The specifics will vary depending on the tools you're using, but here are some general principles to keep in mind. I've found editing screencasts to be a two-way negotiation between the video and audio tracks. In some cases I'll extend a frame of video to cover a crucial bit of narration. In other cases I'll rerecord a snippet of audio so that it covers some crucial action onscreen.
Of course this approach presumes that you're the sole narrator. That's not always true. Some of the screencasts I've done are conversations recorded over remote screensharing sessions. Those situations present fewer editing options. I usually record the audio and video tracks together, with the screen capture tool's built-in audio recorder, and then edit them as a single track. It's quick and easy to excise unwanted segments.
But if you need complete control, record the video track using a screen recorder, record the audio track separately, and then combine segments as needed. I'm working on a project now that requires this treatment; it's challenging but doable.
Here's something that's unique to screencast editing. Capture tools record every little detail of software interaction. A lot of this micro-behavior—wandering around with the mouse pointer, noodling with menus, moving and resizing windows—is (or should be) of great interest to interaction designers. It's quite instructive to see how you're constantly engaged in learning and self-correction, even while driving an application you think you know well. But unless the point of your story is to reveal these low-level and largely unconscious activities, nobody needs or wants to see them. If you ditch the false starts and random hovering, you'll accelerate and intensify your scene.
With this kind of tightening, you can squeeze an eight-minute screencast down to five minutes. That's the difference between one that people will think is too long, and one they'll judge to be just right. Note that this isn't simply a question of whether viewers can spare the extra three minutes. If the five-minute version preserves all of the essential action, it will be far more impactful than the equivalent eight-minute version.
Most screencasting tools target the Flash runtime. Historically they've supported the
.SWF format; more recently they've also begun to support the newer
.FLV format. The idea is that, by leveraging the near-ubiquity of the Flash runtime, you can avoid the hassle of detecting and adapting to the Windows Media, Quicktime, and Real media players. Although
.SWF isn't ideal for conventional video—quality isn't great and quantity is limited to 16K frames—it can work well for screen-oriented content. That's true because screen video can usefully be delivered at a low frame rate (e.g., 5 frames/sec or even fewer), and because it tends to be highly compressible.
Camtasia's codec delivers great compression of screen video but doesn't do nearly so well with motion video. When you're working with a mixture of these elements, one approach is to use an alternate compressor such as Blue Pacific's Turbine Video Encoder for Flash.
If screencasting elements are few and motion video dominates, though,
.SWF becomes less attractive. You can still target the Flash runtime using
.FLV (a technique I've had little experience with so far) or you can of course target the usual suspects: QuickTime, Windows Media, and Real.
Formats and players aside, a 50-50 mix of screencasting and motion video presents a real challenge. Screencasting elements want to maximize screen real estate, and motion video elements want to minimize it. There's no easy way out of this dilemma, although Ze Frank's marvelous Communication #1 demonstrates one effective solution: two frames side-by-side, one small for motion video and the other large for screen video.
The blogging revolution has shown that, while there are few professional writers, there are lots of people who can productively use the textual web to communicate their personal and professional agendas. Podcasting is likewise reshaping the audio web, and videoblogging will do the same for the video web. When the subjects of our videos are experiences that intersect with cyberspace, or occur primarily within it, we'll use screencasts to describe and explain them.
Jon Udell is an author, information architect, software developer, and new media innovator.
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