Paper to be presented at the National UniServe Conference 2007, Sydney, Australia. Download PDF.

Paper presented at ICSOFT 2007, Barcelona, Spain, July 2007. Download PDF

I began using screencasts after seeing John Udell’s and others use them to explain or demonstrate new technologies; they struck me as a very accessible medium for showing how things work whcih is exactly what we often need to do when teaching Computing.

It turns out we can do a few different things with screencasts. The simplest example is just to demonstrate a procedure like installing a piece of software or publishing a file to a web server. The power of a screencast here is the old ‘picture paints a thousand words’ adage since it’s so much easier to show these procedures than it is to describe them. A short video replaces a page of text and screenshots and gets the message off much more clearly. Another type of screencasts demonstrates developing some code - here I can show the code, explain what I’m doing and demonstrate how it works in a compact way. Students can watch the video, pause it and copy down the code to run themselves if they need to. This is so much more powerful than posting a bit of code on the web however good my comments are. However, I think the most powerful use of screencasts is to try to illustrate problem solving strategies by making mistakes, tracking down bugs and generally showing how bad situations can be recovered from. This is an area of computing that is really hard to teach in other media or even face to face; screencasts give us the chance to bring this thinking to the surface and model how real coding is done.

Having said this, I’m not sure I’ve managed to reach the final level in many of these screencasts this year. Most of them are used to introduce new ideas or walk through the solution to a problem. In some cases I’ve made mistakes (sometimes on purpose - the best ones I think come naturally!) but I think there is a lot more scope for carefully planning the errors and recovery strategies that are illustrated in the videos.

Here’s a list of the screencasts from this year’s COMP249. These are all properly the property of Macquarie University and myself so please if you want to make use of them include appropriate acknowledgment.

• HTML Authoring 1
• HTML Authoring 2
• CSS 1
• CSS 2: Zen Garden
• Uploading to Platypus
• Javascript
• Python
• Python, part 2
• These screencasts are from last year and are WMV files, I’ve not
  been able to transcode them to Flash.
  • Python Dictionaries 1
  • Python Dictionaries 2
• Assignment 2 - Using the Database
• Practical 8 - Cryptography with an XML flavour

Shared collaborative distributed annotation using semantic web technologies.

The Semantic Web augments the current Web with machine-processable information enabling humans and machines to work in cooperation; in our context, we are using it as the basis of a linguistic annotation system that is used by language researchers to annotate language resources. This project will look at the issues raised when we allow many people to collaborate on authoring these annotations and making shared annotations available to a community of researchers. This crosses a number of existing areas of research including the semantic web and social computing, and extends the range of interactions available to researchers over the web.

Of course, as usual there is scope for variation on this theme, if you’re interested in this problem space and want to pursue a PhD in Australia, please get in touch. The scholarship is open to Australians and International students.

Having taught COMP249 for some time it’s very interesting to watch the change in experience and knowledge of the Web as the years have gone by. When we first started in 2001 part of the job was to introduce people to the Web, or at least to the more advanced things that were going on there. Now the students are all very sophisticated Web users most of whom have written web pages and many of whom have authored websites of their own. Almost everyone has used more than one web browser. Still though, the fundamental point of COMP249 is to convey the core workings of the Web; HTTP, HTML, URI; to change the students from being consumers to being producers and engineers on the Web.

Back in 2003 Tim Bray noticed traffic arriving at his site from Macquarie and posted his Condolences to COMP249 Sufferers: he thought our assignment (writing an RSS aggregator) was too much to ask. Back then our students managed to complete this task, some producing excellent pieces of work. My view then and now is that working with the core technologies is the best way to learn how they fit together. That assignment included writing code that requested RSS feeds, parsed them and displayed aggregated results. All the ingredients of a modern web application. We still try to give the students a good meaty web application in the assignment work but one that’s doable with very basic tools and a clear understanding of the web. This year, we’ll build a ’social’ application listing the units that students are studying. Should be fun.

I had great fun making the segment, I’ve never done anything like this before and it’s amazing how much work goes in to producing such a short piece. I can’t wait to see how it turns out.

If you watched the show and are interested in having a look at speech you might want to download one of the programs I used in the show. The WaveSurfer tool (you want to get the Binary release for windows from this page). Wavesurfer will let you record your voice and see the spectrogram patterns like the ones I was looking at on the show (you’ll need a microphone for your computer, a cheap headset will do). To get a good looking display, select “New” from the File menu and choose “Demonstration” when asked what configuration to use. Then press the red record button and speak into the microphone.

Here’s an experiment to try: record yourself saying “hid”, “hod”, “head”, “had”. Look at the spectrogram of each word and see if you can tell the difference. Look particularly for the brigher bands in the display — these are called formants and they’re different for every vowel sound.

Another experiment: record two children and an adult saying the same word, for example “SCOPE”. Can you tell the difference between them? Which looks more similar, the children’s voices or one of the children and the adult?

Please leave a comment if you’ve seen the show!

Sort of relatedly, I just discovered LibriVox which hosts volunteer recordings of out of copyright literary works (eg. Project Gutenberg books). I sampled War of the Worlds and the quality seems great. Worth a browse.

I have an ongoing project looking at processing speech recorded in meeting rooms. There are a number of student projects which could be built around this data. Here are some possible projects suitable for Honours

• Tracking speakers through a series of meetings. Given a series of meetings with a stable but changing group of people, we would like to model the speakers in the meetings and for any meeting decide who is present and mark their speech turns. This would involve working with audio signals and building speaker models as well as working with the results of an existing speech segmentation system.
• Integrating multiple microphone signals to improve speaker segmentation. This will involve quite a bit of low level audio processing so would be suitable for someone who had an interest in numerical algorithms. There is some existing code to build upon so you wouldn’t be starting from scratch.