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Skat-Konferenz (sk)

Skat-Konferenz is the popular German card game Skat played online combined with videoconferencing. Copyright (C) 2012-2014, 2021 Carsten Paproth. This program is free software and comes with ABSOLUTELY NO WARRANTY. Licensed under the terms of GPLv3.

Skat-Konferenz is written in C++ using portable libraries exclusively, so it should be compatible with UNIX/Linux (X11), MS Windows, and Mac OS X. Till now, it has been tested on Ubuntu (latest version 20.04) and MS Windows.

Download Skat-Konferenz for Windows


Currently, this software is in beta phase and needs some testing.

  • 1.4: CDF 9/7 wavelet based video codec, a noise gate for the microphone, and the server can act as a relay between the peers
  • 1.3: more robust network connections, pause broadcasting of the video and audio signal, and show the last trick
  • 1.2: MDCT-based audio codec, wavelet-based image codec with range encoding, and a more flexible network protocol
  • 1.1: ported from FLTK2.0 to FLTK1.3
  • 1.0: a more robust audio broadcast method
  • 0.9: all functions are implemented, begin of beta phase
  • 0.8: some unofficial but popular rules (Kontra, Re, Bock, Ramsch) and keeping a list of the played games
  • 0.5: bidding procedure and gameplay according to the international Skat Order rules
  • 0.3: secure dealing out, i.e. one player alone cannot selectively manipulate the deal or identify the other players cards
  • 0.1: videoconferencing between 3 people with audio and video compression


Following portable open source libraries are used by sk:

  • fast light toolkit FLTK1.3 for the graphical user interface and the OpenGL interface
  • Boost for multithreading (boost::thread), asynchronous network I/O (boost::asio), and random number generation (boost::random)
  • open source computer vision library OpenCV for the webcam capture interface
  • PortAudio for the audio hardware interface

Playing card images are copied from GNOME Aisleriot and modified to look more like Skat cards.


To build sk, you need to install the dependencies with the corresponding development files first, use your package manager (if available) to install them. sk comes with a simple CMakeLists.txt file, thus you can use CMake to generate a build-system. CMake generates a makefile on Linux, but it is also possible to generate Visual Studio project files with CMake provided all needed libraries can be found by CMake. The following steps illustrate how to install all dependencies and build sk on Ubuntu. The script contains these steps as well.

  1. Install all the dependencies and CMake by using:

     sudo apt-get update
     sudo apt-get install build-essential libfltk1.3-dev libboost-all-dev libopencv-dev portaudio19-dev cmake
  2. Download and unpack the sk source code.

  3. Build and run sk:

     cd sk-master
     mkdir build
     cd build
     cmake -D CMAKE_BUILD_TYPE=Release ../src/


First of all, you need a webcam, a microphone, headphones and two other players. Skat is a card game played by three people. One player has to be the server. If you want to be the one, start sk, go to the Options tab, tick the Server checkbox, and click Connect. Then tell the other two players your publicly reachable IP address or hostname, and UDP port per e-mail, telephone, or whatever. Now, the other two can start sk and connect to this disclosed address and UDP port. Any firewalls/NATs in between should be configured to allow this connection.

If a connection can be established, the videoconferencing starts. If two peers are connected to the server, the server initiates UDP hole punching between these two peers. If a direct peer-to-peer connection is not successful, the server acts as relay between the peers. The server should provide enough upload bandwidth for this case. After 3 players are connected with each other either directly or through the relay, the game starts. The game consists of secure dealing out, bidding, choosing the Skat cards, announcing the game, playing the hand, and especially small talk: Hinten ist die Ente fett!


Skat-Konferenz is the popular German card game Skat played online combined with videoconferencing.




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