT, &m_VPic) < 0)
      qWarning("Failed to restore video controls.");
 
    // Restore input/tuner
    SetInput(m_CurrentVideoInput);
    SetTuner(m_CurrentTuner);
    return true;
]
 
and from another function I create the QImage like this
 
[
CreateImagesRGB()
{
    int w, h;
    uint u;
    QImage *CImage;
    m_RGB.resize(m_Buffers);
    w = m_ImageSize.width();
    h = m_ImageSize.height();
 
    if (m_Palette == VIDEO_PALETTE_RGB32) {
         // This is easy... map directly onto images
     for (u = 0; u < m_Buffers; u++) {
        m_RGB.insert(u, *(new QImage(vid_io_buffer + vid_io_offsets[u], w, h,  QImage::Format_RGB32)));
      } }
    else {
    for (u = 0; u < m_Buffers; u++) {
      CImage = new QImage(w, h, QImage::Format_RGB32);
      m_RGB.insert(u, *CImage);
    } 
    } }

struct video_window vwin;
    struct video_audio Audio;
    QSize RequestedSize;
    QDomNode v;
    uint i;
    const char * TEMP_NODENAME;
    TEMP_NODENAME = m_NodeName.toStdString( ).c_str( );
    m_CamFD = ::open((const char *) TEMP_NODENAME, O_RDWR);
    
    if (m_CamFD < 0)
      return false;

    /* Check for Philips cams */
    m_HasFramerate = false;

    if (m_IntfName.contains ("Philips", Qt::CaseInsensitive )) {
      m_HasFramerate = true;
    }
    else {
      struct pwc_probe Probe;

    if (ioctl(m_CamFD, VIDIOCPWCPROBE, &Probe) == 0) {
      if (m_IntfName == Probe.name) {
        m_HasFramerate = true;
    } }
    }
   
   /* Probe audio functionality */
    if (ioctl(m_CamFD, VIDIOCGAUDIO, &Audio) == 0) {
      m_Mutable = (Audio.flags & VIDEO_AUDIO_MUTABLE);
    if (m_Mutable)
      qDebug("Device can be muted (usually TV card).");
    }
    else
        qWarning("Cannot query audio capabilities of video device.");
   /* See if device has mmap(); */
    m_VMBuf.size = 0;
    m_VMBuf.frames = 0;
    vid_io_buffer_size = 0;

    if (ioctl(m_CamFD, VIDIOCGMBUF, &m_VMBuf) == 0) {
      vid_io_buffer_size = m_VMBuf.size;
    if (m_RequestedBuffers > 0) {
      // User specified a number of buffers; see if we can match that.
    if (m_VMBuf.frames < m_RequestedBuffers) {
          qWarning("There are more buffers requested than device can provide. Limiting to %d buffers.", m_Buffers);
    } else
     m_Buffers = m_RequestedBuffers;
    }
    else // We grab everything we can.
    m_Buffers = m_VMBuf.frames;
    }
    else {
      m_VMBuf.size = 0; // Just to be sure....
      m_VMBuf.frames = 0;
    }

    /* See if we can actually mmap() the memory */
    if (m_VMBuf.size > 0) {
        vid_io_buffer = (uchar *)mmap(NULL, vid_io_buffer_size, PROT_READ | PROT_WRITE, MAP_SHARED, m_CamFD, 0);
    if (vid_io_buffer == (uchar *)-1) {
        qWarning("mmap() failed (%d). Falling back to non-mmap()ed mode.", errno);
        m_VMBuf.size = 0;
        vid_io_buffer = NULL;
    }
    else {
      vid_io_offsets.resize(m_Buffers);
        for (i = 0; i < m_Buffers; i++)
            vid_io_offsets[i] = m_VMBuf.offsets[i]; 
    }  }

    if (m_VMBuf.size == 0) { // No mmap or failed: allocate a buffer
      m_Buffers = m_RequestedBuffers;
       if (m_Buffers < 0)
         m_Buffers = 4; // In case the user didn't specify a buffer size, we make one.
         vid_io_buffer_size = m_Buffers * m_MaxSize.width() * m_MaxSize.height() * 4;
         vid_io_buffer = new uchar[vid_io_buffer_size];
         vid_io_offsets.resize(m_Buffers);
           for (i = 0; i < m_Buffers; i++)
           vid_io_offsets[i] = i * m_MaxSize.width() * m_MaxSize.height() * 4;
     }
    
    if (vid_io_buffer == NULL) {
       qWarning("Failed to mmap/malloc memory!");
       return false;
    }
    // Try to set default image size (from config)
    memset(&vwin, 0, sizeof(vwin));
    RequestedSize = m_pSettings->GetSize();
    
    if (!RequestedSize.isNull()) {
      vwin.width = RequestedSize.width();
      vwin.height = RequestedSize.height();
         if (m_HasFramerate) {
      vwin.flags |= (m_pSettings->GetFramerate() << PWC_FPS_SHIFT) & PWC_FPS_FRMASK;
    }

    if (ioctl(m_CamFD, VIDIOCSWIN, &vwin) < 0) {
      qWarning("Failed to restore image size (%d, %d)", vwin.width, vwin.height);
    }
    }

    // Query current image size
    if (ioctl(m_CamFD, VIDIOCGWIN, &vwin) < 0) {
      qWarning("Failed to query current image size.");
    }
    else {
    m_ImageSize.setWidth(vwin.width);
    m_ImageSize.setHeight(vwin.height);
 if (m_HasFramerate)
    {
      m_Framerate = (vwin.flags & PWC_FPS_FRMASK) >> PWC_FPS_SHIFT;
      qDebug("Initial image size = (%d, %d), framerate = %d", vwin.width, vwin.height, m_Framerate);
    }
       }

    // Restore brightness, contrast, etc.
    m_VPic.brightness = m_pSettings->GetBrightness();
    m_VPic.contrast = m_pSettings->GetContrast();
    m_VPic.colour = m_pSettings->GetSaturation();
    m_VPic.hue = m_pSettings->GetHue();
    m_VPic.whiteness = m_pSettings->GetGamma();

    if (ioctl(m_CamFD, VIDIOCSPICT, &m_VPic) < 0)
      qWarning("Failed to restore video controls.");

    // Restore input/tuner
    SetInput(m_CurrentVideoInput);
    SetTuner(m_CurrentTuner);
    return true;
]

and from another function I create the QImage like this

[
CreateImagesRGB()
{
    int w, h;
    uint u;
    QImage *CImage;
    m_RGB.resize(m_Buffers);
    w = m_ImageSize.width();
    h = m_ImageSize.height();

    if (m_Palette == VIDEO_PALETTE_RGB32) {
         // This is easy... map directly onto images
     for (u = 0; u < m_Buffers; u++) {
        m_RGB.insert(u, *(new QImage(vid_io_buffer + vid_io_offsets[u], w, h,  QImage::Format_RGB32)));
      } }
    else {
    for (u = 0; u < m_Buffers; u++) {
      CImage = new QImage(w, h, QImage::Format_RGB32);
      m_RGB.insert(u, *CImage);
    } 
    } }

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and it is working.
I need to create the same in Windows.
Please help me..

[high_flyer]

the conversation code to QImage should stay the same.
The only difference between windows and linux is in the sections that deal with the hardware/driver (the ioctl() calls).
But that is something you need to look up with the respective hardware drivers under windows, it has nothing to do with Qt.

[jpn]

Excuse me, but perhaps you should divide the problem into a bit smaller pieces or something? Honestly, it's kind of rude to expect anyone to start interpreting that.

PS. A proper indentation alone would make the code much more readable.

[...]
for (u = 0; u < m_Buffers; u++) {
   m_RGB.insert(u, *(new QImage(vid_io_buffer + vid_io_offsets[u], w, h, QImage::Format_RGB32)));
}
[...]
for (u = 0; u < m_Buffers; u++) {
  CImage = new QImage(w, h, QImage::Format_RGB32);
  m_RGB.insert(u, *CImage);
}
[...]

[...]
for (u = 0; u < m_Buffers; u++) {
   m_RGB.insert(u, *(new QImage(vid_io_buffer + vid_io_offsets[u], w, h, QImage::Format_RGB32)));
}
[...]
for (u = 0; u < m_Buffers; u++) {
  CImage = new QImage(w, h, QImage::Format_RGB32);
  m_RGB.insert(u, *CImage);
}
[...]

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Notice that QImage is an implicitly shared class...