The following offers a description--prefaced by a narrative about whence came my inspiration--of a rather kludgy GNU/Linux solution I cobbled together for enhancing my on-line lectures with a video element. I am far from being technically adept as a GNU/Linux user, having only lately in my 11 years of GNU/Linux use become reasonably proficient at administering my own small stock of GNU/Linux machines and my small LAN. Despite a lack of anything that could really pass as expertise in this field, I want to offer this description for two reasons: 1) it may be of help to others who are equally inexpert as I am and who wish to do something like what I've done; and 2) perhaps those who are more technically adept will weigh in and offer corrections, point out alternative applications, make suggestions for improving what I've come up with, or all of the above. It is with these caveats that I offer a description of my humble and rather unsophisticated attempts.
Perhaps you've seen some of the wonderful learning material khanacademy offers? Since I've done a bit of on-line instruction I was eager to see, once I'd heard about the site, what's being done there. I was quite pleased by what I saw and immediately saw in it an answer to a need I've perceived in my own on-line teaching endeavors; namely, how to incorporate into my on-line lectures some sort of video component.
To date, I've simply been recording lectures for my on-line course as audio files and posting the results on my course web site. I found this somewhat dissatisfying, being myself, as are many others, one who learns perhaps best with visual aids. I'd thought about how I might introduce some video element into my lectures but thus far had only considered filming myself looking into a camera and delivering a lecture. Handsome though I am, I could not see how that would result in any very meaningful enhancement to the lecture. The khanacademy method, which involves writing on a sort of virtual blackboard/whiteboard during lecture delivery, on the other hand, seemed to me a very good way of enhancing on-line lectures with video--video content that should surely enhance and augment the lectures.
A presentation program such as Power Point or OpenOffice/LibreOffice's Impress would certainly be an option for incorporating video into on-line lectures, many readers may now be thinking to themselves. That's undoubtedly true and does remain an area for me to explore further.
In terms of presentation programs, I actually have more experience with a more obscure, less polished presentation program called Magicpoint than I do with either of the more popular ones just named. The latest stable release of this program is a few years old, but it does appear the developer continues working on it as he is still, up to Jan. of 2012, releasing snapshots. As I mentioned, I consider myself still very much in the exploratory stage of enhancing my lectures with video so I undoubtedly will explore in the future the use of presentation programs for doing this. But for the moment I am quite enamored of the approach taken in the khanacademy lecture videos: being able to write or print to the screen, in a sort of chalkboard fashion, while delivering an on-line lecture, may offer the possibility of greater spontaneity and thus of more effectively commanding the student's interest during the lecture.
On seeing but a few minutes of the first lecture I accessed at khanacademy, I felt I'd found my answer--incorporating a sort of chalkboard as the video element to accompany the audio. But being a GNU/Linux user on the one hand, and something of a hardware trash-picker on the other, I wasn't sure I could pull this off. I did, as you'll see, come up with a solution that approximates--sufficiently for my current needs, in any case--the video component of the khanacademy lectures.
According to wikipedia, in addition to a screen capture program and a graphics tablet--a hardware item I do not own--khanacademy uses a freeware program called Smoothdraw for making their lecture videos (see http://www.youtube.com/watch?v=QZJAhfaZnUA for a fuller description of how they make their videos). One would assume that likely some video converting software, for conversion to flash, may also be employed by khanacademy. Thus, 4 basic components are required for producing these sorts of video lectures: a graphics tablet, a graphics program, a screen capture program, and possibly a video file conversion program.
In my initial tests to imitate this under GNU/Linux, I decided I would forego the graphics tablet and just use the hardware I already have--a mouse and keyboard. Should I continue to meet with success, I could later acquire a tablet so as to approximate more closely the results produced by the khanacademy. This also saved me some possible hiccups in trying to get the graphics tablet working under GNU/Linux and within the graphics program with which I'd be using it. Having attempted in the past to draw freehand and write using a mouse, I knew this meant I'd be typing to my chalkboard rather than writing by hand. Mouse use would be restricted to adding emphasis, e.g., underlining typed words, perhaps drawing an occassional simple figure like an arrow or "x," and the like.
Though I cut corners, as it were, on the hardware end, I didn't need to cut corners in two other important areas--namely the screen capture program and the video conversion program. recordmydesktop does an excellent job of screen capture, while ffmpeg does the video conversion for me--in this case from the ogg theora output of recordmydesktop to the flash format. The encoding is quite resource-intensive and correspondingly time-consuming--taking over 2 hours to encode a 54-minute lecture on this old P4 2.6 with 1 GB of RAM. But the resulting video came out perfectly fine, despite the wait.
As for the graphics program I decided to start off using tuxpaint--a graphics program for children. It's not nearly as capable as Smoothdraw--for example, it is not possible in tuxpaint to simply scroll away the screen once it's been filled up with writing. But tuxpaint does have an eraser cursor that works to reasonably good effect. It is also a fairly lightweight program, which to me is always desireable, and especially apropos given the older hardware I'm using. There are undoubteldy better choices for graphics programs--programs that would work as well as or better than Smoothdraw for creating the sorts of effects seen in the khanacademy videos. But for an initial foray into this realm tuxpaint has worked well.
As to the particulars of how I am creating my lecture videos using this system, I first start tuxpaint at 1024x768 resolution (my display is set at 1280x1024): tuxpaint --1024x768 --nosound. I then fire up recordmydesktop, as follows: recordmydesktop -x 300 -y 200 --width 800 --height 600 --pause-shortcut Control+p --no-cursor ---v_quality 12 -o recordd-desktp-vid.ogv. After I've moved tuxpaint around on the screen so that just the drawing-board portion of the program is within the frame recordmydesktop creates, I begin recording my lecture, typing in text as needed. Then, as an additional step that may or may not be needed depending on what will be done with the output file, after recordmydesktop has finished encoding the lecture, ffmpeg can be run as follows: ffmpeg -i recordd-file.ogv -s vga convrtd-file.flv.
A few explanations on the switches I use when running these programs. As for tuxpaint, the --nosound option is imperative if you expect to use this program in conjunction with a lecture. The program makes all manner of sounds in regular use--all calculated to delight children, but which would obviously be out of place in a lecture for adults. As to recordmydesktop switches, I find control+p to be a more intuitive pause key sequence than the default (control Mod1 p): this, of course, allows me to pause the video as I deliver my lecture, then to resume it. The --no-cursor switch, as should be evident, causes the cursor to not be recorded in the video. Finally, since I do not need a very high-quality video in the final output, and since I want to decrease the file's size a bit, I use the --v_quality 12 switch (0 being the lowest possible video quality and 63 the highest).
This is a quick and dirty summary of how I've cobbled together, using a set of GNU/Linux utilities, a means of producing lecture videos that mimic crudely the final products seen on khanacademy's web site. As mentioned, I consider this an initial foray into this area. I hope to implement improvements and enhancements and, with feedback from readers who have more experience and/or expertise, to arrive at a much improved means of producing lecture-augmenting videos under GNU/Linux.
Here is a short demo video made using the kludge described above:
If you have pointers for how more effectively to create lecture videos using GNU/Linux, or can suggest improvements on the method I've developed, please offer your input!