[lwip-users] Problems receiving data from camera using lwip to QTcpSocket under Ubuntu 9.04

[jarno . tuovinen]

Hi.

I'm new with lwip and trying to understand why data connection (or data flow)
between camera (using lwip) and Ubuntu 9.04 won't work properly.

I can't offer you very proper review of this situation (because I'm not the guy
who has made the camera, I'm just trying to receive data correctly) so I'm
expecting you to just give some thoughts what might be wrong.

Camera sends data to my Ubuntu. Ubuntu uses Qt's QTcpSocket to receive data. Qt
uses Ubuntus own sockets and stuff to do it, so Qt is not the point. There is
no particular point where packet flow stops. Sometimes it's the first or second
packet and very rarely I'll get whole structure I want. Usually there is TCP
Out-of-order and/or TCP duplicate ACK warnings when data flow stops. Was there
some bugfix at 1.3.1 conserning that out-of-order-thing? Next time when camera
tries to send data, there might come different amount of packets, but almost
never the whole structure I want.

We have app that receives data correctly under Windows, but using Windows here
is not an option (or its quite bad option). Windows app is compiled using
Visual DSP 5.0 which uses Indy 10.0 for network communication. Camera has lwip
version 1.3.0. We use gigabit ethernet also, if it matters. Camera-team has
done some code in top of lwip also, but I know just a little about that. There
might be some bugs or design flaws in that added code, but the guy who wrote it
in unavailable.

Receiving Qt-app works properly when Windows app communicates with camera and
forwards packets to Qt-app under Ubuntu. So problem should not be in the actual
Qt-app.

So. What could cause that all packets won't come to Ubuntu from camera and data
flows successfully between Windows-app and camera? If I would use lwip also in
Ubuntu, would it help?