BigBlueButton Exporter

Server-side version of the script that enables users to download BigBlueButton recordings as a single video file.

What's supported?

The script was developed for BigBlueButton versions ranging from 2.3 to 2.5.

✅ Annotations

✅ Captions

✅ Chapters

✅ Chat (with an option to anonymize names)

✅ Cursor

✅ Integration with Greenlight

✅ Polls

✅ Screen shares

✅ Slides

✅ Text

✅ Webcams

✅ Zooms

Server-Side Usage

Install the prerequisites (the following packages and RubyGems need to be installed on a BBB v2.5.x server running Ubuntu 20.04):

sudo apt-get install libsystemd-dev ruby-dev
sudo gem install builder optimist loofah nokogiri redis journald-logger open4 absolute_time

Place the file presentation.rb in the /usr/local/bigbluebutton/core/scripts/post_publish directory with executable rights.

Do the same for the file lib/interval_tree.rb, moving it to /usr/local/bigbluebutton/core/lib/recordandplayback.

After a session is over and the presentation is processed, the script will begin to export the recording as a single video file. It can be accessed and downloaded at https://your.bbb.hostname/presentation/meeting-id/meeting.mp4 once rendering completes, or directly in the Greenlight interface.

The meeting's ID is the alphanumeric string following the 2.3 in the recording's URL.

Existing recordings can be re-rendered by running the exporting script on an individual basis:

./presentation.rb -m <meeting_id> -f presentation

Note that this will stop automatic exports unless executed with the bigbluebutton user! See the "Troubleshooting" section below.

Alternatively,

bbb-record --rebuild <meeting_id>

will rebuild the entire recording (including the playback in the browser).

To re-render all existing recordings, run

bbb-record --rebuildall

If you do not have access to a BBB server, check out the branch 'client-side'.

For caption support, recompile FFmpeg with the movtext encoder enabled and uncomment the add_captions method.

The chat component can be disabled by turning HIDE_CHAT on. If you want to keep the messages but anonymize the names, set HIDE_CHAT_NAMES to true.

Requirements

Root access to a BBB 2.3 server.

Rendering options

If your server supports animated strokes on the whiteboard, set the flag REMOVE_REDUNDANT_SHAPES to true in presentation.rb.

Less data can be written on the disk by turning SVGZ_COMPRESSION on.

To make rendering less resource-intensive, download FFMpeg's source code and replace the file ffmpeg/libavcodec/librsvgdec.c with the one in this directory. After compiling and installing FFMpeg, enable FFMPEG_REFERENCE_SUPPORT in presentation.rb . Steps by @felcaetano.

The video output quality can be controlled with CONSTANT_RATE_FACTOR.

Troubleshooting

Exports don't start after the meeting ends: /var/log/bigbluebutton/post_publish.log and /var/bigbluebutton/published/video/ must be chowned to bigbluebutton:bigbluebutton

License

This script was developed for my bachelor's thesis at the Technical University of Munich and is licensed under MIT. Please cite as

@mastersthesis{bbb-recording-exporter,
	author = {Daniel Petri Rocha},
	title = {Development of a Sophisticated Session Recording Exporter for the BigBlueButton Web Conferencing System},
	year = {2021},
	school = {Technische Universität München},
	month = {},
	adress = {80805 Munich},
	pages = {65},
	language = {en},
	abstract = {BigBlueButton is an open-source web conferencing system designed for remote teaching.
              A longstanding feature request by community members has been to give users the
              ability to download the recording of a meeting as a video file, including the presentation,
              webcams, and chat messages. This thesis implemented that enhancement as a script
              executed automatically by the server once a recorded conference ends, performing
              significantly faster than previous solutions capturing the screen of the web player in realtime.
              Additionally, annotated slides can be output as PDF. Processing the presentation into both
              formats can also be done client-side if the user has no access to the server.
              Development of the converter did not introduce new dependencies into BigBlueButton
              and resulted in contributions to a Ruby library providing a data structure for efficient
              queries on intervals and FFmpeg, a command-line multimedia framework. The code
              offers a foundation for other improvements on BigBlueButton’s roadmap, such as giving
              instructors the option to import work done on documents in breakout rooms into the
              main session.},
	keywords = {open-source, web conferencing},
	note = {},
	url = {https://mediatum.ub.tum.de/doc/1632305/1632305.pdf},
}