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Thursday, April 29, 2010

Sharing Powerpoint course content

In the last couple of months I looked into solutions for sharing my course presentations (PowerPoint files) with others. My main goal would be to provide an experience as close as possible to the actual in-class courses for people that missed courses. This means that I would like the course content to be available to others as a full-length presentation with an audio narration.
The easiest way to do it with PowerPoint is to record the audio using the Record Narration feature. The problem with sharing PowerPoint files with narration are multiple. I have some solutions to these problems, but they lead into other problems.
The first major problem comes from PowerPoint itself: it can record narrations only in PCM format. That means that an audio narration (recorded with mono, 16 bit, 22KHz quality) takes about 150MB/hour (about 352Kbps). As a solution, I can link the audio narration file (instead of embedding it into PowerPoint) and compressed later as an MP3. Compressing it with FFmpeg is a painless process (just run one command) and takes only a few minutes. Compressed as an MP3 at 8Kbps, I will get around 3,5MB/hour for the narration which is quite ok. The problem that shows up in this case is that the file are linked (so I have to handle all of them with the main ppt file), and even worse, the PowerPoint stores the absolute path to the file (so moving the ppt file to another is very difficult if you want to keep the narration working).
The second major problem is that students must have PowerPoint (full version or viewer-only) installed and they need to download the file in order to view it. To make things more complicated, if the narration is linked it will not work unless the files are save in the same folder (i.e. same disk, path, folder name) as it was when narration was recorded. A MAJOR blocker. Combined, these two problems, put the ppt file sharing solution out of the game. I'll prepare the course in PowerPoint, but I need another method to share it using Moodle.
Due to certain restrictions (I won't go into details), I can not use presentations or videos sharing services with public access (like or
The solution I'm looking into for my problem is share the presentations as Flash content, so I'm looking into different PowerPoint to Flash converting solutions. To sum up my requirements, I want the solution to have the following features:
  • small file output (I guess that means Flash with MP3 sound files)
  • easy to publish in Moodle (i.e. a single swf file to upload instead of a bunch of different files)
  • easy to create (i.e. click a few programs to transform from PowerPoint to Flash; as few as possible command line typing)
  • free/unexpensive as in open source, freeware or adware (but with a decent sized banner and without affecting usability)
  • fast conversion from ppt to swf (or batch conversion)
  • (optional) as many features as possible (some feature examples are slide notes, slide thumbnails, different controls, search in slides, narrator information)
Obviously, I will not get all there requirements fulfilled, but I'll try to get as close as possible.