Automate the capture a full BigBlueButton conference replay, with bbb-downloader

BigBlueButton, aka BBB, is a webrtc conferencing solution, that among many features, allows to record a conference, for later replay.

We have been working together with my colleague François Trahay, on a set of scripts (bbb-downloader) that will allow to easily (on Linux) download recordings of BBB conferences, for local backup, video editing, upload on video sharing platforms, etc. This is particularly useful in our distance learning contexts where students may have to catch up on a live session that was recorded.

We have integrated a hackish solution to capture, as a single video, presentations that contained slide deck presentations. Let me explain why this was necessary.

A nice feature of BBB is the fact that, to present a slides deck, you don’t need to share your screen (as a video stream), but just have to upload your file, which is then auto-converted to images, that are sent to participants, in sync with your next/previous browsing of the slides.

This is great for participants with low bandwidth, which can see the slides (“static” images) instead of receiving a full screen video stream.

But a side effect is that the recording of a  class/conference that is done by BBB replays the slides just as it was done live : displaying images one after the other.

While it is easy to retrieve the audio, webcams of participants, or screen sharings as video streams, directly available from the recordings replay app, it is thus not the same for the slides, which don’t come as a video.

Our script will perform a replay, using a Docker container which drives Selenium under the hood, to capture the full replay, as a single video, which then includes the slides and everything. You can see my demo of this process in the following video:

bbb-downloader full capture demo.

It takes long to replay, in real-time, the recordings, to perform this capture… but it works. Kudos to elgalu/docker-selenium for the Docker env.

Feel free to test it and profit, or to report issues in the Guthub issues of the repo:

Mixing NRELab’s Antidote and Eclipse Che on the same k8s cluster

You may have heard of my search for Cloud solutions to run labs in an academic context, with a focus on free an open source solutions . You may read previous installments of this blog, or for a shorter, check the presentation I’ve recorded last week.

I’ve become quite interested, in the latest month, in 2 projects: NRELab’s Antidote and  Eclipse Che.

Antidote is the software that powers NRELabs, a labs platform for learning network automation, which runs on top of Kubernetes (k8s). The interesting thing is that for each learner, there can be a dedicated k8s namespace with multiple virtual nodes running on a separate network. This can be used in the context of virtual classes/labs where our students will perform network labs in parallel on the same cluster.

Eclipse Che powers Eclipse “on the Cloud”, making available software development environments, for developers, on a Kubernetes Cloud. Developers typically work from a Web page instead of installing local development tools.

Both projects seem quite complementary. For one, we both teach networks and software developments. So that would naturally appeal for many professors.

Furthermore, Eclipse Che provides a few features that Antidote is lacking : authenticating users (with keycloak), and persisting their work in workspaces, between work sessions. Typically what we need in our academic context where students will work on the same labs during scheduled classes, week after week, during or off-hours.

Thus it would be great to have more integration between the 2 environments.

I intend to work on that front, but that takes time, as running stuff on Kubernetes isn’t exactly trivial, at least when you’re like me and want to use a “vanilla” kubernetes.

I’ve mainly relied on running k8s inside VMs using Vagrant and/or minikube so far.

A first milestone I’ve achieved is making sure that Antidote and Eclipse Che aren’t incompatible. Antidote’s “selfmedicate” script was actually running inside a Vagrant VM, where I had difficulties installing Eclipse Che (probably because of old software, or particular networking setup details). I’ve overcome this hurdle, as I’m now able to install both environments on a single Kubernetes VM (using my own Vagrant setup).

Running Eclipse Che (alongsite Antidote) on a k8s Vagrant VM.

This proves only that there’s no show stopper there, but a lot of work remains.

Stay tuned.

Update: I’ve finally managed to get it to work on the antidote-selfmedicate base too. See my branch at:

Experimenting on distant labs and labs on the Cloud

I have delivered a speech last week about some ideas and experiments I have about the use of remote access and Cloud technologies for labs. I have collected the speech recording and stuff, in french, in another post.

The presentation was in french originaly, so I’ve quickly translated my slides and recorded an english version.

I mention tools like Guacamole, MeshCentral, NRELab’s Antidote, Eclipse Che and Labtainers, as well as k8s and Docker, as interesting tools that may allow us to continue teaching in labs while allowing more flexibility, distant learning, and hopefully improved quality.

You can find the slides here:, and the recording is here:

Experimenting on distant labs and labs on the Cloud.

Antidote and NRELabs presentation at Paris Open Source Summit 2019

I’ve just presented Antidote and the NRELabs platform at Paris Open Source Summit 2019. Here are the slides of the presentation : Antidote: virtualized learning labs running over kubernetes

I made a demo and the speech in front of the few people left, unfortunately, as the conference attendance suffered from the ongoing strikes in France (opposing the pensions system reform).

In any case, I hope it triggered some interest for the platform and the project.

Many thanks to the organizers for the very nice athmosphere, despite the rather low attendance.

Also, thanks to the HubLinked project who allowed me to work on the project and participate to the summit.

Displaying animated diagrams in org-reveal slide decks with SVG

org-reveal can be used to author slide decks with org-mode. The slides are displayed as an HTML document animated with reveal.js.

reveal.js allows to progressively display fragments which reveal parts of a page, for instance a bullet list.

It is also possible to display animated diagrams, as reveal.js fragments, provided that such diagrams are made as embedded SVG images included in the HTML.

Adding class="fragment" (and variations, including the associated data-fragment-index attributes) to the SVG elements helps animate parts of the diagram with the same JS actions as for regular bullet fragments.

The trick is to embed the SVG diagram inside the HTML source using the following code in the org-mode source:

<svg ...>  

I’ve found inspiration for that trick seeing the way SVG content was animated in the following demo.

So far, I’ve edited my diagrams with inkscape, and finally copied the whole <svg> tag from the saved inkscape file, into the #+BEGIN_EXPORT embedded HTML of the org file.

You can see a demo of such an animation in the document (slide 26: “Fragmented SVG display”).

Hope this helps.