NEWSLETTER: Vol. 5, No. 6, March 15, 2000
Web-Based Audio and Video
by Scott Bradley, Ph.D.
Department of Communicative Disorders
University of Wisconsin-Whitewater
The World Wide Web is becoming more popular as a medium to deliver coursework to students. While there are only a limited number of distance education courses delivered entirely over the Web through UW System institutions, hundreds of instructors are using the Web to deliver supplemental material to their classes.
There are many Web-based features available to instructors such as text and graphics, chat and whiteboard, e-mail, and threaded discussion groups. However, instructors should not forget that it is possible to deliver both audio and video over the Web. This was not always the case since a variety of technical issues such as bandwidth, compression schemes, and complicated capture and editing software made Web-based audio and video impractical. As computers have become faster, ethernet bandwidth has become wider, and new compression options for audio and video have become available, it is becoming more practical to deliver audio and video over the Web.
I have been using Quicktime and SoundEdit 16 software for several years to produce and deliver audio to my students over the Web. I have found this technology to be indispensable in audiology, a field in which all types of auditory stimuli are used across all classes and clinical practicums.
Many people are familiar with streaming technology in which the data is sent to a computer, buffered, and played back with little if any interruption. The problem with streaming, especially for video, is that the signal is often of poor quality and sometimes becomes interrupted, especially during peak traffic times.
An alternative to streaming is Quicktime-generated audio and video files. This technology is different since it converts and compresses audio and video that can then be downloaded. Quicktime estimates how long it will take to download the entire file and will begin playing the audio or video so that the playback will correspond with the completion of the download. Often, the files will play back immediately since the download speed is faster than the playback speed, especially for ethernet connections. Moreover, the files may be saved locally and played back later if the user is using Quicktime Pro. The main advantage of using Quicktime, however, is that the quality is usually far superior to streamed media.
I have used Web-based audio quite extensively across my hearing science and audiology courses. Below are a few examples.
Hearing loss simulator: I have filtered and distorted several audio clips in an attempt to simulate hearing loss. I use these clips in almost all of my classes. These audio clips may be accessed from http://facstaff.uww.edu/bradleys/radio/hlsimulation/
On-line lectures: During the fall semester, I recorded my lectures for an Audiometry class to a DAT tape and then transferred the recordings to a Mac G3 computer where the audio was converted and compressed using SoundEdit 16 and Quicktime. Since the lectures were about 50 minutes I used a 19:1 compression ratio. The average file size was slightly over 3 MBs. Using a 56 kB modem Iíve found that the clips could be listened to instantaneously. See http://126.96.36.199/audioclips/archives.html for sample clips.
PowerPoint HTML presentations with Quicktime narration: Many users are familiar with using Real Presenter to deliver narrated PowerPoint presentations over a Real server. I had considered using this format but found many slides to be difficult to read because of the degraded streamed video signal. Another problem was trying to review specific parts of the presentation which I found slow and awkward. Instead I converted the PowerPoint slides to HTML format and embedded Quicktime audio clips with each slide. I found this to be much better solution since it gave the user more control over the stopping and starting of the audio narration. Since the PowerPoint slides were converted to jpeg images, the slides were much easier to read than the streamed version. To view examples of these slides, see http://facstaff.uww.edu/bradleys/ohcpp/
Within the next several months I hope to add Quicktime video to my course materials. Using iMovie and Quicktime, I have found the video capturing and editing process to be extremely intuitive and have found the playback over ethernet to be instantaneous with good quality.
For further examples of Web-based audio and video, and a short tutorial on how to create Quicktime audio, please see the Audio Library in Communication Sciences and Disorders at http://facstaff.uww.edu/bradleys/radio/library.html