ABSTRACT
The purpose of this article is to heighten awareness concerning an alternative method for delivery of multimedia-rich digital classroom presentations in a manner providing significant ease of access and portability. The method targets Windows® PC-Based presentations and employs syndication by simple internet broadcasts, currently referred to as podcasts, of large volumes of such presentations in a video-feed format for viewing on small hand-held devices. The goal is to offer students another alternative format for some of the materials currently used in the classroom or published on the internet in various formats. The methods for producing this content require: 1) special formatting of the initial digital presentation for maximum clarity on the small screen; 2) rendering and translating the video product for podcasting; and 3) production of a web page and appropriate links for the end-user to gain access to and use the materials at large.
To date, podcasting has primarily been used to feed simple text, still photos or MP3 audio. What makes this method somewhat novel is the production of the next level of podcast output: video MP4 files. Currently, video podcasts are being offered to first- and second-year students in gross anatomy and neuroscience classes at Ross University School of Veterinary Medicine to offer an alternative learning format to facilitate the needs of students with varied learning styles.
INTRODUCTION
As new technology emerges, it is the responsibility of faculty at all levels to keep abreast of these advancements and to remain open-minded, concerning the applications of such technology in their own teaching endeavors. Software applications that were once mind-boggling to utilize have become more user-friendly as methods toward their application and frequency of their use expands. The introduction and advancement of IT resources in schools and colleges has sparked more interest and facilitated many educators to apply techniques for learning beyond the typical classroom environment; one such application target being digital distance learning.
Distance learning itself is not a new idea, having beginnings in the mid 1800s with correspondence courses via the mail being conceived by Sir Isaac Pitman1, but the availability of the World Wide Web and advancements in computer technology have made the digital application of these practices mainstream in contemporary education.
This article explores a novel method for the application of distance learning and introduces educators to the techniques necessary to produce podcasts of their lectures in a multimedia format using RSS (Really Simple Syndication) feeds.
The term “podcast” is a relatively new term combining the words “iPod” (Apple, Inc.) and “broadcasting” first coined by British journalist Ben Hammersley in 2004.2-4 The technology for such productions emerged and developed in 2000-2001 and podcasts started hitting the web commonly after the first transmission in 2003.5 Currently, most podcasts are related to news and audio feeds and exhaustive web searches for digital multimedia presentation podcast feeds of higher education content will yield few, if any, published links.
In the practical application of podcasting, the multimedia content will be broadcast via the internet and loaded into one or more devices for viewing. In reality, such devices can be anything that can play video content of the specific type produced (computers, hand-held devices, DVD players), but the idea presented here is to target a small, portable device for ease and frequency of access to the information podcasted.
An alternative use for this format targets the presenter. Persons that must deliver lectures or seminars utilizing digital presentations can use podcasts on their own devices for study and rehearsal prior to delivery of their presentation. The ease of access of small portable devices makes this a favorable choice to consider.
TECHNIQUES
The sample podcasts produced and published for this tutorial were designed for an end-user with a handheld-type multimedia device capable of playing the specific type of media, a computer to dock the device to and a broadband internet connection. The specific device utilized to view the final video podcasts produced is an iPod® with color video capability. Herein, we will explore the techniques and necessary hardware and software to complete such podcast content.
Four major steps to accomplish the podcasts will be outlined below: 1) Proper formatting of the digital presentation; 2) rendering of the digital presentation to a continuous-feed video format; 3) translating the initial video to device-compatible video format; and 4) electronic publication of the final product with instructions to the end-user for their application. The details of each of these steps is completely outlined in an online presentation which provides complete instructions including examples and links to any and all software necessary to implement your own podcasts of similar content at www.rossvet.edu.kn/podcasts/test/tutorial.htm.
The first steps employ the use of PowerPoint® (Microsoft Corporation) as a standard digital classroom presentation medium. The presentation content must be conformed to high-resolution and contrast standards and specifically formatted for viewing on a small-screen as a continuous video feed. Poor formatting includes the use of incorrect fonts or font sizes, too much text per slide, poor color schemes, inadequate contrast between backgrounds and foregrounds, inadequate or excess animation. Basically, if it presents poorly on the large screen, it may appear even worse on the small screen.
It is recommended to employ the default presentation ratio and dimensions (4:3 width:height ratio: 10×7.5 inches) with a dark-colored gradient background and off-white colored text. For readability, the font should be a sans-serif face (Arial, Comic Sans MS) with an optimal size of 32-40 point and a minimal size of 28 point. To maximize the esthetic quality of the presentation, text should be animated so that it does more than simply appear and lie on the screen. Text that is animated to appear word by word or paragraph by paragraph allows the viewer to read along as text appears.
Further formatting is done so as to ensure that the final presentation podcast video flows from slide to slide with some calculated delay time; otherwise slides progress before the viewer is finished with them. This is accomplished by using a “pause indicator” to let the viewer know that all content for that slide is finished. Once they see the “pause indicator” appear, they can then hit the “pause” key on their device to temporarily stop the slide sequence and allow for more time on the slide. For the “pause indicator,” the word: “pause” was animated to materialize at the end of each slide after a slight delay from the emergence of the final slide content.
The next considerations involve numbers of slides and details of content that affect file size. First, the initial size of the presentation is critical as it dictates the final size of the podcast. It is imperative to minimize the size of the podcast for timely internet downloading without deteriorating its quality and effectiveness. To accomplish this, keep podcasts under 20 megabytes (MB) in size by sectioning presentations into parts if podcast file sizes become too large.
Further, any images embedded into the presentation should be no larger than the presentation screen size. The type of image used, for example JPEG, GIF, PNG, is not as critical as the clarity of the base image. All images used in presentations in this project are one of these three types. If the base images are larger than the presentation screen size, they are rendered at no greater display resolution, but result in a higher presentation file size. For example, two one-slide presentations were made with the same photograph placed into each one. In the first presentation, the photograph had a base size of 3072×2304 pixels and in the second presentation it was resized to 800×600 pixels (6.8% of the total square pixels of the original image). The presentation file sizes were 1573 kilobytes (kB) and 95 kB, respectively, and the resolution of both photos is the same on screen and the two presentations could not be visibly distinguished.
Likewise, if the original images are too small, they may be difficult to see on a small-screen device and enlarging them within the presentation may result in significant “pixelation.” Optimal image size is between 800×600 and 960×720 pixels. Many simple programs can be utilized to resize base images including the presentation software itself. The file size for a simple podcast of a one-hour lecture, with still images, exclusive of embedded videos and sound, was 23Mb from an initial 60-slide PowerPoint presentation size of 8.9Mb. See this link to view this sample podcast in your browser: http://www.rossvet.edu.kn/podcasts/test/test1.mp4.
Sound files such as clips of the lecturer’s voice can be linked into presentations. However, when the podcast is rendered from the presentation, it will call the sound file and embed it into the final video product, thus increasing output file size significantly. For this reason, it is imperative to keep linked sound files as small as possible and use them only when necessary. In this project, short audio clips (less than 10 seconds) were recorded and linked from certain slides which, in the author’s opinion, needed further explanation. All audio clips were recorded and saved in standard Windows “wav” file format. A podcast of the presentation with embedded audio clips rendered at 14Mb from an initial 18-slide PowerPoint presentation size of 1Mb. See this link to view this sample podcast in your browser: http://www.rossvet.edu.kn/podcasts/test/test2.mp4.
Finally, video files linked within presentations can be rendered into podcasts in a similar manner as audio. However, video clips have much larger file sizes than audio clips of similar length and when they are rendered in this process they become fully embedded. To preserve video quality, while maximizing compression to minimize video file size, the Windows Media Video (WMV) compression format was utilized. A podcast of a short presentation with embedded video rendered at 15Mb from an initial 10-slide PowerPoint presentation size of 1Mb with one embedded video per slide. This link shows this sample podcast in your browser:
http://www.rossvet.edu.kn/podcasts/test/test3.mp4.
The next step involves rendering the presentation into a video file. Inexpensive software packages are available to perform this task with excellent results. For example:
PowerVideoMaker Professional V2.2.0, PresenterSoft,Inc., www.presentersoft.com. Such software is capable of producing feeds in WMV, MPEG or AVI video formats. The format chosen for maximal size compression and quality was WMV at 8000Kbps and a resolution of 640×480 pixels. Conversion of the presentation files to video format is a time-consuming process and typical programs must run uninterrupted on a computer system during the conversion. Conversion of presentation number 1 (test1.mp4 above) took about 42 minutes on a Pentium®-4 system with 1MB RAM and a 2.8GHz processor.
Then, to render the podcast involves translation of the video to a device-compatible mode. Our target devices utilize video in DVD-quality MPEG-4 with Advance Audio Coding (AAC) audio compression. The podcast videos were produced from the raw WMV videos using a simple freeware package (Videora iPod Converter V 0.91, Videora Holdings, www.videora.com). The program default output format was chosen for all podcasts produced: 320×240 pixel video resolution at 768kbps and stereo audio at 128kbps.
The final step is to publish the podcast in some manner. This involves using Extensible Markup Language (XML) and Really Simple Syndication (RSS) to construct the podcast feeds. The student can then use their RSS capable browser or other software to subscribe to the podcast. In this project, a freeware program (RSSReader, V 1.0.88.0, www.rssreader.com) was tested and utilized to subscribe to podcasts and download the videos. Using this podcast subscription program allows the podcasts to be automatically updated so that changes to existing podcasts as well as podcasts added or deleted is routine and inherent to the RSS feed program’s notification mode. Once the video podcasts are located, they can be downloaded to your computer system and then migrated into your handheld device with the appropriate device synchronization program (iTunes 7, Apple Computer, Inc.). Figure 1 demonstrates a summary flowchart of the steps of this publication process.
Assuming the use of presentations of typical type and average length and in comparison with results demonstrated in the test examples published above, it would take somewhere between 25 to 50 MB of video podcast feeds with video runtimes of at least 15 minutes to deliver a typical one-hour lecture. This equates to nearly 4000 MB (4.0 gigabytes [GB]) of video with a total runtime of 20 or more hours for 5 hours of lecture per course weekly over an entire semester. With current handheld devices having storage capacities in the tens of gigabytes, there is adequate room for storage of video podcasts for multiple courses on a single hand-held device.
REFERENCES
- Matthews, D. The Origins of Distance Education and its Use in the United States. The Journal 1999. Available at http://www.thejournal.com/articles/14278. Accessed September 25, 2006.
- Wikipedia.org Podcast. Wikipedia Foundation, Inc. 2006. Available at http://en.wikipedia.org/wiki/Podcast. Accessed September 26, 2006.
- Hammersley, B. Audible Revolution. The Guardian Unlimited, Digital Edition. 2004. Available at http://technology.guardian.co.uk/online/story/0,,1145689,00.html. Accessed October 11, 2006.
- Meyers, M. ‘Podcast,’ the Word of the Year. CNET Networks. 2005. Available at http://news.com.com/2061-11199_3-5986198.html Accessed October 11, 2006.
- Doyle, B. The First Podcast.Information Today. 2005. Available at http://www.econtentmag.com/Articles/ArticleReader.aspx?ArticleID+13515. Accessed October 10, 2006.