Μηνιαία αρχεία: Νοε 2020


BigBlueButton 2

BigBlueButton is a free software web conferencing system for Linux servers. Its intended use is online learning. BigBlueButton is an affiliate member of the Open Source Initiative.

Features

BigBlueButton offers certain core features including:

  • real-time sharing of audio, video, screen
  • public/private chat
  • Upload of PDF and Microsoft Office documents
  • Interactive whiteboard
  • Integration with phone systems (using FreeSWITCH)

Certain use cases are intended for teachers using the software, including:

  • Tutoring/virtual office hours
  • Flipped classroom
  • Group collaboration
  • Full online classes

BigBlueButton is a pure HTML5 client; no application is required to use it. It uses the browser’s support for web real-time communications WebRTC to send/receive audio, video, and screen.

Architecture

As a web page application, BigBlueButton front-end uses React and the backend uses MongoDB and Node.js. It also uses Redis to maintain an internal list of its meetings, attendees, and any other relevant information.

The BigBlueButton server runs on Ubuntu 16.04 64-bit and can be installed either from packages or install script. There is work underway to move to Ubuntu 18.04 in BigBlueButton 2.3.

Security

In October 2020 the German tech news portal golem.de published an article about several vulnerabilities in BigBlueButton. They criticized the unsafe use of LibreOffice, cookies without a secure flag and the use of old Ubuntu and Node.js versions. “I found a bunch of other security issues in BigBlueButton and proposed some hardening changes.” wrote Hanno Böck. “This took a lot of back and forth, but all significant issues are resolved now.”

The above material were retrieved from Wikipedia, the free encyclopedia (https://en.wikipedia.org/wiki/BigBlueButton)


Latex/Beamer: Notes page would not use whole space when in 16:9 aspect ratio

In a recent presentation we did, we added a lot of long notes…
At the specific document we had changed the aspect ratio to 16:9 using the following documentclass.

%[aspectratio=169] changes aspect ratio for slides from 4:3 to 16:9, should be better with columns
\documentclass[aspectratio=169]{beamer}

When we compiled the presentation showing the notes on the second screen, we noticed that the notes were not utilizing all of the white space. There was a huge empty column to the right, most probably it was the space that was added after changing the aspect ratio from 4:3 to 16:9.

The template we were using for the notes page was plain. To fix this issue we used the following commands to create a new version for the plain template, called wideplain.

\makeatletter
\defbeamertemplate{note page}{wideplain}{
	\vskip.25em
	\nointerlineskip
	\begin{minipage}{.9\paperwidth}
		\insertnote
	\end{minipage}
}
\makeatother

After we used this new template, the notes became wider and they used all of the available space.

%Enable to produce notes
\usepackage{pgfpages}
\setbeameroption{show notes on second screen=right}
\setbeamertemplate{note page}[wideplain]

Note:

In the code we defined the new template, initially we used \textwidth instead of \paperwidth which resulted in the same result as the plain template. So we assume that there is an issue somewhere that the notes template does not adapt its \textwidth properly when changing the paper aspect ratio.


Latex/Beamer: Do you type too many notes?

We most certainly do!

For that reason we needed to make the template for the notes as simple as possible. To avoid developing our own template for the notes page, we used one of the three basic predefined templates named plain.

Using plain we got an empty slide in the notes page which allowed us to add a lot more content!

The basic 3 template options for the notes slide are the following

  1. default The default template shows the last slide in the upper right corner and some information that should help you match a note page to the slide that is currently shown (e.g. title of section and subsection).
  2. compress The option produces an output that is similar to the default, it fits more content onto each note page at the price of legibility.
  3. plain An empty page to add notes to.

Usage example:

\documentclass{beamer}
\usepackage{pgfpages}
\setbeameroption{show notes on second screen=right}
\setbeamertemplate{note page}[default]
\begin{document}
\begin{frame}
Some content.
\note{Some note for the content}
\end{frame}
\end{document}

Beamer: Reasons to avoid allowframebreaks

Recently we were relying too much on allowframebreaks to automatically split a frame to multiple slides.

We were trying to make our notes spread across all slides that were automatically generated. After reading the Beamer User Guide, we learned a couple of new things.

A) Once you use allowframebreaks then you cannot use overlays.

B) Any notes for the frame created using the \note command will be inserted after the first page of the frame and will not be split among other pages.

C) We should refrain from using the option allowframebreaks except for long bibliographies (which by the way should be avoided anyway in presentations).

D) The use of this option is evil ^___^ as it promotes bad design and lack of thought when creating a presentation.

Anyway, back to the drawing board!