Review: Epiphan DVI2USB 3.0 Frame Grabber

Since I started filming conference sessions for Information Today, Inc., Streaming Media’s parent company, in April 2013, one of the ongoing challenges I’ve faced is how to capture presenters’ PowerPoint and Keynote presentations effectively within a very limited budget. The best way to do this is to split the feed from the presenter’s laptop to the projector and send one feed to a device such as the Barco ImagePro, which captures the presentation as a video feed, and provides scaling, scan conversion, and transcoding into a video file that can be fed to a switcher, streamed, and/or recorded for editing in post without additional conversion, transcoding, or scaling. The current model, the ImagePro-II (Figure 1 below), costs $9,700 at B&H, and rents for $350-$450 per unit per day, depending on whether you rent it directly or get it through your onsite A/V provider.

Figure 1. The Barco ImagePro-II ($9,700).

Another way is to assemble a capture system using discrete components--scalers, transcoders, multiple converters, and the like. Typically, this approach can also require either retrieving a presentation from a local network (which can be iffy when you're on the road in hotels and other conference venues), or installing drivers for your gear on presenters’ laptops (a logistical nightmare if you’re working with a dozen or more presenters, some or all of whom may be presenting from their own laptops rather than the one provided for the room by the conference organizers or A/V crew).

Shooting the Screen

Assuming you don’t have an ImagePro-II in your budget, and either your budget or your workflow won’t accommodate assembling the puzzle pieces of other hardware/software solutions, the lowest-common-denominator approach is to shoot the screen. A projection screen is a fixed target, so, assuming you’ve got a second camera handy, you can mount it on a tripod, point it at the screen, white balance, frame and focus the shot as best you can, hit record at the start of each session, and use your other camera to follow and capture the speaker.

Visually, this approach is far from ideal (Figure 2, below). Video of projected images never looks great. Dim and low-contrast PowerPoints look even more dim and low-contrast on video, and blacks/shadows in particular never come out right (although sometimes you might get lucky and find that exceptionally bright and high-contrast presentations can look reasonably good).

Figure 2. "Shooting the screen" is a passable content acquisition strategy when you don't have other options, and having at least one shot with the screen in it is necessary for creating a reference video if you're going to sync slides later, but visually it's far from ideal.

What’s more, trying to get a properly framed shot of a flat screen that’s not directly angled at your camera is virtually impossible, and something you can generally improve only mildly in post. But if you sync your camera sources in post, and either composite them or switch between them at appropriate times, with this approach you’ll always get a complete, if not especially impressive-looking, archive of a session. That said, unless you have no budget, no alternative, and no crew (or everything else fails), this is your last option. Here's a screen-shot presentation/composited video from last November's Streaming Media Producer Live conference.