“We have a staff of more than 12 developers, so we have the luxury of being able to say, ‘We want it just so,’ and be able to do that,” said Russell. “Our primary model now is a dual streaming player: two HD windows side by side. Students can customize the layout, which is something we didn’t see in other solutions.”

The layout comprises a “presenter” window and a “presentation” window. The presenter window is a camera shot of the lecturer, while the presentation window shows the feed from the projection system, be it a laptop or some other device. Students can choose among four different setups: In the side-by-side view, one window is larger than the other and the feeds can be flipped between the two; the other setup is a picture-in-picture layout that can also be flipped.

“Key for us was being able to read small text on PowerPoint slides and see full-motion video,” said Russell. “We’re looking at Hulu and Netflix as our benchmarks for quality, and they use really high bit rates.”

HDCE currently provides four different bit rates depending on the user’s screen size, but the school is looking to increase that number to allow students in high-speed connection zones to receive an even crisper signal. “We’re also looking at adaptive bit rates that are based on bandwidth,” said Russell. “Some of our users in other parts of the world have pretty bad connections. We’d like to serve them better by automatically giving them lower bit rates.”

Reliable Capture Agents

Determining the best bit rate is worthless, however, if there’s no video to stream in the first place. HDCE’s other challenge was to create a reliable network of capture agents that could deal with unpredictable video feeds, since half of the videographers at HDCE are freelancers who use their own cameras. “We can’t guarantee a continuous signal for a host of reasons: We don’t know the freelancer’s camera settings; the videographer might turn the camera off during a break to change batteries; or perhaps he hasn’t finished setting up when the recording window opens,” said Russell, noting that recordings automatically start five minutes before lectures begin. “We needed a solution that could adapt to whatever was coming in.”

According to Russell, HDCE experimented with several different capture agents, but reliability was a major concern. “Most products would either crash or stop recording if they didn’t get the preset signal or if the signal dropped in the middle of the recording,” he said.

Ultimately, the school selected Epiphan Pearl, a capture agent produced by Ottawa-based Epiphan Video. HDCE has now installed more than 25 of the units in classrooms throughout the school. “Pearl can auto-detect whatever format’s coming in and lock onto it really well,” said Russell. “It was the only product that could do this gracefully. We can throw it in the classroom, hook it up to the feeds, and it will just work.”

With each of HDCE’s Pearls pumping out twin feeds of high-definition video, though, the school quickly discovered that its Opencast system couldn’t cope. “We were running it on local hardware,” said Russell. “With the volume of content we were pushing through and at the bit rates we were using, we just couldn’t get it to work fast enough.”

HDCE is committed to putting lectures online no later than 24 hours after a class ends, but it was falling short of that goal. As a solution, the school decided to take advantage of Harvard’s existing relationship with Amazon Web Services and moved its Opencast operations into the cloud.

Most of the school’s classes meet in the evenings, so the bulk of the video-preparation work occurs in a two- to three-hour period after 10 PM. “For that period, we can scale up 20 AWS worker machines to transcode the video,” said Russell. “You pay for them only when you’re using them. We don’t have to invest hundreds of thousands of dollars in hardware that might only be used for three hours a day.”

Opencast was not designed to spool up servers on demand, so HDCE had to commit significant resources to customize the product for use in the cloud. Russell believes the investment was worth it, however. “With Amazon, you really get to control the infrastructure—it’s easy to make changes and set rules for preventing cost overruns,” he said.

What HDCE has done with Opencast is probably beyond the means of most universities, but Russell thinks the open source platform could nevertheless benefit a wide range of educational institutions. “Opencast is free and you can get it up and running if you have a couple of knowledgeable staff members, although it helps if you have a developer that can dig into the configuration,” he said. “Ultimately, our plan is to commit all these improvements into the main Opencast product, so these features will be available to other institutions for free.”

Andrew Barbour is a contributing editor with eCampus News.


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