Abstract
Today, classroom lectures are often based on electronic materials, such as slides that have been produced with presentation software tools and complemented with digital images, video clips, and so forth. These slides are used in the live event and verbally explained by the teacher. Some lecture rooms are equipped with pen-based interfaces, such as tablet PCs, graphics tablets, or electronic whiteboards (Figure 1). These are used for freehand writing or to graphically annotate slides. Lecturers put a tremendous effort into the preparation of such electronic materials and the delivery of the respective live event. The idea of approaches for so-called automatic lecture recording is to exploit this effort for the production of educational learning material. Although it is still controversial if such documents could ever be a substitute for actual classroom teaching, it is generally agreed that they make useful, gaining complements to existing classes, and their value for education is generally accepted (Hürst, Müller, & Ottmann, 2006). While manual production of comparable multimedia data is often too costly and time consuming, such “lightweight” authoring via automatic lecture recording can be a more effective, easier, and cheaper alternative to produce high quality, up-to-date learning material. In this article, we first give a general overview of automatic lecture recording. Then, we describe the most typical approaches and identify their strengths and limitations.
TopIntroduction
Today, classroom lectures are often based on electronic materials, such as slides that have been produced with presentation software tools and complemented with digital images, video clips, and so forth. These slides are used in the live event and verbally explained by the teacher. Some lecture rooms are equipped with pen-based interfaces, such as tablet PCs, graphics tablets, or electronic whiteboards (Figure 1). These are used for freehand writing or to graphically annotate slides. Lecturers put a tremendous effort into the preparation of such electronic materials and the delivery of the respective live event. The idea of approaches for so-called automatic lecture recording is to exploit this effort for the production of educational learning material. Although it is still controversial if such documents could ever be a substitute for actual classroom teaching, it is generally agreed that they make useful, gaining complements to existing classes, and their value for education is generally accepted (Hürst, Müller, & Ottmann, 2006). While manual production of comparable multimedia data is often too costly and time consuming, such “lightweight” authoring via automatic lecture recording can be a more effective, easier, and cheaper alternative to produce high quality, up-to-date learning material. In this article, we first give a general overview of automatic lecture recording. Then, we describe the most typical approaches and identify their strengths and limitations.
Figure 1. Pen-based interfaces commonly used in classrooms: Tablet PC (top left), graphics tablets (middle left and top right), and electronic whiteboards (bottom)
TopApproaches For Content Production Via Lecture Recording
Processing Phases
The process of automatic lecture recording can be described by a sequence of different phases as illustrated in Figure 2. First, the teacher prepares the lecture and the required materials in a pre-processing phase. During the lecturing phase, the presentation is given to a live audience and simultaneously recorded. This live event is followed by a post-processing phase in which the final files and related Meta data are automatically created from the recordings. Depending on the respective approach, this post-processing might include activities such as an automatic editing of the recorded data and its transformation into different target formats, an automatic analysis of the produced files in order to generate a structured overview of its content and an index for search, and so forth. The final documents can be included into a learning management system (LMS) or distributed to the students via streaming servers, as download packages, or on CDs/DVDs.
Figure 2. Consecutive phases in the automatic authoring process
Key Terms in this Chapter
Raster-Based Recording: A raster-based recording produces a raster graphic or a sequence of raster graphics of some visual input. Raster graphics describe pixel-based images or bitmaps of visual information usually encoded in a rectangular grid of pixels with the respective color information for each pixel. Digital video is usually composed from a temporally ordered sequence of single raster graphics (called “frames”).
VGA Capturing/VGA Grabbing: Similar to a screen capture, but instead of producing the respective video file by recording directly from the machine’s memory, additional hardware is used to grab the signal between the computer’s visual output and the connected monitor or data projector.
Screen Capture/Screen Recording: Continuous production of screen shots in regular intervals over a specific amount of time in order to create a video file of the respective screen output during this time period. The output is generally stored in a common video file format, such as AVI or MPG.
Vector-Based Recording: Images or movies are not recorded as bitmaps or raster graphics, but instead all visual elements are represented in an abstract representation of geometrical primitives (points, lines, polygons, etc.). Single images recorded in a vector-based format are usually referred to as “vector graphics,” while the phrase “vector-based grabbing” or “vector-based capturing” is often used to describe a movie or animation stored in a vector-based format.
Screen Shot/Screen Dump: An image taken from the visual output of a computer as seen, for example, on the connected computer screen or data projector. The respective snapshot is normally done by a special software tool or by a mechanism directly integrated in the operating system. The output is generally stored as a bitmap in a common image format, such as JPEG, BMP, or PNG.
Lecture Recording/Presentation Capturing: A phrase describing techniques to record, post-process, and preserve live events in a classroom or lecture hall for further usage. Most related approaches try to automate the recording and post-processing as much as possible, thus realizing a special kind of rapid authoring or lightweight content production of educational multimedia data. Typical scenarios for the deployment of this kind of learning material are using them as multimedia complements to lectures for self-study or as a core around which to build courses for online and distance learning.