Yes you can but the Webcast software does not have this capability all by itself. You can do this with another laptop AND the Webcast device.
Instead of connecting a camera to the Webcast device, connect the laptop. You will need get a composite video signal from a laptop, which can be done with a VGA-to-composite video (adapter). Connect the VGA video adapter to the VGA output of the laptop, connect the yellow composite video output of the VGA adapter to the Webcast video input and clone screens. The same process can be done with HDMI but use an HDMI-to-composite adapter.
Another way is to use the presentation software in an iPad instead of PowerPoint and purchase the optional iPad video dongle. Connect the yellow composite video jack of the dongle to the Webcast video input and run your presentation from the iPad.
If you are looking for a way to do the hymns on the screen, here are a few ways this can be done.
1. Use an A/B video switch between the webcast input and camera. Connect the inputs of the switch to the camera source and the other to your PowerPoint presentation. Use the switch to select either the camera feed or laptop video.
2. Use software to create the text and mix on top of video (VLC, VLyriC, etc.).
3. Use a stand-alone device to mix laptop video over a video signal.
4. Use a video mixer with 'chroma-key' capabilities (superimpose text over video). This is how professionals do it (weatherman in front of the radar map)
Check out these posts for additional information.
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IMO, the Videonics MX-1 mixer is the easiest and most affordable way to superimpose PowerPoint slides over video. In addition to the ability to mix text over video, the mixer adds the ability to connect additional cameras or video sources and switch or dissolve video sources.
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