Video Editing : Feel the Power!

Mention running video from within PowerPoint (or any other popular presentation program) and don't be surprised if someone involved in the production process rolls their eyes. It's not that you can't run video from within a presentation program: People do it successfully every day. It's just that experienced professionals know that if problems are going to appear during a presentation, it's likely that those problems will appear when the embedded video portion of the show begins.

Most presentation programs do their primary task efficiently and don't take well to distractions by the necessity of running a whole different type of program, while maintaining their original task in the background. This is particularly true when the subordinate task is something as processor intensive as playing back full-screen, full-motion video.

The smart presentation designer, therefore, will learn how to increase the odds that the embedded video runs as efficiently as possible. This month, we'll take a look at how to make video clips that are presentation friendly.

The whole idea of playing video from within another program is very cool and potentially useful, but it's still a relatively new capability. For a long time, computers didn't have the horsepower to do this kind of multi-tasking and didn't have the spare hard disk space for the video anyhow. Furthermore, there was no way to save your presentation to any kind of portable media for taking it on the road. Advanced compression technologies and widely available CD burners have solved those problems. Today's computers are so sophisticated (and so darn fast), that even mid-priced laptops are perfectly capable of playing back embedded video.

A smart video creator, tasked with creating a program to run within a computer presentation, will shoot and edit video with an eye toward making it presentation friendly. Rule number one for presentation video is to make sure your video is both clean and compact. Full frame, 30 frames per second video looks great, but do you need that kind of playback to get your video's message across?

Perhaps smooth running, dependable quarter-sized video (e.g. 320 x 240) will better serve your communications purposes than jerky, hit or miss full screen playback. Or you could go with full frame, but cut the frame rate in half. Let's say you do need both maximum size and maximum quality. Where do you start?

First, look for ways to shrink the data throughput rate of your video: this means data compression. And compression mean a loss of quality. All video shot by digital camcorders is already compressed to the DV standard, which requires slightly more than 3.6 megabytes per second of transmission throughput to display. That's not obscene, but it's pretty high.

Using judicious compression, you can make your data stream much smaller and still get the same size video image with a lower data rate, taking a substantial load off your computer's processor. So, compression-friendly video is king when it comes to embedded video clips.

Long-time Videomaker readers will recognize that this means your video should avoid complex, changing backgrounds and busy scenes in your shots, where possible. It also means you need to consider not just your shooting, but your editing as well.

And, while transition effects can be nice, they can also cause compression artifacts. I've seen countless presentations bog down when the video producer decided to take two simple adjacent scenes and slap a complex transition between them. The incoming and outgoing clips play fine, but when the compression software hits a dissolve or other complex pixel-based transition, everything bogs down as the data rate skyrockets.

So, when you're doing video for playback within a presentation package, keep things simple. Simply produced video that keeps the show going is always better than fancy-shamancy video that stops your presentation cold.

Another concern is to make sure that the type of video encoding and compression you use is appropriate not just for your presentation, but for the actual computer system you'll be using to play it back.

There is a bewildering array of video compression schemes out there and not all presentation packages are happy to see video compressed with a competing standard.

On the Windows side, AVI files seem to be giving way to Windows Media 9 as the preferred codec for desktop video presentations. (Although Windows Media 10 is out, not all computers have this installed.) On the Mac side, QuickTime (QT) rules. But beware: In both systems, there are older and newer versions of the core video technology. Like QT, there are wide arrays of codec wrappers that come into play. You may be tempted to use a newer, more efficient codec such as DivX to save the maximum space during your video encoding, for example. If you do, however, it's critical that you test your playback system to make sure that your presentation software will parse and playback those clips dependably.