README.md: initial revision

README.md

+![PULT logo](www/pult/pult-logo-192x74.png)
+
+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.]