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The EPFL MOOC Factory
Patrick Jermann, Gwenaël Bocquet, Gilles Raimond and Pierre Dillenbourg
Teacher independence
At a beginning of a recording session, a video specialist
from the Center for Digital Education sets up the lighting
and the audio. Critical steps include setting the exposure
for the camera to over-expose the white background and
tuning the audio gain so as to avoid clipping. After the
setup, the teachers start and stop the recording by themselves
through a button press on the tablet. After each
take, they can watch their recording and choose whether
they want to keep the take or not. This tremendously facilitates
the work of the video editors. A session lasts 3-4
hours during which teachers produce 1-2 hours of useable
video material. At the end of the session, the material
is copied onto an external storage for further processing.
High quality
We strive for professional picture and audio quality. This
requires the use of professional equipment. The price of
professional audio and video equipment can become very
high depending on the level of quality. Since we are still developing
the studio, some of our equipment is not yet up
to the standards that we set ourselves. For example, the
lighting kits and backdrops that we currently use, work
well, but will progressively be enhanced and replaced by
more robust and reliable material. A good approach is to
rent material to test before purchase. Audio quality has
been our main focus during early developments. The use
of two decent microphones, a mixer and the isolation of
the room with echo absorbent foam have tremendously
enhanced the sound quality.
Figure 2. The MOOC studio in the Rolex Learning Center.
Multisource
One of the “tricks” that is featured on EPFL MOOCs consists
of the “invisible hand” effect (see links for a video
tutorial). The hand of the teacher is recorded from above
the tablet and mixed with the slide content by the video
editors. As a result, students see the teacher writing and
pointing at the content (See Figure 3). Eye-tracking experiments
show that the deictic gestures are very efficient to
attract students’ attention to the important aspects of the
slides (see link for a video demonstration).
Flexibility
Some teachers want to sit, other want to stand. Some
teachers want to appear a lot on the recordings while
others simply want to annotate slides. Some want a green
screen set because they want appear “standing” inside
their content, while others need a white background. The
studio has to be reconfigured for each session in a short
time frame while retaining full functionality. To facilitate
these transitions, we installed an aluminum structure in
the studio that allows fixing lighting and cameras on “magic
arms” (moveable holders which can be clamped to any
structure, see Figure 2). Small custom-built tables are
placed on the main table and allow teachers to place their
laptop nearby.
Figure 3. Invisible hand effect. In the course “L’Art des Structures”
by Olivier Burdet and Aurelio Muttoni, the teacher is drawing
a construction by using a protractor. The image from a camera
placed above the tablet is mixed with the screen capture from the
presentation software.
The studio we have used to record our first MOOCs is
based on off-the-shelf screen recording software that allows
the simultaneous recording of a camera and a screen.
A single computer was used to produce (i.e. run the presentation
software) and to record the course (i.e. run the
screen recording). This solution, while economical and
simple, has presented some limitations. First, the recording
of the teachers’ hand and face along with the screen
capture involves three video sources and is not suited for
a basic screen recording solution. Second, screen-record-
Experience Track |232