Client-server app, "send image" having problems

[deleted571]

Hi,
I am trying to send an image (OpenCV Mat) from client to server over a QDataStream. The first item is an int, the size of the buffer. It works for 10 to 15 images, then the server reads the first int a random number (usual ~2^30) which causes the app to crash. Please help. Thanks in advance!
This is the client side, in a loop (the images come from webcam with period 500ms):
@
//1) encode to jpg
cv::vector<uchar> buf;
cv::imencode(".jpg", *mat, buf);

//2) write to buffer
QByteArray buffer;
QDataStream out(&buffer, QIODevice::WriteOnly);
out << int(0); // save place for an int which represents the buffer size

for(cv::vector<uchar>::iterator it = buf.begin(); it != buf.end(); ++it)
{
out << *it; //write each byte
}

out.device()->seek(0); //write the buffer size
out << buffer.size();
qDebug() << "Sent " << buffer.size() << "bytes";

qint64 bytesSent = socket->write(buffer);
if(bytesSent < buffer.size())
{
if(bytesSent != -1)
{
qDebug() << "Transmit Error! Sent " << bytesSent << " out of " << buffer.size();
}
else
{
qDebug() << socket->errorString();
}
}
@

Server side:

@QDataStream in(socket);
int msgSize = -1;

//first read the size as an int
if(socket->bytesAvailable())
{
in >> msgSize;
}

qDebug() << "Read image size: " << msgSize << "bytes";
//wait until all bytes all available
while(socket->bytesAvailable() < ( qint64 ) ( ( qint64 )msgSize - sizeof(int) ) )
{
if(!socket->waitForReadyRead())
{
qDebug() << "Disconnected: " << socket->errorString();
socket->disconnectFromHost();
break;
}
}
qDebug() << "Bytes recieved: " << msgSize;

QByteArray ba;
quint8 byte;
for(int i = 0; i < msgSize - 1; ++i)
{
in >> byte;
ba.append(byte);
}
cv::Mat imgbuf = cv::Mat(FRAME_WIDTH, FRAME_HEIGHT, CV_8UC3, ba.data());
cv::Mat matImg = cv::imdecode(imgbuf, CV_LOAD_IMAGE_COLOR);
@

Both sockets are QTcpSocket.

Output example:

The server side:

@Read image size: 67551 bytes
Bytes recieved: 67551
Read image size: 56924 bytes
Bytes recieved: 56924
Read image size: 70027 bytes
Bytes recieved: 70027
Read image size: -2046830337 bytes
Bytes recieved: -2046830337
Read image size: -536866742 bytes
Bytes recieved: -536866742
Read image size: 1179207168 bytes@

At this point it tries to read 1179207168 bytes.

The client side:
@Sent 67551 bytes
Sent 56924 bytes
Sent 70027 bytes
Sent 70277 bytes
Sent 85633 bytes
Sent 65155 bytes

etc ...
Only the first three are successful.
@