Experiences with real-time streaming


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Experiences with real-time streaming

  1. 1. Experiences with Real-time Streaming Audio/video in Delivering Web-based Courses Thomas I. M. Ho Department of Computer Technology http://www.engr.iupui.edu/cpt/ Indiana University Purdue University Indianapolis USA tho@iupui.edu Abstract: Over two years of experience with the application of real-time streaming audio and video (RealAudio/Video) to Web-based courses has yielded a wealth of experience in synchronous delivery of live instructional content and asynchronous delivery of archived content. Outcomes include: 1. Live broadcast a. Audio/video lecture content b. Visual aids “pushed” to remote viewers c. Chat feature for remote audience participation 2. Archived lectures with the soundtrack synchronized with the Web pages displayed during the live lecture (Synchronized Multimedia) 3. Multimedia annotations of Web page links including: a. Explanation of examination questions and answers b. Motivational messages to explain Web pages c. Oral instructions for assignments An example of a course with these features can be found at: http://oncourse.iupui.edu/in (log in as guest) Products of this experimentation include: 1. User interfaces for: a. live broadcast b. archived lectures 2. Productivity tools for: a. constructing Synchronized Multimedia content b. creating voice annotations c. Economical classroom premise equipment for originating live broadcast and encoding archived lecture What is RealAudio/Video? The RealNetworks Basic Server, RealEncoder, and RealPlayer comprise the RealMedia System created by RealNetworks (1997). The RealNetworks Basic Server streams files created with the RealEncoder to free RealPlayers on sound card-equipped personal computers, which continuously decompress the audio and play it in real time without download delays, even over 14.4 Kbps modems. RealAudio has been widely deployed on the World Wide Web especially to distribute news and music as described at the RealGuide (1998) site guide. More recently, RealVideo has added video capability to RealAudio within the RealMedia architecture. Educational applications have become more common and examples can be found at RealNetworks’ (1998) education page.
  2. 2. Experiments with RealAudio Beginning in September 1996, Introduction to Data Processing (CPT 115) broadcast lectures live from Indiana University Purdue University Indianapolis (1996) via RealAudio. Figure 1 is a diagram describing how the live broadcast was done. In addition, the lectures were archived on the Web site. As a result of this audio content being available, the Web site was significantly enhanced by the addition of voice annotations and oral instructions for assignments. Voice annotations were used to provide motivational messages to explain Web pages such as the one at: http://www.engr.iupui.edu/cpt/courses/cpt299/1997fa/it/itaids.html During the Spring and Fall 1997 semesters, Internet Skills (CPT 299) at Indiana University Purdue University Indianapolis (1997) continued the experiment by using Synchronized Multimedia to synchronize the lectures with visual aids on Web pages. An example of Synchronized Multimedia by Thomas I. M. Ho (1997) explains this experiment in greater detail. To experience it, one will need:  A personal computer with sound card  An Internet connection with a speed of 14.4 Kbps or better  RealPlayer 5.0 (free to download from the RealNetworks Web site at www.real.com) Experiments with RealVideo Beginning in January 1998, Electronic Commerce (CPT 423) broadcast lectures live from Indiana University Purdue University Indianapolis (1999) via RealVideo. Origination of live broadcast and archiving were accomplished via the ClassCast project developed by the CyberLab (1997). Figure 2 describes ClassCast’s improvements to the original live broadcast environment described in Figure 1. In addition, the archived lectures were significantly enhanced by the addition of “highlighting” which draws the students’ attention to lecture segments that the instructor emphasizes because they are important and likely to be tested in examinations. A red bar that appears above the visual aids that are synchronized to the sound track indicates highlighting. As a by-product of these “highlighting” events, the important segments are indexed in the archived lectures so that these segments are then subsequently hyperlinked to the correct responses in the examination key so that the student can play back the video clips in which the answer to the corresponding examination question was given. RealVideo requires an Internet connection with a speed of 28.8 Kbps or better. Results of experiments Products The major products of this experiment include:  User interfaces  Productivity tools User interface for archived playback The primary user interface has been developed for playing back archived lectures synchronized to the Web pages displayed during the live lecture. An example at: http://rmedia.engr.iupui.edu/cpt/archive/archive.asp? course=423&sem=spring2001&sec=b487&date=0227&start=12:0.0&end=47:0.0 demonstrates the controls for the video/soundtrack with a frame for displaying the synchronized Web pages and another frame for displaying the highlighting visual cue.
  3. 3. User interface for originating live broadcast The live lecture is broadcast to remote viewers via the ClassCast user interface [Williamson, 1999] with the following capabilities:  Delivery of audio/video content  “Pushing” Web pages displayed to students in the classroom  Chat to enable remote viewers to ask questions and to participate in classroom “discussions” A notable contribution of the ClassCast user interface for the instructor is its ability to “time-stamp” each mouse click while “pushing” Web pages to remote listeners. This capability has greatly facilitated the creation of event files for producing Synchronized Multimedia versions of the lectures for archived playback! Another notable outcome is the fact that an ordinary classroom was equipped with the ClassCast originating equipment for only about $20,000! For this modest amount, this classroom can serve a global audience! Another capability developed by the CyberLab (1998) is LectureCast which enables RealAudio content to be originated (broadcast live and archived) from anywhere via telephone. This capability is convenient for originating lectures from home when the instructor is ill or even for delivering conference presentations at remote locations without traveling to the conference venue. Although LectureCast is conceptually similar to the original RealAudio origination capability depicted in Figure 1, LectureCast has the additional capability of scheduling the encoder via the World Wide Web as well as equipping the encoder with “auto answer” rather than requiring human intervention to answer the phone when initially connecting to the encoder. Experiences This experiment has demonstrated that significant instructional content can be delivered via real-time streaming audio and video that can be received by a modest computing platform with no more than a 28.8 Kbps dial-up connection to the Internet. An anecdote serves to remind us why it is so important for us to experiment! Our experiments with RealVideo have led us to consider whether RealVideo can be used practically to broadcast signing to reach deaf students. Remember that we first experimented with real-time streaming audio to enable us to reach students who could hear! References CyberLab (1997). ClassCast, [WWW document]. URL http://cyberlab.iupui.edu/CyberLabHtml/classcast.htm CyberLab (1998). LectureCast, [WWW document]. URL http://cyberlab.iupui.edu/Projects/netcast.htm Ho, Thomas I. M. (1997) How We Do RealAudio [WWW document] URL http://weblab.iupui.edu/ho/cpt299_f97/lecture_frame.html?101797 Indiana University Purdue University Indianapolis (1997). Internet Skills (CPT 299), Fall 1997 Web site [WWW document]. URL http://www.engr.iupui.edu/cpt/courses/cpt299/1997fa Indiana University Purdue University Indianapolis (1999). Electronic Commerce (CPT 423), Web site [WWW document]. URL http://oncourse.iu.edu/in/ (under “Advanced Search” select semester Fall 1999, enter “B684” for “Find a course” and log in as guest) RealGuide (1998). Web site [WWW document]. URL http://www.real.com/realguide/index.html RealNetworks (1997). Web site [WWW document]. URL http://www.real.com RealNetworks education page (1998). Web site [WWW document]. URL http://www.realnetworks.com/education/index.html
  4. 4. Williamson, David (1999). A Template for Web-Based Interactive Distance Learning. Fifth Americas Conference on Information Systems, 1999, Association for Information Systems, Atlanta, GA. Figure 1. Originating a live broadcast via RealAudio
  5. 5. Figure 2. ClassCast environment for live broadcast