Volume Two - Academic Conferences

Paul Newbury et al.
multimedia facilities are available so that sound, video and animation are common components of
lectures.
2.2 Live recording
The objective of the proposed system is that presentation material is captured as efficiently as
possible, and that means in real-time. In most systems this involves the use of a single camera used
to record the presenter and often all or part of the presentation area. Additionally, as mentioned
previously, systems usually record a separate capture of the slides straight from the presentation
machine. However, the system discussed in this paper produces high-quality engaging output by
using multiple cameras to cut between camera views in real-time. The Media Technology Lab (MTL)
in the School of Informatics consists of two broadcast studios and associated control galleries and
nonlinear editing facilities. However, for the majority of this work a single studio and gallery is used as
shown in Figure 5. Generally 3 cameras and slide capture is used in presentations, although it is
possible to get reasonable results using just a single camera and slide capture. The studio has been
built in a highly configurable manner, which enables quick conversion and setup between different
presentations.
Figure 5: The control gallery and one of multiple camera views of the presenter/screen
The use of a multiple camera set-up does involve the resource implication that a second person (the
director) is required for each lecture to cut the material as it is captured. However, this is a vast
improvement on the alternative of post-production editing from multiple camera recordings.
When reviewing lectures through the web-streaming framework, students are presented with a clear
representation of the material covered through a selection of views (including multiple views of the
presenter, screen and slide capture). The director is responsible for the views provided from the live
edit and selects material to best focus the students’ attention, therefore aiding the learning impact of
the material. This is unlike the experience that students receive from standard video lecture capture
where the whole scene is captured and it is down to the student to select the most relevant material
from the presentation (Figure 1). For the viewer the experience from the live studio recording is much
like that, for example, of the television viewers of the Royal Institution Christmas lectures.
2.3 Delivery
Captured lectures are available to students as on-demand programmes from a dedicated website.
The video-on-demand distribution system takes recorded material and makes it ready for distribution
online. As the material is recorded live, it does not require any post-production or editing so it can be
encoded and uploaded to the web within minutes of the presentation ending. Each programme is
automatically encoded into three video types shown in Table 1.
Two streams of differing quality are provided for desktop web-based viewing using an Adobe Flash
web-based player – in this case JWPlayer (Longtailvideo 2011). The Flash player is hosted within a
JavaScript web application driven by a content management system, and fed with a Real Time
Messaging Protocol (RTMP) video stream from a Wowza media server (Wowza 2011) system (see
Figure 6).
The high-quality stream offers the smoothest video, largest picture size and highest bit rate, see
Figure 7.
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