PULT is the ULTimate Learning/Teaching Tool

What is PULT?

• PULT is a video platform for learning and teaching.

  There are a lot of video systems designed for conferencing, which are commonly used for learning and teaching. PULT is designed for learning and teaching.

• PULT is simple.

  To participate in a lecture you just go to a web page, type your password, and watch. As a lecturer you have a few buttons to control whether something becomes full-screen or whether someone may contribute something. Focus on contents, not on the tool.

• PULT is reliable.

  Even when the network connection isn't the best, you still get your lecture through.

• PULT is 100% Free Software (Open Source).

  You can run it on your own server for best-possible data protection and privacy. You can study how it works, adapt it to your needs, and publish your improvements for everyone to benefit. Also, there are no licensing fees.

• PULT husbands your CPU power and network bandwidth.

  Neither the server nor the client computers need to be high-end. PULT can even work when the lecturer's Internet access is rather slow.

• PULT integrates your favourite platform.

  We didn't reinvent the wheel. When you like Jitsi Meet and you want to use it to show your face to 120 participants, PULT makes that possible – in a way which makes it even simpler for your participants than if they joined Jitsi Meet.

  When you like the shared whiteboard of OpenMeetings, PULT enables you to present it to a big audience, where only those who actually write on the whiteboard need to join and to understand OpenMeetings.

Okay, more technically, what is PULT?

PULT is a collection of small programs, mostly Unix shell scripts. It provides a console (in German: „Pult“:–) where the lecturer can select which visual content is offered to the audioence via a web interface, noVNC. These visual contents can be a shared desktop, a camera view, an uploaded image or screenshot, or some arbitrary content provided by some other tool via a web interface, for instance a BigBlueButton presentation or the shared whiteboard of OpenMeetings.

PULT itself only handles video. For the audio part it cooperates with Mumble.

The virtual “meeting rooms” in PULT are called channels. For each channel, there is one instance of noVNC, showing a virtual desktop, provided by TigerVNC, to the audience.

Each channel is controlled by a deamon, pultd, a shell script, which loads the modules configured for this channel, also shell scripts. The pultd takes the role of the window manager for the channel's virtual desktop; the modules are the application software running on it.

For each channel, the lecturer has a web interface with a row of buttons for each module to start and stop it, to make it fullscreen, or to take a pre-configured window in the channel. We intentionally don't let the lecturer drag and drop the window with the mouse. Pressing a button is by far less distracting.

The audience has, also intentionally, no control over the contents of the desktop. They just view their channel via noVNC. That way they can concentrate on the learning content rather than on the viewing tool.

Currently we provide the following modules:

• VNC

  The lecturer can share a destkop content via VNC and/or invite participants to share theirs.

  VNC provides a pixel-correct transmission of the desktop contents at a reasonable speed, using only moderate CPU resources and network bandwidth.

  For best performance, we recommand installing a local VNC server. For a quick solution, we provide yesVNC, a VNC server via a web interface.

• CVH-Camera*

  The lecturer or a participant can place a camera view in the channel.

  One of the videos provided this way can be transmitted via the Janus WebRTC Gateway. This allows for a high-quality transmission at a moderate, and adjustable, network bandwidth. (We are working on making this possible for all camera views.)

• Upload

  The lecturer or a participant can upload an image file or a screenshot via a web interface.

• BBB-Camera and JM-Camera

  The lecturer or a participant can transmit a camera view via BigBlueButton or Jitsi Meet, which then becomes visible in the channel.

• OM-Board and BBB-Board

  OpenMeetings and BigBlueButton provide shared whiteboards, where the lecturer and participants can draw and upload presentations. This module makes these boards visible in the channel.

Each channel is easily configurable to meet the needs of the lecturer. One lecturer might want as few buttons as possible, while another one might prefer to have all modules enabled, just in case.

For each configured module, the lecturer's console features a row of buttons to start and stop the module, and to hide and show its contents. Modules can also be configured to get an additional button to make them run in a pre-defined region of the screen rather than full-screen. For camera modules this is the default. A typical application is to run a VNC shared desktop full-screen and to show a camera view of the lecturer at the edge.

How does this look like in practice?

Students S1, S2, ... want to take part in a lecture by lecturer L. They connect to Mumble for the audio part. For the video part, they go to the web page of the channel, type in the channel's password, and see a welcome screen.

Lecturer L goes to another specific web page, the PULT console. L presses the buttons labeled “VNC start” and “Camera start”. L starts the VNC server software and connects to the server. L's shared desktop appears in the channel. L follows a link from the PULT console to a separate web page to activate the camera. The camera view becomes visible in the lower right corner of the channel.

For welcoming the students, L presses the button labeled “Camera max“. The camera view becomes full-screen, hiding the shared desktop. After the welcoming, L presses “Camera min” to switch back to the previous screen arrangement.

Student S1 wants to ask a question. For this purpose, S1 needs to upload a screenshot. L presses the “Upload start”. The PULT console displays a URL. L forwards this URL to S1 via the Mumble chat. S1 follows the link and presses the “Screenshot” button. S1's screenshot appears in the channel, hiding L's desktop, but not the camera view.

While L answers S1's question, L presses “Upload hide” to switch to L's desktop, and later “Upload show” to switch back to S1's uploaded screenshot. When the question is answered, L presses “Upload stop”. S1's screenshot vanishes, we are back to the full-screen view of L's desktop with a camera view in the corner.

After a while, S2 wants to share a desktop to discuss some results. L presses “VNC guest start”. Since S2 does not have a VNC server installed, L copies a URL from the PULT console to S2 in the Mumble chat. S2 follows the URL and presses a button. S2's desktop is presented full-screen in the channel, with L's camera view in the corner. L decides that the camera view hides important parts of S2's desktop, and presses “Camera hide”. The camera view vanishes. After the discussion, L presses “VNC Guest stop”. S2's desktop vanishes; L's desktop is visible again.

At the end of the lecture, L presses “Camera max” to make the camera view full-screen to say goodbye. L presses “Camera stop” and “VNC stop”. The channel shows a welcome screen again. To end the session, everyone closes their browser windows.

[To be continud.]