How Dartmouth Produces Video Podcasts

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How Dartmouth Produces Video Podcasts

8/22/2007

By Dian Schaffhauser

With an $8,000 investment, Dartmouth's Department of Physics and Astronomy has set up the capability to provide video podcasts for courses that enable students to watch lectures they may have missed or that warrant review. Now, said Lab Manager John Largent, the New Hampshire school is exploring how it can make lecture capture available campus-wide.

Up until the summer of 2004, only a single professor in the department was in the practice of making one of his courses available for viewing after class. The media format was videotape, which had to be checked out from the library.

Video Capture Technology
With seed money in hand and based on the recommendation of other AV groups on campus, Largent invested in a Canon GL2 camcorder. But its MiniDV tape limited him to a single hour of recording time, not enough capacity for the lectures he needed to capture. He switched to 80-minute tapes, and then added the Focus Enhancements FireStore FS-4 portable DTE recorder to the mix. The FS-4 can capture three hours--about 40 gigabytes--worth of video. The tape simply acts as a backup to the FS-4 and vice versa. If the tape in the camcorder runs out during filming, the FS-4 continues recording.

Now Largent can move from one lecture to another without having to download the video store first. Even better, the time taken up by post-production work has shrunk considerably.

He hooks up the FS-4 to his iMac and does a file transfer, which takes about five minutes. The FS-4 saves the lecture in 10-minute clips, so Largent uses Apple's Final Cut Express HD to put the clips together and to edit out "problem sessions," where the professor has spent five or 10 minutes in class having the students work on a problem. That takes another five or 10 minutes.

The big time-consumer, said Largent, is compression. "We put the .mov file into an iPod M4V format." That compresses the file from 11 [gigabytes] to 12 gigabytes down to a file that's 700 [megabytes] to 800 megabytes, small enough to play on an iPod. An hour of lecture took about four hours of compression time until Largent's G5's non-Intel CPU was traded out for an Intel chip; that boosted the computer's processing power, enabling it to do the compression time in two hours.

He said he's hoping to reduce that even more by ramping up the use of Xgrid, Apple's distributed computing utility. "If other computers in the department have that turned on, the computer where all the compression is being done actually uses those computers to do the [work]," Largent said. "It can drop an hour of video the compression down to 20 minutes.... Then we could have lectures up on the Web an hour after the lecture runs."