OpenCV VideoWriter C++ not Writing to Output.avi - c++

Question

I'm attempting to write code that takes a frames and writes to an output file .avi / .mp4 using cv VideoWriter in C++.
System setup is Linux Ubuntu 18.04.4 LTS, Qt 5.9.5 (GCC 7.3.0, 64 bit)
I'm getting frames from camera, convert them to QImage and display them on GUI well.
void FrameThread::run()
{
while (m_isWaitting)
{
if (SUCCESS == Buf_WaitForFrame(m_Cam, &m_frame))
{
int channels = m_frame.ucChannels;
int width = m_frame.usWidth;
int height = m_frame.usHeight;
int elementBytes = m_frame.ucElemBytes;
QImage img;
img = QImage(width, height, QImage::Format_Grayscale8);
uchar *pSrc = (uchar *)m_frame.pBuffer + m_frame.usHeader;
uchar *pDst = (uchar *)img.bits();
if (2 == elementBytes)
{
pSrc += (elementBytes / 2);
if (1 == channels)
{
int pixels = width * height * channels;
for (int i = 0; i < pixels; ++i)
{
*pDst++ = *pSrc;
pSrc += elementBytes;
}
}
}
emit signalUpdateImage(img);
if (m_isSaving)
{
saveImage();
}
if (m_isRecording)
{
if(!m_isCreateVideoWriter)
{
QString savedPath = "/home/nvidia/Pictures/";
CvSize size = cvSize(2048, 1148);
char cur[1024];
timespec time;
clock_gettime(CLOCK_REALTIME, &time);
tm nowtm;
localtime_r(&time.tv_sec, &nowtm);
sprintf(cur, "%s%04d%02d%02d%02d%02d%02d.avi", savedPath.toLocal8Bit().data(), nowtm.tm_year+1900, nowtm.tm_mon+1, nowtm.tm_mday, nowtm.tm_hour, nowtm.tm_min, nowtm.tm_sec);
video = cv::VideoWriter(cur,cv::VideoWriter::fourcc('M','J','P','G'),25.0, size, 1);
m_isCreateVideoWriter = true;
}
else
{
//Clicked 'Stop Record' button
//Close video writer
if (CamObject::getInstance()->m_bFinishRec)
{
video.release();
m_isRecording = false;
m_isCreateVideoWriter = false;
return;
}
// Recording...
else
{
videoFrame = QImageToCvMat(img);
video.write(videoFrame);
}
}
}
}
}
}
Also I created method QImageToCvMat because their is not write method with QImage :
cv::Mat QImageToCvMat(QImage &inImage)
{
cv::Mat mat(inImage.height(), inImage.width(),
CV_8UC1, inImage.bits(), inImage.bytesPerLine());
return mat;
}
The code failing to produce output and program collapse on line
video.write(videoFrame);
Any one familiar with this issue or can kindly give advice? Other way to create video file?